CMI decoder

Claim 1

A decoder for decoding a digitized signal into a CMI (Coded Mark Inversion) coded signal, comprising: a voltage controlled oscillator (VCO); 1/2 frequency dividing means for dividing an output of said VCO; first logic means supplied with an output of said VCO and an output of said 1/2 frequency dividing means for producing three clock signals, two of said three clock signals being individually deviated in phase by +1/4 and -1/4 of a period relative to a reference clock signal which is a remaining one of the three clock signals; first discriminating means for sampling a CMI coded input signal by the clock signal which is deviated by +1/4 of a period and outputted by said first logic means; second discriminating means for sampling the input signal by the reference clock signal, said VCO being controlled by an output of said second discriminating means; and third discriminating means for sampling the input signal by the clock signal which is deviated by -1/4 of a period; and second logic means supplied with an output of said first discriminating means and an output of said third discriminating means for producing a NRZ (Non-Return to Zero) format signal.