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Call progress signal detector

  • US 4,028,493 A
  • Filed: 12/22/1975
  • Issued: 06/07/1977
  • Est. Priority Date: 12/22/1975
  • Status: Expired due to Term
First Claim
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1. A system for analyzing audio telephone call progress signals including means for coupling the audio signal on the telephone system to said analyzing means,means for minimizing transient signal effects present in received signals, and normalizing the signal magnitudes,detector means for removing the AC component from said normalized signal,means for detecting the cadence of said pulses and,means responsive to said cadence detector for indicating which one of a particular call progress signal is present on the telephone line.

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