Wavex
System 5.5
User
Manual
PR-002/TH/007 Rev.1
Supplier
Document No.
1300/DD/011
Document Title
WAVEX - PRINCIPLES OF OPERATION
Project
1300
Revision No.
1
2
17.09.01
10.02.04
Prepared By
ØG
ØG
Checked By
RG
RG
Approved By
ØG
ØG
Date
3
4
5
6
Abstract:
The WAVEX Wave Monitoring System developed by MIROS provides a means of
measurement of directional ocean wave spectra and sea surface currents based on analysing
portions of radar images of the sea surface. This document provides a theoretical basis for
WAVEX.
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REVISION RECORD
Rev
Description
This document replaces DD/007/98/ØG/1300/D
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2
Document updated to include new functionality of Wavex version 4. Section
“Radar Requirements” removed. To be included in separate document.
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7
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9
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TABLE OF CONTENTS
1 INTRODUCTION
............................................ 4
2 WAVEX SYSTEM CONCEPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 DATA CAPTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 DATA PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 SPECTRAL ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 WAVE SPECTRUM ESTIMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7 SURFACE CURRENT ESTIMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8 MEASUREMENT PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9 TYPICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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1 INTRODUCTION
The WAVEX system developed by MIROS provides a means of capturing and
subsequently analysing portions of radar images of the sea surface. Data processing of a
time sequence of these images allows qualitative directional wave spectra as well as spectra
scaled in absolute wave height and surface current to be obtained.
Typical Wavex system applications are harbour and costal water monitoring, high speed
craft and conventional vessel wave measurements and research.
This document gives a theoretical description of the method employed for spectral
processing, estimation of the directional wave spectrum as well as important wave
variables. The operation of the radar is not described. However, certain specifications of
the radar connected to the WAVEX system are required. These are reviewed in some
detail.
2 WAVEX SYSTEM CONCEPT
The WAVEX system captures, processes and displays sea surface backscatter data from a
standard non-coherent X-band marine navigation radar. The radar sea-echo amplitude
depends on the "roughness" of the sea surface. The roughness is caused by the wind acting
on the sea surface. Gravity waves and currents form images on the radar display because
they modulate the sea surface radar cross section by angular modulation, hydrodynamic
interaction and shadowing. The system collects a sequence of polar radar sea clutter
images. From each polar image Cartesian sections are selected for further processing.
A two dimensional wave-number spectrum may be derived from a single Cartesian image.
Based on a single image the wave direction can only be determined with an ambiguity of
180 degrees, i.e. one cannot tell wether the waves are approaching or receding. The
direction ambiguity is resolved by full three dimensional spectral processing of a sequence
of consecutive radar images, equally spaced in time.
There is no unique relation between wave height and radar back-scatter modulation
amplitude. The measured wave spectrum therefor needs to be calibrated to provide absolute
spectral densities m2/Hz. This calibration is automatic and part of the Wavex algorithm.
Wavex also provides measurement of the relative surface current speed and direction.
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The Wavex system comprises:
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An X-band radar scanner (a special purpose or an existing unit may be used
as long as the radar requirements are met)
A radar control module (required if a special purpose scanner is used)
A radar interface module (to condition the radar signals)
A WAVEX computer including a special purpose data acquisition board
Display
Software, including signal processing and graphical user interface (GUI)
software.
The system is depicted in the figure below:
Figure 2.1 The Wavex System
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The main steps in the Wavex signal processing are:
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Collection of a sequence of 32 subsequent polar sea clutter images
Removal of nonlinear trend (in range and azimuth) in the polar images
Polar image noise removal
Selection of two sets of orthogonal Cartesian sub sections from each polar image for
further processing
3D spectrum analysis
Applying the dispersion filter
Assessing the image quality based on the relative signal from the dispersion filter
Wave number to frequency/direction conversion
Directional noise removal
Estimation of image to wave spectrum transfer function parameters (estimates based
on measured data)
Applying the system response filter
Calculation of wave spectrum estimate (applying the transfer function)
Calculation of integrated wave variables
Calculation of the surface current vector
3 DATA CAPTURE
3.1
Radar Sea Scatter
The radar signal is back-scattered off the sea surface and the resulting image on the radar
screen is known as sea clutter. A typical sea clutter image is shown on the front page of
this document. Wave-like patterns are easily identified. The wave like patterns are
caused by the modulation of the sea clutter cross section by the gravity waves. The
modulation is due to grazing angle variation, hydrodynamic interaction and shadowing.
At grazing angles above 10 degrees the radar will illuminate the whole wave profile and
the radar image contrast will be low. For grazing angles less than approx. 1 degrees
there will be little radar return from the sea surface and modulation will be dominated by
shadowing. Hence, there is an optimum range between approximately 1 and 10 degrees
where appropriate image contrast is achieved mainly by angular modulation and some
shadowing, see figure 3. 1 below.
Figure 3.1 Radar Sea Scatter Geometry
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Capture Geometry
The data capture geometry, capture parameters and the rationale for determining their
quantities are discussed in the following section.
The system captures a sequence of raw, polar radar images. From each polar image two
orthogonal sets of Cartesian image sections are selected for further processing, see figure
3.2 below. The size of the captured polar radar image is determined by the following
parameters:
Start range:
Range interval:
Start angle:
Azimuth interval angle:
Rs
Ri
1s
1i
Figure 3.2
Data Capture Geometry
3.3
Capture Parameters
Start Range
The Start Range sets the minimum distance to the selected portion of the polar image.
For a given radar scanner height, the Start Range should be selected in conformance
with the sea scatter geometry requirements of figure 3.1.
Range Interval
The range extent of the selected polar image should be selected in conformance with the
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sea scatter geometry and signal processing requirements so that the required area of sea
coverage is captured (see figure 3.2).
Azimuth Start Angle
This value depends upon the position of the North marker on the Radar. This sets the
orientation of the polar image.
Azimuth Interval Angle
This value sets the angular extent of the captured polar radar image. It should be chosen
so that the required area of sea coverage is captured (see figure 3.2)
Sampling Rate
The A/D converter sampling rate chosen depends on the available bandwidth of the radar
in use. For WAVEX processing, we are interested in the average intensity from an
image pixel. Therefore, we sample at the bandwidth of the signal, obtaining one sample
per radar range resolution cell.
The range resolution ) R of the radar is defined as:
(3.1)
where c is the speed of light, J is the radar pulsewidth and BW is the radar video
bandwidth. One should select the Sampling Rate which is larger but nearest to the Video
Bandwidth of the radar. Increasing the sampling rate beyond the Video Bandwidth will
not give increased radial resolution, only increased size of the data file.
Number of images
The number of consecutive polar radar images will normally be set to 32. Note that the
inverse of the sampling time interval, which is equal to:
Number of Images x Time Per Revolution,
sets the frequency resolution of the resulting wave spectra.
With a nominal antenna rotation speed of 24 rpm, 32 images span an interval of
32 x 60/24 = 80 s
corresponding to a frequency resolution of 0.0125 Hz.
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4 DATA PREPARATION
The radar echo falls off with range as
where the power n normally is between 2 and 4. The echo also displays an azimuthal
dependance:
where 2 is the angle between the radar look direction and the up-wind direction. The first
step in preparing the data for spectral processing is to correct for the range law and the
azimuthal dependance. Note that the use of two orthogonal Cartesian image sets (see below)
also reduces the effect of the relative wind direction.
The radar image may contain echoes from boats and interference patterns caused by
unwanted electromagnetic radiation from external sources cluttering the sea echo image.
These echoes are detected and removed by a tresholding technique and the image is then
repaired by interpolation.
Before spectral processing can take place, the corrected polar images have to be
transformed into Cartesian images. This is necessary to allow use of the optimum fast
Fourier transform (FFT) routines available for spectral processing. A Cartesian grid
contained within the polar image is set up with an appropriate spatial resolution, ) x= ) y.
The polar to Cartesian transformation routine calculates the range and azimuth of the
current pixel and calculates the intensity from the polar image by linear interpolation in two
dimensions. For ease of symmetry, the y-coordinate is chosen along the mid angle of the
sampled image, see figure 4. 1 below.
Figure 4.1 Polar to Cartesian transformation
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The Cartesian images are normalized by subtracting and dividing all pixel values by the
arithmetic mean value. For each sequence of polar images, a corresponding set of
normalized Cartesian binary image intensities is prepared in readiness for 3-dimensional
spectral processing, consistent with the radar range and azimuth sampling resolution.
The time required to scan a polar image is in the order of one second (depending on the
antenna rotation speed). During this time the waves moves a significant distance causing a
geometrical distortion of the image. This is corrected for in the data processing.
As can be seen the azimuth (cross range) resolution is a function of range. High image
resolution is required to measure short waves, while large Cartesian images are required to
measure long waves. As large Cartesian images and high resolution cannot be obtained
simultaneously each Cartesian image set consists of two images, one high resolution image
at close range and one large at long range.
5 SPECTRAL ANALYSIS
The wave-number magnitude resolution is determined by the range extent of the Cartesian
image. The FFT routine applied in the Wavex algorithm may use an arbitrary number of
data points (it does not have to be a power of 2). The analysis described below is carried
out for each of the four Cartesian images and the final spectrum is a combination of
spectrum data from all images.
5.1
3D Spectral Analysis
Each time sequence of 32 Cartesian images, each image of size Lx*Ly and separated by
the radar antenna rotation time, is passed through a 3-dimensional FFT (fast Fourier
transform) from x= (x, y, t) space to S = (kx, ky, T )-space, where:
(5.1)
direction
1 = arctan(ky/kx)
wave-number
k = 2B / 8 where 8 is water wavelength
angular frequency T = 2B f where f is frequency
f = 1/T where T is wave period
T
is related to k by the dispersion relation
(5.2)
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where d is the water depth. For deep water, as assumed here, this reduces to
(5.3)
For a fixed frequency T o, this equation describes a circle in the k-plane centred on the
origin.
The assumption of deep water is made for this analysis, although this may not be
accurate for the longest wavelengths.
In the presence of a current U (or ship' s velocity) relative to the observer, there will be a
Doppler shift in the wave frequency so that the observed or encounter frequency F is
related to T by
(5.4)
This results in an asymmetry about the origin in the k -plane which has to be corrected
for.
If we define x = (x, y, t) and S = (k, T ), and by definition
(5.5)
then the weighted 3-dimensional Fourier transform of the time series of Cartesian radar
images I(x, t) is
(5.6)
where W(x) is the weighting function. We assume that the complex 2D wave-number
spectrum has been corrected for Doppler due to the ship’s speed before the final
transformation over the time domain is carried out. The variance or power spectrum is:
(5.7)
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where the normalisation factor is chosen so that
(5.8)
where F 2 is the variance of the radar image. Observe that the 3D power spectrum (Eqs.
5.10 and 5.11) is point symmetric, i.e.
(5.9)
Consequently, two points in S space lying mirror symmetric in the k plane will differ in
phase speed by 180 deg (assuming correction for Doppler shift is done).
A two dimensional wave-number spectrum may be obtained by integrating E(S ) with
respect to frequency, T .
(5.10)
The frequency information in the above equation allows separation of wave energy at
positive frequencies from that at negative frequencies. This method provides an
unambiguous wave-number spectrum, i.e. the directional ambiguity in the 2D radar
image spectrum can be fully resolved on the assumption that the antenna rotation speed
is sufficiently high.
5.2
Dispersion filtering
The Wavex version 4 algorithm includes full dispersion filtering. The function of eq
5.10 is implemented by means of the dispersion filter which can be defined for either
positive or negative frequencies. Temporal under-sampling due to slow radar scanner
antenna rotation is for all practical purposes no longer a problem. The dispersion filter
automatically extracts the wave energy from the correct location in the wave numberfrequency space fully eliminating all aliasing problems. The wave number spectrum
ambiguity is fully resolved as long as the spectrum is not aliased more than once.
Integration over the positive frequencies gives the spectrum in the “direction to” (i.e.
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wave propagation direction) convention:
(5.11)
5.3
System Response Filter
The Wavex measurement principle involves transformations between different domains
(time, space, wave-number and frequency). Some of these transformations undesirably
affect the estimate of the scaled directional wave spectrum. Wavex version 4 algorithm
includes a system response filter that compensates for most of this non-ideal behaviour.
The filter also takes into account some of the imperfections of the radar scanner used to
collect the polar sea echo images.
6 WAVE SPECTRUM ESTIMATION
6.1
Image frequency spectrum
The 2-dimensional power image spectrum E(f, 1 ) is obtained from the wave number
spectrum eq.(5.15) by the transformation:
(6.1)
Where J(f, 1 ) is the Jacobian. From eq.(6.1) and the dispersion relation, eq. (5.7) we
have:
(6.2)
so
(6.3)
where the substitutions
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and
should be made in E(kx, ky).
