Accession Number : AD0663748

Title :   DIGITAL COMBINER STUDY.

Descriptive Note : Final rept. Sep 66-Jul 67,

Corporate Author : PHILCO-FORD CORP PHILADELPHIA PA COMMUNICATIONS AND ELECTRONICS DIV

Personal Author(s) : Wenzel,Samuel B. ; Cramer,Bruce G. ; Harcar,Andrew R. ; Leonard,Jay F. ; Hauer,Charles A.

Report Date : DEC 1967

Pagination or Media Count : 324

Abstract : The report analyzes the effect of the troposcatter medium on transmission of analog and high-speed digital data signals, with emphasis on the latter. Solutions to alleviate the problems are proposed. Principal results are given in equations, design curves, and in other specific data forms useful in troposcatter system design. Performance limitations posed by the medium to conventional differential coherent phase-shift-keyed (DCPSK) and frequency-shift-keyed (FSK) system are examined. Signals processing techniques, specifically designed to alleviate the deleterious effect of multipath time spread, are proposed. The performance of various signal-processing techniques is examined and results are compared. A recommended approach is a frequency hopping system using quaternary PSK modulation. Another is the adaptive statistical detector. This looks promising but requires additional development effort; hence, it would represent the next generation of tropo modems. A survey and study of conventional diversity techniques including maximal ratio, equal gain, and switching is made. Performance (under realistic conditions) of each type is considered. This includes an analysis of predetection versus post-detection operation. (Author)

Descriptors :   (*DATA TRANSMISSION SYSTEMS, *MULTIPATH TRANSMISSION), DIGITAL SYSTEMS, ATTENUATION, FREQUENCY SHIFT KEYERS, SIGNALS, PROCESSING, PHASE SHIFT CIRCUITS, MODULATION, ERRORS, RAYLEIGH SCATTERING, PERFORMANCE(ENGINEERING)

Subject Categories : Radio Communications
      Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE