Abstract: A data valid detector circuit for Manchester encoded data monitors two parameters to determine single bit validity, namely, the location and number of edges in one bit period, and the output count of an integrator type Manchester decoder circuit. Circuits analyze each received bit waveform to see that the data falls within reasonable limits of what can be said to be a valid Manchester bit. By retaining bit-by-bit information on validity for a sample of N bits, a determination is made of the validity of this string of N bits. A data valid signal is then generated indicating reception of a usable signal, even when disturbed by noise, if a sufficient number of bits in the string are valid.