US5317392A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noise reducing device for up-going signals in bidirectional CATV system
Assignee: NEC Corp
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Filing: 1991-12-23
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Granted: 1994-05-31
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Expires: 2011-12-23
Abstract
Abstract A device incorporated in a bidirectional CATV system for reducing noise introduced in an up-going channel at a subscriber station. A terminal unit and a protector perform monodirectional or bidirectional switching operations on the basis of a DC current which the terminal station selectively outputs.
Inventors
- 👤 Ryouji Ishibashi
- 👤 Naomasa Nishimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:23
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/173; H04B; H04B3/00; H04B3/02; H04B3/32; H04H; H04H60/00; H04H60/76; H04H60/81; H04H60/93; H04H60/96; H04H60/97; H04H20/00; H04H20/65; H04H20/76; H04H20/77; H04H20/78
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
148 words
In a CATV system of the type having a central unit interconnected with a terminal unit, a noise reducing device for an up-going signal from the terminal unit to the central unit comprising: controller means at the terminal unit for superposing a DC current on an up-going signal only when said terminal unit sends an up-going signal to the central unit; high-pass filter means connected between the central unit and the terminal unit and passing only a down-going signal from the central unit to the terminal unit; bidirectional circuit means paralleling the high-pass filter means and passing both of an up-going signal and a down-going signal; and switching means responsive to the DC current from the controller means for selecting said high-pass filter means when said controller means does not output a DC current or selecting said bidirectional circuit means when said controller means outputs said DC current.
Claim 2
Dependent Claim
148 words
In a CATV system of the type having a central unit interconnected with a terminal unit, a noise reducing device for an up-going signal from the terminal unit to the central unit comprising: controller means at the terminal unit for superposing a DC current on an up-going signal only when said terminal unit sends an up-going signal to the central unit; high-pass filter means connected between the central unit and the terminal unit and passing only a down-going signal from the central unit to the terminal unit; bidirectional circuit means paralleling the high-pass filter means and passing both of an up-going signal and a down-going signal; and switching means responsive to the DC current from the controller means for selecting said high-pass filter means when said controller means does not output a DC current or selecting said bidirectional circuit means when said controller means outputs said DC current.
Claim 3
Dependent Claim
23 words
A device as claimed in claim 1, wherein said high-pass filter means, said bidirectional circuit means and said switching means constitute a protector.
Claim 4
Dependent Claim
34 words
A device as claimed in claim 1, wherein said controller means comprises communication controller and a switch which is on/off controlled by said communication controller to selectively turn on or off a DC current.
Claim 5
Dependent Claim
20 words
A device as claimed in claim 1, wherein said switching means comprises a relay circuit operated by a DC current.
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) | 1997-05-30 | 1997-11-29 | 1998-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-30 | 2001-11-29 | 2002-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-30 | 2005-11-29 | 2006-05-31 | $7700.00 | Window Closed / Lapsed |