Wavecom W-SPECTRA (Automatic Monitoring System) V1.1.0 - Manual (Page 95)

WAVECOM Monitoring System W-SPECTRA, W-SPEED Manual V1.1.0 Transmission Modes
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cooperative monitoring and thus complete and correct data output is fully dependent on error-free recep-
tion – there is no way to ask for re-transmission.
As transmissions do not contain source or destination addresses the monitor in case of single-frequency
half-duplex traffic must manually select the party to monitor. This may be achieved by adjusting the re-
ceiver squelch, adjusting the receiver HF gain or the use of directional antennas to suppress the unwanted
signal.
Real-time monitoring issues
To capture the contents of a CODAN modem data transmission the monitoring equipment should be placed
as close as possible to the transmitter site of the interesting party. This is the only way to ensure that the
quality of the signal is sufficient to secure that all transmitted packets are correctly captured.
To facilitate the decoding of data the WAVECOM decoder in addition to outputting the decoded data in the
decoder window also saves raw channel data with sequence numbers and including bad packets to a text
file. The text file may be processed manually or by a user provided application.
COQUELET-13
COQUELET-13 is an asynchronous system and uses a start and idle tone of 1052 Hz. As with COQUELET-8,
the first group contains 8 tones for keying, and the second group 4 tones.
Parameter Value
Frequency range HF
Operation modes Asynchronous simplex
Modulation MFSK-13
Speed 50.0 or 75.0 ms
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-2
COQUELET-13 has a tone duration of 75 ms which is equivalent to a 50 Bd Baudot transmission, with 1.5
stop bits. Two code tables are defined for this mode, Code Table 0 and Code Table 1.