Programmable frequency identifier circuit

Abstract From the Canadian patent

A programmable frequency identifier circuit for identifing the frequency of a contaminated signal including a digital finite impulse response filter a zero crossing, detector, a zero crossing counter and a frequency range, decoder. The filter is a programmable filter for filtering signals of the form: S(n)= S1(n) + S2(n)= Acos2.pi. F1(n) Bcos2.pi. F2(n) where S1(n)= desire signal S2(n)=, contamination, F1= passband frequency F2= Stopband, frequency, and A,B= Constants. The zero-crossing detector detects sign changes of the filtered signal. The zero-crossing counter counts the sign changes occuring during a programmably determined frame time. The number of zero crossing during the frame time …