Method and apparatus for improving the sensitivity of an RF receiver at certain frequencies

A method for improving the sensitivity of a radio frequency (RF) receiver at certain frequencies subject to co-channel interference, including the steps of:

• (a) determining that a reference frequency of the RF receiver generates significant interfering harmonic frequencies for a received RF signal in a selected channel;
• (b) generating an offset reference frequency based on such determination;
• (c) changing a multiplier of the reference frequency used to generate an injection frequency such that the injection frequency synthesized from the offset reference frequency using the changed multiplier is approximately equal to the injection frequency synthesized from the reference frequency using the unchanged multiplier;
• (d) determining that the reference frequency of the RF receiver does not generate significant interfering harmonic frequencies for a received RF signal in the selected channel;
• and
• (e) not offsetting the reference frequency and not changing the multiplier based on such determination.

An radio frequency (RF) receiver having improved sensitivity at certain frequencies subject to co-channel interference, including:

• (a) RF signal receiver circuitry for receiving an RF signal in a selected channel, and down converting and decoding the received RF signal to an information signal;
• (b) a reference frequency generator, coupled to the RF signal receiver circuitry, for generating a reference frequency for the RF signal receiver circuitry;
• (c) an injection frequency generator, coupled to the reference frequency generator, for multiplying the reference frequency by a multiplier to generate an injection frequency for down converting the RF signal receiver circuitry;
• (d) a determining element, coupled to the reference frequency generator, for indicating that the reference frequency generates significant interfering harmonic frequencies for a received RF signal in a selected channel;
• and
• (e) an offset generation element, coupled to the reference frequency generator and configured to respond to such indication from the determining element, for causing the reference frequency generator to generate an offset reference frequency and for changing the multiplier such that the injection frequency synthesized from the offset reference frequency using the changed multiplier is approximately equal to the injection frequency synthesized from the reference frequency using the unchanged multiplier.

A computer program, residing on a computer-readable medium, for improving the sensitivity of a radio frequency (RF) receiver at certain frequencies subject to co-channel interference, the computer program comprising instructions for causing a programmable processor to:

• (a) determine that a reference frequency of the RF receiver generates significant interfering harmonic frequencies for a received RF signal in a selected channel;
• (b) generate an offset reference frequency based on such determination;
• and
• (c) change a multiplier of the reference frequency used to generate an injection frequency such that the injection frequency synthesized from the offset reference frequency using the changed multiplier is approximately equal to the injection frequency synthesized from the reference frequency using the unchanged multiplier.

A computer program, residing on a computer-readable medium, for improving the sensitivity of a radio frequency (RF) receiver at certain frequencies subject to co-channel interference, the computer program comprising instructions for causing a programmable processor to:

• (a) determine that a reference frequency of the receiver generates significant interfering harmonic frequencies for a received RF signal in a selected channel;
• (b) generate an offset reference frequency based on such determination;
• (c) change a multiplier of the reference frequency used to generate an injection frequency such that the injection frequency synthesized from the offset reference frequency using the changed multiplier is approximately equal to the injection frequency synthesized from the reference frequency using the unchanged multiplier;
• (d) determine that the reference frequency of the receiver does not generate significant interfering harmonic frequencies for a received RF signal in the selected channel;
• and
• (e) not offset the reference frequency and not change the multiplier based on such determination.