Accession Number : AD0637705

Title :   THE FEASIBILITY OF DETECTING SHOCK WAVES BY PULSE DOPPLER RADAR.

Descriptive Note : Environmental research papers.

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Glover,Kenneth M.

Report Date : MAY 1966

Pagination or Media Count : 33

Abstract : Classical geometric optics estimates of the echo characteristics from both isotropic and directed acoustic shocks are presented together with the detection capability of a typical sensitive pulse Doppler radar (AFCRL Porcupine Doppler) in order to determine the feasibility of detecting large well defined boundaries of refractive index. Both the radar cross-section and the Doppler spectrum of an acoustic shock are sensitive to wind and temperature induced perturbations of the shock surface. For standard deviations in wind and temperature of 0.5 m/sec and 1C, the theoretical values of the maximum radar cross-section and minimum Doppler spectral width of a typical directed shock of 50 meters radius are found to be 0.0008 sq cm and 58 cps respectively. This target cross-section is about 6 dB stronger than the minimum cross-section detectable by the Porcupine radar at a range of only 1.8 kilometers. At this range, the presence of a weak signal may be completely masked by the presence of strong ground clutter signals. Signal processing techniques which improve the mean square to noise ratio and provide sub-clutter visibility are therefore crucial to the success of the experiment. Moreover, the sensitivity of the radar cross-section and the Doppler spectrum to wind and temperature perturbations restricts the experiments to calm conditions. (Author)

Descriptors :   (*SHOCK WAVES, RADAR SCANNING), (*DOPPLER EFFECT, REFRACTIVE INDEX, ACOUSTICS

Subject Categories : Acoustic Detection and Detectors
      Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE