Wavecom W74PC V8.7.0 - Manual (Page 237)

WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V8.7.0 Transmission Modes
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The RUM-FEC alphabet is designed to obtain a maximum Hamming distance for error detection and has
deep interleaving. The actual ITA-2 alphabet is not contained in the code table. As in HNG-FEC error cor-
rection is performed by table look-up of the bit pattern (character) closest resembling the character in er-
ror.
RUM-FEC has a bit interleaving of 128 bits, each new character starting at intervals of 16 bits. The soft-
ware synchronizes to traffic as well as idle bit patterns.
Error correction may be enabled or disabled using the ECC item in the Options menu.
In RUM-FEC mode the signal polarity (sideband) can be manually selected by toggling the Polarity item in
the Demodulator menu. If polarity changes during a transmission, synchronization will not be lost.
SAT-AERO-P, SAT-AERO-R, SAT-AERO-T
The SAT-AERO system carries digital voice, fax and low speed data. The channels between aeronautical
Ground Earth Stations (GES) and Aircraft Earth Stations (AES) are A-BPSK or A-QPSK modulated with
600, 1200, 4800, 8400,10,500 and 21,500 bps.
Parameter Value
Frequency range L-band/C-band
Operation modes, symbol rate,
modulation
Inm-Aero (Forward Pd and Psmc logical channels)
Forward:
- P-channel packet switched data TDM: 600 bps, 1200 bps A-BPSK
(SDPSK), 10.5 kbps A-QPSK (OQPSK), convolutional FEC R = ½, k = 7
- C-channel circuit mode SCPC: 8.4 kbps A-QPSK (OQPSK), convolution-
al FEC R = 2/3, k = 7, 10.5 kbps A-QPSK (OQPSK), convolutional FEC
R = ½, k = 7
Return:
- R-channel slotted Aloha: 600 bps, 1200 bps A-BPSK (SDPSK), 4.8
kbps, 10.5 kbps A-QPSK (OQPSK), convolutional FEC R = ½, k = 7
- T-channel TDMA: 600 bps, 1200 bps A-BPSK (SDPSK), 10.5 kbps A-
QPSK (OQPSK), convolutional FEC R = ½, k = 7
- C-channel circuit mode SCPC: 8.4 kbps A-QPSK (OQPSK), convolution-
al FEC R = 2/3, k = 7, 10.5 kbps A-QPSK (OQPSK), convolutional FEC
R = ½, k = 7
Modulation A-BPSK (Aviation-BPSK), symmetrical, differential PSK (SDPSK)
A-QPSK (Aviation-QPSK), a variant of offset QPSK
Required SNR >15 dB (20 dB recommended)
Input IF
Four channel types are used: P(acket switched), R(andom), T(DMA) and C(ircuit switched).
Two output formats may be selected, All Signaling Units or Messages Only. If All Signaling Units is
selected, all signaling units are shown in hexadecimal except empty signaling units, which are skipped. If
Messages Only is selected, packet-mode user data is converted to readable text.
To interpret decoded ACARS messages following options are available:
Reassemble multipart ACARS messages
This setting enables the reassembling of long messages which are sent in several parts. Instead of dis-
playing each part separately, the messages are shown as one single message when the last part has been
received. The message header is still displayed separately for each part.
Parse ADS-C messages
This setting enables the parsing of ADS-C messages (Automatic Dependent Surveillance - Contact). When
an ADS-C message is received, it is decoded and the additional information is displayed in the output win-
dow.