15
4.1.2 Sensor Initialization Information (PGRMI)
The $PGRMI sentence provides information used to initialize the GPS sensor’s last known
position and to set the time on the real time clock. This information is used by the GPS receiver
on the next power cycle to predict which satellites will be visible in the sky as an aid for more
rapid satellite acquisition. Receipt of this sentence by the GPS sensor during satellite acquisition
causes the software to restart the satellite acquisition process. If there are no errors in the
sentence, it will be echoed upon receipt. If an error is detected, the echoed PGRMI sentence will
contain the current default values. Current PGRMI defaults (with the exception of the Receiver
Command, which is a command rather than a mode) can also be obtained by sending
$PGRMIE<CR><LF> or $PGRMIE*04<CR><LF> to the GPS sensor.
$PGRMI,<1>,<2>,<3>,<4>,<5>,<6>,<7>*hh<CR><LF>
<1> Latitude, ddmm.mmm format (leading zeros must be transmitted)
<2> Latitude hemisphere, N or S
<3> Longitude, dddmm.mmm format (leading zeros must be transmitted)
<4> Longitude hemisphere, E or W
<5> Current UTC date, ddmmyy format
<6> Current UTC time, hhmmss format
<7> Receiver Command, A = Auto Locate, R = Unit Reset
4.1.3 Sensor Configuration Information (PGRMC)
The $PGRMC sentence provides information used to configure the GPS sensor’s operation.
Configuration parameters are stored in non-volatile memory and retained between power cycles.
The GPS sensor will echo this sentence upon its receipt if no errors are detected. If an error is
detected, the echoed PGRMC sentence will contain the current default values. Current default
values can also be obtained by sending $PGRMCE<CR><LF> or $PGRMCE*0E<CR><LF> to
the GPS sensor.
$PGRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>,<13>,<14>*hh<CR><LF>
<1> Fix mode, A = Automatic, 3 = 3D exclusively
<2> Altitude above/below mean sea level, -1500.0 to 18000.0 meters
<3> Earth datum index. If the user datum index (96) is specified, fields <4> through <8> must
contain valid values. Otherwise, fields <4> through <8> must be null. Refer to Appendix A:
Earth Datum List for a list of earth datum and the corresponding earth datum index.
<4> User earth datum semi-major axis, 6360000.000 to 6380000.000 meters (.001 meters
resolution)
<5> User earth datum inverse flattening factor, 285.0 to 310.0 (10
-9
resolution)
<6> User earth datum delta x earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<7> User earth datum delta y earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<8> User earth datum delta z earth centered coordinate, -5000.0 to 5000.0 meters (1 meter
resolution)
<9> Differential mode, A = Automatic (output DGPS data when available, non-DGPS otherwise),
D = Differential exclusively (output only differential fixes)
<10> NMEA 0183 Baud rate, 3 = 4800, 4 = 9600, 5 = 19200, 8 = 38400
<11> No Effect (This field is not used on the GPS 15xH/15xL and is included only for compatibility
with other models.)
<12> PPS mode, 1 = No PPS, 2 = 1 Hz
<13> PPS pulse length, 0-48 = (n+1)*20 ms. Example: n = 4 corresponds to a 100 ms wide pulse
<14> Dead reckoning valid time 1 to 30 seconds
All configuration changes take effect after receipt of a valid value except baud rate. Baud rate
changes take effect on the next power cycle or an external reset event.