Method and arrangement for automatic detection of a communication signal

摘要

The invention relates to a method and an arrangement for automatic detection of a communication signal even when simultaneously affected by interference signals, where the autocorrelation function is formed from the combined signal. The value of the autocorrelation function is used as a criterion for determining whether a communication signal is contained in the combined signal or whether interference signals only are present, and furthermore the envelope is formed from a signal-interference combination and the autocorrelation function is derived therefrom. Particularly in the case of automatic radio monitoring systems, the use of the correlation analysis with the formation of the autocorrelation function for detection of a communication signal, at low cost compared with other methods, offers the advantage of clear and automatic distinction between communication and interference signals. Similarly, as is known, the speed of the evaluation is of major importance, and this is guaranteed by the invention in that delays in operational procedure as a result of superfluous monitoring of interference signals are avoided. Also with the prior formation of the envelope, a recorded signal or signal combination is supplied to the cross-correlator (4), on the one hand directly and on the other hand via a time delay (3). The autocorrelator (3, 4) forms the required autocorrelation function. A threshold switch (5) displays an existing communication signal when a permanently set threshold value is exceeded and, if required, prompts the searching receiver (1) to interrupt the search routine. <IMAGE>