Systemy nawigacji satelitarnej
Przemysław Bartczak
Transmisja między odbiornikiem GPS
a innymi urządzeniami
NMEA
NMEA (National Marine Electronics Association)
Protokół komunikacji wykorzystywany do komunikacji między morskimi
urządzeniami elektronicznymi i urządzeniami GPS.
Transmisja z komputera do urządzenia GPS :
$CCGPQ,GGA, [CR][LF]
Odpowiedz z odbiornika GPS:
$GPGGA,031956,2218.2035,N,11410.7595,E,1,04,3,9,005.9,M,-001.3,M,,*51
NMEA
Sentence
$GPGGA:
$GPGLL:
$GPGSA:
$GPGSV:
$GPRMC:
$GPVTG:
Description
Global positioning system fixed data
Geographic position - latitude / longitude
GNSS DOP and active satellites
GNSS satellites in view
Recommended minimum specific GPS data
Course over ground and ground speed
GGA Sentence Format
$GPGGA,092204.999,4250.5589,S,14718.5084,E,1,04,24.4,19.7,M,,,,0000*1F
Field
Example
Sentence ID
UTC Time
Latitude
N/S Indicator
Longitude
E/W Indicator
Position Fix
$GPGGA
092204.999
4250.5589
S
14718.5084
E
1
Satellites Used
HDOP
Altitude
Altitude Units
Geoid Separation
Seperation Units
Time since DGPS
DGPS Station ID
Checksum
04
24.4
19.7
M
*1F
Comments
hhmmss.sss
ddmm.mmmm
N = North, S = South
dddmm.mmmm
E = East, W = West
0 = Invalid, 1 = Valid SPS,
2 = Valid DGPS, 3 = Valid PPS
Satellites being used (0-12)
Horizontal dilution of precision
Altitude (WGS-84 ellipsoid)
M= Meters
Geoid separation (WGS-84 ellipsoid)
M= Meters
in seconds
always begin with *
GGA Sentence Format (2)
$GPGGA,092204.999,4250.5589,S,14718.5084,E,1,04,24.4,19.7,M,,,,0000*1F
• Fix quality:
– 0 = invalid
– 1 = GPS fix (SPS)
– 2 = DGPS fix
– 3 = PPS fix
– 4 = Real Time Kinematic
– 5 = Float RTK
GLL Sentence Format
$GPGLL,4250.5589,S,14718.5084,E,092204.999,A*2D
Field
ID
Latitude
N/S Indicator
Longitude
E/W Indicator
UTC Time
Status
Checksum
Example
$GPGLL
4250.5589
S
14718.5084
E
092204.999
A
*2D
Comments
ddmm.mmmm
N = North, S = South
dddmm.mmmm
E = East, W = West
hhmmss.sss
A = Valid, V = Invalid
GSA Sentence Format
$GPGSA,A,3,01,20,19,13,,,,,,,,,40.4,24.4,32.2*0A
Field
Sentence ID
Mode 1
Example
$GPGSA
A
Mode 1
Satellite used 1
.
.
.
Satellite used 12
PDOP
HDOP
VDOP
Checksum
3
01
24
2.5
1.3
2.1
*0A
Comments
A = Auto 2D/3D
M = Forced 2D/3D
1 = No fix, 2 = 2D, 3 = 3D
Satellite used on channel 1
Satellite used on channel 12
Position dilution of precision
Horizontal dilution of precision
Vertical dilution of precision
GSV Sentence Format
$GPGSV,3,1,10,20,78,331,45,01,59,235,47,22,41,069,,13,32,252,45*70
Field
Example
Sentence ID
$GPGSV
No. of messages 3
Sequence no.
1
Satellites in view 10
Satellite ID 1
20
Elevation 1
78
Azimuth 1
331
SNR 1
45
Satellite ID 2
01
Elevation 2
59
Azimuth 2
235
.
.
Checksum
*70
Comments
No. of messages in complete (1-3)
Sequence no. of this entry (1-3)
Range is 1-32
Elevation in degrees
Azimuth in degrees
Signal to noise ratio dBHZ (0-99)
Range is 1-32
Elevation in degrees
Azimuth in degrees
RMC Sentence Format
$GPRMC,092204.999,A,4250.5589,S,14718.5084,E,0.00,89.68,211200,,*25
Field
Sentence ID
UTC Time
Status
Latitude
N/S Indicator
Longitude
E/W Indicator
Speed over ground
Course over ground
UTC Date
Magnetic variation
Magnetic variation
Checksum
Example
$GPRMC
092204.999
A
4250.5589
S
14718.5084
E
0.00
0.00
211200
*25
Comments
hhmmss.sss
A = Valid, V = Invalid
ddmm.mmmm
N = North, S = South
dddmm.mmmm
E = East, W = West
Knots
Degrees
DDMMYY
Degrees
E = East, W = West
VTG Sentence Format
$GPVTG,89.68,T,,M,0.00,N,0.0,K*5F
Field
Sentence ID
Course
Reference
Course
Reference
Speed
Units
Speed
Units
Example
$GPVTG
89.68
89.68
89.68
0.00
N
0.00
K
Checksum
*5F
Comments
Course in degrees
T = True heading
Course in degrees
M = Magnetic heading
Horizontal speed
N = Knots
Horizontal speed
K = KM/h
NMEA-0183 data file
Other GPS NMEA sentences
Sentence
$GPALM:
$GPGRS:
$GPGST:
$GPMSS:
$GPZDA:
Description
GPS almanac data
GPS range residuals
GPS pseudorange noise statistics
Beacon receiver status
UTC and local date/time data