If we know the ships velocity U, then we can calculate T = 2B f (see eq.(5.4)), otherwise
we have to assume U= 0 as in this case (i.e. F = T ).
The point spectrum is obtained by integrating eq. (6.3) over all directions:
(6.4)
We may assume that the directional spectrum (eq.6.3) can be written as a product:
(6.5)
where D(f, 1 ) is the directional spectrum normalized to an energy of 1.
6.2
Non-directional Noise Removal
On the assumption that wave energy on a given frequency does not arrive from all
directions simultaneously, a non-directional background noise spectrum can be estimated
and subtracted from the image spectrum.
6.3
Wave to Image Spectrum Transfer Function
It may be assumed that the image energy spectrum is related to the wave spectrum by a
linear wave to image transfer function, T( " , $ , f), so any spectral component of the
observed image intensity spectrum E(f) is proportional to the corresponding component
of the wave spectrum W(f):
(6.6)
"
and $ are unknown parameters of the transfer function. These parameters depend on
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data capture geometry, wind speed and direction and sea state. The system therefore
needs to be calibrated in order to provide a wave spectrum scaled in absolute m2/Hz.
The parameters of the transfer function may be determined by comparison with other
sensors like a wave-buoy, wave radar or altimeter. In many applications this is not
feasible. In the Wavex system new estimates of the transfer function parameters are
derived from measured data and wave theory for each sequence of images. Having
determined " and $ , the Wave spectrum estimate is calculated as:
(6.7)
Based on the wave spectrum all integrated wave variables may be calculated.
6.4 Data Quality Control
Echoes from land, other objects and precipitation in the Cartesian radar images used by
Wavex may cause problems for the Wavex wave spectrum estimation algorithm. This
problem is handled by a robust image quality control routine based on the output from
the dispersion filter (see section 5.2).
The energy in the wave number-frequency space before (P0) and after dispersion filtering
(P1) is calculated. From the relative amount of energy passed through the filter
(6.8)
the so called relative signal R is calculated. The value of the relative signal R is a robust
quality indicator for the sea echo images. For a good quality image we have R$0.6.
The relative signal is also well correlated with the significant wave-height and may be
used to derive a second independent estimator for the wave-height.
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7 SURFACE CURRENT ESTIMATION
The three dimensional wave spectrum
(7.1)
also contains information about the surface currents. According to the dispersion relation
the wave energy for any given wave frequency will be concentrated on a circle in the wavenumber plane:
(7.2)
In the presence of a current U (assuming that the ships velocity has been corrected for or
that radar is mounted on a stationary platform) relative to the observer, there will be a
Doppler shift in the wave frequency so that the observed or encounter frequency F is related
to the intrinsic wave frequency T by (see also section 5.1)
(7.3)
From the resulting asymmetry of the wave spectrum about the origin in the wavenumberplane the surface current vector may be estimated.
The frequency power spectrum for every single wave number is estimated using a-priori
information about the integrated wave number spectrum shape and resolution. Then, by
adding the various Doppler shifts and convolving with the temporal spectral response
function, the current vector U may be estimated using a least squares fit:
(7.4)
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8 MEASUREMENT PERFORMANCE
Measurement range and resolution
Wave-number
The radar samples the ocean surface. The wave-number range is given by the size of the
Cartesian radar image resolution cell (grid size), ) x:
(8.1)
where kN is the Nyquist wave-number. When two Cartesian images are used the maximum
k is determined by the resolution of the small image (see figure 3. 2).
The minimum value of k is given by:
(8.2)
where L x is the image dimension. When two Cartesian images are used the minimum k is
determined by the dimension of the large image (see figure 3.2).
The wave number resolution is given by:
(8.3)
where L x is the size of the Cartesian radar image. When two Cartesian images are used the
minimum ) k is determined by the dimension of the large image (see figure 3. 2).
Frequency spectrum
The frequency spectrum is derived by transformation of the wave-number spectrum.
Assuming that the deep water dispersion relation (eq. (5.3)) applies, the maximum wave
frequency is given by the Nyquist wave-number:
(8.4)
When two Cartesian images are used the maximum wave frequency is determined by the
dimension of the small (close) image (see figure 3.2).
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The minimum frequency is related to the wave-number resolution. From the dispersion
relation, eq.(5.6) and eq.(8.3) we have:
(8.5)
When two Cartesian images are used the minimum wave frequency is determined by the
dimension of the large image (see figure 3. 2).
Due to the nonlinear relation between wave-number and frequency, the frequency resolution
will basically be a function of frequency. From the deep water dispersion relation we have
(by derivation):
(8.6)
or, by substituting for ) k from eq. (8.3):
(8.7)
Equation (8.7) is valid for the frequency range given by equation (8.4) and (8.5). Lx is the
dimension of either the large image or the small image depending on the frequency.
Wave period
The wave period is the inverse of the wave frequency. From the dispersion relation
(eqs.5.7, 8.3 and 8.3) the maximum wave period may be expressed as:
(8.8)
When two Cartesian images are used the maximum T is determined by the dimension of the
large image (see figure 3.2).
The minimum wave period is related to the Nyquist wave-number. From eq.(5.7) and
eq.(8.1) we have:
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(8.9)
When two Cartesian images are used the minimum T is determined by the resolution of the
small image (see figure 3.2).
The wave period resolution is a function of wave period (see also frequency spectrum). By
derivation of the dispersion relation eq. (5.7), using eq.(8.3) we have:
(8.10)
Equation (8.10) is valid for the range of periods given by equations (8.8) and (8.9). Lx is
the dimension of either the large image or the small image depending on the period.
Wave direction
The 180° direction ambiguity is resolved by full 3D processing. The wave direction will
then be given on the interval 0 - 360°.
The wave direction resolution is defined as:
(8.11)
From the dispersion relation eq.(5.6) and eq.(8.3) we then have
(8.12)
Equation (8.12) is valid for the frequency range given by equations (8.4) and (8.5). Lx is
the dimension of either the large image or the small image depending on the frequency.
Directional ambiguity
The directional ambiguity can be resolved for frequencies below twice the Nyquist
frequency using full 3D processing:
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(8.13)
where F is the encounter wave frequency and Ts is the antenna rotation time. Solving
eq.(8.13) with respect to T s and using (5.8) we have:
(8.14)
where U is the ship speed and 1 is the wave direction relative to the ships heading.
Normally the ships speed will be known (or zero). Assuming that the ships speed is
corrected for in the signal processing, the requirement for the antenna rotation time then
simply becomes:
(8.15)
where f is the wave frequency in Hz and T is the wave period.
Statistical measurement error
The accuracy of the wave-height measurements is determined by
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Statistical errors
Error in estimating transfer function parameters
The transfer function errors are difficult to assess. This can only be done by analysing large
quantities of experimental data.
The statistical errors may be estimated from theory. Assuming that the sea surface elevation
is a Gaussian process it can be shown that, for a given image size, the error will be a linear
function of wave-length and therefore a quadratic function of wave period:
(8.16)
is here the standard deviation and Tp is the peak period of the wave spectrum. It is
standard practice to give the confidence interval as ±2standard deviations, hence the
,
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measurement error may be given as
(8.17)
Equations (8.16) and (8.17) are valid for the period range given by equations (8.8) and
(8.9). Lx is the dimension of either the large image or the small image depending on the
period.
When Wavex is used for wave measurements from a moving vessel it must be borne in
mind that the waves will change from one position on the surface of the earth to another
and will differ also due to different physical environments from one location to another.
There are at least two important influencing factors in this respect, sheltering coastlines or
islands and water depth.
9 TYPICAL DATA
A printout of typical a typical Wavex wave spectrum is shown below. The data have been
processed with full 3D processing based on 32 images. A typical polar radar image is
shown on the front page.
Figure 10.1 Typical Wavex wave spectrum
END
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Description of wave parameters
from directional wave spectrum
Doc. No. DF-WM-UK/002/DD
Project
Classification
Wave
Open
Abstract:
This document contains a description of wave parameters calculated from a directional wave
spectrum.
Revision No.
Date
Prepared by
Checked by
Approved by
1
17 pages
2012-11-05
IK
SRS
ØG
Description:
First issue.
Blank page.
Description of wave parameters
Contents
1
2
Introduction
5
1.1
Basis for scalar parameter computations . . . . . . . . . . . . . . . . . . . . . . . . .
5
1.2
Spectral moments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
Scalar parameters
7
2.1
Primary wave spectral density, SDp1 . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
2.2
Significant wave height, Hm0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
2.3
Maximum wave height, Hmax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
2.4
Wave height of maximum wave period, HT max . . . . . . . . . . . . . . . . . . . . .
7
2.5
Primary wave peak period, Tp1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
2.6
Secondary wave peak period, Tp2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.7
Calculated wave peak period, Tpc . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.8
Significant wave period, Ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.9
Energy wave period, Tm0−1 (Ts ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.10 Integral wave period, Tm0−2 (Ts ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.11 Mean zero up-crossing period, Tm02 (Tz ) . . . . . . . . . . . . . . . . . . . . . . . . .
8
2.12 Mean period, Tm01 (Tav ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
2.13 Maximum wave period, Tmax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
2.14 Wave period of maximum wave height, THmax . . . . . . . . . . . . . . . . . . . . . .
9
2.15 Average wave crest period, Tm24 (Tc )
. . . . . . . . . . . . . . . . . . . . . . . . . .
9
2.16 Primary wave peak direction, Dp1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
2.17 Primary wave mean direction, Dm1 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
2.18 Primary wave directional spread, SP R1 . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.19 Total energy peak direction, Dpt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.20 Total energy mean direction, Dmt . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.21 Total energy directional spread, SP Rt . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.22 Spectral bandwidth, ν
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.24 Wave steepness, Sm02 (Ss ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.25 Primary wave phase velocity, Vp1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.23 Skewness, Sk
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3
4
5
2.26 Primary wave length, Lp1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.27 Primary wave group velocity, Cg1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.28 Secondary wave peak direction, Dp2 . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.29 Secondary wave mean direction, Dm2 . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.30 Secondary wave directional spread, SP R2 . . . . . . . . . . . . . . . . . . . . . . . .
12
Appendix A
13
3.1
13
Interpolation algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B
15
4.1
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
4.2
Circular symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
4.3
Mean direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
4.4
Directional spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
References
Miros AS
17
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1
1.1
Introduction
Basis for scalar parameter computations
Below is a graphical presentation of the directional wave spectrum and some of the notation used in
deduction of the scalar wave parameters.
Figure 1.1:
Graphical presentation of a directional wave spectrum.
Sd [m2 /Hz] is the spectral estimate of the wave energy directional distribution, from which all the
scalar wave parameters are derived.
Sn [m2 /Hz] is the point spectrum computed from the directional distribution estimate (Sd ).
Sn (f ) =
J
X
Sd (i · ∆f, j) , for j =1:J , f =i·∆f and i=k :I
(1.1)
j=1
where f is frequencies, ∆f is frequency resolution, I is number of frequencies and j is the direction
number.
Ft [m2 ] is the total energy directional distribution computed from Sd as
Ft (j) =
I
X
Sd (i · ∆f, j)∆f , for i=k :I
(1.2)
i=k
where ∆f is frequency resolution, i is frequency number, k is the lowest frequency index and j is
direction number.
m0 [m2 ] is the zero order moment.
m0 =
I
X
Sn (i · ∆f )∆f , for i=k :I
(1.3)
i=k
or
m0 =
J
X
Ft (j) , for j =1:J
(1.4)
j=1
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Description of wave parameters
where ∆f is the frequency resolution, i is the frequency number, k is the lowest frequency index and
J is number of directions (see also section 1.2).
1.2
Spectral moments
The n’th order spectral moments computed from the point spectrum estimate (Sn ) are used in
computing central scalar parameters.
The n’th order moment is defined as
mn ∼
=
Z
f n · Sn (f )df , for n ∈ Z
(1.5)
and
f = i · ∆f , for i=1:I
(1.6)
where ∆f is frequency resolution and I is number of frequencies.
For a discrete function the n’th order moment is
mn =
I
X
(i · ∆f )n Sd (i) · ∆f
(1.7)
i=k
where Sd (i) [m2 /Hz] is energy for the component number i, ∆f is frequency resolution and k is the
lowest frequency index.
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2
Scalar parameters
This section contains a description of scalar parameters deduced from the non-directional wave
spectrum.
2.1
Primary wave spectral density, SDp1
The primary wave spectral density SDp1 [m2 /Hz] is defined as
SDp1 = Sn (fp1 )
(2.1)
where Sn is the point spectrum and fp1 is the frequency for the primary peak in Sn .
2.2
Significant wave height, Hm0
Significant wave height, Hm0 [m], is derived from the non-directional wave spectrum as
√
Hm0 = 4 m0
(2.2)
where m0 is the zero order moment of the point spectrum (Sn ) (see equations 1.3 and 1.4).
