Dgps Beacon Information; Baud Rate Selection; One-Pulse-Per-Second Output - Garmin GPS 25 LP Technical Specification

<1> True east velocity, -514.4 to 514.4 meters/second
<2> True north velocity, -514.4 to 514.4 meters/second
<3> Up velocity, -999.9 to 9999.9 meters/second
4.2.15 DGPS Beacon Information (PGRMB)
The GARMIN proprietary sentence $PGRMB reports DGPS beacon information.
$PGRMB,<1>,<2>,<3>,<4>,<5>,K*<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
<3> Beacon SNR, 0 to 31
<4> Beacon data quality, 0 to 100
<5> Distance to beacon reference station in kilometers

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.

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 25LP
sensor boards 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
25LP 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 in 20 msec
increments between 20 msec and 980 msec as described in $PGRMC Section 4.1.3
character <13>.
27