US3676596A
Expired / Lapsed
US
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Periodicity analyser for a quasi-periodic signal including a detection circuit
Assignee: US Philips Corp
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Filing: 1970-07-06
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Granted: 1972-07-11
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Expires: 1990-07-06
Abstract
Abstract A periodicity analyzer as a pitch meter for a quasi-periodic signal, for example speech, equipped with a detection circuit which converts the signal into a plurality of pulses the positions of which correspond to those of the peaks of the quasiperiodic signal, which detection circuit includes a peak detector the time constant of which is substantially equal to the shortest period of the quasi-periodic signal to be detected, while the pulses are applied to a cascade arrangement of a plurality of period filters the greater part of which have mutually different characteristic time durations. The greater part of the time durations form an ascending series. With each period filter there is associated an auxiliary circuit comprising a stretcher and an input AND gate in order to distinguish the main periods from the sub-periods. Thus, by measuring the spacings between the peaks in the speech signal to be examined, which have been transformed into pulses, the pitch is directly determined. This is effected by means of a digital analog converter. This periodicity analyzer can advantageously be used in a vocoder as a pitch detector.
Inventors
- 👤 Leonardus Franciskus Willems
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:37
CPC Classifications
G; G01; G01R; G01R23/00; G10; G10L; G10L25/00; G10L25/90
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
168 words
A periodicity analyzer for a quasi-periodic signal, for example speech, comprising a detection circuit means for converting the signal into a plurality of pulses the positions of which correspond to those of the peaks of the quasi-periodic signal, the detection circuit comprising a peak detector the time constant of which is substantially equal to the shortest period of the quasi-periodic signal to be detected; and a cascade arrangement of a plurality of period filter means connected to the detection circuit, the filter means having mutually different characteristic time durations, each filter means comprising means responsive To input pulses separated by an interval greater than the characteristic time duration for providing output pulses having a pulse width equal to the time duration and responsive to a series of input pulses separated by an interval less than the characteristic time duration for providing an output pulse having a pulse width equal to the characteristic time duration plus the total time elapsed between the first and last pulse of the series.
Claim 2
Dependent Claim
168 words
A periodicity analyzer for a quasi-periodic signal, for example speech, comprising a detection circuit means for converting the signal into a plurality of pulses the positions of which correspond to those of the peaks of the quasi-periodic signal, the detection circuit comprising a peak detector the time constant of which is substantially equal to the shortest period of the quasi-periodic signal to be detected; and a cascade arrangement of a plurality of period filter means connected to the detection circuit, the filter means having mutually different characteristic time durations, each filter means comprising means responsive To input pulses separated by an interval greater than the characteristic time duration for providing output pulses having a pulse width equal to the time duration and responsive to a series of input pulses separated by an interval less than the characteristic time duration for providing an output pulse having a pulse width equal to the characteristic time duration plus the total time elapsed between the first and last pulse of the series.
Claim 3
Dependent Claim
24 words
A periodicity analyzer as claimed in claim 1, wherein the characteristic time durations of the greater part of the period filters have ascending values.
Claim 4
Dependent Claim
29 words
A periodicity analyzer as claimed in claim 1, wherein the characteristic time durations of the period filters differ from one another by not more than 1/10 in ascending order.
Claim 5
Dependent Claim
37 words
A periodicity analyzer as claimed in claim 1, further comprising with substantially each of the period filters an associated auxiliary circuit means for distinguishing the main periods from the sub-periods of the quasi-periodic signal to be analyzed.
Claim 6
Dependent Claim
50 words
A periodicity analyzer as claimed in claim 4, wherein each auxiliary circuit consists of a stretcher of a design similar to that of a period filter and of an input AND gate connected to the output of the associated period filter and to the output of the preceding period filter.
Claim 7
Dependent Claim
57 words
A periodicity analyzer as claimed in claim 5, wherein in the circuit connecting the input AND gate to the output of the associated period filter there is included an AND gate the input of which is connected to an OR gate which is connected to the preceding stretcher, to the succeeding stretcher and to the associated stretcher.
Claim 8
Dependent Claim
33 words
A periodicity analyzer as claimed in claim 6, wherein to the said OR gate there is applied a starting signal at the instants at which none of the stretchers delivers an output signal.
Claim 9
Dependent Claim
26 words
A periodicity analyzer as claimed in claim 5, wherein the characteristic time duration of the stretcher is fractionally greater than that of the associated period filter.
Claim 10
Dependent Claim
40 words
A periodicity analyzer as claimed in claim 1, wherein between each pair of successive period filters there is inserted an OR gate the input of which is connected to the outputs of two period filters which precede the OR gate.
Claim 11
Dependent Claim
101 words
A periodicity analyzer as claimed in claim 1, wherein each period filter and each stretcher comprises an electronic circuit arrangement which includes at least a first and a second transistor, the collector of the first transistor being connected to the base of the second transistor, the emitters of the two transistors being interconnected and a capacitor being included between the base of the first transistor and the collector of the second transistor, the base of the first transistor being connected through a differentiating network to an input terminal, while the collector of the second transistor is connected to a Schmitt trigger.
Claim 12
Dependent Claim
42 words
A periodicity analyzer as in claim 1, wherein the outputs of all the stretchers are connected to an indicator which locates that period filter the characteristic time duration of which is greater than the period of the quasi-periodic signal to be analyzed.
Claim 13
Dependent Claim
51 words
A periodicity analyzer as claimed in claim 11, wherein each stretcher is connected to an indicator element which substantially consists of an AND gate the input of which is connected to the output of the associated stretcher and also, through an inverting amplifier, to the output of the next subsequent stretcher.
Claim 14
Dependent Claim
20 words
A periodicity analyzer as claimed in claim 11, wherein all the indicator elements are connected to a digital analog converter.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |