WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V9.1.0 Transmission Modes
263
100 Bd, variable 30-650 Bd
Twinplex transmissions can have widely varying shifts. Seven standard combinations are available from
the Shift item of the Demodulator menu:
 100-100-100 Hz
 200-400-200 Hz
 170-170-170 Hz
 115-170-115 Hz
 200-200-200 Hz
 115-170-515 Hz
 65-170-65 Hz
In addition, any desired combination may be programmed.
In addition to shift variations, Twinplex systems may utilize very different keying assignments. On the V1
and V2 channel the software allows the selection of Y-Y-B-B, Y-B-Y-B, B-Y-Y-B, B-Y-B-Y, Y-B-B-Y settings
via the Y-B V1 Channel item in the Options menu. In the Y-B V2 Channel menu one of four combinations is
selectable.
Most Twinplex stations work with the V1 combination of Y-Y-B-B and Y-B-Y-B (or B-Y-B-Y) in the V2 chan-
nel. Transmissions with a B-Y-B-Y combination in V1 and Y-B-B-Y in V2 are however also possible.
TWINPLEX (F7B) Principle of Operation
Measurement and Determination of TWINPLEX Frequency Shifts
Proper tuning is done using the FSK Analysis. The frequency shifts may be measured using the cursors.
The effective center frequency is the mid-frequency between the two inner tones f2 and f3. This is also
valid in case of asymmetrical shifts, e.g., 115-170-515 Hz.
After the measurements and the determination of the V1 and V2 frequencies, the values found must be
set up via the Shift item in the Options menu.
If no standard combination is used, the shift dialog box will allow the entry of any combination.
After the previously described set-up has been completed, the TWINPLEX mode can now be started by se-
lecting 100.0 Bd or a variable baud rate.
The preferred demodulator type is the MFSK mode: Otherwise the DSP mode may be enabled in the De-
modulator menu using the Mode item.
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