Receiver for radio beacon signals - uses programmable frequency synthesiser as local oscillator for mixing with satellite signals

摘要

The receiver determines the frequency of the carrier wave of received signals in a given band by mixing the received signals with a local oscillator's output whose frequency changes progressively over the band. The local oscillator is a programmable frequency synthesiser. The synthesiser's reference frequency is produced by an ultra-stable oscillator. A frequency divider is used to program the synthesiser and is part of a loop. The divider's denominator is varied. The mixer's output is passed to parallel band-pass filters tuned to centre frequencies arranged in steps.