Mobile radio communications system
Patent 4748685 Issued on May 31, 1988. Estimated Expiration Date: 
October 10, 2006. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
October 10, 2006. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3092772 3614321 3921074 High speed squelch circuit Dual audio capture limiter squelch circuit Radio receiver SSB System with pilot coded squelch Paging universal remote control encoder Muting circuit Patent #: 4627101 InventorAssigneeApplicationNo. 06/917923 filed on 10/10/1986US Classes:455/218, Squelch375/217, Muting circuit and squelch455/410, Security or fraud prevention455/550.1Radiotelephone equipment detailExaminersPrimary: Lev, RobertAttorney, Agent or FirmInternational ClassesH02J 7/00 (20060101)H04Q 7/32 (20060101) AbstractA vehicle mounted mobile transceiver (11) communicates via a secondary mobile unit (51) with a short range portable unit (10). The portable unit (10) can be either a cordless microphone or a transceiver. The portable unit (10) allows a remotely positioned operator to transmit messages to a base station (13). To ensure security and reliable operation, the portable and vehicle mounted units use digitized codes for ID and instruction purposes. These codes are newly generated from time to time by the vehicle mounted unit and are imparted to the portable unit via a battery charging interface. An improved remote squelch detect is also provided. The improved remote squelch detect substitutes the normal input to the vehicle primary mounted mobile transceiver (11) squelch gate for an audio signal. The remote squelch detect can then detect the presence or absence of this input signal at the output of the audio PA for the vehicle mounted mobile transceiver, and this detection can be used to enable the secondary mobile unit to repeat the incoming message to the portable unit. With less delay than the prior art methods.Other References
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