Patent US2724972A successfully refreshed from Google Patents.
Patent US4322129A successfully refreshed from Google Patents.
Patent US3940709A successfully refreshed from Google Patents.
US3940709A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Equalization circuit
Assignee: Ampex Corp
•
Filing: 1974-12-19
•
Granted: 1976-02-24
•
Expires: 1994-12-19
Abstract
Abstract A frequency equalization circuit includes an active filter circuit. The filter circuit differentiates the input signal. A plurality of adjustable resistances are connected to the differentiator corresponding to a plurality of operating or frequency ranges. A switch selects one resistance in accordance with one selected operating range to connect the filter circuit to an amplifier.
Inventors
- 👤 Alastair M. Heaslett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:40
CPC Classifications
H; H03; H03G; H03G5/00; H03G5/02; H03G5/025; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1217; H04; H04R; H04R3/00; H04R3/04
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
87 words
An equalization circuit comprising; an input; amplifying means connected to said input; filter circuit means having an output connected to said input for providing a signal varying in amplitude with frequency at its output; a plurality of adjustable resistances corresponding to a plurality of operating ranges connected to the output of said filter circuit means for adjusting the signal amplitude provided by the output; and, switch means for selectively connecting one of said plurality of adjustable resistances to said amplifying means according to one selected operating range.
Claim 2
Dependent Claim
87 words
An equalization circuit comprising; an input; amplifying means connected to said input; filter circuit means having an output connected to said input for providing a signal varying in amplitude with frequency at its output; a plurality of adjustable resistances corresponding to a plurality of operating ranges connected to the output of said filter circuit means for adjusting the signal amplitude provided by the output; and, switch means for selectively connecting one of said plurality of adjustable resistances to said amplifying means according to one selected operating range.
Claim 3
Dependent Claim
17 words
The circuit of claim 1 wherein: said filter circuit means provides a signal which rises with frequency.
Claim 4
Dependent Claim
19 words
The circuit of claim 1 wherein: said filter circuit means comprises an RC series circuit connect to said input.
Claim 5
Dependent Claim
14 words
The circuit of claim 1 wherein: said filter circuit means comprises active filter means.
Claim 6
Dependent Claim
13 words
The circuit of claim 1 wherein: said filter circuit means comprises differentiating means.
Claim 7
Dependent Claim
127 words
An equalization circuit comprising: an input terminal; a first amplifier having an input and an output; an input resistance connected between said input terminal and the input of said first amplifier; and, a filter circuit connected in parallel with said input resistance including: circuit means having an output to filter a signal received at said input terminal; a plurality of adjustable resistances connected to the output of said filter circuit means, each of said resistances selected according to a different one of a plurality of operating ranges for adjusting the amplitude of the signal provided by said filter circuit means; and, switch means connected between said plurality of adjustable resistances and the input of said first amplifier for selectively connecting said adjustable resistances to said first amplifier.
Claim 8
Dependent Claim
127 words
An equalization circuit comprising: an input terminal; a first amplifier having an input and an output; an input resistance connected between said input terminal and the input of said first amplifier; and, a filter circuit connected in parallel with said input resistance including: circuit means having an output to filter a signal received at said input terminal; a plurality of adjustable resistances connected to the output of said filter circuit means, each of said resistances selected according to a different one of a plurality of operating ranges for adjusting the amplitude of the signal provided by said filter circuit means; and, switch means connected between said plurality of adjustable resistances and the input of said first amplifier for selectively connecting said adjustable resistances to said first amplifier.
Claim 9
Dependent Claim
16 words
A circuit of claim 6 wherein: said filter circuit means provides a signal varying with frequency.
Claim 10
Dependent Claim
16 words
The circuit of claim 6 wherein: said filter circuit means provides a signal rising with frequency.
Claim 11
Dependent Claim
42 words
The circuit of claim 8 wherein: said filter circuit means includes an RC circuit connected to said input terminal and a second amplifier connected to said RC circuit, the output of said second amplifier being connected to said plurality of adjustable resistances.
Claim 12
Dependent Claim
45 words
The circuit of claim 9 wherein: said switch means comprises a plurality of contacts connected respectively to said plurality of variable resistances; and further including: a plurality of frequency pre-emphasis means connected respectively between said plurality of contacts and the output of said first amplifier.
Claim 13
Dependent Claim
20 words
The circuit of claim 6 wherein: said filter circuit means comprises an RC series circuit connected to said input terminal.
Claim 14
Dependent Claim
14 words
The circuit of claim 6 wherein: said filter circuit means comprises active filter means.
Claim 15
Dependent Claim
13 words
The circuit of claim 6 wherein: said filter circuit means comprises differentiating means.
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) | 1979-02-23 | 1979-08-25 | 1980-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-23 | 1983-08-25 | 1984-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-23 | 1987-08-25 | 1988-02-24 | $7700.00 | Window Closed / Lapsed |