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4.3 Baud Rate Selection
Baud rate selection can be performed by sending the appropriate configuration sentence to the sensor
board as described in the NMEA input sentences selection. (Section 4.1)
4.4 One-Pulse-Per-Second Output
The highly accurate one-pulse-per-second output is provided for applications requiring precise timing
measurements. The signal is generated after the initial position fix has been calculated and continues
until power down. The rising edge of the signal is synchronized to the start of each GPS second.
Regardless of the selected baud rate, the information transmitted by the GPS 35LP receiver is
referenced to the pulse immediately preceding the NMEA 0183 RMC sentence.
The accuracy of the one-pulse-per-second output is maintained only while the GPS 35LP can compute a
valid position fix. To obtain the most accurate results, the one-pulse-per-second output should be
calibrated against a local time reference to compensate for cable and internal receiver delays and the
local time bias.
The default pulse width is 100 msec, however; it may be programmed is 20 msec increments between 20
msec and 980 msec as described in $PGRMC Section 4.1.3 character <13>.
4.5 RTCM Received Data
Position accuracy of less than 5 meters can be achieved with the GPS 35LP by using Differential GPS
(DGPS) real-time pseudo-range correction data in RTCM SC-104 format, with message types 1, 2, 3,
and 9. These corrections can be received by the GPS 35LP receiver on RXD2. Correction data at
speeds of 300, 600, 1200, 2400, 4800 or 9600 baud can be utilized, as the GPS 35LP automatically
detects the incoming baud rate. For details on the SC-104 format, refer to RTCM Paper 134-89/SC 104-
68 by the Radio Technical Commission for Maritime Services.