Wavecom W61PC V7.5.0 - Manual (Page 123)

WAVECOM Decoder W61PC/LAN Manual V7.5 Transmission Modes  113
Parameter Value
Frequency range HF
Operation modes Duplex ARQ TDM
Modulation FSK
Symbol rate 96, 87 and 200 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-3
ARQ-M2-342 and ARQ-M2-242 systems operate at Symbol rates of 85.7, 96 or 200 Baud on the radio link.
The ITA-3 7-bit alphabet is used allowing error detection. The ITA-3 alphabet is a balanced code in which
each character has a mark-space bit ratio of 3:4. ARQ-M2-342 and ARQ-M2-242 systems are full-duplex
systems.
Full-duplex systems send a repeat request (RQ) character to the remote station if a character error has
been detected or the distortion or fading becomes excessive. This results in the re-transmission of the last
3 or 7 characters preceded by the RQ request control character.
According to the CCITT recommendation, the repetition cycle may span 4 or 8 characters, as is the case
with ARQ-E. The longer RQ-cycle of 8 characters has never been monitored.
In addition to the time multiplexing of several channels (division channels); each division channel may be
further subdivided into sub-channels resulting in a multitude of possible modes of operation. At present
however no transmissions with sub-channel division are known. Systems employing sub-channel division
may be recognized by a rhythmic blinking of the Error indication (system state) in the decoder status bar.
ARQ-M4-342 and ARQ-M4-242
These operating modes also known as TDM or ARQ-56, conforming to the CCIR recommendations 342-2
and 242. Four 50 Bd Baudot channels are interleaved to form a time multiplexed aggregate bit stream.
Multiplex frames of 56 bits are used.
Parameter Value
Frequency range HF
Operation modes Duplex ARQ TDM
Modulation FSK
Symbol rate 172 and 192 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-3
ARQ-M4-342 and ARQ-M4-242 systems operate at a Symbol rate of 172 or 192 Baud on the radio link.
The ITA-3 7-bit alphabet is used allowing error detection. The ITA-3 alphabet is a balanced code in which
each character has a 3 to 4 ratio between mark and space bits (balanced code). ARQ-M4-342 and ARQ-
M4-242 are full-duplex systems.
Full-duplex systems send a repeat request (RQ) character to the remote station if a character error has
been detected or the distortion or fading becomes excessive. This results in the re-transmission of the last
3 or 7 characters preceded by the RQ request control character.
According to the CCITT recommendation, the repetition cycle may span 4 or 8 characters, as is the case
with ARQ-E. The longer RQ-cycle of 8 characters has never been monitored.
In addition to the time multiplexing of several channels (division channels); each division channel may be
further subdivided into sub-channels resulting in a multitude of possible modes of operation. At present