Wavecom W74PC V8.7.0 - Manual (Page 141)

WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V8.7.0 Transmission Modes
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A Baudot code word consists of a start bit, 5 data bits and 1, 1.5 or 2 stop bits giving each character a
length of 7, 7.5 or 8 bits. Baudot is an asynchronous code in which synchronization is performed for each
character by the start and stop bits.
Baudot transmissions may be rendered unreadable by inverting one or several data bits. Using the Bit In-
version item in the Options menu any of the 32-bit inversion patterns may be pre-selected.
Isochronous or synchronous Baudot uses 7 bits and is especially used for on-line crypto systems.
BIIS
Binary Interchange of Information and Signaling is an ETSI-standard (ETS 300 230) used for transmission
of signaling information for selective calls, status messages, short text messages and data.
Parameter Value
Frequency range VHF/UHF
Operation modes CRC and parity
Modulation FM, SUB FFSK
Symbol rate 1200 Baud
Center frequency 1500 Hz
Shift 600 Hz
Receiver settings FM, BW = 15 kHz
Input format(s) AF, IF
Additional Info Signaling data, Short Data transfer, HDLC possible, ETSI-standard (ETS 300
230)
The system operates at 1200 Bit/s using indirect FSK modulation in the VHF or UHF band. To accommo-
date the different types of data, a number of code words have been defined. Every transmission consists
of at least one address word. Additional data such as telephone numbers or short text messages may be
appended to the address word as one or more data blocks.
For the transmission of longer data packets the High-Level Data Link Control (HDLC) protocol may be im-
plemented in the BIIS devices.
Status messages are transmitted within the address word. The address word contains the Operational
Mode Characteristic (OMC), a regional code indicating the country of the device, a common address part,
the transmitter address and the receiver address. The address data is displayed in hexadecimal format.
OMC code and regional code are displayed as short strings. There are 64 OMC codes consisting of a cate-
gory part (CAT) and a function part (FNC). Some codes are custom, status or reserved codes. The follow-
ing table shows all valid codes in string and binary representation.