Decoder for Delay-Modulation Coded Data

"Delay modulation," originally developed in conjunction with high density digital (saturation) tape recoding, combines the advantages of narrow bandwidth of pulse-code modulation (PCM) nonreturn to zero (NRZ) and the advantages of self-timing information inherent in phase modulation. This paper describes a decoding technique for the conversion of delay-modulated digital data to NRZ data. A potential time-phase ambiguity in reception and decoding of delay-modulated data is resolved in real time, through monitoring the data stream for a unique waveform inherent in delay-modulated data. Statistical backup is provided. Included are logic implementation and timing diagrams.