A means and method for fast determination of the frequency of an input signal comprising mean for digitizing and storing the digitized bits of the input signal in an input register of N bits at a bite rate f.sub.c. Other means generate a series of digitized reference signals whose frequencies are represented by patterns of binary 1's and 0's and spaced apart by predetermined frequency intervals. At least one digitized reference signal is clocked into a reference signal register during each time period 1/f.sub.c. The digitized reference signals are successively compared to the digitized input signals to produce output signals whose magnitudes are proportional to the degree of correlation therebetween. Further, means are provided to determine the largest output signal and the frequency of the reference signal which produced said largest output signal.