Wavecom W61PC V7.5.0 - Manual (Page 122)

112  Transmission Modes WAVECOM Decoder W61PC/LAN Manual V7.5
Parameter Value
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-2 with parity and identification bit
ARQ-E synchronization may be started by the selection of a baud rate. An AUTO program start causes the
automatic determination of the frequency shift and baud rate to be executed first. The signal polarity (USB
or LSB sidebands) is automatically detected.
After synchronization to an ARQ-E system has been achieved, the detected repetition rate is displayed (4,
5 or 8 cycles). This parameter may give clues to the identity of the transmission.
If a continuously repeated character (often FFFF) is decoded whilst working in the ARQ-E mode, it is most
likely an ARQ-E3 system being monitored. ARQ-E employs the ARQ-1A alphabet with parity checking
which allows the detection of transmission errors.
Full-duplex systems transmit a RQ character after having detected an erroneous character or in the pres-
ence of excessive signal distortions. The remote station subsequently repeats the last three, four or seven
characters preceded by the RQ character.
To maintain synchronization between the two stations both transmitters operate continuously and send
the idle bit pattern if no traffic is transmitted.
ARQ-E3
ARQ-E3 systems often operate at Symbol rates of 48, 50, 96, 192 and 288 Baud on the radio link.
Parameter Value
Frequency range HF
Operation modes Full-duplex ARQ
Modulation FSK
Symbol rate 48, 50, 96, 192 and 288 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-3
ARQ-E3 synchronization may be started with the selection of a baud rate. An AUTO program start causes
the automatic determination of the frequency shift and baud rate to be executed first. The signal polarity
(USB or LSB sidebands) is automatically detected.
After synchronization to an ARQ-E3 system has been achieved the detected repetition rate is displayed (4
or 8 cycles). This parameter may give clues to the identity of the transmission.
If the same continuously repeated character (often FFFF) is decoded whilst working in the ARQ-E3 mode,
it is most likely an ARQ-E system which is being monitored. ARQ-E3 employs the ITA-3 alphabet (balanced
3:4 mark-space ratio) for data transmission and error detection.
Full-Duplex systems transmit a RQ character after having detected an erroneous character or in the pres-
ence of excessive signal distortions. The remote station subsequently repeats the last three or seven char-
acters preceded by the RQ character.
To maintain synchronization between the two stations both transmitters operate continuously and send
the idle bit pattern if no traffic is transmitted.
ARQ-M2-342 and ARQ-M2-242
These operating modes also known as TDM or ARQ-28, conforming to CCIR recommendations 342-2 and
242. Two 50 Bd Baudot channels are interleaved to form a time multiplexed aggregate bit stream. Multi-
plex frames of 28 and 56 bits are used.