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US3852672A
Expired / Lapsed
US
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Four-quadrant multiplier-notch filter demodulator
Assignee: Boeing Co
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Filing: 1973-10-29
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Granted: 1974-12-03
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Expires: 1993-10-29
Abstract
Abstract A carrier-suppressed amplifier demodulator employing a fourquadrant multiplier in such a fashion that all of the signal generated sidebands of the carrier and the carrier frequency are multiplied times the carrier center frequency by the multiplier. A notch filter coupled to the output of the multiplier is tuned to twice the carrier center frequency and removes the multiplier doubled carrier center frequency, leaving only the signal which generated the carrier sidebands. This produces an output signal which has improved transient response and low carrier frequency ripple.
Inventors
- 👤 E Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:59
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22; H03D1/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
73 words
A carrier-suppressed amplifier demodulator comprising: means for generating a carrier signal of fixed frequency, means for generating an oscillatory modulating signal, means for modulating said carrier signal with said modulating signal to produce a modulated signal, means for multiplying said modulated signal with said carrier signal to produce an output multiplied signal, and means for passing said multiplied signal through a notch filter to produce an output signal proportional to the modulating signal.
Claim 2
Dependent Claim
73 words
A carrier-suppressed amplifier demodulator comprising: means for generating a carrier signal of fixed frequency, means for generating an oscillatory modulating signal, means for modulating said carrier signal with said modulating signal to produce a modulated signal, means for multiplying said modulated signal with said carrier signal to produce an output multiplied signal, and means for passing said multiplied signal through a notch filter to produce an output signal proportional to the modulating signal.
Claim 3
Dependent Claim
101 words
A carrier-suppressed amplifier demodulator comprising: means for generating a carrier signal of fixed frequency SIN A, means for generating a modulating signal K(SIN B), means for modulating said carrier signal with said modulating signal to produce a modulated signal K(SIN B) (SIN A), means for multiplying said modulated signal with said carrier signal to produce an output multiplied signal K(SIN B) ( 1/2 (1 - COS 2A)), and means for passing said multiplied signal through a notch filter tuned to the frequency COS 2A to produce a signal K/2 SIN B which is proportional to K SIN B, the modulating signal.
Claim 4
Dependent Claim
101 words
A carrier-suppressed amplifier demodulator comprising: means for generating a carrier signal of fixed frequency SIN A, means for generating a modulating signal K(SIN B), means for modulating said carrier signal with said modulating signal to produce a modulated signal K(SIN B) (SIN A), means for multiplying said modulated signal with said carrier signal to produce an output multiplied signal K(SIN B) ( 1/2 (1 - COS 2A)), and means for passing said multiplied signal through a notch filter tuned to the frequency COS 2A to produce a signal K/2 SIN B which is proportional to K SIN B, the modulating signal.
Claim 5
Dependent Claim
15 words
The amplifier demodulator of claim 2 wherein said means for multiplying comprises a four-quadrant multiplier.
Claim 6
Dependent Claim
48 words
The amplifier demodulator of claim 3 wherein said four-quadrant multiplier includes a logarithmic compressor to which said modulated signal is applied, a voltage-to-current converter to which said modulating signal is applied, and a variable gain amplifier coupled to the output of said logarithmic compressor and said voltage-tO-current converter.
Claim 7
Dependent Claim
20 words
The amplifier demodulator of claim 4 including an operational amplifier interposed between said variable gain amplifier and said notch filter.
References Cited (Backward Citations)
US3283574A
Cited
US3493876A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |