Transmission system for sending two signals simultaneously on the same communications channel
US5073899A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1989 |
| Grant date | Dec 17, 1991 |
| Priority date | — |
| Expiry date | Jul 12, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J13/0022
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A transmission system in which a suitably modulated speech or data signal is combined with a low bit rate (100b/s) spread spectrum signal and transmitted simultaneously on the same channel with the modulated speech lying within the bandwidth of the spread spectrum signal. At a receiver the modulated speech or data signal is demodulated and the modulated speech or data signal together with the spread spectrum signal are applied to a multiplier in which the spread spectrum signal is despread. A code synchronizing signal may be included in the modulated signal prior to transmission and when recovered in the receiver, the synchronizing signal is applied to a pseudo-random code generating means. The transmission system may include a text transmission system in which case the low bit rate signal comprises pages of data. A number of pages may be transmitted simultaneously by spreading the data associated with each page by orthogonal psuedo-random codes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.