Frequency synthesized tuning system using a microprocessor

摘要

A tuning system is provided in which the tuning function is substantially integrated in a microprocessor. A fixed modulus counter is cascaded with a programmable counter (or timer) found within the microprocesor thereby extending the counting range of the programmable counter. Then by prescaling the output of the local oscillator to a value below the toggle frequency of the microprocessor counter, the microprocessor may periodically measure the output frequency of the oscillator and, if necessary, generate correction signals therefor.