Accession Number : AD0674525

Title :   A COMPARISON OF THREE SCHEMES FOR FILTERING SIGNALS WHICH HAVE PROPAGATED THROUGH A RANDOM MULTIPATH MEDIUM.

Descriptive Note : Technical rept.,

Corporate Author : WESTERN ELECTRIC CO INC NEW YORK

Personal Author(s) : Mangano,D. T.

Report Date : 02 OCT 1967

Pagination or Media Count : 34

Abstract : Three filtering techniques that can be employed in the recovery of a signal after it has propagated through a nonrandom, distortionless, multipath channel have been studied. The generalization of these studies to the random medium situation is the purpose of this report. A fixed, omnidirectional source emits a signal which propagates through a multipath medium and is detected by an array of point receiving elements located at some arbitrary distance from the source. The medium is characterized by a set of attenuation and delay random variables associated with each of the multiple paths. In addition, the additive noise contributed by the medium is assumed to be negligible. The detected signals are then processed by delay filtering, matched filtering, or frequency-inverse filtering. The criterion for comparison of these three filtering schemes is the ratio of the standard deviation of the filtering scheme's output time-average power to the expected value of this power. It is found that under certain constraints this ratio is approximately independent of the delay statistics of the medium, and the duration and frequency of the input for the three filtering schemes. In addition, this ratio is approximately equal for delay and matched filtering and is square root of 2 times greater for frequency-inverse filtering. (Author)

Descriptors :   (*ACOUSTIC SIGNALS, *MULTIPATH TRANSMISSION), PROCESSING, ELECTRIC FILTERS, DETECTION, NOISE, ATTENUATION

Subject Categories : Cybernetics
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE