Automatic frequency control processing in multi-channel receivers

摘要

A multiple channel receiver ( 200 ) includes a communications receiver synthesizer ( 204 ) and at least one numerically controlled oscillator (NCO) ( 406 ) that produce local oscillator signals that are derived from a common reference oscillator ( 202 ). A DSP ( 212 ) and CPU ( 214 ) perform automatic frequency control (AFC) by adjustment of the reference oscillator ( 202 ) based upon a signal received by a receive channel using the local oscillator signal produced by the communications receiver synthesizer ( 204 ). The CPU ( 214 ) also provides a synchronous indication of adjustments to the reference oscillator ( 202 ) to control circuitry for the at least one NCO ( 406 ) so that the configuration of the NCO ( 406 ) can be altered so as to maintain a substantially constant frequency output during the adjustment of the reference oscillator ( 202 ).