Two port signalling voltages filter arrangement
US5623543A · kind A · utility
41Cited by
4References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 24, 1994 |
| Grant date | Apr 22, 1997 |
| Priority date | — |
| Expiry date | Mar 24, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/40
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A twisted-pair telephone line is connected to a conventional telephone via a low-pass filter and equipment for receiving signals in an upper frequency range, e.g., 25-1000 kHz via a high-pass filter. The low-pass filter is primarily passive (to allow passage of line power, ringing and signalling voltages) but, to improve matching to non-resistive line and telephone impedances, at least the main part of the filter is flanked by impedance convertors in which amplifiers having an appropriate transfer function feed voltages back into the line via transformers through which power, ringing and dialing may pass unimpeded.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.