Doppler Warp Correction For Wideband Burst Communications

Burst communications in a wideband environment subject to Doppler, multipath, and noise is challenging. An example is the Underwater Acoustic (UWA) channel. Compared to the over-the-air radio frequency (RF) channel, the UWA channel is subject to severe distortions due to Doppler as well as multipath. The challenge of interest is wideband burst communications in such an environment. Thereto the effect of Doppler is modeled as a quadratic time warp. A procedure is developed to estimate the parameters of the time warp based on observed burst signal components, so that subsequently the Doppler time warp can be undone. Two different methods are compared. The first technique uses sinusoids in a pre- and in a post-amble to a communications burst, while the second technique uses out of band (communication signal bandwidth) sinusoids present during the burst. The results, from over-the-air acoustic proxy experiments, show that performance improvements can be realized using the Doppler time warp model and correction process.