All rate bit synchronizer with automatic frequency ranging
AssigneeFord Aerospace & Communications Corporation
InventorWilliam B. Kuhn
Life of this patent
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Abstract
A bit synchronizer capable of operation over all frequencies, limited only by the speed of the integrated circuits and other components. The input data can be any random antipodal data. A programmable scaling circuit allows the operator to select the desired half octave range of operation. Half octaves can be scanned automatically by the autorange feature of the invention. An acquisition circuit sweeps over the selected half octave, diverting frequency correction pulses in order to sweep a voltage controlled oscillator (VCO). Lock is recognized when a preselected number of data transitions with phase error below a preset maximum occur consecutively. A second order phase lock loop (PLL) provides both phase and frequency correction.
Claims6
A bit synchronizer for generating a recovered clock in synchronization with a random antipodal input data bit stream, comprising:
- phase detector means for measuring phase differentials between transitions within said input data bit stream and said recovered clock, said detector means having a first input coupled to the input data bit stream, and two outputs, i.e., a phase error signal and the recovered clock;
- means for adjusting the frequency of the recovered clock in response to the phase error signal, said adjusting means having an input coupled to the phase error signal and an output system clock coupled to a second input of the detector means via a variable frequency scaling means for selectively determining one frequency subrange of operation of the synchronizer during a first phase of operation prior to synchronization and during a second phase of operation subsequent to synchronization;
- wherein the scaling means has an input coupled to the system clock and an output coupled to a second input of the detector means for changing the frequency of signals therewithin;
- wherein said determined frequency subrange is one of a set of at least two subranges, where no subrange can be nested within any other subrange.
Dependencies are inferred from the claim text.