Accession Number : AD0433630


Title :   A STUDY OF ' 'PROPAGATION MEDIUM RF NOISE' '.


Descriptive Note : Interim engineering rept. no. 3, Jan-Mar 64.


Corporate Author : SMYTH RESEARCH ASSOCIATES SAN DIEGO CALIF


Report Date : Mar 1964


Pagination or Media Count : 29


Abstract : The effects of the propagation medium noise upon long distance, line-of-sight, tropospheric microwave circuits are examined. The propagation medium noise modulates the phase, amplitude, and angle of arrival of the signal. Based upon the limited amount of experimental data available, it is concluded that the phase noise (time frequency noise) will not be serious in the case of transmissions between fixed terminals if the video bandwidth is properly chosen. In particular, frequency components of less than 0.1 cps should be excluded by the video filter. The angle of arrival noise (space frequency noise) may become serious if fixed antennas with beamwidths of less than one degree are used. The amplitude modulation, which is apparently due to some sort of atmospherically modified multipath situation, lead to 25 db fades for a period of time which will be important for high reliability circuits. When one or both of the terminals are moving, the effects of the propagation medium noise should be considerably more serious. Experimental data for this case is extremely limited and numerical estimates are therefore very tentative. (Author)


Descriptors :   *NOISE(RADIO) , RADIO SIGNALS , ANGLE OF ARRIVAL , MULTIPATH TRANSMISSION , WAVE PROPAGATION , PHASE MODULATION , AMPLITUDE MODULATION , IONOSPHERIC PROPAGATION , TROPOSPHERE


Distribution Statement : APPROVED FOR PUBLIC RELEASE