US3725674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impulse noise blanker including broadband level sensing
Assignee: Motorola Solutions Inc
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Filing: 1971-07-08
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Granted: 1973-04-03
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Expires: 1991-07-08
Abstract
Abstract An impulse noise blanking circuit for decreasing the impulse noise in a receiver includes a level sensing circuit coupled to a stage in the signal path following the blanking elements, and to at least one amplifier stage in the noise amplifiers which amplify the impulse noise signals. The level sensing circuit senses the level of the on-channel and adjacent channel energy in the signal path and develops a level sensing signal. The level sensing signal is coupled to the noise amplifiers to vary the gain in accordance with the level sensing signals, thereby reducing the blanking rate and the resultant receiver degradation due to an excessive blanking rate. The level sensing circuit includes a field effect transistor amplifier stage and feedback circuitry to minimize the production of undesired intermodulation producing signals therein.
Inventors
- 👤 D Schaeffer
- 👤 L Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 00:37
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/345
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
262 words
An impulse noise blanking circuit for use in a radio receiver having a signal path which includes a first circuit for conducting and translating a desired signal which may be accompanied by undesired signals and impulse noise disturbances, a second circuit for repeating the desired signal, and a third circuit coupling said first circuit to said second circuit and which is adapted to be interrupted by the application of blanking pulses thereto, said impulse noise blanking circuit including in combination, amplifying means having a variable amplification characteristic for amplifying said impulse noise disturbances connected to said first circuit, pulse circuit means coupled to said amplifying means and operative in response to the impulse noise disturbances to develop blanking pulses, means coupling said blanking pulses from said pulse circuit means to said third circuit for applying said blanking pulses thereto to interrupt said third circuit, and a level sensing circuit including a first stage having a field effect transistor coupled to said second circuit for receiving said repeated signals therefrom, said level sensing circuit being adapted to develop a level sensing signal which varies in response to the level of the signal repeated by said second circuit, said level sensing circuit being coupled to said amplifying means for coupling said level sensing signal thereto, said amplifying means being responsive to said level sensing signal to vary the amplification characteristic thereof, said level sensing circuit further including circuit means operative in response to said level sensing signal exceeding a predetermined level to reduce the level of said repeated signals in said level sensing circuits.
Claim 2
Dependent Claim
262 words
An impulse noise blanking circuit for use in a radio receiver having a signal path which includes a first circuit for conducting and translating a desired signal which may be accompanied by undesired signals and impulse noise disturbances, a second circuit for repeating the desired signal, and a third circuit coupling said first circuit to said second circuit and which is adapted to be interrupted by the application of blanking pulses thereto, said impulse noise blanking circuit including in combination, amplifying means having a variable amplification characteristic for amplifying said impulse noise disturbances connected to said first circuit, pulse circuit means coupled to said amplifying means and operative in response to the impulse noise disturbances to develop blanking pulses, means coupling said blanking pulses from said pulse circuit means to said third circuit for applying said blanking pulses thereto to interrupt said third circuit, and a level sensing circuit including a first stage having a field effect transistor coupled to said second circuit for receiving said repeated signals therefrom, said level sensing circuit being adapted to develop a level sensing signal which varies in response to the level of the signal repeated by said second circuit, said level sensing circuit being coupled to said amplifying means for coupling said level sensing signal thereto, said amplifying means being responsive to said level sensing signal to vary the amplification characteristic thereof, said level sensing circuit further including circuit means operative in response to said level sensing signal exceeding a predetermined level to reduce the level of said repeated signals in said level sensing circuits.
Claim 3
Dependent Claim
77 words
The impulse noise blanking circuit of claim 1 wherein said level sensing circuit includes, a second stage coupled to said field effect transistor and being operative to amplify said repeated and amplified signals, said second stage including at least one bipolar transistor, and a detector stage coupled to said second stage and operative in response to the signals coupled thereto to develop a level sensing signal which varies in accordance with the level of said repeated signals.
Claim 4
Dependent Claim
55 words
The impulse noise blanking circuit of claim 2 wherein said circuit means operative in response to said level sensing signal includes feedback circuit means coupled to said stages thereof and operative in response to said level sensing signal exceeding a predetermined level to reduce the level of said repeated signals in said level sensing circuit.
Claim 5
Dependent Claim
96 words
The impulse noise blanking circuit of claim 3 wherein said feedback circuit means includes, diode means coupled to said second stage and to a reference potential, and circuit means coupling said level sensing signal to said diode means, said diode means being rendered conductive in response to said level sensing signal exceeding a predetermined level for providing a conduction path to said reference potential for said repeated and amplified signals, said diode conduction varying in accordance with said level sensing signal to reduce the level of said repeated and amplified signals coupled to said second stage.
Claim 6
Dependent Claim
44 words
The impulse noise blanking circuit of claim 4 wherein said amplifying means includes, at least one stage having a field effect transistor, having gate, drain and source electrodes, said level sensing signal being coupled to said gate electrode to vary the amplification characteristics thereof.
Claim 7
Dependent Claim
55 words
The impulse noise blanking circuit of claim 5 wherein said second circuit includes, a field effect transistor amplifier having gate, drain and source electrodes, said gate electrode being coupled to said third circuit for receiving the desired signals therefrom, said drain electrode being coupled to said level sensing circuit for coupling the repeated signals thereto.
Claim 8
Dependent Claim
98 words
The impulse noise blanking circuit of claim 6 wherein said detector stage includes, first transistor means having a base, emitter and collector electrode, said base electrode being coupled to said second stage for receiving amplified repeated signals therefrom, bias circuit means coupled to said electrodes for applying a bias voltage thereto, reactance means coupled to said collector electrode and to the reference potential, said reactance means developing said level sensing signal thereacross, said first transistor means being rendered operative in response to said signals coupled thereto for varying the level sensing signal developed across the said reactance means.
Claim 9
Dependent Claim
52 words
The impulse noise blanking circuit of claim 7 wherein said feedback circuit means includes, second transistor means coupled to said first transistor means collector electrode and to said diode means, said second transistor means operative in response to said level sensing signal exceeding said predetermined level to render said diode means conductive.
Claim 10
Dependent Claim
23 words
The impulse noise blanking circuit of claim 8 wherein said second stage of said level sensing circuit is constructed in integrated circuit form.
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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) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |