Spectral Variability As A Source Of Fluctuations Within Received Sonar Fm Pulses

Fh4 sonar pulses transmitted in a multi-path shallow water environment have been observed to exhibit substantial fluctuations in amplitude within the pulse duration. Corresponding CW pulses are much less distorted. This frequency-related phenomenon has been studied as an example of spectral variability. By comparing measured results with theoretical expectations, it is shown that the characteristic time for the multi-path interference field to establish is directly linked to the distortions of the FM pulses. These results show that the extent of pulse distortion may be estimated from a knowledge of the sonar environment.