Digital RF Delay Line for ECM (Electronic Countermeasure) Look-Through

摘要

Jamming signals, when reflected from structure to receiver, produce unwanted reflected signal interference in a countermeasure system. Elimination of these reflections would increase look-through capability. It is the goal of this project too demonstrate Digital RF Memory (DRFM) techniques which would null these unwanted reflected signals. Controlled injection of a transmitter signal into a receiver is a method of nulling this interference. Successfull nulling requires control of delay, phase, and gain of the feedback signal. The feasibility of using sampling electronics for storage and delay control was demonstrated in this project. The DRFM was used to simulate the electronic countermeasure (ECM) transmitter. Delays in the injection path were generated with high rate shift registers. The phase and gain of the injection paths were set with linear elements. The results from the experiment include bandwidth and quality of available nulls, as well as recommendations for the selection of nulling strategy.