Voice band multiplex transmission system
US4328579A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 1980 |
| Grant date | May 4, 1982 |
| Priority date | — |
| Expiry date | May 23, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/062
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A system for simultaneously transmitting over the same voice circuit a voice signal and input information other than the voice. First and second sine-wave signals which do not bear any harmonic relation to each other in the band of the voice circuit are simultaneously frequency modulated by the input information, and the modulated outputs are superimposed on the voice signal and transmitted. On the receiving side, the pitch frequency of the voice signal is extracted from the received signal, and the pitch frequency and its integral multiples are removed from the received signal to remove a voice component. At this time, at least one of the first and second sine-wave signals is detected. One of these detected outputs is made to have the same frequency as the other frequency. The converted frequency and the detected frequency are demodulated to obtain the original input information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.