Detection Performance of Time-Varying Adaption Rate Adaptive Beamformer.

摘要

The previously developed time-varying adaptation rate adaptive beamformer (ABF) was modified for the purpose of using a fixed set of design parameters in different levels of noise and signals. The ABF performance was evaluated in terms of its capability to suppress seismic coda wavetrains of strong earthquakes, accuracy of its bodywave magnitude (m sub b) measurements and detection capability, as compared with those of single sites and the conventional beamsteer using recorded data from the Korean Seismic Research Station (KSRS) short-period array. A total of 129 events recorded in winter were processed. On the average, the ABF yielded the same magnitude difference (0.1 m sub b units smaller) as the beamsteer, when compared with the NEIS and NORSAR bulletin mb. However, preliminary results indicated that the ABF may have improved the array detection capability by 0.5 mb units from the conventional beamsteer based on subjective analyst interpretation of the detection status of processed events. More data with automatic detection criteria applied are needed to more accurately estimate the detection gains which are possible by applying the ABF as a field operating front-end detector. (Author)