G-TOR operates as a synchronous ARQ mode, like AMTOR and Pactor. At 300,
200, or 100 baud, G-TOR’S ARQ cycle remains at 2.4 seconds. All data frames
are 1.92 seconds in duration and contain one control byte and two checksum
bytes (CRC). Data frames contain 69, 45, and 21 data bytes at 300, 200, and 100
baud respectively. Acknowledgements are 0.160 seconds in duration. The effec
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tive performance of two stations linked in G-TOR relies on the combined use of
forward error correction, data interleaving, and its ARQ cycle with CRC check
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ing. Operation in the G-TOR mode is described in the following sections.
G-TOR activity, at present, is found on all the HF bands near AMTOR and
RTTY. CW will typically be found at the bottom of the digital portion of each
band while AMTOR, RTTY, G-TOR, and Pactor are higher up the band in fre
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quency. For example, on 20 meters, activity can generally be found as listed be-
low. Note that G-TOR, Pactor, and AMTOR may tend to overlap.
CW 14.000 - 14.070 MHz
AMTOR, G-TOR, Pactor 14.070 - 14.085 MHz
RTTY 14.080 - 14.095 MHz
Packet 14.095 - 14.111 MHz
G-TOR Operation
The G-TOR protocol is a linked mode where two stations communicate with
each other. Although the G-TOR mode does not incorporate a broadcast mode,
G-TOR uses AMTOR fec for its broadcasts (from G-TOR Standby), such as call
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ing CQ. If you have the MONITOR command turned on when entering the
G-TOR mode, you will be able to monitor AMTOR fec transmissions.
The following example illustrates G-TOR operation with your KAM’98.
Turn the MONITOR command ON by typing MONITOR ON at the command
prompt (cmd:) and press return. This will enable you to copy CQ calls.
The G-TOR mode will use the mark and space tones set in your KAM’98. The
default values for these are MARK 2125 and SPACE 2295. You may wish to
change these to permit use of filtering or IF shift tuning in your radio.
Next, place your KAM’98 in G-TOR mode by typing GTOR at the command
prompt and pressing return. Your KAM’98 will respond with G-TOR STANDBY.
If you now tune your KAM’98 to a station transmitting AMTOR FEC, you’ll be
G-TOR Mode Non-Packet Modes of Communication
KAM’98 v 8.3 127 User’s Guide
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