Improved channel estimator for an HF radio link

Abstract The paper describes a novel technique for estimating the sampled impulse-response of a time-varying channel, where the latter involves an HF radio link with two independent Rayleigh fading sky waves. The channel estimator operates on the sampled demodulated baseband signal in the receiver of a synchronous serial data-transmission system, which transmits a 16-level quadrature amplitude modulated signal at 9600 bit/s over the HF radio link. By making a more effective use of the available prior knowledge of the channel the estimator obtains a more accurate estimate of the sampled impulse-response of the channel than that given by more conventional techniques. Results of computer simulation tests are presented to compare the performance of the new estimator with that of an arrangement previously described.