US3783398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fm pulse averaging demodulator
Assignee: INT VIDEO CORP
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Filing: 1972-09-01
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Granted: 1974-01-01
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Expires: 1992-09-01
Abstract
Abstract An FM pulse averaging demodulator particularly useful in high quality broadcast television video tape recorders and reproducers employing high carrier frequencies. Extremely constant area pulses are generated in response to a well limited FM signal by generating ramps in response to successive FM wave zero crossings. The ramps are applied to respective differential comparator/clipper pairs whose threshold level sets the demodulator gain. The resulting constant area pulses at each zero crossing are applied to a low pass filter which provides a demodulated signal having high linearity and excellent differential gain characteristics.
Inventors
- 👤 B Dann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:21
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
91 words
A pulse averaging type FM demodulator receiving a well limited FM signal comprising: a. means for generating first and second repetitive ramps in response to alternate successive zero crossings of said signal, b. means for generating a predetermined threshold level signal, c. means responsive to said last recited means and receiving said first and second repetitive ramps for differentially comparing and clipping said respective repetitive ramps at said predetermined threshold level, d. means for combining said compared and clipped ramps, and e. means for filtering said combined, compared and clipped ramps.
Claim 2
Dependent Claim
91 words
A pulse averaging type FM demodulator receiving a well limited FM signal comprising: a. means for generating first and second repetitive ramps in response to alternate successive zero crossings of said signal, b. means for generating a predetermined threshold level signal, c. means responsive to said last recited means and receiving said first and second repetitive ramps for differentially comparing and clipping said respective repetitive ramps at said predetermined threshold level, d. means for combining said compared and clipped ramps, and e. means for filtering said combined, compared and clipped ramps.
Claim 3
Dependent Claim
34 words
The combination of claim 1 further comprising means for adjusting said means for establishing a predetermined threshold level signal to thereby adjust the comparator and clipping level of said differential comparing and clipping means.
Claim 4
Dependent Claim
17 words
The combination of claim 2 further comprising means for balancing the drop or rise of said ramps.
Claim 5
Dependent Claim
15 words
The combination of claim 3 further comprising means for balancing the slope of said ramps.
Claim 6
Dependent Claim
63 words
The combination of claim 1 wherein said ramp generating means comprises first and second PNP emitter follower transistor stages receiving the input signal 180* out of phase at their bases and having the emitter of each stage connected to respective resistor-capacitor junctions of first and second series circuits each consisting of a series positive voltage source, charging resistor, capacitor, diode clamp and ground.
Claim 7
Dependent Claim
63 words
The combination of claim 2 wherein said differential comparator and clipper means comprises first and second differential comparator pair NPN transistors each connected to a reSpective current source and receiving the first and second repetitive ramps at the base of one of each of the NPN pairs and receiving said threshold level signal at the base of the other of the NPN pair.
References Cited (Backward Citations)
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US2434965A
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US2510983A
Cited
US2571017A
Cited
US2895784A
Cited
US3458729A
Cited
US3521084A
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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) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |