Accession Number : AD0282967

Title :   BANDWIDTH LIMITING EFFECTS OF FREQUENCY SELECTIVE FADING OVER TROPOSPHERIC SCATTER PATHS

Corporate Author : POLYTECHNIC INST OF BROOKLYN N Y MICROWAVE RESEARCH INST

Personal Author(s) : SHAFT,PAUL DAVID

Report Date : 12 DEC 1961

Pagination or Media Count : 1

Abstract : A set of design curves of intermodultion distortion due to frequency selective fading were derived for tropospheric scatter systems. These curves are applicable to systems frequency modulated with frequency division multiplexed telephone and telegraph channels. The reduction in distortion due to the use of diversity reception was not calculated, but a general discussion of some of the problems involved in determining the reduction is given. A two-ray model was selected to derive general results. This, however, restricts the use of the design curves to the region where the information bandwidth is less than the propagation bandwidth. Equations for intermodulation distortion are evaluated using the parameter normally encountered in tropospheric scatter systems. A method of obtaining a probability stribution of distortion is indicated, and an example is worked out in detail. The design curves are compared to experimental measurements of intermodlation istortion due to propagation and agree to a first order approximation. The principal result is the development of design curves which can be used to predict the intermodulation distortion introduced by the tropospheric scatter medium. he intermoduation dstortion will exceed thermal noise in many systems. (Author)

Descriptors :   *RADIO TRANSMISSION, *TELEGRAPH SYSTEMS, *TELEPHONE SIGNALS, *VOICE COMMUNICATIONS, ATMOSPHERES, DISTORTION, DIVERSITY RECEPTION, FREQUENCY DIVIDERS, FREQUENCY MODULATION, MULTIPLEXING, SCATTERING

Distribution Statement : APPROVED FOR PUBLIC RELEASE