Wavecom W61PC V7.5.0 - Manual (Page 244)

234  Transmission Modes WAVECOM Decoder W61PC/LAN Manual V7.5
SITOR-TWINPLEX systems employ the second channel to double the data transmission rate from the
equivalent of 50 Bd to 100 Bd. The V1 and V2 channels each contain 3 telegraph characters from the SI-
TOR alphabet.
Parameter Value
Frequency range HF
Operation modes Simplex ARQ
Modulation 4FSK
Symbol rate 100 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info SITOR Alphabet
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.