Communication receiving apparatus employing several samples of baseboard noise to detect an incoming signal and turn on the apparatus

Claim 1

Communication receiving apparatus which operates in response to incoming signals comprising radio receiver equipment including RF, IF, and audio sections, said IF section having a portion generating pulses of baseband noise in the absence of incoming signals; a power supply; switching means coupled to the power supply and the sections of the radio receiver equipment; a source of periodic clock pulses; said switching means being coupled to the source of periodic clock pulses and being operable during clock pulses therefrom to connect the power supply to the RF section and said portion of the IF section of the radio receiver equipment; filter means coupled to said portion of the IF section and operable to pass pulses of baseband noise generated within said portion while blocking signals at the IF frequency and noise generated in other portions of the radio receiver equipment; digitizing means coupled to said filter means and operable to produce a pulse in response to each noise pulse of predetermined amplitude passed by the filter means; counting means coupled to the digitizing means and the source of periodic clock pulses and operable to count the pulses from the digitizing means occurring duRing a clock pulse; latch means coupled to the counting means and operable to produce a first indication when the counting means counts less than a predetermined number of pulses during a clock pulse and a second indication when the counting means counts the predetermined number of pulses during a clock pulse; storage means coupled to the latch means for storing a plurality of indications from said latch means; and decision means coupled to the storage means and to the switching means for producing a first switching signal when in a first condition and a second switching signal when in a second condition, said decision means being operable to change from the second condition to the first condition in response to a first predetermined combination of first and second indications being stored in said storage means and being operable to change from the first condition to the second condition in response to a second predetermined combination of first and second indications being stored in said storage means; said switching means being coupled to said decision means and being operable during a first switching signal to connect the power supply to all the sections of the radio receiver equipment whereby the radio receiver equipment operates to receive incoming signals, said switching means being operable during a second switching signal to disconnect the power supply from the radio receiver equipment whereby during a second switching signal the switching means connects the power supply to the RF section and said portion of the IF section only during clock pulses.