Recognition using frequency sweep sonar

This paper describes the use of arbitrarily chosen transmission signals (e.g. frequency sweeps) in a pulse-echo sonar system. An experimental platform has been built where software generated signals can be loaded into a transmission unit and echoes can be sampled and analyzed by the software. The current experiments utilizes electrostatic transducer elements. The multi-frequency measurement methods in sonar systems gives a much larger statistical material than those using a single frequency. Standing wave phenomena that may result in a zero amplitude at a certain frequency and distance do not deteriorate the measurement since the frequency is varied. Multi-frequency methods can be applied to pure distance measurements as well as to more complicated tasks. An experiment where the system is used for recognition is described.