Wavecom W-SPECTRA (Automatic Monitoring System) V1.1.0 - Manual (Page 137)

WAVECOM Monitoring System W-SPECTRA, W-SPEED Manual V1.1.0 Transmission Modes
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Waveform Burst duration Preamble Payload
BW2 640 + (400 * n) ms,
1536 + (960 * n) PSK symbols,
n = 3, 6, 12, or 24
26.67 ms, 64 PSK symbols 1881 * n bits
BW3 373.33 + (13.33 * n) ms,
896 + (32 * n) PSK symbols,
n = 64, 128, 256, or 512
266.67 ms, 640 PSK symbols 8 * n + 25 bits
BW4 640.0 ms, 1536 PSK symbols None 2 bits
The data in the different burst waveforms is used for different purposes:
 BW0 is used for 3G-ALE PDUs (Protocol Data Unit)
 BW1 for traffic management PDUs and HDL (High-rate Data Link Protocol) acknowledgement PDUs
 BW2 for HDL traffic data PDUs
 BW3 for LDL (Low-rate Data Link Protocol) traffic data PDUs
 BW4 for LDL acknowledgement PDUs
The MIL-188-141B decoder processes the waveforms BW0, BW1 and BW4 only, because the configuration
(number of data packet, FEC encoding and interleaver) of BW2 and BW3 is negotiated during the peer-to-
peer communication, e.g., between two modems.
The decoder displays the payload data of BW0 and BW1 in BINARY, HEX, ASCII ASYNC, ASCII ASYNC
(7 data bits, 0 stop bit) and ASCII SYNC formats selected from Options/Message Type.
In the HEX mode the payload data is displayed as it is, MSB first.
In the ASCII ASYNC mode the payload data is displayed as ASCII character, i.e., one start-bit (0), 8 da-
ta-bits (one ASCII character) and at least one stop-bit (1). The 8 data-bits are LSB first. The display is
stopped when 300 NULL (all zero in 8 data-bits) characters are received or if the async data structure is
violated more than 80 times.
In the ASCII ASYNC (7 data bits, 0 stop bit) the data is displayed in a similar way – one start bit (0),
7 data bits (LSB first) and no stop bit. Also the display terminates when more than 300 NULL characters
occur or the async data structure is violated more than 80 times.
In the ASCII SYNC mode the payload data is segmented into 8-bit (LSB first) ASCII characters and dis-
played.
The waveform BW4 has only 2 bits payload data, they are displayed in HEX format (MSB first).
Tuning the decoder
The decoder processes the signal in both SSB settings: USB and LSB. This can be selected with Polarity
in the menu: NOR means USB and INV means LSB signal.
MIL-M-55529A NB/WB
MIL-M-55529A is an asynchronous FSK system and is based on ASCII. No error detection or error correc-
tion is implemented.
Parameter Value
Frequency range HF
Operation modes Broadcast
Modulation FSK
Symbol rate 50,75, 100 or 110 Bd
Center frequency 2000 Hz
Shift 85 Hz (NB), 850Hz (WB)