System for reducing radio communication frequency bandwidth and increasing number of channels available
US3962639A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1973 |
| Grant date | Jun 8, 1976 |
| Priority date | — |
| Expiry date | Jun 11, 1993 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/66
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A modulated communication system having radio frequency bandwidth reduction in which level sensing circuits at the transmitter control the modulations such that information signals up to a predetermined and selected percent of the modulation level commonly used are transmitted as before, and information signals above that percentage are reduced so that they also begin at the zero amplitude level. That is, once the preselected threshold percentage is reached the signal level is reduced by that threshold amount so that, although all the information in the signal is retained, the signal level is prevented from being greater than the predetermined and selected threshold percentage. At the receiver, the rapid transistions of the transmitted signal between maximum and zero are responded to by a circuit which switches between its low level and high level to reverse the reduction of the high level signals at the transmitter. The present invention is applicable to both amplitude and frequency modulation systems.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.