Patent ID: 6671504
Filing Date: 2003-12-30
Classification: H03G

Abstract:
In a radio receiver adapted to receive a radio frequency carrier signal, apparatus for providing signal squelching comprising:carrier processing circuitry arranged to generate a baseband carrier signal in response to said radio frequency carrier signal; a detector arranged to generate a detected signal in response to said baseband carrier signal; a noise estimator arranged to generate a noise estimate signal by estimating at least the noise in the detected signal due to atmospheric conditions; a threshold calculator arranged to calculate a threshold signal defining a predetermined signal level in response to the noise estimate signal and one or more predetermined signal parameters; a threshold detector arranged to generate a first signal in the event that a signal derived from said detected signal has a first predetermined relationship with respect to said predetermined signal level and to generate a second signal in the event that said signal derived from said detected signal has a second predetermined relationship with respect to said predetermined level, said noise estimator being responsive to said detected signal in the event said second signal is generated and being unresponsive to said detected signal in the event said first signal is generated; and a signal conditioner arranged to pass said detected signal in response to said first signal and to squelch said detected signal in response to said second signal.