A system and method of improving the rejection of intermodulation (IM) distortion in receivers (100) employing varactor tuning preselecters by exploiting the attenuating properties of a tunable preselecter at specific voltages. The invention takes advantage of a first preselecter (101) and a second preselecter (105) already present in existing receiver circuits enabling them to provide attenuation to incoming radio frequency (RF) signals. This enables the receiver to better operate without the burden of interference and without the need to retrofit the receiver with added attenuator circuitry.

 
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> Method for preventing an unauthorized device from operating in an 800 MHz trunked radio communications system using channels 319 to 0

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