Alarm filter circuit
US6472992B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 2001 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Dec 12, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An alarm filter circuit used in telecommunication systems for interconnecting between incoming telephone lines and alarm unit located at a subscriber's premises so as to block DSL data signals to and from the alarm unit for preventing interference is provided. In one preferred embodiment, the alarm filter circuit includes a second-order low-pass filter section for blocking the DSL data signals to and from the alarm unit, a first-order high-pass filter section for bypassing the DSL data signals on the incoming telephone lines to the house wiring, and a first-order low-pass filter section for blocking high-frequency signals between the house wiring and the alarm unit. In a second embodiment, a fourth-order elliptical low-pass filter section replaces the second-order low-pass filter section. In a third embodiment, a third-order high-pass filter section replaces also the first-order high-pass filter section. In fourth through sixth embodiments, the first-order low-pass filter section is replaced by a second-order low-pass filter section. Further, the fourth through sixth embodiments includes surge protection circuitry for protecting the alarm unit from being damaged by transients.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.