Wavecom W40PC, Manual

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WAVECOM Decoders v6.15 W40PC, W41PC, W51PC Transmission Modes
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117
kHz BPSK DSB subcarrier with suppressed carrier and a bitrate of 1187,5 bps. In the case of
ALF-RDS the transmission is made in SSB with a decreased pilot carrier to reduce bandwidth.
The RDS basic data unit is a group which consists of four blocks each having 16 data bits and
10 error detection and correction bits. Groups are divided into type A and B each containing 16
different groups.
In the upper window, a display mode can be selected. The default display mode is "All
Blocks", which displays the information of each block. "Raw Bits" will display the contents of
a group in binary format.
In the lower window, several things like various flags, time, program information and
transmitted text are displayed.
ALIS
Parameter Value
Frequency range HF
System Simplex ARQ system
Baudrate 228.66 Baud, variable 30-650 Baud
Modulation SSB or DIRECT-FSK
Receiver settings CW, LSB or USB
Signal source(s) AF, HF or IF
Alphabet ITA-2 with block coding
ALIS is a simplex system and operates at a speed of 228.66 Baud on the radio link.
ALIS is described in report 551-2 of the ITU "Reports of the CCIR 1990 - Fixed Services at
Frequencies below about 30 MHz”. The abbreviation ALIS is derived from
A utomatic Li nk
S
et-up.
The transmission block of the standard ARQ system consists of 2 identification bits, 30 data
bits and 16 CRC bits. Data transmission is transparent for ALIS. Known systems are however
structured around six ITA-2 characters.
The two identification bits indicate one of four possible system states. The CRC checksum
enables detection and correction of transmission errors.
The acknowledgement block is 16 bits in length. The total transmit-receive cycle for ALIS is
111 bits which corresponds to a duration of 485.4 ms. An error free transmission is equivalent
to a terminal baud rate of 100 Baud Baudot.
The ALIS system automatically determines the optimal operating frequency after having
received a CALL command. The station then sends a synchronization word, address, block
counter and a status word. The receiving station correlates this bit sequence and synchronizes
itself. If the data transmission link fails, ALIS will search for a new frequency to re-establish
the link.
ALIS-2
Parameter Value
Frequency range HF
System Simplex ARQ system
Baudrate 240.82 Baud
Modulation SSB or DIRECT-FSK
Receiver settings CW, LSB or USB