An Investigation of the Transmission of Digital Signals Through a Dispersive Chaff Channel

摘要

The purpose of the Abstract Task III effort was to quantitatively determine the information capacity (and its behavior) of a cloud of chaff dipoles. The effort was directed to theoretical and experimental investigations of binary FSK transmission through a dispersive chaff scatter channel. The experimental work was performed at a frequency of 4650 MHz. Good agreement was obtained between experimental data and theoretical results. Probability of error for a modulating signal of 600 KBPS varied from 0.25 to 0.00015. Measured coherent bandwidth varied from 0.27 to 2 MHz. The median value of measured signal to noise ratio was 23 db. The median value of fading bandwidth was 8 Hz. It was concluded that dispersion of the chaff dipoles adversely affected both signal to noise ratio and probability of error. The linear, time variant, random parameter filter modeled the chaff scatter channel for binary FSK operation. It was determined that the chaff scatter channel met the conditions of a time flat-frequency selective channel; i.e., the predominate effect of the cloud on the received waveform was intersymbol influence. (Author)