US5553192A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for noise removal during the silence periods in the discontinuous transmission of speech signals to a mobile unit
Assignee: NEC Corp
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Filing: 1993-10-12
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Granted: 1996-09-03
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Expires: 2013-10-12
Abstract
Abstract The disclosure is to eliminate discomforting background noise regenerated at a receive side (viz., a base station) in a mobile radio communications system wherein discontinuous transmission (DTX) is utilized. When speech pause is detected at the receive side, synthesis filter coefficients are produced using a background noise code which has been transmitted from a mobile unit. Subsequently, a Q value of the synthesis filter is measured using the above-mentioned synthesis filter coefficients. If the Q value is larger than a threshold level, each of the filter coefficients is lowered by a predetermined value. Thus, the regenerated discomforting background noise can effectively be reduced.
Inventors
- 👤 Toshihiro Hayata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:35
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/012; G10L21/00; G10L21/02; G10L21/0316; G10L21/0364; G10L25/00; G10L25/78
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
159 words
An arrangement for demodulating speech code sequences discontinuously transmitted from a mobile unit and for demodulating background noise code sequences transmitted from said mobile unit while said speech code sequences pause, said arrangement receiving speech pause/start indicators, said arrangement comprising: first means for generating synthesis filter coefficients using either of said speech code sequence or said background noise code sequence; second means for synthesizing either of speech signals or background noise signals using said synthesis filter coefficients; third means for discriminating speech pause and speech start using said speech pause/start indicators; fourth means for estimating Q value of said second means using said synthesis filter coefficients and generating an estimated Q value if said third means discriminates said speech pause; and fifth means for generating reduced synthesis filter coefficients by reducing said synthesis filter coefficients if said estimated Q value is larger than a threshold level, said fifth means supplying said second means with said reduced synthesis filter coefficients.
Claim 2
Dependent Claim
159 words
An arrangement for demodulating speech code sequences discontinuously transmitted from a mobile unit and for demodulating background noise code sequences transmitted from said mobile unit while said speech code sequences pause, said arrangement receiving speech pause/start indicators, said arrangement comprising: first means for generating synthesis filter coefficients using either of said speech code sequence or said background noise code sequence; second means for synthesizing either of speech signals or background noise signals using said synthesis filter coefficients; third means for discriminating speech pause and speech start using said speech pause/start indicators; fourth means for estimating Q value of said second means using said synthesis filter coefficients and generating an estimated Q value if said third means discriminates said speech pause; and fifth means for generating reduced synthesis filter coefficients by reducing said synthesis filter coefficients if said estimated Q value is larger than a threshold level, said fifth means supplying said second means with said reduced synthesis filter coefficients.
Claim 3
Dependent Claim
45 words
An arrangement as claimed in claim 1, further including a comparator which is coupled to compare said estimated Q value with said threshold level, said comparator issuing a control signal indicative of a result of comparison, said fifth means being responsive to said control signal.
Claim 4
Dependent Claim
41 words
An arrangement as claimed in claim 1, further including a memory for storing said reduced synthesis filter coefficients, said reduced synthesis filter coefficients stored in said memory being applied to said second means at a predetermined time interval until being updated.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-09-03 | 2000-03-04 | 2000-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-09-03 | 2004-03-04 | 2004-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-09-03 | 2008-03-04 | 2008-09-03 | $7700.00 | Window Closed / Lapsed |