الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 172 |  |  |
| | | from | 172 | | |
Abstract
Radio communication with moving vehicles is almost old as radio itself. only recently, the technology had advanced to the point where realization of instant communication with the mobile public appears possible. an increasingly important communication system involves the use of radio links for the transmission of speech or data, both to and from mobile vehicles, which could be cars, aircraft, satellite, and military communications. It is now possible to implement highly sophisticated techniques of modulation demodulation (modem) and detection for digital signals. Thus, it means that each mobile can be fitted with a small digital modem. Whereby, it can both receive and transmit digital signals.
Serve congestion of the mobile communication spectrum in some geographic areas dramatically illustrates the need to seek a communication technique that offers the potential for utilizing the spectrum more efficiently. The system proposed here employs wide band time frequency coded signals to accomplish this objective. A comparison between many digital techniques tips in favor of the spread spectrum system because of its more uniform spectrum occupancy and its immunity to interference.