Jackson Labs RSR GNSS Transcoder, Руководство пользователя

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© 2017 Jackson Labs Technologies, Inc. 37
RSR GNSS Transcoder™ User Manual
DC SIGNAL LEVEL: 1.17
HEAT PACKAGE: 9.34
TEMPERATURE: 38.57
SN: 1607CS06361
FIRMWARE REV: 1.09
LIFETIME: 740
POWER: ON
On units without the optional CSAC oscillator The RSR GNSS Transcoder™ will discipline its
internal TCXO to an external 1PPS reference when provided. Before the CSAC achieves atomic lock
which typically takes less than 3 minutes after power-on, the system timing uses the internal TCXO
as the timing and frequency reference. In the event that the CSAC GPSDO fails to obtain an atomic
lock or fails during operation after obtaining atomic lock, the internal TCXO will be used for system
timing instead. To enable calibration of the built-in TCXO-based GPSDO or to reduce the overall
power consumption, the CSAC can also be manually disabled with the CSAC:POWer command
which will power-down the internal CSAC and revert to TCXO disciplining only. The ON/OFF
power status of the CSAC is output on the last line of the CSAC? query response as seen above.
3.8.16 Monitoring the External and Internal GNSS Receivers
An optional external GPS receiver can provide a PVT serial data stream to be transcoded and
simulated using the 1PPS timing reference for time synchronization and internal TCXO/CSAC
oscillator disciplining. This PVT data stream can be monitored using the standard GPS SCPI
subsystem common to many JLT GPSDO products with commands such as SERV?, SYST:STAT?,
GPS? and others. Details of each GPS command are available in Section
4.10.3 .
The RSR GNSS Transcoder™ also includes an internal GNSS receiver for monitoring the transcoded
or simulated GPS RF signals for accuracy, power level, and correctness. The status of this internal
GNSS receiver is monitored through the INTGPS SCPI subsystem that has many of the same
commands available as the GPS SCPI subsystem. It is possible to send the 1Hz NMEA output stream
of the internal GPS monitoring receiver to the USB serial port via SCPI commands. Details of the
various different INTGPS command are available starting in Section
4.11.1 .
3.8.16.1 External Rockwell Microgram and RSR Features
The RSR GNSS Transcoder™ supports special features when an external Rockwell Collins
Microgram or Rockwell Collins RSR SAASM receivers with updated, custom JLT firmware are
connected. These features include DAGR Pass-Through mode and SAASM key-fill status
monitoring.
A DAGR Pass-Through hot-start assisted mode is available when a DAGR is connected to the
COM2 interface on the external Microgram or RSR. This mode allows hot-starting the MicroGRAM
or RSR receiver by automatically transferring almanac, ephemeris, time, date, and position data from
the external DAGR to the MicroGRAM/RSR. The DAGR Pass-Through mode can be controlled
through the RSR GNSS Transcoder™’s SCPI interface. In DAGR Pass-Through mode the PVT data
including the 1PPS reference from an external DAGR device is used in place of the PVT data
generated by the MicroGRAM or RSR. Using a DAGR that already has a GPS fix, the SAASM HD