Data transmission system receiver having phase-independent bandwidth control

A data receiver having a phase lock-circuit for producing a phase-adjusted clock signal, the phase-lock circuit having as its inputs the phase-adjusted clock signal and a formatted data stream being received at a predetermined data rate, the phase-lock circuit operating in one of at least a first bandwidth mode and a second bandwidth mode, the formatted data stream including a periodic synchronization pattern interposed among data segments, the data receiver comprising:

• means, coupled to the phase-adjusted clock signal, for sampling the data stream to produce a recovered data signal;
• means, coupled to the phase adjusted clock signal, for generating a predetermined synchronization pattern to produce a reference synchronization pattern;
• means for comparing the recovered data signal with said reference synchronization pattern to produce a synchronization value;
• counter means coupled to said means for comparing for indicating that a predetermined number of said synchronization values has occurred;
• and
• means for enabling said counter means during periods when the periodic synchronization pattern is expected.