Tracking bit synchronizer

Claim 1

A bit synchronizer comprising: a phase locked loop circuit including a phase detector having an input for receiving an encoded data signal, a filter coupled to said phase detector and a voltage controlled oscillator (VCO) which is coupled to said filter and which produces a clock signal coupled to the input of said phase detector; wherein said phase detector compares the phase of zero crossings of said encoded data signal with said clock signal produced by said VCO to produce a phase error signal which is filtered by said filter; and wherein said filtered voltage is applied to said VCO to effect phase lock of said clock signal with said data signal; data decoder means, coupled to said phase lock loop circuit, for decoding said encoded data signal as a function of said phase locked clock signal, and data error detector means, coupled to said data decoder menas, for producing a data error signal indicating absence of phase lock with said data signal when said decoder means produces decoded data having a preselected number of errors; and control means for controlling said phase locked loop circuit either (1) in a seek mode, when a data error signal is produced, to sweep said VCO through a predetermined range of frequencies until no data error signal is produced by said data error detector means; or (2) in a tracking mode, when no data error signal is produced by said data error detector means.