20
3) If either the target sentence mode field or the target sentence description field is
not valid, the PGRMO sentence will have no effect.
4) $PGRMO,GPALM,1 will cause the sensor board to transmit all stored almanac
information. All other NMEA sentence transmission will be temporarily
suspended.
4.1.6
Tune DGPS Beacon Receiver (PSLIB)
The $PSLIB sentence provides the ability to tune a GARMIN GBR-21 or equivalent
beacon receiver.
$PSLIB,<1>,<2>*hh<CR><LF>
<1>
Beacon tune frequency, 0.0, 283.5 – 325.0 kHz in 0.5 kHz steps
<2>
Beacon bit rate, 0, 25, 50, 100, or 200 bps
If valid data is received, the GPS 25LP will store it in the EEPROM and echo the PSLIB
command to the beacon receiver. At power up or external reset, any stored frequency
other than 0.0 causes the GPS 25LP to tune the beacon receiver.
4.2 NMEA Transmitted Sentences
The subsequent paragraphs define the sentences which can be transmitted on TXD1
by the GPS 25LP sensor boards.
4.2.1
Sentence Transmission Rate
Sentences are transmitted with respect to the user selected baud rate.
Regardless of the selected baud rate, the information transmitted by the GPS 25LP is
referenced to the one-pulse-per-second output pulse immediately preceding the
GPRMC sentence.
The GPS 25LP will transmit each sentence (except where noted in particular
transmitted sentence descriptions) at a periodic rate based on the user selected baud
rate and user selected output sentences. The sensor board will transmit the selected
sentences contiguously. The contiguous transmission starts at a GPS second
boundary. The length of the transmission can be determined by the following equation
and tables:
total characters to be transmitted
length of transmission = --------------------------------------------
