Apparatus for detecting a loop during ringing
US4540853A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 21, 1983 |
| Grant date | Sep 10, 1985 |
| Priority date | — |
| Expiry date | Jul 21, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/026
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The apparatus comprises a zero pass detector (2) for detecting zero passes in a voltage signal proportional to the line current to generate a pulse signal constituted by positive and negative rectangular pulses of equal amplitude and of width dependant on the duty ratio of the line signal, a pulse signal processor constituted by a saturable integrator circuit (4) connected to integrate the pulse signal and to deliver a triangular signal having a positive peak value which increases after ringing has been answered, a comparator (6) connected to compare the triangular signal with a positive reference voltage (+Vr) and to deliver a loop detected signal when the peak value reaches the reference value, the loop detected signal being applied to a bistable logic device (8) which serves to store the loop detected signal and to deliver an output signal from the apparatus based on the stored signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.