Wavecom W74PC V8.7.0 - Manual (Page 239)

WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V8.7.0 Transmission Modes
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SAT-B-C-TFC
SAT-B-C-TFC mode is used to monitor the C-band return signal of SAT-B, down converted to an IF of 70
MHz.
Parameter Value
Frequency range C-Band
Operation modes Inm-B (Return Msg Chnl)
Symbol rate 12000 Bd
Modulation OQPSK
Required SNR >15 dB (20 dB recommended)
Input format(s) IF
Unlike the other SAT Modes, this mode does not automatically select a frequency. The user has to manual-
ly set the frequency and offset to the desired signal, which will then not be interfered with or changed by
the mode. The signal level should be at least 16dB over noise - a 20dB level will produce good results.
Session start and end are automatically recognized, but if the signal is too weak meaningful sessions can-
not be decoded, and consequently a session file will not be generated, even if some intermittent decoding
has occurred. The mode has a filtering function, which deletes short session fragments having been termi-
nated by loss of synchronization.
The following services are decoded:
 Voice
 Low speed data
 Fax
Operation
With the help of the FFT-Analysis-Tool look for a SAT-B signal (bandwidth 20 kHz, OQPSK 12 kSym-
bol/sec) with a lot of traffic.
In the Satellite mode menu choose Inmarsat, SAT-B-C-TFC.
The Session Window displays the start and end of a session; only if the service of a session is recognized
it will be started, even if the "Progress" field increases its number. The "MES_ID" displayed is the return
MESId of the MES; the "Frequency" is a dummy value.
The Session List Window displays the results of the successfully decoded sessions. The decoded data is
saved as “_Dat.txt” or “_.WAV” files.
The data extracted from the SCPC frames is examined for duplicate or missing packets. In case of dupli-
cate packets the duplicate packet is discarded..
Especially the case of missing packets may be critical for subsequent upper protocol layer decoding there-
fore an error mark will be inserted into the file name as “_DatError.txt“. However, for some upper layer
protocols it is possible to reconstruct the missing data.
Additional information:
See “ SAT Settings… ” on page 43.
See “ SAT System ” on page 291.
SAT-B-C-HSD
SAT-B-C-HSD is used to monitor the return channel of SAT-B-HSD transmissions.
Parameter Value
Frequency range C-Band
Operation modes Inm-B (Return Msg Chnl)