Jackson Labs RSR GNSS Transcoder, Руководство пользователя

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RSR GNSS Transcoder™ User Manual
38 © 2017 Jackson Labs Technologies, Inc.
CSAC GPSDO can immediately provide valid PVT data through the SCPI interface and discipline
the CSAC oscillator.
DAGR Pass-Through mode is especially useful when the MicroGRAM or RSR receiver does not
have valid almanac data which could take up to 12.5 minutes to download from the GPS satellites
before a GPS fix and valid UTC time is available. The DAGR pass-through mode is typically used
when the RSR GNSS Transcoder™ is deployed in a dismounted application, and the user is sitting
inside of a shielded vehicle such as a troop transporter etc, and cannot receive GNSS signals
themselves. In this case the vehicle DAGR with its externally mounted antenna can provide the
necessary PVT solution and almanac/ephemerides etc to enable continuous operation and
disciplining of the RSR GNSS Transcoder™ inside the vehicle for as long as the user’s MicroGRAM
or RSR receiver is connected to the DAGR DB-15 connector, and the DAGR is receiving valid GPS
fixes. The DAGR pass-through mode requires the JLT-specific Rockwell Collins NMEA firmware
load on the external MicroGRAM or RSR, and this firmware can only be loaded at the Rockwell
Collins factory and is only available to JLT customers.
The GPS:DAGR:MODE command described in Section
4.10.32 enables and disables the DAGR
Pass-Through mode. The GPS:DAGR:PVTstate? query command described in
Section
4.10.35 returns the status of the DAGR Pass-Through mode.
When in DAGR Pass-Through mode, the external DAGR can also provide Hot Start data to the
MicroGRAM or RSR, so the MicroGRAM or RSR can immediately obtain a GPS fix. Hot start data
includes precise time, GPS alamanc and ephemeris data, and current position. Once the SAASM HD
CSAC GPSDO is in DAGR Pass-Through mode, a Hot-Start transfer is initiated on the DAGRs user
menu.
The SAASM key, Y tracking status and key zeroizing of an external Microgram or RSR receive can
also be monitored and controlled through the RSR GNSS Transcoder™’s GPS:SASTAT...
commands. Details on the parameters that can be monitored and the zeroize function are available in
Section
4.10.36 through Section 4.10.46 .
An externally connected Rockwell Collins MicroGRAM, or RSR SAASM receiver may also be
zeroized by using pin 1 of connector J3. Grounding pin 1 of connector J3 during normal operation
through a switch etc will initiate a zeroize command to be sent to the externally connected SAASM
GPS receiver, and is thus useful as an emergency zeroize feature.