US4166925A
Expired / Lapsed
US
⏱️ 0.0 years remaining
FM stereo demodulator
Assignee: Hitachi Ltd
•
Filing: 1978-04-03
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Granted: 1979-09-04
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Expires: 1998-04-03
Abstract
Abstract In an FM stereo demodulator, a detector circuit for detecting a low supply voltage is used. The detection level of this detector circuit is made substantially equal to a supply voltage value at the time when the oscillation frequency of an oscillator circuit for reproducing a subcarrier signal begins to change. The stereo reproduction of the demodulator is compulsorily switched to monaural reproduction by an output from the detector circuit. As a result, the generation of an abnormal sound which is attributed to the beat between the reproduced subcarrier signal having fluctuated and a subcarrier signal component of a received broadcast signal is prevented.
Inventors
- 👤 Masanori Ienaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:50
CPC Classifications
H; H04; H04H; H04H40/00; H04H40/18; H04H40/27; H04H40/36; H04H40/45; H04H40/72; H03; H03D; H03D1/00; H03D1/22; H03D1/2209; H03D1/2236; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/1646; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
53 words
An FM stereo demodulator comprising a detection unit which detects a power supply voltage deficiency of sufficient absolute value to induce a fluctuation in the oscillation frequency of an oscillator circuit, and a control circuit which compulsorily switches stereo reproduction to monaural reproduction on the basis of an output of said detection unit.
Claim 2
Dependent Claim
53 words
An FM stereo demodulator comprising a detection unit which detects a power supply voltage deficiency of sufficient absolute value to induce a fluctuation in the oscillation frequency of an oscillator circuit, and a control circuit which compulsorily switches stereo reproduction to monaural reproduction on the basis of an output of said detection unit.
Claim 3
Dependent Claim
66 words
An FM stereo demodulator according to claim 1, wherein said detection unit consists of a source voltage generator circuit which generates a voltage at least somewhat related to the power supply voltage, a reference voltage generator circuit which delivers a reference voltage previously set, and a comparator circuit which receives the output of said voltage generator circuit and the output of said reference voltage generator circuit.
Claim 4
Dependent Claim
30 words
An FM stereo demodulator according to claim 2, wherein said source voltage generator circuit is constructed as a constant-voltage circuit which feeds said oscillator circuit with a constant supply voltage.
Claim 5
Dependent Claim
22 words
An FM stereo demodulator according to claim 1, wherein said oscillator circuit is a voltage-controlled oscillator circuit in a phase locked loop.
Claim 6
Dependent Claim
31 words
An FM stereo demodulator according to claim 4, wherein said control circuit is constructed of a gate circuit which inhibits a reproduced subcarrier signal from entering an FM stereo demodulation circuit.
References Cited (Backward Citations)
US3916321A
Cited
US4091241A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-09-03 | 1983-03-05 | 1983-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-03 | 1987-03-05 | 1987-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-03 | 1991-03-05 | 1991-09-04 | $7700.00 | Window Closed / Lapsed |