Accession Number : AD0903724

Title :   Evaluation of Atmospheric Correlation Techniques.

Descriptive Note : Final technical rept. Mar-May 72,

Corporate Author : ENSCO INC SPRINGFIELD VA

Personal Author(s) : Maloney, John E. ; Sebastian, Richard L. ; Mathieu, Kathleen F.

Report Date : AUG 1972

Pagination or Media Count : 36

Abstract : This report describes the successful application of methods for extracting propagation time and Doppler information from radiated acoustic signals. The application of these methods was undertaken to investigate the feasibility of passively tracking vehicles by using their radiated noise. This work shows that both signal prewhitening and Doppler compensation are important to the successful use of signal cross-correlations in tracking moving vehicle targets. Prewhitening is necessary because prominent spectral lines lead to periodic structure in the correlation function which obscure the features of interest. Doppler correction is required because the Doppler difference between signals received from separated microphones imposes a limit on the bandwidth over which the signals can be cross-correlated. These procedures have been applied to signals generated by multiple vehicles. For long baseline applications the signal processing was bolstered with 'stochastic correlation' techniques which show high promise in combating short term signal fluctuation due to turbulence. (Author)

Descriptors :   (*ACOUSTIC DETECTORS, CORRELATION TECHNIQUES), (*TRACKING, ACOUSTICS), ATMOSPHERES, MICROPHONES, PROPAGATION, DOPPLER EFFECT, DETECTORS, STATISTICAL FUNCTIONS, VEHICLES, ACOUSTIC SIGNALS, STOCHASTIC PROCESSES, COSTS, DATA PROCESSING, MATCHED FILTERS, RAIN, TIME.

Subject Categories : Atmospheric Physics
      Statistics and Probability
      Acoustic Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE