Jackson Labs FireFly-1A GPSDO, Руководство пользователя

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FireFly-1A User Manual
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.
3.3.5 GPS:GPGGA
This command instructs the FireFly-1A to send the NMEA standard string $GPGGA every N
seconds, with N in the interval [0,255]. The command is disabled during the initial 4 minute OCXO
warmup phase.
This command has the following format:
GPS:GPGGA <int> [0,255]
GPGGA shows height in MSL Meters, this is different from traditional GPS receivers that display
height in GPS Meters. The difference between MSL and GPS height can be significant, 35m or more
are common.
3.3.6 GPS:GGASTat
This command instructs the FireFly-1A to send a modified version of the NMEA standard string
$GPGGA every N seconds, with N in the interval [0,255]. The command is disabled during the initial
7 minute OCXO warmup phase.
This command has the following format:
GPS:GGASTat <int> [0,255]
This command replaces the regular NMEA GGA validity flag with a decimal number indicating the
lock-state of the unit. Please see section SERVo:TRACe for a detailed description of the lock state
variable. The command allows capture of the position and other information available in the GGA
command, as well as tracking the lock state and health of the unit’s OCXO performance.
GGASTat shows height in MSL Meters, this is different from traditional GPS receivers that display
height in GPS Meters. The difference between MSL and GPS height can be significant, 35m or more
are common.
3.3.7 GPS:GPRMC
This command instructs the FireFly-1A to send the NMEA standard string $GPRMC every N
seconds, with N in the interval [0,255]. The command is disabled during the initial 4 minute OCXO
warmup phase.
This command has the following format:
GPS:GPRMC <int> [0,255]
3.3.8 GPS:XYZSPeed
Firmware version 0.909 and later add a 3D velocity vector output command. Enabling this command
will output a 3 dimensional velocity vector indicating the unit’s speed in centimeters per second as
well as the Time Of Week in milliseconds.
X, Y, and Z speed are individually given, and are independent of each other. An accuracy estimate in
centimeters per second is also given. The velocity data is time-stamped using the time-of-week with