Abstract :
High frequency (HF) radio links can introduce a combination of multipath propagation and Rayleigh fading, which result in severe frequency selective fading. The multipath spread, Doppler shift and the various additive interferences constitute the main disturbances on an HF link and attribute to the unpredictability of practical HF links. In principle, efficient use of bandwidth, together with a better tolerance to additive noise, should be achieved by a serial system, employing at the receiver both coherent demodulation, and near-maximum likelihood detection. This is the approach taken, where the application of interest is the transmission of digital data at 9.6 kbit/s over a voiceband HF radio link. An approach, using an adaptive linear filter is as shown, where the Viterbi algorithm is replaced by a near maximum likelihood detector and the filter is adjusted to make the resultant sample impulse response of the channel and filter (which is input to the detector) minimum phase
Keywords :
HF radio propagation; adaptive filters; data communication; demodulation; digital radio; fading; filtering theory; maximum likelihood detection; multipath channels; radio links; telecommunication computing; 9.6 kbit/s; Doppler shift; Rayleigh fading; adaptive linear filter; additive interference; additive noise; bandwidth; channel impulse response; coherent demodulation; computer modelling; digital data transmission; frequency selective fading; high frequency channels; high frequency radio links; multipath propagation; multipath spread; near maximum likelihood detector; near-maximum likelihood detection; receiver; serial system; voiceband HF radio link;
