Dual mode telephone subscriber loop current detector
US4164713A · kind A · utility
3Cited by
1References
2Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1977 |
| Grant date | Aug 14, 1979 |
| Priority date | — |
| Expiry date | Oct 25, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M3/2272
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A detector circuit is shown for detecting off-hook and dial pulse signals in a telephone system which, under the control of a ringing relay, reconfigures itself to provide ring-trip detection. The detection circuit includes a bridge which is responsive to circulating loop currents, while at the same time unresponsive to longitudinally balanced currents, and a two-stage voltage level detector circuit. An RC timing circuit is included between the two stages to insure that the detector is unresponsive to short duration pulses and, at the same time, once energized, will bridge over short duration interruptions of detected pulses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.