US3839649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Signal discriminating circuit
Assignee: Sony Corp
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Filing: 1973-03-02
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Granted: 1974-10-01
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Expires: 1993-03-02
Abstract
Abstract Input signals of different frequencies are discriminated by the circuit of the invention which comprises an oscillator supplied with one of the input signals as an external synchronizing signal and operative to be locked by a specific one of the input signals having a frequency in a predetermined frequency range and a comparator which is also supplied with the input signal and with the output of the oscillator for producing an output signal when the input signal and the oscillator output are not the same in frequency. In one preferred embodiment the signal discriminating circuit is utilized to detect between PAL and NTSC color television signals in a color television receiver.
Inventors
- 👤 M Morio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:57
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/642
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
147 words
A signal discriminating circuit to discriminate between input pulse signals having first and second frequencies, said first frequency being higher than said second fRequency, said circuit comprising: A. a signal input circuit to receive said pulse signals; B. free-running oscillator means to generate pulse signals having a natural frequency higher than said second frequency, said oscillator being synchronizable to operate in phase-locked condition with respect to said first frequency but not with respect to said second frequency; C. connecting means joining said input circuit to said oscillator means to supply said received pulse signals to said oscillator means; and D. combining means connected to said signal input terminal and to said oscillator means to combine said received pulse signals and said generated pulse signals to produce an output voltage signal depending on whether said received pulse signals are of the same frequency as said generated pulse signals.
Claim 2
Dependent Claim
147 words
A signal discriminating circuit to discriminate between input pulse signals having first and second frequencies, said first frequency being higher than said second fRequency, said circuit comprising: A. a signal input circuit to receive said pulse signals; B. free-running oscillator means to generate pulse signals having a natural frequency higher than said second frequency, said oscillator being synchronizable to operate in phase-locked condition with respect to said first frequency but not with respect to said second frequency; C. connecting means joining said input circuit to said oscillator means to supply said received pulse signals to said oscillator means; and D. combining means connected to said signal input terminal and to said oscillator means to combine said received pulse signals and said generated pulse signals to produce an output voltage signal depending on whether said received pulse signals are of the same frequency as said generated pulse signals.
Claim 3
Dependent Claim
30 words
The signal discriminating circuit of claim 1 comprising, in addition, a smoothing circuit connected to said combining means to produce a direct voltage when said output voltage signal is present.
Claim 4
Dependent Claim
58 words
The signal discriminating circuit of claim 1 in which said received pulse signals are applied to said combining means in one effective polarity and said generated pulse signals are applied to said combining means in the opposite effective polarity, said combining means remaining non-conductive when said received pulse signals and said generated pulse signals are applied thereto simultaneously.
Claim 5
Dependent Claim
105 words
The signal discriminating circuit of claim 1 in which said combining circuit comprises a transistor biased to be normally non-conductive and said received pulse signals and said generated pulse signals are both connected to the base of said transistor in mutually opposite polarity, the polarity of one type of said pulse signals being such as to cause said transistor to remain non-conductive, and the polarity of the other type of such pulse signals being such as to make said transistor conductive, the duration of each pulse of said other type being at least as great as the duration of each pulse of said one type.
Claim 6
Dependent Claim
85 words
The signal discriminating circuit of claim 4 in which said signal input circuit comprises: A. a second transistor; B. load impedance means connected thereto and comprising first and second load impedances in series, said connecting means being connected to said first impedance to apply the pulse signals thereacross to said oscillator means and the base of said first-named transistor being connected to said second load impedance to apply the total pulse signals across both of said load impedances to the base of said first-named transistor.
Claim 7
Dependent Claim
27 words
The signal discriminating circuit of claim 5 in which said first-named transistor is of one conductivity type and said second transistor is of the opposite conductivity type.
Claim 8
Dependent Claim
77 words
The signal discriminating circuit of claim 5 in which said oscillator means is an emitter-coupled multivibrator comprising: A. third and fourth transistors; B. a controllable bias voltage source for said fourth transistor; C. a capacitor connected in series between the emitters of said third and fourth transistors; and D. an emitter load connected to each of said third and fourth transistors, respectively, the collector of said fourth transistor being connected to the base of said third transistor.
Claim 9
Dependent Claim
38 words
The signal discriminating circuit of claim 7 in which said connecting means joining said input circuit to said oscillator means is a diode conductive to the pulse signals across said first impedance to make said third transistor non-conductive.
Claim 10
Dependent Claim
55 words
The signal discriminating circuit of claim 8 comprising, in addition, a fifth transistor biased to be normally non-conductive and having its base connected to said oscillator means to receive pulse signals generated thereby, the collector of said fifth transistor being connected to the base of said first-named transistor to supply said generated pulse signals thereto.
Claim 11
Dependent Claim
48 words
The signal discriminating circuit of claim 8 comprising, in addItion, a rectifier and smoothing circuit connected to said first-named transistor to produce a direct voltage in response to output pulse signals of said first-named transistor when said received pulse signals and said generated pulse signals have different frequencies.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |