Each frame begins with a The EOM sequence is followed by flush bits, which are for FEC coder flushing and for the complete transmission of the remainder of the interleaver data block. In most cases FEC and interleaver are used to combat the effects of fading, frequency shift , multipath effects and burst noise. User data is in this case first FEC encoded, interleaved, then mapped into PSK symbol and transmitted in 32 symbol data segment. The 16 symbol channel segment transmitted between every 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.
|Published (Last):||11 September 2012|
|PDF File Size:||3.66 Mb|
|ePub File Size:||18.73 Mb|
|Price:||Free* [*Free Regsitration Required]|
Tojakora User data rate bps. The 8 data-bits are LSB first. The modulation speed symbol rate is stanah Bd. After the symbol data-probe segment another frame beginning with the same symbol preamble follows immediately. This feature enables the user to analyse the demodulated symbol when the above coding scheme deviates from the standard. This can be set by toggling the Polarity field: In addition to the EOM pattern, the display will stop if more than NULL characters are received or if the asynchronous data structure is violated more than 80 times.
When the Confidence value is greater than 95 i. Small frequency deviations are automatically tracked and compensated during the decoding. The decoder stops displaying data after the EOM bit pattern is received. The EOM sequence is followed by flush bits, which are for FEC coder flushing and for the complete transmission of the remainder of the interleaver data block.
User data is in this case first FEC encoded, interleaved, then mapped into PSK symbol and transmitted in 32 symbol data segment. The 7 data-bits are LSB first. Using different M-PSK modulations 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.
The modulation technique used in this mode consists of phase shift keying 8-PSK of a single tone sub-carrier of Hz. This frame structure makes the synchronization of the demodulator in the mid of the transmission very easy. In most cases FEC and interleaver are used to combat the effects of fading, frequency shift, multipath effects and burst noise.
By using the bar-graph, any remaining frequency difference can be compensated for by fine-tuning of the receiver frequency or by adjusting the center frequency of the decoder. This should be set manually in the Frame Format menu. The mode decoder can process signal in both SSB settings: The center frequency of the decoder should staag set to Hz when the receiver is correctly tuned to the sending station. Using the Frame Format field the decoder can be set to one of the signal configurations.
STANAG 4285 PDF