Communication system, and transmitter therefor, including special announcement recognition
Patent 4584708 Issued on April 22, 1986. Estimated Expiration Date: 
January 14, 2005. 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.
January 14, 2005. 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 2008082 2414431 3922607 System for transmitting data simultaneously with audio Patent #: 4379947 InventorsAssigneeApplicationNo. 06/690840 filed on 01/14/1985US Classes:455/45, Via subcarrier332/120, Including amplitude modulation370/204, Plural diverse modulation techniques370/486, Program distribution381/4, AM subcarrier455/102, Plural modulation455/70Receiver control signal originates at message transmitterExaminersPrimary: Bookbinder, Marc E.Attorney, Agent or FirmInternational ClassG08G 1/09 (20060101)Foreign Application Priority Data1981-05-27 DEAbstractFM transmission system in which, besides program content, an auxiliary carrier of, for example 57 kHz, is radiated, which auxiliary carrier is modulated by an announcement recognition (AR) signal and by a region or radio-station recognition (RR) signal, the AR and RR signals being low-frequency, AM modulations on the auxiliary carrier. To enhance recognition of an AR signal, e.g. between 142 and 170 Hz, is enhanced, in spite of reception difficulties, for example due to multi-path reception and the like, by decreasing the modulation of the 57 kHz subcarrier by the RR signal to 30% or less, while the AR signal is modulating the subcarrier, so that the AR modulation may extend to 60 and even 90% modulation. Multiple AR frequencies can be used, for example to characterize different announcements, e.g. in different languages, or of different characteristics, such as traffic, news, sports, or others, recognition of the AR signal in the receiver permitting switch-over from other reproduced programs, e.g. tape, to the demodulator from the receiver tuned to the station emitting the AR signal, to reproduce the announcement, or the like.Other References
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