Patent ID: 7873337

Claim:
A method for detecting clear radio frequencies comprising; tuning a receiver to a frequency channel; detecting a radio frequency (RF) signal on the tuned frequency channel; determining a received signal strength indicator (RSSI) voltage signal, wherein the RSSI is proportional to the received RF signal strength at the tuned frequency channel; converting the RSSI voltage signal into a digital value; triggering a low level flag indicator when the digital value is below a predetermined value; tuning the receiver to at least one different frequency channel and repeating the detecting, the determining, the converting and the triggering; storing the tuned frequency channels with the low level flag indicators; if two or more tuned frequency channels with low level flags are stored, then determining at least one RSSI signal level of at least one adjacent frequency channel for each of the two or more tuned frequency channels; comparing the respective RSSI signal levels of the at least one adjacent frequency channels to determine a lowest RSSI signal level, and selecting the tuned frequency channel with the at least one adjacent frequency channel having the lowest RSSI signal level; and transmitting a short range signal on the selected tuned frequency channel.