Seismic alert system for earthquake warning - applies multiple channel spectrum analysis and compares output levels thresholds providing alert

摘要

Low frequency seismic waves (SE) between 21 and 80 KHz are passed to a number of parallel channels (MR1-MRN). The signals are amplified (AS) in each channel then mixed (M) with a local oscillator (OL) to produce an IF. Each channel has a filter (F1 -FN) examining a section of the frequency band using narrow band and low pass filters to cover the band. Each channel has a peak detector (VA), followed by a mean value detector (VM). The mean level is compared with preset levels (GS) in a logic gate (MC), to provide a pre-alert signal (G) if the threshold level in any channel is exceeded. ADVANTAGE - Measurement system filter out short term man made parasitic. Enhanced measurement of pre-seismic earthquake activity. Early alert.