Spread spectrum signal performance investigation in a bandlimited channel

Abstract

The paper investigates performance of spread spectrum signals performance in a bandlimited channel. Available spectrum spreading techniques are discussed. The performance is evaluated as the time of flight (ToF) accuracy estimation using the direct correlation technique. Numerical simulations have been carried out. Ultrasonic transducer was approximated as a bandlimited channel for simulation. The influence of ToF estimation with a constant chirp center frequency spreading and continuously rising chirp center frequency where analyzed. Random errors of ToF and how effective bandwidth of chirp signal is affected by a bandlimiting channel where evaluated. It has been shown that when chirp sweep frequencies are around the constant center frequency then the ToF deviation is insignificant. When the upper chirp sweep frequency is increasing, the random errors are reduced. The results showed that the optimum chirp signal bandwidth can be beyond the channel bandwidth.