SYSTEMS AND METHODS FOR FREQUENCY DRIFT COMPENSATION FOR RADIO RECEIVERS

摘要

A frequency drift compensation system for a radio receiver includes a pilot signal generator that is configured to generate two pilot signals, a local oscillator that is configured to generate a local oscillator frequency signal, a first mixer that generates a first offset pilot signal, a second mixer that generates a second offset pilot signal, and a summer that is configured to add the first offset pilot signal and the second offset pilot signal to the intermediate frequency signal to obtain a composite signal. The frequency drift compensation system includes a processor that is configured to detect frequency drift in the offset pilot signal responsive to the composite signal and to generate a frequency drift control signal to compensate for the frequency drift. Related radio receivers, GPS receivers, and methods are described.

主权项

1. A frequency drift compensation system for a radio receiver, the radio receiver comprising a first mixer that is responsive to a received radio signal and to a first local oscillator at a first local oscillator frequency to down-convert the received radio signal into an intermediate frequency signal, and a filter that is configured to filter the intermediate frequency signal, the frequency drift compensation system comprising:
a pilot signal generator that is configured to generate a first pilot signal at a first pilot signal frequency and a second pilot signal at a second pilot signal frequency; a second local oscillator that is configured to generate a second local oscillator frequency signal at a second local oscillator frequency; a second mixer that is responsive to the first pilot signal and to the second local oscillator signal to generate a first offset pilot signal at a first offset pilot frequency; a third mixer that is responsive to the second pilot signal and to the second local oscillator signal to generate a second offset pilot signal at a second offset pilot frequency, a summer that is configured to add the first offset pilot signal and the second offset pilot signal to the intermediate frequency signal to obtain a composite signal; and a processor that is responsive to the composite signal and is configured to detect frequency drift in the first offset pilot signal and/or in the second offset pilot signal to generate a frequency drift control signal to compensate for the frequency drift, wherein the first local oscillator is configured to adjust the first local oscillator frequency and/or the second local oscillator is configured to adjust the second local oscillator frequency, responsive to the frequency drift control signal.