WAVECOM Decoder W-PCI/e, W-CODE, W

Parameter Value

Frequency range

Operation modes

HF

FSK, Duplex ARQ

Modulation

Symbol rate

Receiver settings

Input format(s)

Additional Info

FSK

250.0 Bd

DATA, CW, LSB or USB

AF, IF

ITA-5 with block coding

DUP-ARQ-2 operates at a Symbol rate of 250 Baud on the radio link. A complete transmission cycle is 176 bits (704 ms). Both stations alternate in transmitting data blocks of 64 bits each.

The data format is 2 data blocks of 32 bits each. The blocks correspond to the DUP-ARQ (ARTRAC) system. Each of the two blocks contains a 5 bit checksum (inverted Hamming) for error detection and a single bit for the global parity (odd parity). Three 8 bit characters are transmitted in the data block. Two bits remain unused and are set to zero.

Special blocks defining IDLE, INTERRUPT and other special functions are transmitted. For these blocks the two normally unused bits specify the particular special functions with the combinations "10" or "11".

DUP-ARQ-2 has automatic channel selection facilities. Before transmission starts, the best available shortwave transmission channel is selected and its quality is continuously checked for the duration of the transmission. Within a given frequency range the system may select one of 5 possible channels which are spaced at 400 Hz intervals. Because of this channel selection mechanism the linked stations may transmit at different frequencies.

DUP-FEC-2

DUP-FEC-2 is a further development of the DUP-ARQ-2 system and the system characteristics are very similar. DUP-FEC-2 allows transmission of ITA-2 (Baudot) or ITA-5 (ASCII) characters.

Parameter Value

Frequency range

Operation modes

Modulation

HF

Broadcast/Duplex FEC

FSK

Symbol rate

Receiver settings

Input format(s)

Additional Info

125.0 and 250.0 Bd, variable 30-650 Bd

DATA, CW, LSB or USB

AF, IF

ITA-5 with block coding

DUP-FEC-2 has a radio channel rate of 125 or 250 Baud. A data frame is 32 bits long. For error protection a five bit CRC-sum (inverted Hamming) and a single bit for global parity (odd parity) is used.

DUP-FEC-2 is often used as a full-duplex system. As is the case with other full-duplex systems transmission simultaneously takes place on two different frequencies. If an error occurs special sequences are transmitted to signal this condition and a block repetition is requested (RQ).

If errors are received the two last 32 bit blocks are retransmitted when the radio channel rate is 125 Baud and three blocks when working at 250 Baud.

Like DUP-ARQ-2, DUP-FEC-2 has many special blocks for IDLE and RQ.

WAVECOM Decoder W-PCI/e, W-CODE, W-CLOUD Manual V8.3.00 Transmission Modes

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