Spread spectrum sequence design for the study of outdoor noise propagation
Jamie A. S. Angus, David C. Waddington · The Journal of the Acoustical Society of America · 2007
The design of carrier-modulated code sequence signals that can be used for the study of outdoor propagation, are presented. In particular, the construction of these signals such that they are robust to the time-variance of the outdoor acoustic path is discussed. The design of these signals so that they can also occupy known bandwidths is also described. The result is an audible frequency signal that is biphase-modulated by two pseudorandom code sequences in a way that is specially designed for simultaneous fine time resolution and large range ambiguity. A particular advantage of this signal is that an estimate of the time-varying Doppler can be derived by recovering the suppressed carrier from the received signal, and various means of extracting the Doppler are explained. Extensions of these signals to allow multiple simultaneous measurements are also described. [Work supported by EPSRC UK]