Methods and apparatus for determining a dominant frequency contained in a multi-frequency analog signal. An apparatus includes a first matched filter pair and a second a second matched filter pair. Both the first matched filter pair and the second matched filter pair are configured to receive in-phase (I-phase) and quadrature-phase (Q-phase) digital samples of a digitized multi-frequency analog signal. The summed magnitudes of outputs of the first and second matched filter pairs provide an indication of a dominant frequency represented in the digital samples. The first matched filter pair may include first and second matched filters, where the first matched filter includes a multiplier operable to multiply, on a sample-by-sample basis, a sample by a coefficient. A sample comprises an n-bit digital representation of either the I-phase amplitude or the Q-phase amplitude at a given instant. The coefficients are the terms required to complete the matching functions (e.g. 1-bit Walsh coefficients).