2.3
Maximum wave height, Hmax
An estimate of the average maximum wave height, Hmax [m], derived from the non-directional wave
spectrum is [1]
Hmax

r
T
0.57722

= 1.84 · Hm0 ·  0.125 · ln(
)+ q
Tm02
T
32 · ln( Tm02
)
(2.3)
where Tm02 is an estimate of the mean zero up-crossing period Tz (see section 2.11). T is the
observation period (30 min) and Hm0 is the calculated significant wave height from the non-directional
wave spectrum (see section 2.2).
2.4
Wave height of maximum wave period, HT max
An estimate of HT max [m] is
HT max = Hm0 · thf
(2.4)
where thf = 0.7 is an empirical constant found by numerical simulation of a Pierson-Moskowitz
spectrum [4].
2.5
Primary wave peak period, Tp1
The non-directional primary wave peak period (modal period) Tp1 [s] is
Tp1 =
1
fp1
(2.5)
where fp1 is the frequency for the primary peak in point spectrum (Sn ). fp1 is found by using
parabolic interpolation (see Appendix A).
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2.6
Secondary wave peak period, Tp2
The non-directional secondary wave peak period Tp2 [s] is
Tp2 =
1
fp2
(2.6)
where fp2 is the frequency for the secondary peak in the point spectrum (Sn ). fp2 is found by using
parabolic interpolation (see Appendix A).
2.7
Calculated wave peak period, Tpc
Calculated estimate of the non-directional wave peak period Tpc [s] is [2]
Tpc =
m−2 · m1
m20
(2.7)
where m0 is the zero order moment, m1 is the 1st order moment and m−2 is the negative 2nd order
moment of the point spectrum (Sn ).
2.8
Significant wave period, Ts
An estimate of the non-directional significant wave period Ts [s] is [1]
Ts = 0.9 · Tp1
(2.8)
where Tp1 is the wave peak period (see section 2.5).
2.9
Energy wave period, Tm0−1 (Ts )
The energy wave period Tm0−1 [s] (or Ts [s]) is [2]
Ts ≈ Tm0−1 =
m−1
m0
(2.9)
where m0 is the zero order moment and m−1 is the negative 1st order moment of the point spectrum
(Sn ). Tm0−1 is used for an estimate of the significant wave period Ts [3].
2.10
Integral wave period, Tm0−2 (Ts )
The integral wave period Tm0−2 [s] (or Ts [s]) is [2]
r
Ts ≈ Tm0−2 =
m−2
m0
(2.10)
where m0 is the zero order moment and m−2 is the negative 2nd order moment of the point spectrum
(Sn ). Tm0−2 is used for an estimate of the significant wave period Ts [3].
2.11
Mean zero up-crossing period, Tm02 (Tz )
An estimate of the mean zero up-crossing period Tm02 [s] (or Tz [s]) is [2]
r
Tz ≈ Tm02 =
m0
m2
(2.11)
where m0 is the zero order moment and m2 is the 2nd order moment of the point spectrum (Sn ).
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2.12
Mean period, Tm01 (Tav )
An estimate of the mean period Tm01 (or Tav [s]) is
Tav ≈ Tm01 =
m0
m1
(2.12)
where m0 is the zero order moment and m1 is the 1st order moment of the point spectrum (Sn ).
2.13
Maximum wave period, Tmax
An estimate of the maximum wave period Tmax [s] is
Tmax = Tz · tmf
(2.13)
where tmf = 1.83 is an empirical constant found by numerical simulation of a Pierson-Moskowitz
spectrum [4].
2.14
Wave period of maximum wave height, THmax
An estimate of the wave period of maximum wave height THmax [s] is
THmax = Tz · thmf
(2.14)
where thmf = 1.23 is an empirical constant found by numerical simulation of a Pierson-Moskowitz
spectrum [4].
2.15
Average wave crest period, Tm24 (Tc )
An estimate of the average period between wave crests Tm24 [s] (or Tc [s]) is [2]
r
Tc ≈ Tm24 =
m2
m4
(2.15)
where m2 is the 2nd order moment and m4 is the 4th order moment of the point spectrum (Sn ).
2.16
Primary wave peak direction, Dp1
Dp1 [deg] is the direction for the primary peak of Sd (fp1 , Θ). Dp1 is found by using parabolic
interpolation (see Appendix A).
2.17
Primary wave mean direction, Dm1
The mean direction of the primary peak Dm1 [deg] is defined as
" PJ
Dm1 = arctan
j=1 Sd (fp1 , j)sinΘj
PJ
j=1 Sd (fp1 , j)cosΘj
#
, for j =1:J
(2.16)
where fp1 is the frequency for the primary peak in Sn and j is direction number. See Appendix B for
further details.
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2.18
Primary wave directional spread, SP R1
The directional spread for the primary peak SP R1 [deg] around the mean is defined as
SP R1 =
s P
J
2 j=1 [1 − cos(Θj − Dm1 )]Sd (fp1 , j)
Sn (fp1 )
, for j =1:J
(2.17)
where fp1 is the frequency for the primary peak in Sn and j is the direction number. See Appendix B
for further information.
2.19
Total energy peak direction, Dpt
Dpt [deg] is the direction for the peak in the total energy directional distribution (Ft ). Dpt is found by
using parabolic interpolation (see Appendix A).
2.20
Total energy mean direction, Dmt
The total energy mean direction Dmt [deg] is defined as
" PJ
Dmt = arctan
j=1 Ft (j)sinΘj
PJ
j=1 Ft (j)cosΘj
#
, for j =1:J
(2.18)
where Ft is the total energy directional distribution and j is the direction number. See Appendix B for
further details.
2.21
Total energy directional spread, SP Rt
The total energy directional spread SP Rt [deg] around the mean is defined as
SP Rt =
s P
J
2 j=1 [1 − cos(Θj − Dmt )]Ft (j)
m0
, for j =1:J
(2.19)
where j is the direction number. For further details see Appendix B.
2.22
Spectral bandwidth, ν
The spectral bandwidth ν is defined as [2]
r
ν=
m0 · m2
−1
m21
(2.20)
where m0 is the zero order moment, m1 is the 1st order moment and m2 is the 2nd order moment of
the point spectrum (Sn ).
2.23
Skewness, Sk
The skewness Sk (of the wave spectrum) is defined as [2]
Sk =
m20 ·m3
m31
− 3ν 2 − 1
(2.21)
ν3
where ν is the bandwidth parameter defined in section 2.22 and m0 , m1 and m3 are the zero, 1st and
3rd order moments respectively.
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2.24
Wave steepness, Sm02 (Ss )
An estimate of the wave steepness Sm02 (or Ss ) based on Hm0 and Tm02 is [2]
Ss ≈ Sm02 =
2π · Hm0
Hm0
'
2
2
g · Tm02
1.56 · Tm02
(2.22)
where Hm0 and Tmo2 are derived from the non-directional wave spectrum (see sections 2.2 and 2.11).
2.25
Primary wave phase velocity, Vp1
The primary wave phase velocity Vp1 [m/s] is defined as the phase velocity of a wave with period Tp1 .
Assuming deep water then
Vp1 =
g
· Tp1 ' 1.56 · Tp1
2π
(2.23)
where g is the Earth’s gravity constant and Tp1 is the primary wave peak period (see section 2.5).
2.26
Primary wave length, Lp1
The primary wave length Lp1 [m] is defined as the length of a wave with period Tp1 . Assuming deep
water then
g
2
2
· Tp1
' 1.56 · Tp1
(2.24)
Lp1 =
2π
where g is the Earth’s gravity constant and Tp1 is the primary wave peak period (see section 2.5).
2.27
Primary wave group velocity, Cg1
The primary wave group velocity Cg1 [m/s] is defined as the group velocity of a wave with period Tp1 .
Cg1 =
∂ω
g
Vp1
=
=
∂κ
2ω
2
(2.25)
where g is the Earth’s gravity constant, ω is wave number and Vp1 is the primary wave phase velocity
(see section 2.25).
2.28
Secondary wave peak direction, Dp2
Dp2 [deg] is the direction for the secondary peak in Sd (fp2 , Θ). Dp2 is found by using parabolic
interpolation (see Appendix A).
2.29
Secondary wave mean direction, Dm2
The mean direction of the secondary peak Dm2 [deg] is defined as
" PJ
Dm2 = arctan
j=1 Sd (fp2 , j)sinΘj
PJ
j=1 Sd (fp2 , j)cosΘj
#
, for j =1:J
(2.26)
where fp2 is the frequency for the secondary peak in Sn and j is direction number. See Appendix B
for further details.
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2.30
Secondary wave directional spread, SP R2
The directional spread for the secondary peak SP R2 [deg] around the mean is defined as:
SP R2 =
s P
J
2 j=1 [1 − cos(Θj − Dm2 )]Sd (fp2 , j)
Sn (fp2 )
, for j =1:J
(2.27)
where fp2 is the frequency for the secondary peak in Sn and j is the direction number. See
Appendix B for further information.
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Description of wave parameters
3
3.1
Appendix A
Interpolation algorithm
Figure 3.1:
Graphical presentation of a parabolic equation.
A convenient expression for finding the curve through tree points is a parabolic equation (see
figure 3.1).
y = a − b(x − c)2
(3.1)
y1 = a − b(x1 − c)2
(3.2)
y2 = a − b(x2 − c)2
(3.3)
y3 = a − b(x3 − c)2
(3.4)
a = y1 + b(x1 − c)2
(3.5)
For three different points we then have
Solving the unknowns yields
b=
y2 − y1
(x1 − c)2 − (x2 − c)2
(3.6)
y3 − y1
(x1 − c)2 − (x3 − c)2
=
y2 − y1
(x1 − c)2 − (x2 − c)2
(3.7)
∆ = x2 − x1
(3.8)
x1 − c = ∆ + δ
(3.9)
x2 − c = δ
(3.10)
x3 − c = ∆ − δ
(3.11)
We have that
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δ=
∆
y1 − y3
·
2 y3 − 2y2 + y1
(3.12)
where the maximum point is
c = x2 + δ
(3.13)
using (3.1), (3.5), (3.6) and (3.13) gives the maximum value
y(c) = a
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4
Appendix B
4.1
General
The directional wave energy spectrum Sd (f, Θ) can be written as
Sd (f, Θ) = Sn (f ) · D(f, Θ) , for Θ ∈ h0,360]
(4.1)
where Sn (f ) is the point spectrum and D(f, Θ) is the normalized directional distribution with the
property
Z
π
D(f, Θ)dΘ = 1 , for all f
(4.2)
−π
4.2
Circular symmetry
To implement the algorithms for directional mean and spread it is important to arrange the directional
distribution in a way that avoids possible border value problems in the circular symmetry.
This is achieved by shifting the array elements left or right so that the directional distribution becomes
symmetric. The original directional relation to the real world must of course be kept track of. With an
even number of antenna point directions the following rules are applied:
• Find the direction for maximum energy (Θjmax ).
• If E(Θjmax − 1) > E(Θjmax + 1) then place E(Θjmax ) in the upper center position of the array.
• If E(Θjmax − 1) < E(Θjmax + 1) then place E(Θjmax ) in lower center position of the array.
An example with 6 antenna point directions is shown below.
Figure 4.1:
4.3
Original array elements re-arranged.
Mean direction
The mean direction is defined as the direction of the vector
Z
π
−π
D(f, Θ)ejΘ dΘ =
Z
π
Z
−π
D(f, Θ)sinΘdΘ
(4.3)
−π
"R π
Θ̄(f ) = arctan
Miros AS
π
D(f, Θ)cosΘdΘ + j
R−π
π
−π
D(f, Θ)sinΘdΘ
D(f, Θ)cosΘdΘ
Page 15 of 17
#
(4.4)
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Description of wave parameters
Instead of the normalized directional distribution, Sd (f, Θ) can be used as follows:
π
Z
Z
π
Sd (f, Θ)sinΘdΘ = Sn (f )
−π
Z
D(f, Θ)sinΘdΘ
(4.5)
D(f, Θ)cosΘdΘ
(4.6)
−π
π
Z
π
Sd (f, Θ)cosΘdΘ = Sn (f )
−π
−π
so that
"R π
Θ̄(f ) = arctan
R−π
π
−π
Sd (f, Θ)sinΘdΘ
#
(4.7)
Sd (f, Θ)cosΘdΘ
For discrete distribution we then have
" PJ
j=1 Sd (fx , j)sinΘj
PJ
j=1 Sd (fx , j)cosΘj
Dmx = arctan
#
, for j =1:J
(4.8)
where fx is the frequency for the desired directional mean and j is direction number.
4.4
Directional spread
Instead of normal variance the circular variance with the definition below is used.
Z
2
π
[1 − cos(Θ − Θ̄)]D(f, Θ)dΘ
σ (f ) = 2
(4.9)
−π
The circular variance is close to normal variance for “narrow” distributions and has the advantage that
problems with the periodicity of the directional distribution are avoided.
