US3798550A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fm receiver
Assignee: Pioneer Corp
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Filing: 1972-12-08
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Granted: 1974-03-19
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Expires: 1992-12-08
Abstract
Abstract A portion of a demodulated signal derived from a demodulator circuit, in an FM receiver having a phase locked loop to generate a subcarrier, is phase-inverted and applied to counterbalance demodulation components generated by a phase comparator circuit of the phase locked loop.
Inventors
- 👤 S Takaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:30
CPC Classifications
H; H04; H04H; H04H40/00; H04H40/18; H04H40/27; H04H40/36; H04H40/45; H04H40/54; H03; H03D; H03D1/00; H03D1/22; H03D1/2209; H03D1/2236
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
169 words
In an FM receiver including a. a demodulator circuit for demodulating a composite signal with a phase locked subcarrier; and b. a sub-carrier generating circuit comprising a voltage controlled oscillator for generating a sub-carrier, a phase comparator circuit for comparing the phase of a comparison signal derived from said voltage controlled oscillator to a pilot signal comprising a part of an FM composite input signal, a low pass filter for rejecting obstacle signal components from an error voltage representative of the phase difference obtained by said phase comparator circuit, and a DC amplifier for amplifying the filtered error voltage to phase control said voltage controlled oscillator; the improvement comprising phase inverter means having its input connected to said demodulator circuit and its output connected to said low pass filter for receiving a portion of the demodulated signal derived from said demodulator circuit, phase inverting said portion and applying said inverted portion to an input of said low pass filter to counterbalance demodulation components generated by said phase comparator circuit.
Claim 2
Dependent Claim
169 words
In an FM receiver including a. a demodulator circuit for demodulating a composite signal with a phase locked subcarrier; and b. a sub-carrier generating circuit comprising a voltage controlled oscillator for generating a sub-carrier, a phase comparator circuit for comparing the phase of a comparison signal derived from said voltage controlled oscillator to a pilot signal comprising a part of an FM composite input signal, a low pass filter for rejecting obstacle signal components from an error voltage representative of the phase difference obtained by said phase comparator circuit, and a DC amplifier for amplifying the filtered error voltage to phase control said voltage controlled oscillator; the improvement comprising phase inverter means having its input connected to said demodulator circuit and its output connected to said low pass filter for receiving a portion of the demodulated signal derived from said demodulator circuit, phase inverting said portion and applying said inverted portion to an input of said low pass filter to counterbalance demodulation components generated by said phase comparator circuit.
Claim 3
Dependent Claim
27 words
An FM receiver as set forth in claim 1 wherein the comparison signal is derived by a frequency divider from the output of said voltage controlled oscillator.
Claim 4
Dependent Claim
107 words
In a method of demodulating a composite FM signal including a pilot signal comprising the steps of a. generating a sub-carrier signal; b. comparing the phase of said sub-carrier with the phase of said pilot signal; c. generating an error signal in accordance with said comparison; d. controlling the phase of said sub-carrier in accordance with said error signal to phase lock said sub-carrier and said pilot signal; e. demodulating said composite signal with said phase locked sub-carrier; the improvement comprising: phase inverting a portion of the demodulated signal and mixing said phase inverted portion with said comparison signal to counterbalance demodulation components in said comparison signal.
Claim 5
Dependent Claim
107 words
In a method of demodulating a composite FM signal including a pilot signal comprising the steps of a. generating a sub-carrier signal; b. comparing the phase of said sub-carrier with the phase of said pilot signal; c. generating an error signal in accordance with said comparison; d. controlling the phase of said sub-carrier in accordance with said error signal to phase lock said sub-carrier and said pilot signal; e. demodulating said composite signal with said phase locked sub-carrier; the improvement comprising: phase inverting a portion of the demodulated signal and mixing said phase inverted portion with said comparison signal to counterbalance demodulation components in said comparison signal.
References Cited (Backward Citations)
US3111625A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |