User's Manual

Atlas PT Technical Manual
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begin sequentially numbering the MYID of the ATLAS PT transponders at ID 0001. The
second RV-M7 should be ID 0002, and so on.
The ATLAS PT transponders have internal clocks with 100 ticks-per-second. They can
measure time and initiate transmissions 100 times every second (every 10mS). The
TDMA time slot is configured to be some number of these ticks. The factory default
allocation is 200mS long TDMA slots, and thus in 10 seconds, up to 50 ATLAS PT
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 PT 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
Bit Number
(zero based)
Bit Mask
(hex format / decimal)
GGA
0
0×001 / 1
GLL
1
0×002 / 2
RMC
9
0×100 / 256
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.