Performance of the PHILTRE Processor at Low Signal-to-Noise Ratios

• Main Authors: Sobel, P A, Von Seggern, D H
• Other Authors: TELEDYNE GEOTECH ALEXANDRIA VA SEISMIC DATA ANALYSIS CENTER
• Format: Text
• Language: English
• Published: 1975
• Subjects: Seismology; Seismic Detection and Detectors; *SEISMIC DETECTION; *SEISMIC WAVES; *SIGNAL PROCESSING; ADAPTIVE SYSTEMS; NONLINEAR SYSTEMS; RAYLEIGH WAVES; SEISMIC ARRAYS; SIGNAL TO NOISE RATIO; Vela Uniform; Seismic discrimination; Adaptive filters; PHILTRE processor; Alpa; Kamchatka
• Online Access: http://www.dtic.mil/docs/citations/ADA016537; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA016537

In this report it is shown that a non-linear, adaptive processor called PHILTRE is useful in detecting long-period Rayleigh waves in various low signal-to-noise ratio situations: signals buried in noise at various levels, two signals mixed at various azimuths and relative amplitudes, and a suite of visually undetected signals at LASA, ALPA, and NORSAR from the Kurils-Kamchatka region. PHILTRE lowered the detection threshold for Rayleigh waves buried in noise by about 6 dB. It was able to separate two signals if their azimuthal spearation was greater than 60 degrees and if at the same time the amplitude of the second signal was at least 20 percent of the amplitude of the first signal. It lowered Rayleigh-wave 50% detection thresholds by roughly 0.2 (m sub b) unit at the three long-period arrays.