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The ATLAS PL transponders have internal clocks with 20 ticks-per-second. They
can measure time and initiate transmissions 20 times every second (every 50mS).
The TDMA time slot is configured to be some number of these ticks. The factory
default allocation is 4-ticks for one time-slot. So each TDMA time slot is 200mS
long, and thus in 10 seconds, up to 50 ATLAS PL transponders may report
position. These parameters are programmable, and may be re-configured based
upon the type of system they are used in.
Normally, the time slot is the same as the radio's ID. But, the user may modify the
time slot without affecting the ID of the unit by using the SLOTNUM command.
SLOTNUM xx will set the slot number to xx without affecting the ID. Once the
SLOTNUM command is used, the slot number will not change when the ID is
changed.
6.7.
Local NMEA data from the internal GPS
The Atlas PL personal locator may be configured to output standard NMEA 0183
GPS messages from its internal GPS receiver. For GPS tracking, these GPS
transponders can receive GPS position reports from other radios, and they may
also be configured to output their own GPS location via their serial port.
Following is a list of the NMEA messages that are available (as of revision C2 of
the Firmware).
NMEA
Message
GGA
GLL
RMC
Once you set the "GPS Mode" of the radio using the GPS X command, you can
change the NMEAMASK parameter to modify with of the NMEA sentences will
come out the serial port.
For example, to have only the RMC sentence come out the serial port, use the
following command"
NMEAMASK 256
To have the GGA and GLL come out the serial port use this command:
NMEAMASK 3
The NMEAMASK parameter is the sum of all of the decimal values of the individual
bits corresponding to the NMEA messages.
M7 PL Technical Manual
Bit Number
(zero based)
0
1
9
32
Bit Mask
(hex format / decimal)
0×001 / 1
0×002 / 2
0×100 / 256
Raveon Technologies Corp.
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