If Sd (f, 0) is used instead of the normalized directional distribution D(0) then
Z
π
Z
π
[1 − cos(Θ − Θ̄)]Sd (f, Θ)dΘ = 2
2
−π
[1 − cos(Θ − Θ̄)]Sn (f )D(f, Θ)dΘ
(4.10)
−π
Z
π
Sn (f ) · 2
[1 − cos(Θ − Θ̄)]D(f, Θ)dΘ = Sn (f ) · σ 2 (f )
(4.11)
−π
σ 2 (f ) =
2
Rπ
−π
[1 − cos(Θ − Θ̄)]Sd (f, Θ)dΘ
(4.12)
Sn (f )
For discrete distribution
SP Rx =
s P
J
2 j=1 [1 − cos(Θj − Dmx )]Sd (fx , Θj )
Sn (fx )
, for j =1:J
(4.13)
where fx is the frequency for the desired directional spread and j is the direction number.
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Description of wave parameters
5
References
[1] S. Haver, Statoil.
[2] M.J. Tucker and E.G. Pitt, Waves in Ocean Engineering, 2001.
[3] A. K. Magnusson, DNMI.
[4] Ø. Grønlie, Miros AS.
This document replaces 1100/DD/001 rev. 3.
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Wavex 5.5
Operation and Maintenance Manual
Doc. No
PR-002/DD/015
Project
Wavex
Classification
Open
Abstract:
This is the operation and maintenance manual for Wavex version 5.5.
The Wavex system extracts wave and surface current information from the sea clutter back-scatter
of an X-band marine radar.
Revision No.
Date
Prepared by
Checked by
Approved by
1
40 pages
2016-04-28
IK
EW
IK
Description:
Original issue.
Blank page.
Wavex 5.5
TABLE OF CONTENTS
1
Safety and Warnings
6
1.1
Safety Instructions ............................................................................................................... 6
1.2
Operational Warnings ......................................................................................................... 6
2
2.1
2.2
2.3
3
Introduction
7
Abbreviations ...................................................................................................................... 7
2.1.1
General Abbreviations ............................................................................................ 7
2.1.2
Specific Abbreviations ............................................................................................ 8
About This Manual .............................................................................................................. 9
2.2.1
Defining the User .................................................................................................... 9
2.2.2
Qualifications .......................................................................................................... 9
2.2.3
Finding the Way Through the Manual .................................................................... 9
How to Contact Miros ........................................................................................................ 10
System Description
10
3.1
System Introduction .......................................................................................................... 10
3.2
Hardware Configuration .................................................................................................... 10
3.3
4
3.2.1
X-Band Radar ....................................................................................................... 11
3.2.2
EM-129 Integrated Video Digitizer ........................................................................ 11
3.2.3
System Computer ................................................................................................. 11
3.2.4
Keyboard and Pointing Device ............................................................................. 11
3.2.5
Display .................................................................................................................. 12
Software Configuration...................................................................................................... 12
3.3.1
Wavex Software .................................................................................................... 12
3.3.2
Data Presentation Module .................................................................................... 12
3.3.3
System Manager ................................................................................................... 12
Principles of Operation
13
4.1
General Description .......................................................................................................... 13
4.2
Theory of Operation .......................................................................................................... 13
5
4.2.1
Wave Data Calculation ......................................................................................... 14
4.2.2
Surface Current Data Calculation ......................................................................... 14
User Interface
15
5.1
General.............................................................................................................................. 15
5.2
Commanding Tools ........................................................................................................... 15
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Wavex 5.5
5.3
6
5.2.1
Pointing Device ..................................................................................................... 15
5.2.2
Keyboard............................................................................................................... 15
Data Presentation ............................................................................................................. 15
MirPresF Data Presentation Module
16
6.1
General Description .......................................................................................................... 16
6.2
Layouts .............................................................................................................................. 16
6.3
Data Modules .................................................................................................................... 16
6.3.1
Single Parameter .................................................................................................. 17
6.3.2
History ................................................................................................................... 18
6.3.3
Vector .................................................................................................................... 19
6.3.4
Wave Spectrum .................................................................................................... 19
6.3.5
Time Series ........................................................................................................... 21
6.3.6
Image .................................................................................................................... 21
6.4
MirPresF Menus ................................................................................................................ 22
6.5
MirPresF Layouts .............................................................................................................. 23
6.6
7
6.5.1
Default Layout “Wave 1” ....................................................................................... 24
6.5.2
Default Layout “Wave 2” ....................................................................................... 24
6.5.3
Default Layout “Radar Im” .................................................................................... 25
6.5.4
Default Layout “Time Ser”..................................................................................... 25
6.5.5
Default Layout “Spectrum” .................................................................................... 26
6.5.6
Default Layout “BIG” ............................................................................................. 26
6.5.7
Default Layout “Control” ........................................................................................ 27
Information and Status ...................................................................................................... 27
6.6.1
Date and Time ...................................................................................................... 27
6.6.2
Radar Mode .......................................................................................................... 27
6.6.3
Radar Antenna Height Above Sea Level .............................................................. 28
6.6.4
Data Quality .......................................................................................................... 28
6.6.5
System Status ....................................................................................................... 28
Operating Wavex
28
7.1
Wavex Power-Up .............................................................................................................. 28
7.2
Wavex Restart ................................................................................................................... 29
7.2.1
System Software Restart ...................................................................................... 29
7.2.2
Computer Software Restart .................................................................................. 29
7.2.3
Computer Hardware Reset ................................................................................... 29
7.2.4
Computer Power Off/On ....................................................................................... 29
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7.3
Operating Procedures ....................................................................................................... 29
7.3.1
Check Wavex Radar Mode ................................................................................... 29
7.3.2
Check Wavex Radar Antenna Height Above Sea Level ...................................... 30
7.3.3
Set Operation Height ............................................................................................ 30
7.3.4
Set Water Depth ................................................................................................... 30
7.3.5
Check Wavex Data Quality. .................................................................................. 30
7.3.6
Take Screen Dumps ............................................................................................. 31
7.3.7
Save Wavex Source Data Files ............................................................................ 31
7.3.8
Export Wavex Data Buffers .................................................................................. 31
7.3.9
Save Wavex Status Information ........................................................................... 31
7.3.10 Check Wavex System Status ............................................................................... 31
7.3.11 Check Wavex Radar Status.................................................................................. 31
7.3.12 Check Available Wavex Computer Disc Space .................................................... 32
8
Maintenance
33
8.1
Wavex System .................................................................................................................. 33
8.2
Radar................................................................................................................................. 33
9
Technical Data
34
9.1
Radar................................................................................................................................. 34
9.2
Wavex Performance Data ................................................................................................. 34
9.3
Software ............................................................................................................................ 34
10 Troubleshooting
35
10.1 General.............................................................................................................................. 35
10.2 Indication of Trouble .......................................................................................................... 35
10.3 Troubleshooting Action List ............................................................................................... 35
10.4 Support .............................................................................................................................. 37
11 Frequently Asked Questions
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1
Safety and Warnings
1.1
Safety Instructions
RADIO FREQUENCY RADIATION HAZARD
The Wavex radar antenna emits electromagnetic radio frequency (RF) energy
which can be harmful, particularly to human eyes. Never look directly into the
radar antenna aperture from a close distance while the radar is in operation,
or expose yourself to the transmitting radar antenna at a close distance.
Consult the radar Operator’s Manual for more information.
If the radar antenna unit is installed at a close distance to an area where
people reside, this may require halt of transmission within a certain sector of
antenna revolution. This is possible on nearly all X-band marine radars. Ask
your radar representative or dealer to provide this feature.
ELECTRICAL SHOCK HAZARD
Do not open the radar components or any of the Wavex hardware
components. Only qualified personnel should work inside this equipment.
WARNING
Do not disassemble or modify the equipment. Fire, electrical shock or serious
injury can result.
1.2
Operational Warnings
WRONG RADAR MODE
Always ensure that correct radar mode (short pulse 50 - 80 ns) is selected on
the radar when using the Wavex system. Incorrect radar mode will result in a
malfunctioning Wavex system.
ALIEN SOFTWARE
Do not install other, not Wavex related software on the Wavex computer.
Doing so may result in a malfunctioning Wavex system.
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2
Introduction
The Wavex (WAVe EXtractor) is a system for extracting wave and surface current information
from the sea clutter back-scatter of an X-band marine radar.
This is the Wavex version 5.5 operation and maintenance manual and contains guidelines for
how to operate, maintain and do troubleshooting on the Wavex 5.5 system. This manual also
gives a brief system description, explains theory of operation and contains maintenance,
troubleshooting and FAQ sections.
2.1
Abbreviations
2.1.1
General Abbreviations
Below is a table listing general abbreviations used in this document.
Abbreviation
deg
DNV
FAQ
Meaning
Degrees.
Det Norske Veritas.
Frequently Asked Questions.
GB
Gigabytes.
GUI
Hz
Graphical User Interface.
Hertz.
kB
Kilobytes.
kW
Kilowatts.
LAN
Local Area Network.
LED
m
m/s
Light Emitting Diode.
Metre.
Metres per second.
MB
Megabytes.
MMI
Man-Machine Interface.
ns
PDF
PRF
RPM
s
SP
Nanosecond.
Portable Document Format.
Pulse Repetition Frequency.
Revolutions Per Minute.
Second.
Service Pack.
Std. Dev.
Standard Deviation.
Sync
TFT
UTC
VGA
Synchronization.
Thin Film Transistor.
Coordinated Universal Time.
Video Graphics Array.
W/m2
Watt per square meter.
XGA
Extended Graphics Array.
Remark
Unit of direction.
Classification society.
Unit of file size and storage capacity
(1 GB = one billion bytes).
The visible part of a software system.
Unit of frequency.
Unit of file size and storage capacity
(1 kB = one thousand bytes).
Unit of energy (1 kW = 1000 Watts).
System for sending data between
computers.
Status indicator “lamp”
Unit of distance.
Unit of speed.
Unit of file size and storage capacity
(1 MB = one million bytes).
Typically display, keyboard and pointing
device (mouse, trackball).
Unit of time (1 ns = 10-9 seconds).
Developed by Adobe Systems.
Number of pulses per second.
Unit of rotation speed.
Unit of time.
Software upgrade.
Measure of variability or diversity used
in statistics.
In this context also called radar trigger.
A type of LCD display.
Replaces Greenwich Mean Time.
Computer display standard.
Unit of radar cross-product of field
energy.
Computer display standard.
General abbreviations.
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2.1.2
Specific Abbreviations
Below is a table listing abbreviations related to Wavex calculated wave and surface current
parameters. Surface current data is optional in Wavex systems, and may not be present in a
given system.
Abbreviation
CM
CDr
CDt
Cg1
Dm1-r
Dm1-t
Dm2-r
Dm2-t
Dmt-r
Dmt-t
Dp1-r
Dp1-t
Dp2-r
Dp2-t
Dpt-r
Dpt-t
Hm0
Hmax
HTmax
Lp1
m-1
m-2
m0
m1
m2
m3
m4
SDp1
Sk
Sm02
SPR1
SPR2
SPRt
THmax
Tm0-1
Tm0-2
Tm02
Tm01
Tm24
Tmax
Tp1
Tp2
Tpc
Ts
ʋ
Vp1
Meaning
Current magnitude.
Current direction, relative.
Current direction, true.
Primary wave group velocity.
Primary wave mean direction, relative.
Primary wave mean direction, true.
Secondary wave mean direction, relative.
Secondary wave mean direction, true.
Total energy mean direction, relative.
Total energy mean direction, true.
Primary wave peak direction, relative.
Primary wave peak direction, true.
Secondary wave peak direction, relative.
Secondary wave peak direction, true.
Total energy peak direction, relative.
Total energy peak direction, true.
Significant wave height.
Maximum wave height.
Wave height of maximum wave period.
Primary wave length.
1st order negative moment.
2nd order negative moment.
Zero order moment.
1st order moment.
2nd order moment.
3rd order moment.
4th order moment.
Primary wave spectral density.
Skewness.
Wave steepness.
Primary wave direction spread.
Secondary wave directional spread.
Total energy directional spread.
Wave period of maximum wave height.
Energy wave period.
Integral wave period.
Mean zero up-crossing period.
Mean period.
Average wave crest period.
Maximum wave period.
Primary wave peak period.
Secondary wave peak period.
Calculated wave peak period.
Significant wave period.
Spectral band width.
Primary wave phase velocity.
Unit
m/s
deg
deg
m/s
deg
deg
deg
deg
deg
deg
deg
deg
deg
deg
deg
deg
m
m
m
m
m 2s
m 2s 2
m2
m2/s
m2/s2
m2/s3
m2/s4
m2/Hz
(no unit)
(no unit)
deg
deg
deg
s
s
s
s
s
s
s
s
s
s
s
(no unit)
m/s
Abbreviations for Wavex calculated parameters.
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2.2
About This Manual
2.2.1
Defining the User
The Wavex system is used by a wide range of professionals, and the user group is diverse. This
manual aims mainly at the operational user and is a concise user manual explaining mainly the
practical use of the system.
2.2.2
Qualifications
It is assumed that the user is acquainted with the use of personal computers and Windows
operating systems.
2.2.3
Finding the Way Through the Manual
Chapter 1 - Safety and Warnings
This chapter contains information about safety and proper use. Make sure that the safety
instructions and operational warnings are read and understood before the Wavex equipment is
put into operation.
Chapter 2 - Introduction
This chapter contains various important information, two abbreviation lists and information how
to contact Miros.
Chapter 3 - System Description
This chapter gives a presentation of the hardware and software that form the Wavex system.
Chapter 4 - Principles of Operation
This chapter gives an overview of the fundamentals behind Wavex, and how the system works.
Chapter 5 - User Interface
This chapter contains the basic principles of how an operator interacts with the Wavex system.
It describes the commanding tools as keyboard and pointing device as well as the graphical
user interface (GUI).
Chapter 6 - MirPresF Data Presentation
In this chapter the MirPresF Data Presentation module is described in detail.
Chapter 7 - Operating Wavex
This chapter describes how to do the initial power-up, how the start-up and restart sequences
are running, how to access additional operating procedures and how to access the data
presentation system.
Chapter 8 - Maintenance
This chapter describes Wavex periodic system maintenance.
Chapter 9 - Technical Data
This chapter contains information about Wavex performance and various data outputs.
Chapter 10 - Troubleshooting
This chapter describes how to recognize any Wavex abnormal behaviour, and what to do if
service is required.
Chapter 11 - Frequently Asked Questions
This chapter gives answers to Wavex system and radar related questions that are often asked.
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2.3
How to Contact Miros
Mail Address:
Miros AS
Solbråveien 20
NO-1383 Asker
Norway
Switchboard:
+47 66 98 75 00
E-mail:
[email protected]
Web:
www.miros.no
3
System Description
3.1
System Introduction
The Wavex system measures surface wave parameters in the basis of digitized sea clutter
images provided by a standard marine X-band (3 cm) radar.
Since “copies” of the raw radar signals are used, the Wavex system will not interfere or affect
the radar signals to the navigation display for a radar that is used both with Wavex and for
navigation purposes.
Wavex collects sea clutter data during a defined time period. The calculated wave parameters
are therefore an average of the wave parameters during the data collection period. The Wavex
system does not measure individual waves.
3.2
Hardware Configuration
The Wavex system consists of the following hardware components:
•
Marine X-band radar (shared or dedicated).
•
EM-129 Integrated Video Digitizer (not for IP radars).
•
System Computer (certified or non-certified).
•
Display (certified or non-certified).
•
Keyboard.
•
Pointing device (trackball or mouse).
•
Gyro data input (for non-fixed sites).
•
GPS data input (for non-fixed sites).
•
Wind sensor data input (option).
Wavex hardware block diagram.
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An IP radar may be used in a Wavex system, in which case the EM-129 Integrated Video
Digitizer is omitted.
A GPS and gyro are not part of the standard Wavex system as these sensors are usually
available on ships or other vessels where access to such data is required.
3.2.1
X-Band Radar
The X-band (marine) radar can be a vessel’s navigation radar or a dedicated radar, operating in
short pulse mode.
Minimum recommended antenna size is 6 feet with antenna speed between 20 and 60 RPM.
3.2.2
EM-129 Integrated Video Digitizer
The Miros EM-129 Integrated Video Digitizer is designed to be the radar interface in Miros
systems using a non-IP radar as signal source. It comprises a radar interface board and a radar
image processing board.
EM-129 Integrated Video Digitizer (radar interface).
3.2.3
System Computer
The computer used in a Wavex system can be a marine certified computer, non-certified
computer, laptop computer or a server.
Typical Wavex system computer.
3.2.4
Keyboard and Pointing Device
Operator input is supported by a standard 104-keys UK/US keyboard and a pointing device
such as a trackball or mouse.
The keyboard is only required during administration of the system and more advanced use, to
provide character and numerical inputs. During normal operation it is sufficient to use the
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pointing device alone, and the keyboard could be put away. However, the keyboard must not be
disconnected from the computer.
The advantage of using a trackball instead of a regular mouse is that the movement of the
cursor is controlled by rolling the ball located on top while the unit itself is not moving. The
space required to use a trackball is therefore limited to the space occupied by the trackball itself.
3.2.5
Display
To present data to the user Wavex is equipped with a standard flat screen display or a marine
certified flat screen display. The latter is DNV approved for maritime use, fully dimmable down
to zero brightness and can be mounted in a bridge console or rack, or fixed on a desktop or
under a ceiling using brackets.
Marine certified display (left) and standard flat screen display (right)
3.3
Software Configuration
3.3.1
Wavex Software
The Wavex software comprises a number of services and software modules performing various
tasks. User interaction with Wavex is mainly through:
•
MirPresF - Data Presentation Module
•
MirAdm04 - Miros System Manager
3.3.2
Data Presentation Module
The MirPresF is a standalone software module for data presentation, and is where most users
will interact with the Wavex system.
Please see chapter “User Interface” for more detailed information and how to use MirPresF.
3.3.3
System Manager
The MirAdm04 System Manager is used for monitoring Wavex status and Wavex software
modules running in the system. The System Manager also:
•
Automatically starts all Wavex software modules on system start-up.
•
Maintains and displays Wavex log files.
•
Monitors Wavex system computer status.
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MirAdm04 Miros System Manager example.
4
Principles of Operation
This chapter contains a brief overview of how the Wavex system works. Users that require a
more detailed explanation is referred to Miros document 1300/DD/011; “Wavex - Principles of
Operation” which is found in the Wavex 5.5 User Manual.
4.1
General Description
The Wavex system provides means of capturing and subsequently analysing portions of radar
images of the sea surface. Data processing of a time sequence of these images extracts
qualitative directional wave spectra as well as spectra scaled in absolute wave height and
surface current.
Wavex captures, processes and displays sea surface backscatter data from a standard X-band
marine navigation radar. The radar sea-echo amplitude depends on the “roughness” of the sea
surface, caused by the wind acting on the sea surface.
4.2
Theory of Operation
The X-band radar signal is back-scattered off the sea surface, and the resulting image on the
radar screen is known as sea clutter.
Gravity waves and currents form images on the radar display because they modulate the sea
surface radar cross section by angular variation, hydrodynamic interaction and shadowing. The
Wavex system collects sequences of polar radar sea clutter images. From each polar image,
Cartesian sections are selected for further processing.
Cartesian sections on a digitized radar image.
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The easily identified, wave-like pattern is caused by the modulation of the sea clutter radar
cross-section by the gravity waves. The modulation is mainly due to grazing angle variation and
shadowing.
There is an optimum range between approximately 1 and 10 degrees where appropriate image
contrast is achieved mainly by angular variation and shadowing.
Radar back-scatter geometry.
At grazing angles above 10 degrees the radar will illuminate the whole wave profile and the
radar image contrast will be low. For grazing angles less than approximately 1 degree there will
be little radar echo from the sea surface, and modulation will be dominated by shadowing.
Note that the X-band radar must operate in short pulse mode, 50 - 80 ns. Undefined wave and
surface current data values may be experienced in situations with low wind speeds (< 2 m/s)
and a calm sea, echoes from land or other objects or precipitation in the Cartesian sections.
4.2.1
Wave Data Calculation
A two dimensional wave-number spectrum may be derived from a single Cartesian image
section. Based on a single image the wave direction can only be determined with an ambiguity
of 180 degrees, i.e. one cannot tell whether the waves are approaching or receding. The
direction ambiguity is resolved by full three dimensional spectral processing of a sequence of
consecutive radar images, equally spaced in time.
Wave parameters, including wave direction, are calculated from the directional wave spectra.
4.2.2
Surface Current Data Calculation
Wavex can provide measurement of the relative surface current speed and direction as the
three-dimensional (wavenumber-frequency) wave spectrum, in addition to wave information,
also contains information about the surface current.
According to the dispersion relation, the wave energy for any given wave frequency will be
concentrated on a circle in the wave-number plane. In the presence of a current there will be a
Doppler shift in the observed or encountered wave frequency. The current vector is then
estimated on these Doppler shifts.
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5
User Interface
5.1
General
The user interface is the means by which the operator interacts with Wavex. It consists of
commanding tools and the data presentation system.
5.2
Commanding Tools
The operator controls the system by giving his commands through the following tools:
•
Pointing device such as a trackball or mouse.
•
Keyboard.
5.2.1
Pointing Device
The pointing device is usually a trackball or mouse. In the remaining chapters of this document
the pointing device is referred to as a mouse.
5.2.2
Keyboard
Even if it is possible to use the keyboard during normal operation of the Wavex system, this is
not very common. Operator interaction is done more easily using the pointing device. However,
do not disconnect the keyboard, during service and configuration of the Wavex system the
keyboard must be available for use.
5.3
Data Presentation
The Wavex data presentation module is described in detail in chapter MirPresF Data
Presentation Module.
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6
MirPresF Data Presentation Module
6.1
General Description
MirPresF is a standalone data presentation module for real time and history data. MirPresF
reads Wavex data from files and builds its own history over time for the graphical and tabular
historic presentation.
The MirPresF menu is located at the right side of the screen when MirPresF is running in normal
mode and not minimized.
Example of a MirPresF data layout.
6.2
Layouts
The various screen setups, called Layouts, can be customized and changed to present a
combination of Wavex real-time and history data, in various formats. Layouts are built using
data modules.
MirPresF can be configured with twelve layouts, each accessible from the MirPresF menu.
6.3
Data Modules
Wavex data is presented on a monitor by MirPresF using data modules. A data module can
have one or two selected parameters, a wave spectrum, time series or an image.
MirPresF data modules can be divided into six groups:
•
Single Parameter
•
History
•
Vector
•
Wave Spectrum
•
Time Series
•
Image
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The data modules have their own individual configuration panels. These can only be accessed
when in MirPresF layout composing mode (advanced use).
Most of the data modules have a pop-up menu used to make individual settings. A pop-up
menu is accessed by clicking the right mouse button while pointing at the desired data module
with the mouse cursor.
Below is an overview of each of the six MirPresF data modules.
6.3.1
Single Parameter
The single parameter data modules present the last calculated Wavex parameter values in a
plain numeric representation.
MirPresF Single parameter data module, parameter valid.
MirPresF Single parameter data module, parameter undefined.
MirPresF Single parameter data module, parameter timeout.
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Undefined (//) values may be experienced in situations with very low wind speeds (< 2 m/s) and
a calm sea in the Wavex Cartesian sections.
Timeout usually happens because the radar is turned off or operates with a pulse length
unsuitable for Wavex.
The table below gives a brief explanation of some of the more common wave and surface
current parameters available from the Wavex system. Surface current parameters are optional.
Parameter code is written inside parenthesis, parameter unit inside square brackets.
Wavex Parameter With (Code) and [Unit]
Explanation
Significant wave height (Hm0) [m].
The wave height equal to the average of the
highest 1/3 of the wave heights.
Significant wave period (Ts) [s].
The estimated average period of the 1/3
highest waves.
Primary wave peak period (Tp1) [s].
The wave period of the wave with the highest
energy in the wave spectrum.
Maximum wave height (Hmax) [m].
The estimated highest wave that occurs
during a 30 minutes observation period. The
likely maximum wave height can be up to
nearly twice the Hm0.
Total energy mean direction, true (Dmt-t) [deg].
The average direction from where the total
wave energy is coming, relative to true north.
Total energy mean direction, relative (Dmt-r)
[deg].
The average direction from where the total
wave energy is coming, relative to a vessel’s
heading.
Total energy peak direction, relative (Dpt-r) [deg].
The peak direction, relative to a vessel’s
heading, from which the total wave energy is
coming.
Total energy directional spread (SPRt) [deg].
The statistical spread (variance) around the
waves’ average direction.
Primary wave length (Lp1) [m].
The wave length of the wave with the highest
energy in the wave spectrum.
Primary wave phase velocity (Vp1) [m/s].
The phase velocity of the wave with the
highest energy in the wave spectrum.
Current speed (CM) [m/s].
The current speed extracted from the wave
spectrum.
Current direction, true (CDt) [deg].
The current direction in the sense of the
direction the water is flowing (going to). The
direction is relative to true north.
Common Wavex wave and surface current parameters.
6.3.2
History
A History data module can represent the history for one or two parameters. Time span can be
selected from a pop-up menu with values from 20 minutes and up to eight days.
The first parameter is displayed in a green colour for name, scale and graph, with the name and
scale located to the left of the graph area. The second parameter (if selected) is displayed in a
blue colour for name, scale and graph, with the name and scale located to the right of the graph
area.
