US3571736A
Expired / Lapsed
US
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Demodulator for pulse width modulated signals
Assignee: International Business Machines Corp
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Filing: 1969-01-14
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Granted: 1971-03-23
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Expires: 1989-01-14
Abstract
Abstract The subject disclosure relates to a frequency demodulator. The demodulator produces two pulse trains from the transitions which are square wave trains with one train being inverted with respect to the other. These transitions define ''''transition periods.'''' During During the first transition period, a capacitor is discharged so that at the end of that period, it provides a signal that is a function of the time width of the first odd transition period of the first train of square waves. During the second even transition period, another capacitor is discharged so that at the end of this period the capacitor provides a signal which is a function of the time length of the second transition period. Thus, the two trains provide alternately a voltage level that is a function of alternate transition periods. These signals are then added to produce a quantitized version of the frequency modulation.
Inventors
- 👤 Lynn P West
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:21
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
110 words
A circuit for demodulating a frequency modulated input signal having: a train of pulse widths, said pulse widths defining a plurality of alternative odd and even transition time periods; first means developing a first signal with portions of said signal having amplitudes developed as a function of the time length of even alternate transition time periods; second means developing a second signal with portions of said signal having amplitudes developed as a function of the time length of odd alternate transition time periods; and means summing the portions of said first and said second signals, thereby to provide an output consisting alternately of said first signal and said second signal.
Claim 2
Dependent Claim
110 words
A circuit for demodulating a frequency modulated input signal having: a train of pulse widths, said pulse widths defining a plurality of alternative odd and even transition time periods; first means developing a first signal with portions of said signal having amplitudes developed as a function of the time length of even alternate transition time periods; second means developing a second signal with portions of said signal having amplitudes developed as a function of the time length of odd alternate transition time periods; and means summing the portions of said first and said second signals, thereby to provide an output consisting alternately of said first signal and said second signal.
Claim 3
Dependent Claim
61 words
A circuit as set forth in claim 1 wherein said first means develops said first signal during the even alternate transition time periods and holds the same amplitude during the odd alternate transition time periods; and said second means develops the second signal during the odd alternate transition time periods and holds its amplitude during the even alternate transition time periods.
Claim 4
Dependent Claim
42 words
A circuit as set forth in claim 2 wherein said summing means includes gating means to alternately apply to the output, said first signal during the odd alternate transition time periods and said second signal during the even alternate transition time periods.
Claim 5
Dependent Claim
68 words
A circuit as set forth in claim 3 wherein said first means develops said first signal having an amplitude which is a function of the time length of even alternate transition time period less a constant time length and said second means develops said second signal, the amplitude of which is a function of the time length of odd alternate transition time periods less a constant time length.
Claim 6
Dependent Claim
54 words
A Circuit as set forth in claim 4 wherein said first means includes an integrator for integrating the time length of even alternate transition time periods less a constant time length and said second means includes an integrator for integrating the time length of odd alternate transition time periods less a constant time length.
References Cited (Backward Citations)
US2716189A
Cited
US2904683A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-22 | 1974-09-21 | 1975-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-22 | 1978-09-21 | 1979-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-22 | 1982-09-21 | 1983-03-23 | $7700.00 | Window Closed / Lapsed |