Method and apparatus for dynamically adjusting receiver squelch threshold

Claim 1

An adaptive digital squelch which dynamically changes a receiver squelch threshold when no valid signal is being received, comprising: means for receiving a radio frequency signal; demodulating means, coupled to said signal receiving means, for converting said radio frequency signal to a demodulated signal; measuring means, coupled to said signal receiving means, for measuring a radio frequency signal strength of said radio frequency signal; and processor means, coupled to said demodulating means and said measuring means, comprising means for 1) determining if said demodulated signal is a valid signal using said radio frequency signal strength measurement and thereupon disabling squelch, for 2) monitoring said radio frequency signal strength measurement during intervals when no valid signal is being received to determine an ambient RF background noise level, and for 3) adjusting the receiver squelch threshold responsive to changes in the ambient RF background noise level by integrating a plurality of noise signal measurements at a plurality of frequencies of the radio frequency signal to produce an average noise signal strength, a noise signal measurement being defined as a radio frequency signal strength measurement that is less than the receiver squelch threshold.

Claim 6

A method of automatically adjusting a receiver squelch threshold in a receiver, comprising the steps of: receiving a radio frequency signal; converting said radio frequency signal to a demodulated signal and a radio frequency signal strength measurement; measuring a radio frequency signal strength of said radio frequency signal to obtain a radio frequency signal strength measurement; using a processor to determine if said radio frequency signal strength measurement is greater than the receiver squelch threshold, indicative of a valid signal; using the processor to periodically adjust the receiver squelch threshold during intervals in which no valid signal is being received according to changes in ambient RF background noise by integrating a plurality of noise signal measurements obtained at a plurality of frequencies to produce an average noise signal measurement, a noise signal measurement being defined as a radio frequency signal strength measurement that is less than the receiver squelch threshold; and using the processor to disable squelch in the presence of a valid signal.

Claim 7

A method of automatically adjusting a receiver squelch threshold in a receiver, comprising the steps of: receiving a radio frequency signal; converting said radio frequency signal to a demodulated signal and a radio frequency signal strength measurement; measuring a radio frequency signal strength of said radio frequency signal to obtain a radio frequency signal strength measurement; using a processor to determine if said radio frequency signal strength measurement is greater than the receiver squelch threshold, indicative of a valid signal; using the processor to periodically adjust the receiver squelch threshold during intervals in which no valid signal is being received according to changes in ambient RF background noise by integrating a plurality of noise signal measurements obtained at a plurality of frequencies to produce an average noise signal measurement, a noise signal measurement being defined as a radio frequency signal strength measurement that is less than the receiver squelch threshold; and using the processor to disable squelch in the presence of a valid signal.

Claim 10

A method of automatically adjusting a receiver squelch threshold when no valid signal is being received, a valid signal being a signal that has a signal strength greater than the receiver squelch threshold, comprising the steps of: (a) obtaining an initial receiver squelch threshold; thereafter (b) enabling ambient noise threshold calculations; (c) testing whether ambient noise threshold calculations are enabled and proceeding to step (e) if they are disabled; (d) adjusting receiver squelch threshold responsive to ambient noise as indicated by the signal strength in the absence of a valid signal; (e) testing if the signal strength of the signal currently being received is greater than the receiver squelch threshold indicating a valid signal is being received and proceeding to step (g) if a valid signal is not being received; thereafter (f) disabling subsequent ambient noise threshold calculations and proceeding to step (i); (g) testing whether a specified amount of time has elapsed since the last valid signal was received and proceeding to step (i) if the specified amount of time has not elapsed; thereafter (h) enabling ambient noise threshold calculations; and (i) repeating steps (c) through (i) during receiver operation.

Claim 11

A method of automatically adjusting a receiver squelch threshold when no valid signal is being received, a valid signal being a signal that has a signal strength greater than the receiver squelch threshold, comprising the steps of: (a) obtaining an initial receiver squelch threshold; thereafter (b) enabling ambient noise threshold calculations; (c) testing whether ambient noise threshold calculations are enabled and proceeding to step (e) if they are disabled; (d) adjusting receiver squelch threshold responsive to ambient noise as indicated by the signal strength in the absence of a valid signal; (e) testing if the signal strength of the signal currently being received is greater than the receiver squelch threshold indicating a valid signal is being received and proceeding to step (g) if a valid signal is not being received; thereafter (f) disabling subsequent ambient noise threshold calculations and proceeding to step (i); (g) testing whether a specified amount of time has elapsed since the last valid signal was received and proceeding to step (i) if the specified amount of time has not elapsed; thereafter (h) enabling ambient noise threshold calculations; and (i) repeating steps (c) through (i) during receiver operation.