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US5159281A
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Digital demodulator using numerical processor to evaluate period measurements
Assignee: NUMA TECHNOLOGIES Inc
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Filing: 1991-11-20
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Granted: 1992-10-27
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Expires: 2011-11-20
Abstract
Abstract A digital demodulator provides efficient demodulation of frequency modulated, pulse-width modulated, and other temporally modulated signals. Without employing an analog-to-digital converter, modulating signal information is extracted from a modulated signal as numerical information. For frequency demodulation, a high gain stage is applied to an incoming FM signal to produce a corresponding sequence of square waves. The period between zero-crossings of the square waves is accurately measured to within one clock pulse using a high-speed clock and at least one counter. Period information is then provided to a numerical processor, wherein it is at least scaled and low-pass filtered to produce a high-quality demodulated signal with a high signal-to-noise ratio.
Inventors
- 👤 Mark D. Hedstrom
- 👤 Robert B. Porter
- 👤 Charles R. Crego
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:33
CPC Classifications
H; H03; H03K; H03K9/00; H03K9/06; H03D; H03D3/00; H03D3/02; H03D3/04
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
100 words
A digital demodulator for efficient demodulation of temporally modulated signals, the demodulator comprising: a zero-crossing event detector, responsive to a temporally modulated signal, that serves to detect zero-crossing events of said temporally modulated signal, and thereby provide zero-crossing event information; a period measurer, connected to said zero-crossing detector, that serves to receive said zero-crossing event information and measure the period between said zero-crossing events, thereby providing a sequence of period measurement values; and a numerical processor, connected to said period measurer, that serves to convert said sequence of period measurement values into a demodulated signal with a high signal-to-noise ratio.
Claim 2
Dependent Claim
100 words
A digital demodulator for efficient demodulation of temporally modulated signals, the demodulator comprising: a zero-crossing event detector, responsive to a temporally modulated signal, that serves to detect zero-crossing events of said temporally modulated signal, and thereby provide zero-crossing event information; a period measurer, connected to said zero-crossing detector, that serves to receive said zero-crossing event information and measure the period between said zero-crossing events, thereby providing a sequence of period measurement values; and a numerical processor, connected to said period measurer, that serves to convert said sequence of period measurement values into a demodulated signal with a high signal-to-noise ratio.
Claim 3
Dependent Claim
51 words
The digital demodulator of claim 1 wherein said numerical processor includes: a digital data stream generator that receives and converts said sequence of period measurement values into a digital data stream representative of said demodulated signal; and an digital-to-analog converter that receives said digital data stream and provides said demodulated signal.
Claim 4
Dependent Claim
24 words
The digital demodulator of claim 1 wherein said numerical processor converts said sequence of period measurement values into said demodulated signal in real time.
Claim 5
Dependent Claim
31 words
The digital demodulator of claim 1 wherein said zero-crossing detector provides zero-crossing event information as a sequence of square waves with zero-crossings commensurate with the zero-crossings of said temporally modulated signal.
Claim 6
Dependent Claim
55 words
The digital demodulator of claim of claim 1 wherein said period measurer includes: a clock; a counter; and a clock pulse gate, connected to said clock, said counter, and said zero-crossing detector, that permits clock pulses to propagate from said clock to said counter in response to zero-crossing event information provided by said zero-crossing detector.
Claim 7
Dependent Claim
32 words
The digital demodulator of claim 5 further including: a second clock pulse gate, connected to said clock and said zero-crossing detector; and a second counter, connected to said second clock pulse gate.
Claim 8
Independent Claim
47 words
A method for demodulating a temporally modulated signal, the method comprising the steps of: measuring the period between zero-crossings of an intermediate signal of a modulated signal to provide a sequence of period values; and numerically processing said sequence of period values to provide a demodulated signal.
Claim 9
Independent Claim
47 words
A method for demodulating a temporally modulated signal, the method comprising the steps of: measuring the period between zero-crossings of an intermediate signal of a modulated signal to provide a sequence of period values; and numerically processing said sequence of period values to provide a demodulated signal.
Claim 10
Dependent Claim
58 words
The method of claim 7 wherein the step of numerically processing includes the steps of: weighting and scaling said sequence of period values to provide a sequence of weighted and scaled values; filtering said sequence of weighted and scaled values to provide a sequence of filtered values; and converting said sequence of filtered values into an analog signal.
Claim 11
Dependent Claim
44 words
The method of claim 8 further including the step of: after the step of weighting and scaling, and prior to the step of filtering, averaging the weighted and scaled values within a sliding window to provide a sequence of averaged values to be filtered.
Claim 12
Dependent Claim
20 words
The method of claim 9 wherein the sliding window includes two values and is advanced two values at a time.
Claim 13
Dependent Claim
46 words
The method of claim 8 further including the step of: after the step of weighting and scaling, and prior to the step of filtering, executing a Hamming window function upon the sequence of weighted and scaled values to provide a sequence of values to be filtered.
Claim 14
Dependent Claim
47 words
The method of claim 8 further including the step of: after the step of weighting and scaling, and prior to the step of filtering, executing a Von Hann window function upon the sequence of weighted and scaled values to provide a sequence of values to be filtered.
Claim 15
Dependent Claim
63 words
The method of claim 8 further including the steps of: after the step of weighting and scaling, averaging the weighted and scaled values within a sliding window to provide a sequence of averaged values; and prior to the step of filtering, executing a Hamming window function upon the sequence of weighted and scaled values to provide a sequence of values to be filtered.
Claim 16
Dependent Claim
96 words
The method of claim 7 wherein the step of numerically processing includes the steps of: weighting and scaling said sequence of period values to provide a sequence of weighted and scaled values; averaging the weighted and scaled values within a sliding window to provide a sequence of window averaged values; executing a Von Hann window function upon the sequence of window averaged values to provide a sequence of Von Hann values; filtering said sequence of Von Hann values to provide a sequence of filtered values; and converting said sequence of filtered values into an analog signal.
Claim 17
Dependent Claim
93 words
The method of claim 7 wherein the step of numerically processing includes the steps of: weighting and scaling said sequence of period values to provide a sequence of weighted and scaled values; averaging the weighted and scaled values within a sliding window to provide a sequence of window averaged values; executing a Hamming window function upon the sequence of window averaged values to provide a sequence of Hamming values; filtering said sequence of Hamming values to provide a sequence of filtered values; and converting said sequence of filtered values into an analog signal.
References Cited (Backward Citations)
US4412339A
Cited
US4992748A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-10-27 | 1996-04-27 | 1996-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-10-27 | 2000-04-27 | 2000-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-10-27 | 2004-04-27 | 2004-10-27 | $7700.00 | Window Closed / Lapsed |