US5390345A
Expired / Lapsed
US
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Method for preventing desensitization and radio interference of radio receivers
Assignee: Toyo Communication Equipment Co Ltd
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Filing: 1991-05-31
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Granted: 1995-02-14
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Expires: 2011-05-31
Abstract
Abstract A signal which results from cross modulation of two or more nearby received waves contained in the output of a high-frequency amplifier or mixer of a radio receiver, for example, a low-frequency signal corresponding to a channel separation frequency is extracted. The gain of the high-frequency amplifier or attenuation of a variable attenuator provided in the preceding stage of the amplifier is controlled in accordance with the level of the low-frequency signal. Alternatively, the gain of the high-frequency amplifier or attenuation of the variable attenuator is controlled in accordance with the level of the low-frequency signal when it is equal to or larger than a predetermined value. This permits normal reception of a desired wave, even if the signal receiving level is high.
Inventors
- 👤 Masahiro Wada
- 👤 Kazuo Tominaga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:31
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3052; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/1027; H04B1/109
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
145 words
A radio receiver capable of preventing radio interference caused by cross modulation of two or more disturbing waves, comprising: a high-frequency amplifier for amplifying a received signal, a gain of said high-frequency amplifier being controlled by a direct current signal; a local oscillator; a mixer for outputting an intermediate frequency signal caused by mixing an output signal of said local oscillator and an output signal of said high-frequency amplifier; and interference detector means for detecting a cross modulated product within said intermediate frequency signal, comprising a filter which separates said cross modulated product from said intermediate frequency signal, said cross modulated product having a low frequency which is at least equal to the channel separation frequency of said two or more disturbing waves, and a rectifier for generating said direct current signal from said cross modulated product for controlling said gain of said high-frequency amplifier.
Claim 2
Dependent Claim
145 words
A radio receiver capable of preventing radio interference caused by cross modulation of two or more disturbing waves, comprising: a high-frequency amplifier for amplifying a received signal, a gain of said high-frequency amplifier being controlled by a direct current signal; a local oscillator; a mixer for outputting an intermediate frequency signal caused by mixing an output signal of said local oscillator and an output signal of said high-frequency amplifier; and interference detector means for detecting a cross modulated product within said intermediate frequency signal, comprising a filter which separates said cross modulated product from said intermediate frequency signal, said cross modulated product having a low frequency which is at least equal to the channel separation frequency of said two or more disturbing waves, and a rectifier for generating said direct current signal from said cross modulated product for controlling said gain of said high-frequency amplifier.
Claim 3
Dependent Claim
148 words
A radio receiver capable of preventing radio interference caused by cross modulation of two or more disturbing waves, comprising: an attenuator which controls an attenuation level of a signal by application of a direct current signal; a high-frequency amplifier for amplifying an output signal of said attenuator; a local oscillator; a mixer for outputting an intermediate frequency signal generated by mixing an .output signal of said local oscillator and an output signal of said high-frequency amplifier; interference detector means for detecting a cross modulated product within said intermediate frequency signal, comprising a filter which separates said cross modulated product from said intermediate frequency signal, said cross modulated product having a low frequency which is at least equal to the channel separation frequency of said two or more disturbing waves, and a rectifier for generating said direct current signal from said cross modulated product for controlling said attenuation level.
Claim 4
Dependent Claim
148 words
A radio receiver capable of preventing radio interference caused by cross modulation of two or more disturbing waves, comprising: an attenuator which controls an attenuation level of a signal by application of a direct current signal; a high-frequency amplifier for amplifying an output signal of said attenuator; a local oscillator; a mixer for outputting an intermediate frequency signal generated by mixing an .output signal of said local oscillator and an output signal of said high-frequency amplifier; interference detector means for detecting a cross modulated product within said intermediate frequency signal, comprising a filter which separates said cross modulated product from said intermediate frequency signal, said cross modulated product having a low frequency which is at least equal to the channel separation frequency of said two or more disturbing waves, and a rectifier for generating said direct current signal from said cross modulated product for controlling said attenuation level.
Claim 5
Dependent Claim
124 words
A radio receiver according to claim 1, wherein: said high-frequency amplifier is comprised of at least two transistors, a base of the first transistor receiving a signal from an antenna of said radio receiver, said base being connected to a capacitor, said base of said first transistor also being connected to a ground via a choke coil and a collector and an emitter of the second transistor, said choke coil being capable of obstructing passage of high-frequency signals, a collector of said first transistor being connected to a power supply via a primary coil of a tuning transformer, a base of said second transistor being connected to a rectifier, said rectifier being connected to said interference detector means to receive said direct current signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-02-13 | 1998-08-15 | 1999-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-02-13 | 2002-08-15 | 2003-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-02-13 | 2006-08-15 | 2007-02-14 | $7700.00 | Window Closed / Lapsed |