Ringing signal generator
US4239941A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1979 |
| Grant date | Dec 16, 1980 |
| Priority date | — |
| Expiry date | Mar 1, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/02
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A telephone ringing signal generator which produces a signal that can ring a plurality of connected ringers tuned to different frequencies. The ringing signal comprises sequentially varying frequencies and each ringer will ring in response to its particular frequency. A counter is used to define the duration of the ringing signal and enable each frequency sequentially. A variable sweep frequency oscillator is connected to the counter and generates a signal having a different frequency for each counter increment. A programmable filter shapes the signal into a sine wave which is amplified to ringing voltage levels by a ringing signal amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.