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US5568202A
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System for echo cancellation comprising an improved ghost cancellation reference signal
Assignee: Philips North America LLC
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Filing: 1992-09-22
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Granted: 1996-10-22
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Expires: 2012-09-22
Abstract
Abstract A system for improved echo cancellation for use in particular in television receivers. The system features a superior ghost cancellation reference signal which exhibits improved performance in noisy environments and which exhibits the flat and wide bandwidth necessary for effective channel characterization while exhibiting a higher and more evenly distributed amplitude versus time characteristic than that provided by known, non-cyclic ghost cancellation signals.
Inventors
- 👤 David Koo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:36
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/08; H04N7/087; H04N7/088; H04L; H04L1/00; H04L1/24; H04L1/242; H04L25/00; H04L25/02; H04L25/0202; H04L25/0224; H04L25/0226; H04L25/024; H04L25/0242; H04L25/0244; H04N5/00; H04N5/14; H04N5/21; H04N5/211
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
103 words
An electronic reference signal in a system for minimizing the effects of ghosts occurring during the transmission and reception of a television signal over a communications path, wherein said reference signal is embodied in a processor readable memory, is non-cyclic, has a substantially flat frequency response within the bandwidth of said communications path and has a plurality of substantially uniform amplitude peaks over a time interval, and wherein a replica of said reference signal is transmitted as part of said television signal and is utilized by a decoder to derive coefficients which are used with at least one filter to remove said ghosts.
Claim 2
Dependent Claim
103 words
An electronic reference signal in a system for minimizing the effects of ghosts occurring during the transmission and reception of a television signal over a communications path, wherein said reference signal is embodied in a processor readable memory, is non-cyclic, has a substantially flat frequency response within the bandwidth of said communications path and has a plurality of substantially uniform amplitude peaks over a time interval, and wherein a replica of said reference signal is transmitted as part of said television signal and is utilized by a decoder to derive coefficients which are used with at least one filter to remove said ghosts.
Claim 3
Dependent Claim
28 words
The reference signal of claim 1 further defined by the equation: ##EQU4## where A, b and Ω are real numbers; and where W(ω) is a windowed window function.
Claim 4
Dependent Claim
39 words
The reference signal of claim 1 further defined by the equation: ##EQU5## where ##EQU6## where α, A, C n , b and Ω are real numbers; where N is an integer; and where W(ω) is a windowed window function.
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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) | 1999-10-22 | 2000-04-22 | 2000-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-22 | 2004-04-22 | 2004-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-22 | 2008-04-22 | 2008-10-22 | $7700.00 | Window Closed / Lapsed |