8
Name Example
Units
Description
Message ID
$GPGSV
GSV protocol header
Number of Messages
2
Range 1 to 3
Message Number
1
Range 1 to 3
Satellites in View
07
Satellite ID
07
Channel 1 (Range 1 to 32)
Elevation
79
degrees
Channel 1 (Maximum 90)
Azimuth
048
degrees
Channel 1 (True, Range 0 to 359)
SNR (C/No)
42
dBHz
Range 0 to 99, null when not tracking
.... ....
Satellite ID
27
Channel 4 (Range 1 to 32)
Elevation
27
degrees
Channel 4 (Maximum 90)
Azimuth
138
degrees
Channel 4 (True, Range 0 to 359)
SNR (C/No)
42
dBHz
Range 0 to 99, null when not tracking
Checksum *71
End of message termination
NOTE: Items ,, and repeat for each satellite in view to a maximum of four (4) satellites per sentence.
Additional satellites in view information must be sent in subsequent sentences. These fields will be null if unused.
2.2.1.4 Recommended Minimum Specific GNSS Data (RMC)
Table 2-8 contains the values for the following example:
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598, ,*10
Table 2-8 RMC Data Format
Name Example
Units
Description
Message ID
$GPRMC
RMC protocol header
UTC Time
161229.487
hhmmss.sss
Status
A
A=data valid or V=data not valid
Latitude 3723.2475
ddmm.mmmm
N/S Indicator
N
N=north or S=south
Longitude 12158.3416
dddmm.mmmm
E/W Indicator
W
E=east or W=west
Speed Over Ground
0.13
knots
Course Over Ground
309.62
degrees
True
Date 120598
ddmmyy
Magnetic Variation1
degrees
E=east or W=west
Checksum *10
End of message termination
1.SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are geodetic
WGS84 directions.
2.2.2 RTCM Received Data
The default communication parameters for DGPS Input are 9600 baud, 8 data bits, stop bit, and no parity. Position
accuracy of less than 5 meters can be achieved with the GPS-270 by using Differential GPS (DGPS) real-time
pseudo-range correction data in RTCM SC-104 format, with message types 1,2, or 9. As using DGPS receiver with
different communication parameters, GPS-270 may decode the data correctly to generate accurate messages and save them
in battery-back SRAM for later computing.