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Transmission Modes
WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V9.1.0
Following the address at the beginning of a frame, a message of any desired length may be sent. In the
case of numeric pagers, digits are sent in BCD code while for alphanumeric pagers the message is trans-
mitted using 7 bit ASCII codes.
The example shows the transfer of a message of 350 bits in frame 3. The first 32 bits of frame 3 are the
address codeword (Add). Then follow 4 1/2 frames equivalent to 9 x 32 bits which extend up to the next
synch word (SC). The remaining 62 bits fit into frame 0. If the frame containing the end of a message is
not required to send a new address, it is filled with IDLE codes until a new address or a new synch word
must be sent.
POCSAG mode uses direct frequency modulation. Proper decoding is only possible from the receiver IF
output.
POL-ARQ
POL-ARQ is a full-duplex system with two transmitting frequencies. The system is based on the SITOR-
ARQ alphabet. This alphabet having a 4:3 mark-space ratio allows error detection. Like all duplex systems,
POL-ARQ initiates a request for repetition cycle (RQ) when transmission errors occur.
Parameter
Value
Frequency range
HF
Operation modes
Duplex ARQ
Modulation
FSK
Symbol rate
100, 150 and 200 Bd, variable 30-650 Bd
Receiver settings
DATA, CW, LSB or USB
Input format(s)
AF, IF
POL-ARQ operates at a symbol rate of 100 and 200 Bd on the radio link.
To synchronize to this mode select a baud rate. By selecting the
Auto
button, the automatic determina-
tion of center frequency, shift frequency and baud rate is performed. Signal polarity (LSB or USB side-
bands) is automatically detected.
To maintain synchronization between the two duplex stations, both transmitters operate continuously. If
no data is transmitted an idle bit pattern is sent.
At 100 Bd the last three characters are repeated after the RQ character. At 200 Bd the last four characters
are repeated (5 character repetition cycle). Due to mode characteristics the character repetition cycle
must be controlled manually.
PRESS-FAX
The transmission of press fax images on short-wave is based on gray levels and specific IOC values. A
number of IOC assignments were modified for press image transmissions. These special characteristics are
taken into account in the PRESS-FAX software.
Parameter
Value
Frequency range
HF
Operation modes
Graphic mode, Broadcast
Center frequency
1900 Hz
Speed
60, 90, 120, 180 and 240 RPM, IOC 288, 352 and 576
Receiver settings
FAX, DATA, CW, LSB or USB
Input format(s)
AF, IF
