Electronically-switched multifrequency generator with transducer control
US4352958A · kind A · utility
2Cited by
3References
34Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1979 |
| Grant date | Oct 5, 1982 |
| Priority date | — |
| Expiry date | Dec 13, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/505
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a multifrequency generator providing tone signaling for a telephone, the common switching functions are performed by solid state switching circuitry (1200). Improved signal transfer between the telephone line and transmit and receive transducer of the telephone is provided by arranging the solid-state transmit and receive switches (1201, 1401) in a gain configuration to increase the level of the speech signal. The tone signals are digitally synthesized and use an integrated R-C oscillator (600) as a reference. Button down and button up debouncing of a contact closure signal from a single contact per button keypad is provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.