ALARM_FOR_SPECTRUM_ANALYZER

Published:2009/7/1 21:21:00 Author:May | From:SeekIC

Circuit drives audible alarm when frequency of interest appears in spectrum range. Display cursor can be preset to initiate narrow search band in which fx is expected to appear. 100-μs pulse representing cursor position in display sweep triggers mono IC1 so its output becomes window whose time-out is equivalent to band in which fx is center. Comparator A1 supplies high output when fx appears. Simultaneous arrival of this signal and timer window at gate A sets output of left flip-flop high. At end of window period, right flip-flop also goes high and initiates alarm via Q1. Loss of fX stops alarm.-R. L. Messick, Alarm Simplifies Spectrum-Analyzer Measurements, EDN Magazine, JuneS, 1978, p 152.



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