DIGITAL SYNCHRONIZATION OF BROADCAST FREQUENCY

摘要

A dynamic, self adjusting synchronization system for real time control of the frequency and bandwidth of a modulated signal comprising a voltage controlled oscillator for generating a carrier signal to be modulated having a predetermined frequency and bandwidth an adjustment device includes a center frequency adjustment circuit for providing a voltage level to the voltage controlled oscillator; a modulation generator for generating a modulation signal for modulating the carrier signal to produce a modulated carrier signal and a co-generated measurement signal synchronized with the modulation signal; means for selectively inhibiting the modulation signal; a measurement device including a counter device for selectively counting the pulses of the modulated carrier signal for a first predetermined period of time and counting the pulses of the carrier signal for a second predetermined period of time while the modulation signal is inhibited and including a measurement circuit, responsive to the co-generated measurement signal, for synchronously defining the first predetermined period of time during which the modulated carrier pulses are counted and responsive to a timing signal for defining the second predetermined period of time during which the modulation signal is inhibited for counting the carrier pulses; the adjustment device is responsive to the measurement device, for varying the voltage applied to the voltage controlled oscillator to maintain the predetermined frequency of the carrier signal and is responsive to the measurement device for varying the voltage applied to the voltage controlled osciallator to maintain the predetermined bandwidth of the modulated carrier signal.