Telephone system ring period detector
US4390843A · kind A · utility
10Cited by
5References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1981 |
| Grant date | Jun 28, 1983 |
| Priority date | — |
| Expiry date | Feb 9, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/82
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An improved ring detector circuit is provided to discriminate between ring signals and low frequency dial signals. The circuit times the interval between pulses generated each time the incoming waveform exceeds a threshold and, if the interval is greater than 50 ms disables a ring detect circuit which is set by a pulse train, the interval between adjacent pulses of which is less than 50 ms. Pulses having a duration of less than 5 ms are eliminated to insure that chatter and sliver are not misconstrued as a ring signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.