The two vertical axes can be scaled manually or automatically.
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MirPresF History data module.
6.3.3
Vector
A Vector data module holds two parameters that are configured individually. Typically these two
parameters are related to give information such as speed and direction for surface current,
wind, waves or vessel. Direction can be configured as “coming from” or “going to”.
MirPresF Vector data module.
6.3.4
Wave Spectrum
MirPresF has a total of three different wave spectrum data modules, Polar Spectrum, Frequency
Spectrum and Directional Spectrum.
Polar Spectrum is a 3D frequency/direction/energy presentation which gives a quickly readable
picture of the present sea state.
MirPresF Polar spectrum data module.
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The contour colours give relative information about the wave energy, where red represents the
highest energy and violet the lowest. The location of the majority of the contour lines tells in
which direction the main wave energy is coming from, and at what frequency.
Frequency Spectrum is a 2D presentation of the wave energy/frequency distribution for a point
spectrum. A point spectrum is a wave spectrum where the wave energy is integrated over all
measured directions, resulting in a non-directional wave spectrum.
The vertical scale gives wave energy as square meters per Hertz (m2/Hz).
MirPresF Frequency spectrum data module.
Directional Spectrum is a 2D presentation of the directional distribution of the wave energy
over a 360 degrees span.
MirPresF Directional spectrum data module.
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6.3.5
Time Series
A Time Series data module is an accumulated list of data sets with time stamps for each data
type (data block) in the Wavex system. Wavex has several data blocks and each typically
represents parameter values for one group of data, such as wave data, surface current data,
wind data, vessel speed data etc. Some of the data groups are optional.
MirPresF Time Series data module.
6.3.6
Image
MirPresF has three Wavex Images data modules for presentation; Radar Image, Polar Image
and Cartesian Image.
Radar image is a digitized radar backscatter image.
MirPresF Radar Image data module.
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Polar Image is also a digitized radar backscatter image, but with the radar rays placed parallel
along the vertical axis. This gives a distorted image of the sea surface.
MirPresF Polar image data module.
6.4
MirPresF Menus
MirPresF has two menus, Main and More. The Main menu is visible by default when MirPresF is
started. The More menu appears when the Main menu’s “More” button is clicked. The Main
menu reappears when the More menu’s “Return” button is clicked.
MirPresF Main and More menus (compressed).
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The two MirPresF menus have twenty visible buttons in a standard Wavex configuration. One or
more of these buttons may be hidden, or other user defined buttons may be visible depending
on the actual Wavex configuration:
1.
Wave 1 to display the first wave data presentation layout.
2.
Wave 2 to display the second wave data presentation layout.
3.
Radar Im to display the radar image data presentation layout.
4.
Time Ser to display the time series data presentation layout.
5.
Spectrum to display the wave spectrum data presentation layout.
6.
BIG to display the big numbers data presentation layout.
7.
Control to display the system control layout.
8.
More to access the more menu.
9.
Scr Dmp… to take screen dump of whatever is on the screen, as a single shot or
continuously at a given interval, depending on MirPresF configuration.
10. Save... to copy Wavex source data files to a specified folder.
11. Export... to copy data buffers to a specified folder.
12. About… to view the about box with MirPresF and Wavex system versions info.
13. Config… for access MirPresF configuration. A password is required.
14. Layout… to access MirPresF layout composition. A password is required.
15. North Up This button is not relevant for Wavex.
16. Heading Up This button is not relevant for Wavex.
17. Return to return to the main menu.
18. Save Stat. for saving Wavex system status information to a zip file.
19. Minimize to minimize MirPresF to the Windows taskbar, including its menus.
20. Exit to exit MirPresF.
Two predefined custom menu buttons are used in some Wavex configurations, but hidden in a
standard Wavex configuration:
1.
Set Height to set Wavex operation parameters, i.e. radar antenna altitude and
Cartesian sections start range.
2.
Set Depth to set a single water depth for all Wavex Cartesian sections.
6.5
MirPresF Layouts
A MirPresF layout is one or more data modules put together and configured in order to display
Wavex data in a certain way. MirPresF has seven layouts by default, but up to twelve can be
configured by the user and accessed during Wavex operation.
The various layouts are accessed from the MirPresF menu located on the right side of the
screen. The active layout button has the layout name written in green. Re-clicking an active
layout button will hide the last used layout and reveal the computer desktop. The MirPresF
menu will, however, remain on the screen.
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6.5.1
Default Layout “Wave 1”
The “Wave 1” default layout has a History data module, a Polar spectrum data module,
Frequency- and Directional spectrum data modules and six Single data modules for
presentation of the most common Wavex data.
MirPresF layout “Wave 1” default configuration.
6.5.2
Default Layout “Wave 2”
The “Wave 2” default configuration has four History data modules and eight Single data
modules for the most common Wavex data. Each History data module shows the history for two
parameters, and the two Single data modules on each side show the last calculated value for
the same two parameters.
MirPresF layout “Wave 2” default configuration.
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6.5.3
Default Layout “Radar Im”
The “Radar Im” default configuration displays the Radar- and Polar images together with the
Directional- and Frequency spectrum module, and two Single modules.
MirPresF layout “Radar Im” default configuration.
6.5.4
Default Layout “Time Ser”
The “Time Ser” default configuration has a History module presenting data for two parameters
with two corresponding Single data modules, and a large area listing the time series for all
Wavex wave parameters. As the number of time series entries in this data module is limited
(1000 entries by default), the history span depends on the time interval between each data set.
MirPresF layout “Time Ser” default configuration.
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6.5.5
Default Layout “Spectrum”
The “Spectrum” default configuration has the Polar spectrum, a Frequency- and Directional
spectrum data modules in addition to four Single data modules. The Frequency- and Directional
spectrum data modules are made quite large for better readability.
MirPresF layout “Spectrum” default configuration.
6.5.6
Default Layout “BIG”
The “BIG” default configuration has four Single data modules only. These are very big and can
be used in situations where Wavex parameter data has to be read from a distance.
MirPresF layout “BIG” default configuration.
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6.5.7
Default Layout “Control”
The “Control” default configuration displays two windows. The window to the left contains
information about radar status, collected from the EM-129 Integrated Video Digitizer (Wavex
radar interface) using an internal web browser.
The window to the right contains information about radar pulse mode and system record mode.
Record On means that all Wavex raw data is stored on the Wavex history data hard drive.
MirPresF layout “Control” default configuration.
6.6
Information and Status
The MirPresF bottom line has information fields for information to the user and for system
status.
6.6.1
Date and Time
Located to the left. Date and time is presented as set in the local Wavex computer. Default time
zone for Wavex systems is UTC.
6.6.2
Radar Mode
Located to the middle left. This field shows one of four possible texts, depending on whether the
system receives mode information from the radar or not:
•
“Correct radar pulse mode detected”
•
“Correct radar pulse mode detected for OSD. Wavex is disabled”
•
“Incorrect radar pulse mode detected - please correct!”
•
“The radar must be in short pulse mode (50-80 ns)”
The last of the four listed text strings is presented when the Wavex system has no radar mode
information.
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6.6.3
Radar Antenna Height Above Sea Level
Located to the middle right. This field tells the distance from the sea surface up to the radar
antenna location as given in the Wavex configuration. The text is:
•
“Radar antenna height set to <x> m above sea level.”
where <x> is height in meters.
6.6.4
Data Quality
Located to the right. Data quality is a whole number from 0 to 100 and gives an indication in
percent on how many good (accepted) Cartesian sections are used for calculating waves and
surface currents (surface current is option) during the last data averaging period. Default
averaging period is 20 minutes.
A data set may be good even if not all Cartesian sections were accepted during the data set
acquisition period. If 50 % or more of the Cartesian sections were accepted, then the data set is
good. This means that even if all data sets collected during the averaging period are good, the
status indicator will be 100 % only if all Cartesian sections for all data sets were also accepted.
The quality indicator must be 50 % or higher for data to be accepted and visible in MirPresF.
6.6.5
System Status
The rightmost field has the text “Normal” written in green when all Wavex software modules are
working correctly and receiving data where applicable. The text changes to “INDICATION”
written in yellow if one or more software modules have an abnormal state. This could be loss of
data from the radar, gyro or GPS, or something else. By clicking on the text itself with the
mouse pointer a new window is opened giving more information on what has happened.
7
Operating Wavex
7.1
Wavex Power-Up
To start-up a powerless Wavex system, proceed as follows:
•
Make sure the Wavex X-band marine radar is turned on and operates in short pulse
mode, 50 - 80 ns.
•
If a gyro and a GPS are connected to Wavex, make sure that data from these units is
transmitted to the Wavex system.
•
If a wind sensor (optional) is connected to Wavex, make sure that wind data is
transmitted to the Wavex system.
•
Turn on the Wavex hardware in this order:
o EM-129 Integrated Video Digitizer (if present).
o Display.
o System Computer.
After the Wavex computer is turned on and the Windows operating system has started, the
Miros System Manager (MirAdm04) will automatically be launched. MirAdm04 starts the other
Wavex software modules.
When the start-up sequence has completed, the display will show the MirPresF data
presentation module. Allow the Wavex system to perform data collection and calculation for a
period of time corresponding to the Wavex data averaging time, which is 20 minutes by default.
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The status button in the lower right corner of the MirPresF display has the text “Normal” in a
green colour or “INDICATION” in a yellow colour written on it. “Normal” means that the Wavex
system operates normally, “INDICATION” means that something about Wavex needs the
operator’s attention.
When clicking on the system status button, a window pops up with a list of the running Wavex
software modules, and their status. A green check mark in front of a module name means OK
status, while a red cross means not OK. If a software module is listed with a red cross then
open this module from the Windows taskbar for further investigation.
7.2
Wavex Restart
If a Wavex system restart is required then these alternatives are available.
7.2.1
System Software Restart
1.
Shut down the Wavex software by terminating MirAdm04 from its menu File → Exit.
2.
Start the Windows desktop or start menu shortcut Wavex System Start-up.
3.
Wait while Wavex is relaunched.
7.2.2
Computer Software Restart
1.
Shut down the Wavex software by terminating MirAdm04 from its menu File → Exit.
2.
Select computer “Restart” from the Windows start menu.
3.
Wait while the computer restarts and relaunches Wavex.
7.2.3
Computer Hardware Reset
1.
Note: Use the computer hardware reset only if computer software restart fails.
2.
Press the computer “Reset” button.
3.
Wait while the computer is reset, restarts and relaunches Wavex.
7.2.4
Computer Power Off/On
If the system does not respond normally to a computer hardware reset, a power off/on may
be the only way out:
1.
Push the computer power button and hold it until the computer shuts down.
2.
Wait for a minimum of 30 seconds and push the “Power Button” again until the
computer starts.
3.
Wait while the computer restarts and relaunches Wavex.
7.3
Operating Procedures
Although the Wavex system in principle is fully operational after a successful start-up, there are
some procedures the operator should be aware of. They are described in the subsequent
chapters.
7.3.1
Check Wavex Radar Mode
At the bottom of the MirPresF display, in the middle left area, is a text field which has one of
three information texts printed:
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“Correct radar pulse mode detected.”
This text is printed when Wavex receives mode status from the radar, and the radar mode
is correct for collecting Wavex data.
“Correct radar pulse mode detected for OSD. Wavex is disabled”
This text is printed when an OSD (Oil Spill Detection) system is running without Wavex, and
the radar mode is correct for collecting OSD data.
“Incorrect radar pulse mode detected - please correct.”
This text is printed when Wavex receives mode status from the radar, and the radar mode
is not correct for collecting Wavex data.
“The radar must be in short pulse mode (50 - 80 ns).”
This text is printed when Wavex does not receive mode status from the radar. It is then up
to the Wavex operator to assure that the radar is in correct mode.
7.3.2
Check Wavex Radar Antenna Height Above Sea Level
At the bottom of the MirPresF display, in the middle right area, is a text field which gives the
height of the Wavex radar antenna above sea level, as set in Wavex configuration:
“Radar antenna height set to <x> m above sea level.”
This text is printed when a DF-047 radar image NOW file is available in the Wavex
NowFiles folder, which means always during normal Wavex operation. The expression <x>
is radar antenna height in meters.
It is of outmost importance for the Wavex performance that the set (configured) height
above sea level for the Wavex radar antenna reflects the real situation. If changes are
required then use the procedure “Set Operation Height” described in the next chapter.
Typical situations when the “Set Operation Height” procedure may be required is for example
when a jack-up vessel has jacked up or down, or after a ship has gone from loaded to ballasted
or vice versa.
7.3.3
Set Operation Height
If this function is enabled the button “Set Height” is visible in the menu and can be used to set
the Wavex radar operation height and Cartesian sections start range from predefined
selections.
