Ring signal detection circuit
US5258721A · kind A · utility
49Cited by
5References
6Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 27, 1990 |
| Grant date | Nov 2, 1993 |
| Priority date | — |
| Expiry date | Aug 27, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/066
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone network interface integrated circuit with digitally based loop current detection and digitally based ring signal detection. The ring signal detection includes discrimination with a cutoff frequency of about 13 Hz to distinguish ring signals from dialing signals. The discrimination includes filtration followed by triggering an oscillator for one time period and checking whether the number of oscillations exceeds a threshold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.