WAVECOM Decoder W-PCI/e, W-CODE, W

In ASCII ASYNC (7 data bits and no stop bit) mode, the bit stream is correlated with another ASYNC structure, i.e., one start bit (0) and 7 data bits. The 7 data bits are displayed LSB first. In addition to the EOM pattern, the display will stop if more than 300 NULL characters are received.

In ASCII SYNC mode, each 8 bits (LSB first) represent one ASCII character. The display will stop when either the EOM pattern was recognized or more than 20 NULL characters have been received.

Tuning the decoder

The decoder can process signals in both SSB settings: USB and LSB. The sideband is selected by toggling the Polarity field of the display: NOR will select USB and INV will select LSB.

The center frequency of the decoder is set to the default value of 1800 Hz, but can be adjusted within a range from 800Hz to 2400Hz. Small frequency deviations are automatically tracked and compensated during the decoding. By using the bar graph, any remaining frequency difference can be compensated by fine-tuning of the receiver frequency or by adjusting the center frequency of the decoder.

In the Confidence field, the quality of decoding can be observed. A well recognized stream is determined by a confidence value being stable and greater than 95 (i.e., 95% of the message is correct).

STANAG-4529

STANAG-4529 is specified by the NATO (North Atlantic Treaty Organization) Military Agency for Standardization in "Characteristics of Single Tone Modulators / Demodulators for Maritime HF Radio Links with

1240Hz Bandwidth" (14. December 1995).

1200

1200

1200

1200

1200

1200

1200

Parameter Value

Frequency range

Operation modes

Modulation

Symbol rate

Center frequency

Receiver settings

Input format(s)

HF

PSK, Broadcast/Simplex FEC

8-PSK

1200.0 Bd

1700 Hz

DATA, CW, LSB or USB

AF, IF

Additional Info 16 Bit redundancy

The modulation technique used in this mode consists of phase shift keying (8-PSK) of a single tone subcarrier that is selectable in 100Hz steps from 800Hz to 2400 Hz, with a default value of 1700 Hz.

The modulation speed (symbol rate) is always 1200 Bd. Through the use of different M-PSK modulation formats and FEC (Forward Error Correction) coding rates, serial binary user information (raw data) accepted at the line side input can be transmitted at different user data rates.

STANAG 4529 single tone waveform has the following format characteristics which may be selected from

Options | Frame Format...

Baud Rate User data rate (bps) Bits per symbol (M-PSK) FEC coding rate

1200

600

300

150

75

1800

1200

3 (8-PSK)

2 (QPSK)

1 (BPSK)

1 (BPSK)

1 (BPSK)

3 (8-PSK)

2 (QPSK)

2 / 3

1 / 2

1 / 2

1 / 4

1 / 8 uncoded uncoded

Interleaver

SHORT or LONG

SHORT or LONG

SHORT or LONG

SHORT or LONG

SHORT or LONG

ZERO

ZERO

WAVECOM Decoder W-PCI/e, W-CODE, W-CLOUD Manual V8.3.00 Transmission Modes

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233

Baud Rate User data rate (bps) Bits per symbol (M-PSK) FEC coding rate

Interleaver

1200 600 1 (BPSK) uncoded ZERO

The user data is transmitted using a continuous frame structure with 213.33 ms per frame. Each frame starts with a preamble containing 80 symbols. The following 176 symbols are divided into four 32 symbol data segments and three 16 symbol channel probe segments.

The 176 symbol data probe segment immediately follows a next frame beginning with the same 80 symbol preamble. This repeated frame structure allows synchronization of the demodulator at any time of transmission.

T = 213.33 ms

80 32 16 32 16

32

16

32

Preamble Block 1 Block 2 Block 3 Block 4

80

80

Preamble symbols

32 Data symbols

16 Channel probe symbols

At the end of transmission, an EOM bit pattern (4B65A5B2, in hexadecimal notation, MSB first) is sent to mark the end of message. The EOM sequence is followed by flush bits, to flush the FEC coder and to complete the transmission of the remainder of the interleaver data block.

In most cases FEC and interleaving is used to combat the effects of fading, frequency shift, multipath, and burst noise. User data is in this case first FEC encoded, interleaved, then mapped into PSK symbols and transmitted in 32 symbol data segments. The 16 symbol channel probe segment transmitted between each succeeding data segment has a known PSK pattern. Its purpose is to keep the demodulator, mainly the equalizer, on track in spite of adverse propagation conditions during the HF transmission.

Generally STANAG-4529 transmits the user data in transparent binary mode. This should be defined by the higher layer using the STANAG 4529 mode. For this reason the decoder displays the user data in BI-

NARY, HEX, ASCII ASYNC, ASCII ASYNC (7 Data bits and No Stop bit) or ASCII SYNC format selected from

Options | Message Type.... The decoder stops displaying data after the EOM bit pattern is received.

In the HEX display mode, the decoded binary data is just displayed as it is, MSB first.

In ASCII ASYNC mode, the bit stream is correlated with an ASCII ASYNC structure, i.e., one start-bit (0),

8 data bits and at least one stop bit (1). The 8 data bits are displayed LSB first. In addition to the EOM pattern, the display will stop if more than 300 NULL characters are received or if the asynchronous data structure is violated more than 80 times.

In ASCII ASYNC (7 data bits and no stop bit) mode, the bit stream is correlated with another ASYNC structure, i.e., one start bit (0) and 7 data bits. The 7 data bits are displayed LSB first. In addition to the EOM pattern, the display will stop if more than 300 NULL characters are received.

In ASCII SYNC mode, each 8 bits (LSB first) represent one ASCII character. The display will stop if the

EOM pattern is received or if more than 20 NULL characters are received.

Tuning the decoder

The decoder can process signals in both SSB settings: USB and LSB. The sideband is selected by toggling the polarity field of the display: NOR means USB and INV means LSB.

The center frequency of the decoder is set to the default value of 1700 Hz, but can be adjusted within a range from 800Hz to 2400Hz. Small frequency deviations are automatically tracked and compensated during the decoding. By using the bar graph, any remaining frequency difference can be compensated by fine-tuning of the receiver frequency or by adjusting the center frequency of the decoder.

Using the Frame Format field, the decoder can be set to one of the above listed user data configurations.

A correct coded frame format is determined by a confidence value being stable and greater than 95 (i.e.,

95% correct), while for uncoded formats the value has no meaning and remains stable at 75.

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Transmission Modes WAVECOM Decoder W-PCI/e, W-CODE, W-CLOUD Manual V8.3.00