Pccir – Wavecom W-SPECTRA (Automatic Monitoring System) V1.1.0 User Manual
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Transmission Modes
WAVECOM Monitoring System W-SPECTRA, W-SPEED Manual V1.1.0
TONE
SL=1
SL=2
SL=3
SL=4
SL=5
SL=6
TF
9
B
Q
Q
Q
1560
10
B
B
Q
Q
Q
1680
11
B
Q
Q
Q
1800
12
B
B
B
Q
Q
Q
1920
13
B
Q
Q
Q
2040
14
B
B
Q
Q
Q
2160
15
B
Q
Q
Q
2280
16
Q
Q
2400
17
Q
2520
Tone numbers (TN) and respective frequencies (TF) in Hz as well as modulation types (B = DBPSK, Q =
DQPSK) for the 6 Speed Levels (SL).
As propagation conditions change, PACTOR-III is able to select the most suitable speed level. Under very
poor conditions PACTOR-III changes to speed level 1, whereas, under optimum conditions, speed level 6 is
used. As in the previous PACTOR standards, the frame durations are still 1.25 seconds (short cycle) and
3.75 seconds (long cycle for data mode). Again, a long path option is available to enable contacts up to
40.000 km. In such a case, the duration of the short and long cycle is extended to 1.4 and 4.2 seconds,
respectively.
Initial link establishment is achieved using the frequency shift-keying (FSK) protocol of PACTOR-I, corre-
sponding to the lowest protocol level. If both calling and called stations are capable of PACTOR-III, auto-
matic switching to this protocol is done.
For data transmission, which is robust against all kinds of disturbances, a decision must be made, whether
a short or a long frame-length should be used. Each frame consists of the user data, a status byte, and
two CRC bytes. This input bit stream is then bit-interleaved and convolutional encoded. After that, the
symbol mapping for the different channels is done, and the resulting signals are applied to the DxPSK
modulators.
To extract the data from a PACTOR-III signal, the signal is demodulated with the appropriate number of
DxPSK-demodulators, according to the speed level. The center frequency must be adjusted to the center
between the lowest and highest tone in use. AFC (automatic frequency control) can be switched on or off.
After demodulation and bit synchronization, the symbols of the channels are combined to one bit stream,
which is de-interleaved and passed through a Viterbi-decoder. The CRC is used to check whether trans-
mission errors occurred. After successful synchronization, it may take several tens of seconds before any
text is output in the GUI.
In PACTOR-III, the data may be transmitted as ASCII without compression or can be compressed with
HUFFMAN or PSEUDO-MARKOV compression (PMC). In addition, run length encoding (RLE) is included.
PCCIR
The entire call number is transmitted by consecutive tones in decade sequence. When two identical digits
are to be transmitted consecutively, then an eleventh frequency is used as a repetition identifier.
Parameter
Value
Frequency range
VHF/UHF
Operation modes
Analogue Selcal
Modulation
FM, SUB tone
Receiver settings
FM, BW = 12 kHz