WIDEBAND DIGITAL MODULATION AND DETECTION TECHNIQUES FOR TROPOSCATTER.
Quarterly rept. no. 3, 1 Jan-31 Mar 67,
COMMUNICATION SYSTEMS INC PARAMUS N J
Pagination or Media Count:
The program objective is to identify and breadboard the modulation technique offering best performance for transmission of high digital data rates over tactical troposcatter paths of 50 to 150 miles at 5 ghz. The study is concerned with higher order modulation coding, in-band diversity and other techniques that may bring about an optimal match to the medium. The prime traffic rates under consideration are 0.576 and 1.15 megabits per second. During this quarter, a specific near-optimum modulation technique was chosen for implementation, and the necessary circuits for transmitter and receiver were planned and analyzed in detail. A tentative set of circuit block diagrams was completed. This circuit was then refined and it was found possible to simplify parts of the receiver circuitry by modifying the specific detection process used. With the first-choice modulation pattern fully analyzed, and the required circuits outlined in detail, it became possible to consider trade-offs of cost, complexity, probable reliability and size factors, and overall performance as a function of simplification and modification in the choice of pattern. A particularly attractive simplified choice of modulation pattern results in about two to one reduction in circuit cost and complexity, and appears to have theoretical advantages in links having a wide correlation bandwidth, allowing wider frequency spacing for in-band diversity. Author
- Electrical and Electronic Equipment
- Radio Communications