Abstract: A circuit for detecting digital data recorded on a magnetic recording medium is disclosed wherein data is detected by detecting a missing clock and fixed data at the missing clock location. Clock and data pulses are interleaved on the recording medium and encoded to distinguish data and detecting the missing clock by encoding data corresponding to signal absence into the bit position adjacent to the last bit of the missed clock bit when such condition is present. The clock and data bits are detected from the decoded signal read from the recording medium by timing the first period between succeeding bits which is of greater time duration than the interval between succeeding clock and data bits but shorter than the interval between succeeding clock bits having a data bit interposed therebetween.