190-00879-08 GPS 18x Technical Specifications Rev. BPage 204.2.15 DGPS Beacon Information (PGRMB)Note: The GPS 18x products do not support PGRMB at this time.$PGRMB,<1>,<2>,<3>,<4>,<5>,K,<6>,<7>,<8>*hh<1> No Effect (This field is not used on this model and is included only for backwards compatibility)<2> No Effect (This field is not used on this model and is included only for backwards compatibility)<3> No Effect (This field is not used on this model and is included only for backwards compatibility)<4> No Effect (This field is not used on this model and is included only for backwards compatibility)<5> Distance to beacon reference station in kilometers<6> No Effect (This field is not used on this model and is included only for backwards compatibility)<7> DGPS fix source (R = RTCM, W = WAAS, N = Non-DGPS Fix)<8> DGPS mode, A = Automatic, W = WAAS Only, R = RTCM Only, N = None (DGPS disabled)4.3 BAUD RATE SELECTIONBaud rate selection can be performed by sending the appropriate configuration sentence to the GPS sensor asdescribed in the $PGRMC section 4.1.2 Sensor Initialization Information (PGRMI), field <10>.4.4 MEASUREMENT PULSE OUTPUT (GPS 18x LVC & 18x-5Hz ONLY)4.4.1 One-Pulse-Per-Second (PPS) Output (GPS 18x LVC Only)The highly accurate one-pulse-per-second (PPS) output is provided for applications requiring precise timingmeasurements. After the initial position fix has been calculated, the PPS signal is generated and continues until theunit is powered down. The rising edge of the signal is aligned to the start of each GPS second within 1 μs for allconditions in which the re ceiver has reported a valid and accurate position for at least the previous 4 seconds.The NMEA 0183 sentences that follow each rising edge of the PPS signal tell when you were and where you were atthat previous rising edge of the PPS signal, beginning with the GPRMC sentence as the lead sentence in anyparticular NMEA 0183 record.Regardless of the selected baud rate, the information transmitted by the GPS 18x series products is referenced to thepulse immediately preceding the NMEA 0183 RMC sentence.The accuracy of the one-pulse-per-second output is maintained only while the GPS receiver is computing a validposition fix. To obtain the most accurate results, the one-pulse-per-second output should be calibrated against a localtime reference to compensate for cable and internal receiver delays and the local time bias.The default pulse width is 100 ms, however; it may be programmed in 20 ms increments between 20 ms and 980 msas described in $PGRMC section 4.1.2 Sensor Initialization Information (PGRMI), field <13>.4.4.2 Five-Pulse-Per-Second Output (GPS 18x-5Hz Only)The highly accurate five-pulse-per-second output is provided for applications requiring precise timingmeasurements. After the initial position fix has been calculated, the GPS 18x-5Hz generates the pulse signal, whichcontinues until power down. The rising edge of the signal is aligned to the start of each GPS second within 1 μs forall conditions in which the receiver has reported a valid and accurate position for at least the previous 4 seconds.The NMEA 0183 sentences that follow each rising edge of the Measurement Pulse Output signal tell when andwhere you were at that previous rising edge of the Measurement Pulse Output signal, beginning with the GPRMCsentence as the lead sentence in any particular NMEA 0183 record.Regardless of the selected baud rate, the information transmitted by the GPS 18x-5Hz is referenced to the precedingfive times per-second output pulse.The accuracy of the five-pulse-per-second output is maintained only while the GPS 18x-5Hz can compute a validposition fix. To obtain the most accurate results, the five-pulse-per-second output should be calibrated against alocal time reference to compensate for cable and internal receiver delays and the local time bias.The default pulse width is 100 ms, however; it may be programmed in 20 ms increments between 20 ms and 180 msas described in $PGRMC section 4.1.2 Sensor Initialization Information (PGRMI), field <13>.
