Detection of an echopulse with a frequency dependent background signal

The results are presented of a study on the possibilities of improving the detection performance of a CW-echo ranging system by adapting the Doppler filters to the interfering background signal. This background signal consists of a frequency independent noise component and a component which is strongly frequency dependent. Using an additional filter through which the signal will flow before it enters the set of Doppler filters, the signal to noise ratio is raised significantly. When the background signal has a reverberation to noise ratio of 40 db, which is an average value, the theoretical improvement is about 17 db. With a computer simulation this improvement is shown to exist.