An experimental comparison between a pulse and a frequency-modulation echo-ranging system

Experiments designed to study the operation of a jrequency-modulation echo-ranging system and compare this with a pulse system are described. The results show that a previous theoretical study by the author1 can be used as the basis of the design of a frequency-modulation system which may compare very favourably with a pulse system designed for the same purpose. When the bandwidth of the pulse system is limited, as it sometimes is in underwater sound systems, the frequency-modulation system can give much superior results. On the other hand, the pulse system can provide a much higher resolution in range if the bandwidth of the system is restricted only by that of the transducer arrays.