GI - Chaparral Physics
903 Koyukuk Dr.
P.O. Box 757320
Fairbanks, AK 99775-7320
USA
FAX: 907-474-7290
TEL: 907-474-7107
Email: [email protected]
Select your sensor from Chaparral Physics
This Chart contains models currently, In Production, for ordering and older Models for cross-reference
purposes. Chaparral Physics is very willing to make older models, and special versions to meet your
requirements.
Frequency Range
of Interest
Model Type
Year introduced
0.1 Hz to >100 Hz
Globe 100 ~1964?
Status
Features
Operating
voltage
Availability
Original
Sensor
Original
Sensor
24-28
Not in Production
24-28
Not in Production
Thicker base plate
24-28
Not in Production
9-18 volts
9-18
Not in Production
Superseded by Model 20-21
0.1 Hz to >100 Hz
2.1
0.1 Hz to >100 Hz
2.2A
2005
Replace with
Model 25
Replace with
Model 25
Replace with
Model 25
Replacements
only
0.1 Hz to >100 Hz
2.2B
2005
Replacements
only
Low power
24-28
Not in Production
Superseded by Model 20-21
0.1 Hz to >100 Hz
2.2C 2005
Replacements
only,
ultra-Low power
(non-linear output)
12 -15
Not in production
0.1 Hz to >100 Hz
2.5
2005
Built in manifold
9-18
0.1 Hz to >300Hz
7
2000
For Replacement
of 2.x series
Test Model
24-28
0.1 Hz to 200 Hz
20
2008
Low Cost Model
9-18
In Production
0.1 Hz to 200 Hz
24
2008
Low Cost Model
9-18
In Production
0.1 Hz to 200 Hz
21
2008
Standard Model
9-18
In Production
0.1 Hz to 200 Hz
25
2006
Standard Model
Small & light
Sealed Electronics
Diff. Output
Single Gain
No Self Test
Sealed Electronics
Diff. Output
Single Gain
No Self Test
Sealed Electronics
Diff. Output
Sealed Electronics
Diff. Output
Built-in Manifold
Special Versions
Original
broadband
Not in Production,
Superseded by Model 24-25
Not in Production
9-18
In Production
9-18
As Requested
24-28
Not in Production
9-18
Not in Production
9-18
Not in Production
9-18
Not in Production
0.1 Hz to >100 Hz
0.1 Hz to 200 Hz
2
~1980’s
2004
2x: V, Vx, E
0.02 Hz to >50 Hz
4
1998?
0.02 Hz to >50 Hz
5.0 1999
0.02 Hz to >50 Hz
5.1
2000
0.02 Hz to >50 Hz
5.2
2001
Custom Models
Old CTBT
Prototype Model
Old CTBT Model
Replacements
only
Replacements
only
Replacements
only
Improved
Broadband #1
Improved
Broadband #2
Improved
Broadband #3
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0.01 Hz to 50 Hz
50
2005
0.01Hz to 50Hz
50A 2010
All new Design,
S.Steel, low noise,
Sealed Electronics
Diff. Output
Upgraded sensing
element with
improved linearity
Broadband Model
Broadband
Model
9-18
Not in Production
9-18
In Production
Since the acquisition of Chaparral Physics Consultants of NM, and converting it into the
Chaparral Physics division of the Geophysical Institute, University of Alaska, in early
2004, we have been in a continuous process of updating, improvements, and bringing the
Chaparral Physics product line sensors into the 21st century. With our new models in
production, the Model 25 and Model 50, we believe we have finally achieved significant
improvements in infrasound sensor technology.
The Model 50A is presently the king of all infrasound sensors; it has broadband response
and very low sensor self-noise. While it is an observatory grade sensor it can be used for
quick field deployments, as its IP 67 rating and all stainless steel and Acetal exterior are
weather resistant. It can be used to replace the MB2000 and MB2005, or any of the old
NBS sensors such as the N4, as it exceeds the performance of all of those sensors. It also
exceeds the performance of all of Chaparral Physics own broadband models, such as the
5.x series. Even if you only are interested in the 0.1 to 20 Hz near infrasound band, you
may want to consider the Model 50A as its noise specifications are much better than our
own more economical 20 series.
The Model 25 is the current successor to the original Globe and Chaparral Physics
Consultant’s lines of sensors. The Model 25 exceeds the performance of all our own past
Model 2.x sensors also. The Model 25 has a built-in 4 port manifold complete with
Garden hose thread connectors, with an option for 1 to 12 inlet ports, thus potentially
saving you the cost of building manifolds for use with wind noise reducing systems. The
Model 21 is the same as the Model 25 but without the multiport manifold. The Model 20
and 24 are cost reduced versions of the 21/25 respectively.
Acoustic Spectrum of Gravity Waves thru Infrasound to Ultrasound
16,000 Hz
Near Infrasound
200 Hz
Infrasound
Far Infrasound
50 Hz
16 Hz
1.0 Hz
0.1 Hz
0.01 Hz
Gravity Waves
Audible Sounds
(Limits of human hearing)
Ultrasound
Model 25
Model 50
Figure 1, Relationship of Chaparral Physics sensor models to the Infrasound Bands.
Page 2 of 3
Sensor noise plots and response plots
Power Spectral Density Plot
0
Print Date:27-Feb-2007 10:05
10:00
Global Low Wind Median Curve - Red Dash
Global Low Noise Curve - Blue Dash
Noise Pa 2/Hz @ 1Hz
061886 M25 = -69.2 dB
061889 M50 = -84.7 dB
-20
dB relative to 1 Pa2/Hz
-40
-50
-60
-70
-80
-90
-100
Band Limited RMS Noise from 0.5 to 2Hz and 0.10 to 50.00 Hz in mPa
061886 M25 = 0.371 & 1.29
-110
Band Limited RMS Noise from 0.5 to 2Hz and 0.01 to 50.00 Hz in mPa
061889 M50 = 0.0679 & 0.208
-120
-3
10
-2
10
-1
10
0
10
Freq Hz
1
10
2
10
3
10
Figure 2, Typical Chaparral Physics sensor self noise plots for both the Model 50 (Red)
and Model 25 (Violet). The Red dotted line is the Global Low Wind median noise curve
of a collection of globally diverse infrasound stations. The Blue dotted line is the Global
Low Noise Curve derived from the lowest noise measured at any of the global stations at
each frequency. In cases where low noise is important one should consider using the
Model 50 even if the broad bandwidth of the Model 50 is not need, since the Model 50
has a lower sensor self noise, than the Model 25.
The global noise data is extracted from: Bowman, J.R., G.E. Baker, and M. Bahavar, Ambient Infrasound
Noise, Geophys. Res. Lett., 32, L09803, doi: 10.1029/2005GL022486, 2005, and private communications.
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