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Patent US3631355A successfully refreshed from Google Patents.
US3631355A
Expired / Lapsed
US
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Synchronous demodulator
Assignee: Boeing North American Inc
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Filing: 1970-10-16
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Granted: 1971-12-28
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Expires: 1990-10-16
Abstract
Abstract The invention is a switching type of synchronous demodulator in which the periods of switched closure are controlled in such a way that the filtered output of the demodulator is unaffected by certain harmonics of the carrier. The demodulator is comprised of an input terminal for receiving an amplitude modulated carrier signal and a pair of switching means. Each of the switch means is connected to the input terminal in the closed position. A filter means is connected to the output of each of the switching means and an inverter is connected to one of the switching means to invert the signal passing through that switching means. A control means is provided for alternately holding said switches closed for two periods of 120* each during two complete 360* cycles of the carrier signal and for holding both switches open for the remainder of each cycle.
Inventors
- 👤 Robert W Vail
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:40
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
107 words
A synchronous demodulator comprising in combination: an input terminal for receiving an amplitude modulated carrier signal; a pair of switching means connectable to said input terminal; filter means having an input connected to said pair of switching means, said filter means operating to remove carrier related frequencies from the signal present at its input; an inverter series connected in the path defined between said input terminal, one of said switching means, and the input to said filter means, for inverting any signal traveling said deferred path; and control means for alternately closing said switching means for a period of 120* each 180* period of said carrier signal.
Claim 2
Dependent Claim
107 words
A synchronous demodulator comprising in combination: an input terminal for receiving an amplitude modulated carrier signal; a pair of switching means connectable to said input terminal; filter means having an input connected to said pair of switching means, said filter means operating to remove carrier related frequencies from the signal present at its input; an inverter series connected in the path defined between said input terminal, one of said switching means, and the input to said filter means, for inverting any signal traveling said deferred path; and control means for alternately closing said switching means for a period of 120* each 180* period of said carrier signal.
Claim 3
Dependent Claim
112 words
The synchronous demodulator of claim 1 wherein said control means is comprised of: a reference signal generator for providing a signal which is synchronous with and 30 times greater than the carrier frequency; counter means for counting the phase angle of the reference signal from said generator in increments of 12*; and logic means connected to said pair of switching means for opening and closing said switching means in accordance with the following table for every two cycles of said carrier signal: OPEN 0*-12* CLOSE FIRST SWITCHING MEANS 12*-132* OPEN 132*-228* CLOSE SECOND SWITCH MEANS 228*-348* OPEN 348*-408* CLOSE FIRST SWITCH MEANS 408*-528* OPEN 528*-552* CLOSE SECOND SWITCH MEANS 552*-672* OPEN 672*-720*
Claim 4
Dependent Claim
167 words
A synchronous demodulating system comprising: an input terminal for receiving said modulated carrier signal; a filter means for removing carrier related frequencies; a first and a second switch means each having a first and a second conductive electrode and a third control electrode, said first electrodes of said first and said second switch means connected to said input terminal, said second electrodes of said first and said second switch means connected to the input of said filter means; an inverting means interposed in the conductive path of said first switch means for inverting the signal traversing said path; and control means for providing control signals to said third control electrodes to open and close the conductive path between said first and second conductive electrodes of said first and said second switch means, said control means alternately holding said switch means closed for two periods of 120* each for two 360* cycles of said carrier signal with each 120* period separated by periods which are multiples of 12*.
Claim 5
Dependent Claim
167 words
A synchronous demodulating system comprising: an input terminal for receiving said modulated carrier signal; a filter means for removing carrier related frequencies; a first and a second switch means each having a first and a second conductive electrode and a third control electrode, said first electrodes of said first and said second switch means connected to said input terminal, said second electrodes of said first and said second switch means connected to the input of said filter means; an inverting means interposed in the conductive path of said first switch means for inverting the signal traversing said path; and control means for providing control signals to said third control electrodes to open and close the conductive path between said first and second conductive electrodes of said first and said second switch means, said control means alternately holding said switch means closed for two periods of 120* each for two 360* cycles of said carrier signal with each 120* period separated by periods which are multiples of 12*.
Claim 6
Dependent Claim
120 words
The invention according to claim 3 wherein said control means comprises: a reference signal generator for providing a signal which is synchronous with and 30 times greater than the carrier frequency; and a counter means for counting the phase angle of the reference signal from said generator in increments of 12*; logic means connected to said first and said second control Electrodes for opening and closing the conductive path between said first and second conductive electrodes in accordance with the following table for every two cycles of said carrier signal: OPEN 0*-12* CLOSE FIRST SWITCH MEANS 12*-132* OPEN 132*-228* CLOSE SECOND SWITCH MEANS 228*-348* OPEN 348*-408* CLOSE FIRST SWITCH means 408*-528* OPEN 528*-552* CLOSE SECOND SWITCH MEANS 552*-672* OPEN 672*-720*
References Cited (Backward Citations)
US3403345A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |