ANTI-JAM TROPOSPHERIC SCATTER THEORETICAL ANALYSIS

摘要

We summarize below several important conclusions which have resulted from the study:n1. The fundamental information needed to deter-mine intermodulation noise for scatter circuits is a distribution called the Scattering Power Distribution. This distribution is essentially a plot of echo strength as a function of echo delay.n2. It is demonstrated that in order for the chaff to cause large intermodulation distortion in conventional FM-FDM troposcatter systems, the maximum differential path delay caused by the chaff cloud must be of the order of the reciprocal of the r. m. s. frequency deviation of the transmitted signal. Also it is concluded that the most practical way of causing large" intermodulation distortion is to drop the chaff terminally, that is rightover one terminal in the main beam of the antenna at the opposite terminal.n3. The intermodulation distortion caused by thenchaff can be removed by lowering the frequency deviation sufficiently. When this is done, the only remaining distortion is linear which, at worst, causes frequency selective fading in the baseband.n4. It is shown that a more effective way of re -moving the intermodulation distortion without changing the channel levels is td leave out portions of the transmitted baseband.