Telecommunications – Receiver or analog modulated signal frequency converter – Convertible to different type
Patent
1996-09-23
1999-08-10
Eisenzopf, Reinhard J.
Telecommunications
Receiver or analog modulated signal frequency converter
Convertible to different type
455144, 4551501, H04B 1702
Patent
active
059373377
ABSTRACT:
A technique for reducing FM intrusion in an AM section of an AM/FM receiver. In one embodiment, a first switch is provided between an FM tuner filter circuit and an AM tuner circuit. A second switch is provided between the FM tuner circuit and a reference potential. When the receiver is in an FM mode, the first switch is closed so that a tuning voltage can be applied to the FM tuner circuit, and the second switch is open to prevent the tuning voltage from being affected by the reference potential. When the receiver is switched to the AM mode, the first switch is open to prevent intermodulation product signals generated by the FM tuner circuit from reaching the AM tuner circuit, and the second switch is closed to connect the FM tuner circuit to the reference potential. By connecting the FM tuner circuit to the reference potential when the receiver is in the AM mode, the tuning of the FM tuner circuit is shifted out of the FM bandwidth, thus eliminating intermodulation products at the AM frequencies. In an alternate embodiment, a switch is provided to switch off the power to the FM front end when in the AM mode.
REFERENCES:
patent: 3389338 (1968-06-01), Slavin
patent: 3472967 (1969-10-01), Wofford et al.
patent: 3710143 (1973-01-01), Bray et al.
patent: 3755763 (1973-08-01), Hoshi
patent: 4034298 (1977-07-01), McFadyen et al.
patent: 4135158 (1979-01-01), Parmet
Easterwood Michael John
Marrah Jeffrey Joseph
Pham Linh Ngoc
Armstrong Darnell R.
Delco Electronics Corporation
Eisenzopf Reinhard J.
Funke Jimmy L.
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