Frequency synthesizer for broadcast telephone system having multiple assignable frequency channels

摘要

In a broadcast telephone system for communicating information signals over an assigned frequency channel, the combination of a synthesizer for generating a signal at the assigned frequency and a PROM storing a plurality of sets of first and second signals associated with different predetermined assignable frequencies. The synthesizer includes a first phase-locked loop for generating an output signal at a frequency within a first predetermined range including the plurality of assignable frequencies in response to the combination of a first frequency reference signal having a predetermined frequency and a second reference frequency signal having a frequency within a second predetermined range and derived from a second phase-locked loop a second phase-locked loop for generating a third reference frequency signal within a third predetermined range in response to a combination of a first signal from the PROM associated with a given assignable frequency and a fourth frequency reference signal having a predetermined frequency; and a frequency divider coupled to the PROM for dividing the frequency of the output signal from the second phase-locked loop by an amount indicated by a second signal from the PROM associated with said given assignable frequency to provide the second reference signal to the first phase-locked loop. The phase-locked loops each include a minimizing phase noise and electronic noise due to microphonics.