Bandwidth effects of signal fading for the mid-latitude HF channels

Wideband HF measurements made in August and September of 1989 over a midlatitude 2070-km path are discussed. The channel impulse response, is estimated by correlating the received probe signal with a direct-sequence pseudo-noise coded reference. The impulse response estimate allows concomitant analysis of both the received wideband power statistics as a function of signaling bandwidth and the delay-Doppler characteristics of the channel. Fading statistics are calculated for several receiver bandwidths. These measurements demonstrate that, by increasing the instantaneous signaling bandwidth from 4 kHz to 1 MHz, the required communications fade margin drops more than 10 dB. Data are presented on the time-of-arrival drifts over many minutes of the received wideband signal