15Monitoring The Optional Csac Oscillator - Jackson Labs RSR GNSS Transcoder User Manual

RSR GNSS Transcoder™ User Manual
SIM:MODE MANUAL
SIM:TIME:MODE CONT
SIM:POS:LLH 36,-115,500
The spoofed position in the SIM:POS:LLH command should be nearby the position of the antenna
(within 1000 km) so that the simulated and spoofed satellites are visible at the same time. The current
ephemeris and ionospheric correction data can be uploaded with the SIM:LNAV... commands
described starting in Section
available from a receiver tracking live-sky signals.
Next, confirm that the system time has been updated with the current gps system time with the
command:
PTIME?
If the time and date lines from the query output show the current time and date then the system time
is synchronized.
Finally, the source for the navigation data and the initial RF output power are set, and the simulation
is started with the following commands:
SIM:LNAV:SELect USER
OUT:POWer -125dBm
SIM:COMMAND START
During the spoofing test, the output power is increased from -125dBm with the OUT:POWer
command until the output power is greater than the mixed live-sky signals. Without an external
amplifier the output power can be set as high as -105dBm. An external amplifier may be required in
some cases if power levels above -105dBm are needed.
At some point the target receiver will start tracking the spoofed signals instead of the live-sky signals
and the target receiver's reported position will jump to the simulated spoofed position. Having the
spoofed position very close (<100m) from the antenna position may reduce the output power
required to pull the target receiver away from the live-sky signals. This behavior is very dependent on
the design of the target receiver, and the relevant RF power levels.
3.8.15 Monitoring the optional CSAC Oscillator
The RSR GNSS Transcoder™ with optional CSAC oscillator contains an integrated CSAC GPSDO
module with the same monitoring and control features that the JLT CSAC GPSDO module provides.
The following example CSAC status output is returned in response to the CSAC? query:
RS232: OK
STEER: -35
STATUS: 0
ALARM: 0x0000
MODE: 0x0040
CONTRAST: 3608
LASER CURRENT: 0.98
TCXO VOLTAGE: 1.549
36
4.3.47 . This process could be automated if the raw subframe data were
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