7.3.4
Set Water Depth
If this function is enabled the button “Set Depth” is visible in the menu and can be used to set a
water depth to be used for all Wavex Cartesian sections.
7.3.5
Check Wavex Data Quality.
At the bottom right side of the MirPresF display is an area with the text “Data Quality X %”
where X is a number from zero to one hundred. This number gives the Wavex data quality as
the ratio between the actual and expected number of accepted Cartesian sections in the data
averaging window.
All Cartesian sections are not necessary to calculate one data set. A single data set is accepted
if 50 % or more of the Cartesian sections are accepted, and a valid data reading is given if 50 %
or more of the data sets in the averaging window are accepted. As a consequence, even if all
data sets in the averaging window are accepted, the data status is less than 100 % if one or
more Cartesian sections represented in the averaging window are not accepted.
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The reason why a Cartesian section is not accepted is typically because of low relative signal
due to low wind speed, precipitation, foreign obstacles or current sheers in the measure area, or
the Cartesian section has ended outside the measure area because the ship or vessel has
turned a lot during the data collection period.
Based on the above, even if all data sets in the averaging window are accepted, the data status
quality is 100% only if all Cartesian sections are also accepted. This way the user can be
informed if one or more Cartesian sections are sometimes not accepted, even if all data sets in
the averaging window are accepted and the data quality is good.
7.3.6
Take Screen Dumps
When the “Scr Dmp” button in the MirPresF main menu is clicked, MirPresF will take one screen
dump or several screen dumps at a given interval, depending on the MirPresF configuration.
Default is one single screen dump each time the “Scr Dmp” button is clicked.
7.3.7
Save Wavex Source Data Files
Use the “Save..” button to copy Wavex source data to a folder specified by using the “Browse”
button in the appearing dialogue box. All DF-037 and DF-038 source files are copied as is,
whereas DF-047 radar images are converted to png files before being saved.
7.3.8
Export Wavex Data Buffers
Use the “Export...” button to export a Wavex data buffer to a folder specified in MirPresF
configuration. The selections are the time-lapse buffer, real-time buffer or screen dump buffer.
7.3.9
Save Wavex Status Information
Use the “Save Stat.” button to save Wavex status information to a zip file. The destination folder
is predefined (standard “D:\Miros\Reports”) and the content can be opened by clicking the
“Show in folder...” button. Or just click OK to finish.
7.3.10 Check Wavex System Status
At the bottom right of the MirPresF display, below the menus, is a button with the text “Normal”
printed in green, or “INDICATION” printed in yellow. “Normal” means that the Wavex system
operates normally, “INDICATION” means that something needs the operator’s attention.
Clicking the “Normal/INDICATION” button will result in a window popping up with a list of the
running Wavex software modules, and their status. A green check mark in front of a module
name means OK status, while a red cross means not OK.
If a software module is listed with a red cross then open this module from the Windows taskbar
for further investigation.
7.3.11 Check Wavex Radar Status
The Wavex radar status can be checked from the MirPresF layout called “Control”. MirPresF
collects status from the EM-129 Integrated Video Digitizer (Wavex radar interface) via web
protocol, and presents this for information. When Wavex is operating normally all status lights
are green.
From the MirPresF menu select “Control”.
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Checking Wavex radar status.
7.3.12 Check Available Wavex Computer Disc Space
To prevent loss of data, the data disk drives must have sufficient storage capacity available.
Free disk space can be monitored using the MirAdm04 Miros System Manager under the
System Information tab. Wavex history data files are stored to the E drive by default.
MirAdm04 system information disk usage.
If available space on the history drive becomes less than 100 MB (default value) the Wavex
system stops storing data. An error will then be reported by MirSip30 (the radar interface
software), and the Wavex operator is notified by the text “INDICATION” at the bottom right side
of the MirPresF data presentation display.
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8
Maintenance
8.1
Wavex System
The Wavex system is almost maintenance free. The only regular activity recommended is visual
inspection and cleaning of external surfaces.
On a regular basis, check visually for damage and clean using a soft, lint free cloth and a mild
detergent:
•
The Wavex system computer.
•
The display, keyboard and pointing device.
•
The EM-129 Integrated Video Digitizer (if present).
•
The Wavex radar antenna.
8.2
Radar
For complete maintenance of the Wavex radar please see the manufacturer’s documentation.
All service and maintenance on the radar system must be carried out by an authorized radar
representative.
Because the Wavex system requires higher radar performance than is usually necessary for
navigational purposes, the radar magnetron should be replaced at shorter intervals than
recommended by the radar manufacturer. This is especially important in areas with generally
low wind speeds. For this reason a radar used in a Wavex system should have the magnetron
replaced after a transmit time of 4500 hours. If used continuously this corresponds to about
twice a year.
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9
Technical Data
9.1
Radar
It is recommended that an X-band radar used in a Wavex system complies with the following
characteristics to be suited as a signal source:
Wavex X-band radar requirements
Antenna Beam Width:
1.3 degrees or less.
24 - 60 RPM.
Antenna Rotation Speed:
15 - 90 meters above mean sea level.
Antenna Mounting Height:
Short pulse 50 - 80 ns.
Pulse Length:
Pulse Repetition Frequency:
Output Power:
Radar Signals:
9.2
1000 Hz or higher.
Depends on antenna RPM.
10 kW or more.
Video, Sync, Heading Marker, Azimuth.
Wavex Performance Data
Wavex performance depends on the radar, measurement geometry and site conditions such as
sea surface exposure, water depth, sea bed and wind etc. Due to this fact Wavex may perform
better at some locations compared with others.
Parameter
Range
Significant Wave Height
Wave Period
Wave Direction
Surface Current Speed
Surface Current Direction
1
2
3
0-5m
5 - 10 m
10 - 15 m
5.0 - 13.0 s
3.2 - 5.0 s
13.0 - 25.6 s
1 - 360°
0 - 5 m/s
1 - 360°
Resolution
0.1 m
0.1 m
0.1 m
0.1 s
0.1 s
0.1 s
1°
0.01 m/s
1°
Std. dev.
0.5 m 1
10 % 1
20 % 1
10 % 1
0.5 s 2
20 % 2
20° 1, 2° 2
0.05 m/s 3
10° 3
Wavex DNV Type Approval Certificate.
Theoretical measures.
Using a Terma radar on a fixed installation.
9.3
Software
Wavex software
Miros AS
Operating system:
Windows XP, Windows 7, Windows Server 2003 or
Windows Server 2008 R2, Windows 10.
Application:
Wavex system software version 5.5.
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10 Troubleshooting
10.1 General
The Wavex system keeps logs that keep records of the system status, and gives status
messages that may explain the course of a possible system error. A troubleshooting action list
is made for the purpose of assisting the user in an attempt to recover the Wavex system from
an abnormal situation.
10.2 Indication of Trouble
The following list contains a description of situations that may mean that there is an error with
the Wavex system:
•
Undefined (“//”) data in the “MirPresF” display.
•
“Timeout” in the MirPresF display.
•
Data values in the MirPresF display that are obviously wrong.
•
One or more red crosses in front of software modules in the MirAdm04 window.
•
One or more red lights in the EM-129 web browser status page.
•
Error messages at the display or in log files.
•
Nothing at all at the display (black screen).
10.3 Troubleshooting Action List
This chapter lists the most common reasons for trouble with the Wavex system, and suggests
an action in an attempt to solve the problem. There may be other reasons why the Wavex
system behaves in a strange way, not listed here.
Undefined (“//”) data in the “MirPresF” display.
Possible Reason
The wind is not strong enough to create
capillary waves on the sea surface,
resulting in insufficient radar back-scatter.
The ship’s turning rate is too high.
The Wavex radar operates in wrong
mode.
Foreign obstacle like a ship or island in
the Wavex measure area.
Heavy rain shower.
Windows operating system failure.
Action
There is really not much to do except wait for the wind
speed to increase. Wind speeds of 2 m/s and above
are usually sufficient.
Slow down the ship’s turning rate.
Set radar mode to Short Pulse, 50 - 80 ns.
Move the foreign obstacle away.
Wait until the foreign obstacle disappears.
Move away from the foreign obstacle.
Wait until the rain shower ends or passes.
Restart the Wavex system computer.
“Timeout” in the MirPresF display.
Possible Reason
The Wavex radar is turned off.
The Wavex radar operates in wrong
mode.
Foreign obstacle like a ship or island in
the Wavex measure area.
Action
Turn the radar on.
Set radar mode to Short Pulse, 50 - 80 ns.
The radar magnetron is about to wear
out. Maximum recommended Tx time for
a Wavex radar magnetron is 4500 hours.
Miros AS
Move the foreign obstacle away.
Wait until the foreign obstacle disappears.
Move away from the foreign obstacle.
Replace the radar magnetron.
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Heavy rain shower.
One or more Wavex software modules
have recorded one or several errors.
The Wavex radar antenna needs
maintenance.
One or more Wavex hardware
components are missing power.
One or more Wavex hardware
components are broken.
Time mismatch.
Windows operating system failure.
Wait until the rain shower stops or passes.
Open MirAdm04 and check if any software module
has a red cross in front of its name. If yes, doubleclick on the software module name for further
investigation.
Execute radar antenna maintenance.
Make sure that all Wavex hardware components have
sufficient power.
Contact the local Wavex system supplier for repair or
replacement of defective hardware.
Open the NOW files folder and check that all relevant
NOW files are updated by looking at the storage time
stamp. Compare these time stamps with the Wavex
computer system time. Change computer system time
or time zone if necessary.
Restart the Wavex system computer.
Data in the MirPresF display that is obviously wrong.
Possible Reason
The Wavex radar operates in wrong
mode.
Foreign obstacle like a ship or island in
the Wavex measure area.
Action
Set radar mode to Short Pulse, 50 - 80 ns.
Move the foreign obstacle away.
Wait until the foreign obstacle disappears.
Move away from the foreign obstacle.
One or more red crosses in front of software modules in the MirAdm04 window.
Possible Reason
NMEA-data timeout. Missing external
data from a GPS, gyro or wind sensor.
Wavex radar data timeout.
Action
Double-click on the software module name in the
MirAdm04 window for further investigation.
Check the actual sensor including cabling and
connections for error, and correct if possible.
Check radar status.
Connect to the EM-129 using a web browser and check
status. Correct any errors if possible.
One or more red lights in the EM-129 web browser status page.
Possible Reason
The Wavex radar is turned off.
Low Power.
DSP Failure.
Processing Failure.
Wrong Wavex radar Sync PRF.
Wrong Wavex radar Azimuth Count.
Wrong Wavex radar Heading PRI.
Video Signal Error.
Miros AS
Action
Turn the radar on.
Restart EM-129 using the power button.
Restart EM-129 using the power button.
Restart EM-129 using the power button.
Check radar status.
Set to correct mode (Short Pulse 50 - 80 ns) if incorrect.
Check cabling and connections.
Increase EM-129 Sync PRF Tolerance if needed.
Check cabling and connections.
Check the radar and order service if required.
Check cabling and connections.
Check the radar and order service if required.
Increase EM-129 Heading PRI Tolerance if needed.
Check cabling, connections and impedance jumper
setting.
Adjust EM-129 Video Gain and Video Offset.
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Error messages at the display or in log files.
Possible Reason
The display shows error messages
generated by the Windows operating
system.
Wavex history data cannot be stored.
Action
Try to isolate the error and solve the problem.
Restart the computer.
Click on the MirAdm04 System Information tab and
check that there is sufficient disk space available.
Delete old data if necessary.
Nothing at all at the display (black screen).
Possible Reason
The display is switched off.
Wrong display input channel used.
The display brightness is dimmed all
the way down.
The display is broken.
Windows operating system failure.
Action
Turn the display on.
Switch to correct display input channel from the display
menu.
Increase brightness.
Replace the display.
Restart the Wavex system computer.
10.4 Support
If the Troubleshooting Action List does not help to solve the problem then contact your local
Wavex system supplier for assistance. But before doing so, please note down:
•
Any error messages on the Wavex computer display.
•
Any Wavex software modules with a red cross in front of its name in the MirAdm04
window.
•
Any MirPresF Control or EM-129 web browser status lights with red colour.
•
Any repair or maintenance work carried out recently on the Wavex radar.
•
Local wind condition (wind speed and direction).
•
Local weather situation (rain, snow, temperature, humidity, pressure).
•
Any other findings that may help the Wavex system supplier in providing quick and
correct support.
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11 Frequently Asked Questions
This chapter lists a collection of Frequently Asked Questions (FAQ) related to installation and
operation of the Wavex system, and the answers to them.
Why does Wavex show two slashes (“//”) instead of real data?
The most common reason for the two slashes in the Wavex data display is because the
wind is not strong enough to create capillary waves on the sea surface, resulting in no
radar back-scatter. Wind speeds of 2 m/s and above is usually sufficient.
