FM transmission of video between moving vehicles over a flat earth

The multipath interference to FM transmission of television between vehicles moving over a flat Earth is analyzed. The paper starts with the derivation of the direct path and multipath signals. In this derivation an induction formula is obtained for the RF spectrum of a signal which is produced by frequency modulating with N modulating frequencies. It is pointed out that the direct path signal alone may result in a picture size change and an amplitude modulation interference. The direct and multipath signals are added and processed by the receiver. The multipath interference appears in the video output in a direct but complex form. In the case of a small multipath reflection coefficient the interference form becomes simpler. For this case a signal-to-interference ratio is derived. The results provide both a measure of the TV quality and the basis for an extended analysis. The analysis is applicable to FM transmission of any intelligence possessing a countable spectrum.