Variable loop length compensated barrier circuit
US4228323A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 1979 |
| Grant date | Oct 14, 1980 |
| Priority date | — |
| Expiry date | Jan 31, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/76
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A gain and frequency compensated barrier circuit is disclosed for use with a telephone transmission line having variable loop lengths. A DC component of the input signal is provided to the input side of the barrier circuit. Loop length losses, as well as barrier gain variations, are adjusted on the output side of the circuit by comparing a barrier DC voltage level with a DC reference level and adjusting the AC gain in accordance therewith. Frequency response, which is also a function of loop length, is corrected by using the DC input voltage to generate an effective loop length dependent capacitor for further controlling the output signal level. An optocoupled circuit is disclosed for use in one embodiment of the disclosure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.