Other reasons can be that the ship’s turning rate is too high, the Wavex radar operates
in wrong mode, there are foreign obstacles such as ships or islands in the Wavex
measure area, or there is a heavy rain shower in the Wavex measure area.
Why does Wavex show “Timeout” instead of real data?
There are several reasons why Wavex can display “Timeout” in the data display. Most
common is that the radar is turned off or is set to a pulse mode other that Short (50 - 80
ns).
Other reasons can be:
• A foreign obstacle like a ship or island in the Wavex measure area.
• The radar magnetron is about to wear out. Maximum recommended Tx time for
a Wavex radar magnetron is 4500 hours.
• Heavy rain shower in the Wavex measure area.
• One or more Wavex software modules have recorded one or several errors.
• One or more Wavex hardware components are missing power.
• One or more Wavex hardware components are broken.
• Time mismatch between the data storage time and local computer time.
• The Wavex radar antenna needs maintenance.
• Windows operating system failure.
What are the radar requirements for a Wavex system?
The requirements for a Wavex radar are:
• Antenna beam width:
1.3 degrees or less (6 feet or more antenna length).
• Antenna rotation speed:
24 - 60 RPM.
• Antenna mounting height: 15 - 90 metres above mean sea level.
• Pulse length:
Short pulse 50 - 80 ns.
• Pulse repetition frequency: 1000 Hz or higher. Depends on antenna RPM.
• Output power:
12 kW or more.
• Radar signals:
Raw video, Sync, Heading Marker and Azimuth.
What kind of radars can Wavex use?
Wavex can, in principle, use any X-band marine navigation radar, please see above for
radar requirements. Recommended radars are Furuno, Sperry and Kongsberg K-Bridge.
How often should the radar magnetron be replaced?
Wavex uses the radar in short pulse mode with the highest pulse repetition frequency
possible. Wavex also requires higher radar performance than is necessary for pure
navigation purposes, so the radar magnetron should be replaced at shorter intervals
than recommended by the radar manufacturer. Miros recommends the radar magnetron
to be replaced after 4500 hours of transmit time. If used continuously this corresponds to
about twice a year.
What is the radar safety distance?
This depends on the radar brand and make. The standard dedicated Wavex radars, the
Furuno FAR-2117 and FAR-2127 have safety distances of:
FAR-2117: 0.10 m to 100 W/m2 and 3.00 m to 10 W/m2.
FAR-2127: 0.40 m to 100 W/m2 and 8.60 m to 10 W/m2.
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Can the radar be used with Wavex and for navigation at the same time?
The radar can be used in a limited way for navigation purposes when also used in a
Wavex system. The limitation is that the radar must be in short pulse mode which
reduces the operational range for many types of radars to 2 nautical miles (about 3500
metres).
Why must Wavex use the radar in short pulse mode?
Short pulse mode is the only mode with radar pulses short enough to give the high
resolution Wavex requires to measure waves and surface currents. The radar pulse
length must be between 50 and 80 ns. An 80 ns radar pulse is 12 metres long.
What kind of maintenance is required for the Wavex system?
The Wavex system is almost maintenance free. The only regular activity recommended
is visual inspection and cleaning of external surfaces using a soft, lint free cloth and a
mild detergent.
The radar magnetron should be replaced after 3500 hours of transmit time, which
corresponds to twice a year if used continuously.
Please consult the radar manufacturer or local dealer for additional radar maintenance.
Does Wavex work in heavy rain?
X-band radars are sensitive to rain, so in situations with heavy rain showers Wavex may
not be able to measure waves and surface currents because the radar sea clutter backscatter “drowns” in the reflections from the rain. Two slashes (“//”) may then appear in
the Wavex data display instead of real values. If the heavy rain continues for some time
then “Timeout” may appear in the Wavex data display.
Can Wavex operate in all kinds of weather?
A wind speed of 2 m/s or more is usually required to generate ripples on the sea surface
necessary to create sufficient radar back-scatter. There is no upper wind speed limit.
X-band radars are sensitive to rain, so in situations with heavy rain showers Wavex may
not be able to measure waves and surface currents because the radar sea clutter backscatter “drowns” in the rain. Two slashes (“//”) may then appear in the Wavex data
display instead of real values. If the heavy rain continues for some time then “Timeout”
may appear in the Wavex data display.
What is the maximum range for a Wavex system?
The maximum distance from the location of the Wavex radar antenna to the measure
area circumference is from 1600 to 2000 meters, depending on the radar antenna height
above the sea surface.
How high waves can Wavex measure?
There is no upper limit for wave height that Wavex can measure. However, to measure a
wave height, the Wavex radar antenna must be at least twice this height above mean
sea level.
How low waves can Wavex measure?
There is no lower limit for wave heights that Wavex can measure. The Wavex system is
dependent on wind generated ripples on the sea surface necessary to create radar backscatter. Wind speeds from 2 m/s are usually sufficient.
Can Wavex data be sent to an external computer?
Yes, wave spectrum, wave parameters and surface current parameters (optional) can be
sent to an external computer on a serial line interface. Wavex can also send any Wavex
data to an FTP server.
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How much space is required to store Wavex data?
Required Wavex history data storage space depends on how much data is to be stored,
and for how long time data will remain on the storage drive before they are automatically
deleted.
To reprocess Wavex data at a later stage, 32 radar images for each data set is required.
Radar images are stored in DF-047 format files and can be relatively large in size,
depending on the site situation. A typical DF-047 format file containing a radar image
collected by Wavex is around 500 kB in size. Standard Wavex sampling interval is 5
minutes, resulting in 288 data sets during 24 hours. With this setup, one month (31 days)
of Wavex DF-047 format files require approximately 143 GB of storage space. In
addition are the wave and surface current data, and any GPS-, gyro- and wind data, so
total disk space required is about 145 GB.
If storing only one DF-047 format file for each data set, the total disk space required is
less than 6 GB for a typical Wavex site.
What does the lights outside the EM-129 Integrated Video Digitizer mean?
The EM-129 Integrated Video Digitizer has six outside status lights. Their meanings are:
• PWR : Green light when EM-129 power is on, no light when power is off.
• SYS : Green light when EM-129 firmware is up and running OK.
• LAN : Green light when LAN activities to/from the EM-129.
• SYNC : Yellow light when the EM-129 receives radar sync pulses.
• AZ
: Yellow light when the EM-129 receives radar azimuth pulses.
• HM
: Yellow light when the EM-129 receives radar heading marker pulses.
Note that LAN activities, and reception of radar SYNC- and AZ pulses may happen so
fast that these lights seem to illuminate continuously.
What does the lights in the EM-129 Web Interface mean?
When in the EM-129 Web Interface, click on any of the status lights with the left mouse
button and a help text window will appear with a detailed explanation for each of the
seven status lights.
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Wavex Hardware
Overview
Doc. No
PR-002/DD/016
Project
Wavex
Classification
Open
Abstract:
This document gives an overview and brief description of the Wavex hardware components.
Revision No.
Date
Prepared by
Checked by
Approved by
1
8 pages
2016-04-06
IK
TAA
IK
Description:
Original issue.
Blank page.
Wavex Hardware
TABLE OF CONTENTS
1
Introduction
4
2
Abbreviations
4
3
Component Overview
4
3.1
Standard component list ..................................................................................................... 4
3.2
System configuration - Analogue radar ............................................................................... 4
3.3
System configuration - IP radar .......................................................................................... 5
4
4.1
5
Computer Components
5
SM-145 Marine Certified Computer .................................................................................... 5
Display Components
6
5.1
JH 19T14 Maritime Multi Display ........................................................................................ 6
5.2
LA1951G monitor ................................................................................................................ 6
6
6.1
7
7.1
8
Sensor Components
7
X-band radar ....................................................................................................................... 7
Radar Interface
7
EM-129 Integrated Video Digitizer ...................................................................................... 7
References
Miros AS
8
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Wavex Hardware
1
Introduction
This document gives an overview and brief description of hardware components typically used
in a Wavex system.
For a more detailed description, please refer to the user manuals listed under section 8.
2
Abbreviations
Table 2.1 lists abbreviations used in this document.
Abbreviation
Hz
LAN
ns
RPM
s
Sync
Meaning
Remark
Hertz.
Nano-second.
Unit of frequency.
System for sending data between
computers.
Unit of time (1 ns = 10-9 seconds).
Revolutions Per Minute.
Unit of rotation speed.
Second.
Unit of time.
Local Area Network.
Synchronization.
Table 2.1: Abbreviations.
3
Component Overview
3.1
Standard component list
Wavex hardware comprises three main components and four sensor components:
•
Main components:
o Radar Interface
o Computer
o Display
•
Sensor components:
o Radar
o Gyro
o GPS
o Wind sensor
3.2
System configuration - Analogue radar
In a Wavex standard configuration the sensors, except for the radar, are directly connected to
the system computer’s serial interfaces.
The radar is connected to the system computer through the radar interface.
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Wavex Hardware
Figure 3.1: Block diagram for Wavex hardware standard configuration.
3.3
System configuration - IP radar
When the radar is an IP type radar the video digitizer is omitted, and the radar is connected to
the system computer directly by an Ethernet cable. Optionally a fire wall can be installed
between the system computer and the radar.
4
Computer Components
Wavex hardware includes a marine certified computer as standard.
4.1
SM-145 Marine Certified Computer
The SM-145/01 Marine Certified Computer is a special configuration of the Moxa type MC-5150AC computer. It is based on the Intel Core™ i5 520E processor and comes with 4 serial ports, 2
Gigabit Ethernet ports, 6 USB hosts, 8 NMEA ports, and offers high performance and versatile
peripherals for various industrial applications. For further details, see [2].
Figure 4.1: SM-145 Marine Certified Computer.
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Wavex Hardware
5
Display Components
Wavex hardware includes marine certified and non-certified display variants. The alternatives
are:
•
•
5.1
Hatteland JH 19T14 19”, marine certified.
HP LA1951G, non-certified.
JH 19T14 Maritime Multi Display
The JH 19T14 Maritime Multi Display from Hatteland is designed for navigation and automation
applications. It features 0 - 100% dimming, and comes with a mounting bracket. For further
details, see [3].
Figure 5.1: Hatteland Maritime Multi Display.
5.2
LA1951G monitor
The LA1951G 19” LCD monitor from HP Compaq may be used in situations where 0-100%
dimming is not required. An optional accessory is the VESA-compliant LCD monitor mounting
solution that allows to attach an LCD monitor to a variety of stands, brackets, arms or wall
mounts.
Figure 5.2: HP Compaq LCD monitor.
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Wavex Hardware
6
Sensor Components
Wavex relies on the following four sensor types:
•
•
•
•
X-band radar
Gyro
GPS
Wind sensor
For some applications, gyro and GPS are not required (fixed offshore installations and land- and
coastal installations). Wind data is optional for any application.
6.1
X-band radar
The marine radar is the main sensor in a Wavex system. A vessel’s existing X-band radar may
be used in an HW-002 configuration, but for it to qualify it must comply with the following
requirements:
X-band radar requirements:
•
•
•
•
•
•
•
Antenna beam width:
Antenna rotation speed:
Antenna mounting height:
Pulse modes:
Pulse repetition freq.:
Output power:
Radar signals:
1.3 degrees or less (6.5 feet or wider scanner).
24 - 60 RPM.
15 - 90 metres above mean sea level.
Short pulse (50 - 80 ns).
1000 Hz or higher. Depends on antenna RPM.
10 kW or more.
Raw video, synch, heading marker and azimuth.
The following radar signals must be available:
• Raw video.
• Synch (trigger).
• Antenna heading marker.
• Antenna azimuth.
These above described signals are available from most X-band radars. Signals from older radar
models are normally available on separate cables, but for newer radars the signals may be
coded and multiplexed into one single coaxial cable in form of a composite video signal.
IP radars provide data on an Ethernet cable.
7
Radar Interface
7.1
EM-129 Integrated Video Digitizer
The EM-129 Integrated Video Digitizer is a pre-processor unit, interfacing the computer with a
site’s non-IP X-band radar, providing a digital interface to analogue radar signals.
The EM-129 Integrated Video Digitizer is designed to digitize signals from analogue marine
radars. It comprises a radar interface board and a radar image processing board with analogue
inputs and digital output via Ethernet.
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Wavex Hardware
Figure 7.1: EM-129 Integrated Video Digitizer.
EM-129 connects to the radar’s video, synch, azimuth and heading marker signals. The EM-129
hardware can accommodate to different composite video signal formats, but a firmware upgrade
is then required.
EM-129 connects to the system computer via RJ45 LAN. For further details, see [1].
8
References
[1]
Miros: EM-129/010/DD; “EM-129 Integrated Video Digitizer - User Manual”.
[2]
Miros: SM-145/001/DD; “SM-145 Marine Certified Computer - User Manual”.
[3]
Miros: PR-002/DD/017; “Wavex Monitors - User Manual”.
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