Systems and methods for frequency drift compensation for radio receivers
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.
1. A composite, active, bandpass filter, the filter comprising:
a plurality of prototype filters, each prototype filter including:
a first low noise amplifier (LNA);
a second LNA;
a bandpass filter connected between the first LNA and the second LNA;
wherein the active bandpass filter meets both a 1 dB gain compression objective and an adjacent band selectivity objective.
2. The filter of claim 1 , wherein the composite, active, bandpass filter is used in a GPS receiver.
3. The filter of claim 1 , wherein each of the plurality of protype filters is comprised of identical components.
4. The filter of claim 1 , wherein the plurality of protype filters comprise different components.