Wavecom W61PC V7.5.0 - Manual (Page 153)

WAVECOM Decoder W61PC/LAN Manual V7.5 Transmission Modes  143
Parameter Value
Receiver settings FM, BW = 12 kHz
Input format(s) AF, IF
The entire call number is transmitted by consecutive tones in decade sequence.
In most systems the accuracy of the single frequencies has to be within +1/-1.5% of the nominal value.
If a DTMF call is received, the call sign is displayed on the monitor. In the Options menu a Time stamp
function can be enabled to add date and time to each call.
Tone Allocation
Digit Hz Digit Hz
0 941/1336 8 852/1336
1 697/1209 9 852/1477
2 697/1336 A 697/1633
3 697/1477 B 770/1633
4 770/1209 C 852/1633
5 770/1336 D 941/1633
6 770/1477 * 941/1209
7 852/1209 # 941/1477
Tone duration: 70 ms
DUP-ARQ
DUP-ARQ is a semi-duplex system. The radio channel is used by a DUP-ARQ system in the same way as a
simplex system, both stations alternating in transmitting blocks of five characters and a Hamming check-
sum. If a transmission error occurs a repeat request is initiated and the last data block is re-transmitted.
Parameter Value
Frequency range HF
Operation modes Semi-duplex ARQ
Modulation FSK
Symbol rate 125 Bd, variable 30-650 Bd
Receiver settings DATA, CW, LSB or USB
Input format(s) AF, IF
Additional Info ITA-2 with block coding
DUP-ARQ operates at a Symbol rate of 125 Bd on the radio link.
If only one station is sending data, the other station transmits an IDLE pattern and initiates RQ cycles in
case of transmission errors.
DUP-ARQ has automatic channel selection facilities. Before transmission starts, the best available short-
wave 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 two linked stations may
transmit at different frequencies.