US4633501A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Program dependent crossover filter (PDC)
Assignee: Individual
•
Filing: 1985-04-15
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Granted: 1986-12-30
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Expires: 2005-04-15
Abstract
Abstract An audio crossover filter which automatically tunes the crossover frequency according to the content of the program audio which is being filtered.
Inventors
- 👤 Donn R. Werrbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 04:25
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1217; H03H11/1252
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
91 words
A program dependent crossover filter system comprising: a. tunable filter means including a tunable control means for producing more than one frequency band output where band crossover frequencies are tuned by a control signal; b. detector means to detect band output levels; c. comparator means to compare adjacent band output levels and produce output thereof; d. control filter means to convert output of the comparator means to usable tuning control signal(s); and e. interface means to couple the tuning control signal(s) of the control filter means to the tunable control means.
Claim 2
Dependent Claim
91 words
A program dependent crossover filter system comprising: a. tunable filter means including a tunable control means for producing more than one frequency band output where band crossover frequencies are tuned by a control signal; b. detector means to detect band output levels; c. comparator means to compare adjacent band output levels and produce output thereof; d. control filter means to convert output of the comparator means to usable tuning control signal(s); and e. interface means to couple the tuning control signal(s) of the control filter means to the tunable control means.
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) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |