© 2017 Jackson Labs Technologies, Inc. 13
Mini-JLT GNSS™ User Manual
GPS:INITial:TIME <hour,min,sec>
GPS:SYSTem:SELect [GPS | SBAS | QZSS | GAL | BD ^ GLO]
GPS:JAMlevel?
GPS:FWver?
GPS?
3.3.1 GPS:SATellite
This group of commands describe the satellite constellation.
3.3.2 GPS:SATellite:TRAcking:COUNt?
This query returns the number of satellites being tracked.
3.3.3 GPS:SATellite:VISible:COUNt?
This query returns the number of satellites (PRN) that the almanac predicts should be visible, given
date, time, and position.
3.3.4 NMEA Support
The following four commands allow the Mini-JLT GNSS™ GPSDO to be used as an industry
standard navigation GNSS receiver. The GPGGA,GPRMC, GPGSV, PASHR and GPZDA NMEA
commands comprise all necessary information about the antenna position, height, velocity, direction,
satellite info, fix info, time, date and other information that can be used by standard navigation
applications via the Mini-JLT GNSS™ serial interfaces.
Once enabled, Mini-JLT GNSS™ will send out information on the TTL and USB serial transmit pin
automatically every N seconds. All incoming serial commands are still recognized by Mini-JLT
GNSS™ since the serial interface transmit and receive lines are completely independent of one
another.
For compatibility with existing GPS-only products, the Mini-JLT GNSS™ GPSDO’s NMEA output
only uses the GPS NMEA sentence headers (GPGGA, GPGSV, etc.) regardless of the GNSS systems
enabled. Also, the GPGSV output uses a modified satellite numbering scheme as detailed in Section
3.3.8 to allow all different GNSS system satellites to be differentiated.
Please note that the position, direction, and speed data is delayed by one second from when the GPS
receiver internally reported these to the Mini-JLT GNSS™ Microprocessor, so the position is valid
for the 1PPS pulse previous to the last 1PPS pulse at the time the data is sent (one second delay). The
time and date are properly output with correct UTC synchronization to the 1PPS pulse immediately
prior to the data being sent.
Once set, the following two commands will be stored in NV memory, and generate output
information even after power to the unit has been cycled.
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