Patent ID: 7394878

Claim:
An apparatus for determining a dominant frequency represented in digital samples of a multi-frequency analog signal, said apparatus comprising: a first matched filter pair configured to receive in-phase (I-phase) and quadrature-phase (Q-phase) digital samples of a multi-frequency analog signal, said first matched filter pair including: a first matched filter having an I-channel and a Q-channel, the I-channel including a multiplier operable to multiply the I-phase digital samples by a first set of coefficients, and the Q-channel including a multiplier operable to multiply the I-phase digital samples by a second set of coefficients that are in quadrature to the first set of coefficients, and a second matched filter having an I-channel and a Q-channel, the I-channel including a multiplier operable to multiply the Q-phase digital samples by said first set of coefficients, and the Q-channel including a multiplier operable to multiply the Q-phase digital samples by said second set of coefficients; and a second matched filter pair configured to receive said I-phase and Q-phase digital samples, wherein summed magnitudes of outputs of said first and second matched filter pairs provide an indication of a dominant frequency represented in the digital samples.