Diversity radio receiver automatic frequency control

In a radio-frequency receiver employing antenna diversity and having a plurality of antennas and a local oscillator, a method of automatic frequency control apparatus comprising:

• means for estimating phase errors in respective ones of signals received at respective ones of said plurality of antennas;
• means for forming a weighted sum of said phase errors comprising means for arriving at a measure of reliability of each of said signals and means for applying a larger weight to one of said phase errors representing one of said signals having greater reliability and applying a smaller weight to one of said phase errors representing one of said signals having lesser reliability wherein said weighted sum has a greater reliability than any individual phase error;
• and
• means for controlling frequency of a signal produced by said local oscillator based on said weighted sum.

In a radio-frequency receiver employing antenna diversity and having a plurality of antennas and a local oscillator, a method of automatic frequency control, comprising the steps of:

• estimating an error quantity with respect to a signal received from each antenna of said plurality of antennas;
• arriving at a measure of reliability of each said signal received from each antenna of said plurality of antennas;
• forming a weighted sum of said error quantities by applying a larger weight to said error quantity of one of said signals received having greater reliability and applying a smaller weight to said error quantity of one of said signals received having lesser reliability;
• and
• controlling frequency of a signal produced by said local oscillator based on said weighted sum.

A radio-frequency receiver employing automatic frequency control and antenna diversity and having a plurality of antennas and a local oscillator, comprising:

• means for estimating an error quantity with respect to a signal received at each antenna of said plurality of antennas;
• means for arriving at a measure of reliability of each said signal received at each antenna of said plurality of antennas;
• means for forming a weighted sum of said error quantities by applying a larger weight to said error quantity of one of said signals having greater reliability and applying a smaller weight to said error quantity of one of said signals having less reliability;
• and
• means for controlling a frequency of a signal produced by said local oscillator based on said weighted sum.

In a radio-frequency receiver employing antenna diversity and having a plurality of antennas and a local oscillator, a method of reducing an effect of fading of at least one of a plurality of input signals on an automatic frequency control circuit, comprising the steps of:

• deriving individual error signals from the input signals received respectively at each antenna of said plurality of antennas;
• arriving at a measure of reliability of each of said error signals and applying a larger weight to one of said error signals having a greater reliability and applying a smaller weight to one of said error signals having lesser reliability to arrive at a combined error signal having greater reliability than any one of said individual error signals taken alone;
• and
• controlling a frequency of said automatic frequency control circuit using said combined error signal to reduce the effect of fading of said input signals on said automatic frequency control circuit.