Patent US4975657A successfully refreshed from Google Patents.
US4975657A
Expired / Lapsed
US
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Speech detector for automatic level control systems
Assignee: Motorola Solutions Inc
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Filing: 1989-11-02
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Granted: 1990-12-04
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Expires: 2009-11-02
Abstract
Abstract A speech detection circuit uses a peak detector and a valley detector including offset voltages to reliably detect the absence or presence of speech at audio base band level. This circuit provides a pulse train output when speech is detected which may be used to control an automatic gain control circuit.
Inventors
- 👤 Bruce C. Eastmond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:45
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3005; G; G10; G10L; G10L25/00; G10L25/78
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
208 words
A circuit producing an output signal indicative of speech present in communication signals that include noise and processed speech envelope signals, said circuit receiving noise and processed speech envelope signals at an input, said circuit comprised of: peak detector means for detecting a substantially peak signal value in said processed speech envelope signals and for producing a first signal, representative of said peak signal values; valley detector means for detecting a background noise level present in said processed speech envelope signals input to said valley detector means and for producing a second signal representative of said noise level; first comparator means coupled to said peak detector means and said valley detector means for comparing said first signal to said second signal and for producing, at an output, a first difference signal equal to the greater of said first and second signals; and second comparator means coupled to receive said first difference signal from said first comparator means and receiving said processed speech envelope signals, said second comparator means comparing said first difference signal to said processed speech envelope signals and producing an output signal indicating when speech is present in a communications signal based on the comparison of said first difference signal to said processed speech envelope signals.
Claim 2
Dependent Claim
208 words
A circuit producing an output signal indicative of speech present in communication signals that include noise and processed speech envelope signals, said circuit receiving noise and processed speech envelope signals at an input, said circuit comprised of: peak detector means for detecting a substantially peak signal value in said processed speech envelope signals and for producing a first signal, representative of said peak signal values; valley detector means for detecting a background noise level present in said processed speech envelope signals input to said valley detector means and for producing a second signal representative of said noise level; first comparator means coupled to said peak detector means and said valley detector means for comparing said first signal to said second signal and for producing, at an output, a first difference signal equal to the greater of said first and second signals; and second comparator means coupled to receive said first difference signal from said first comparator means and receiving said processed speech envelope signals, said second comparator means comparing said first difference signal to said processed speech envelope signals and producing an output signal indicating when speech is present in a communications signal based on the comparison of said first difference signal to said processed speech envelope signals.
Claim 3
Dependent Claim
36 words
The circuit of claim 1 including first offset signal means for reducing the first signal from said peak detector means by a first predetermined amount before said first signal is coupled to said first comparator means.
Claim 4
Dependent Claim
36 words
The circuit of claim 2 including second offset signal means for increasing the second signal from said valley detector means by a second predetermined amount before said second signal is coupled to said first comparator means.
Claim 5
Dependent Claim
15 words
The circuit of claim 1 where said peak detector means comprises a voltage peak detector.
Claim 6
Dependent Claim
16 words
The circuit of claim 1 where said valley detector means comprises a noise level voltage detector.
Claim 7
Dependent Claim
37 words
The circuit of claim 1 where said first comparator means comprises a voltage comparator comparing the greater of said first and second signals and said first difference signal comprises the greater of said first and second signals.
Claim 8
Dependent Claim
48 words
The circuit of claim 6 where said first comparator comprises an ideal diode circuit coupled to said peak detector means and an ideal diode circuit coupled to said valley detector, said ideal diode circuits having outputs that are both connected to an input of said second comparator means.
Claim 9
Dependent Claim
14 words
The circuit of claim 1 where said comparator means comprises a two-input voltage comparator.
References Cited (Backward Citations)
US3502993A
Cited
US4631737A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-03 | 1994-06-04 | 1994-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-03 | 1998-06-04 | 1998-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-03 | 2002-06-04 | 2002-12-04 | $7700.00 | Window Closed / Lapsed |