Application of Tuneable Notch Filters for Improved Signal Jamming Protection

Abstract

Adjacent channel interference is an inevitable consequence of the increasing number of radio signals and their widespread accessibility. In addition to this interference, information can be distorted by jamming techniques used by hackers and, in some cases, security services like the military. This research concentrated on enhancing jamming protection using a tunable notch filter, considering the growing need to ensure that accurate information reception. The necessary signal was provided  through a signal source, and a  barrage jammer was used to introduce the jamming signal that would interfere with the original signal. The circuit also featured an adjustable notch filter designed to mitigate the impact of the jamming signal. A spectrum analyzer was used to examine the circuit’s performance. The effectiveness of the notch filter in counteracting the effects of the jammer was examined through simulations using MatLab. Based on the distortion measurement, the signal-to-noise ratio (SNR) of the filtered signal, which was 4.92 dB, which was higher than the original signal's 1.92 dB. This finding indicates that the jamming effect was substantially reduced or eliminated. Additionally, it was discovered that without a notch filter,  an increase in the jammer-to-signal noise ratio significantly decreased the signal-to-noise ratio value. However, the implementation of the notch filter prevented a drastic decline in performance, demonstrating that as the jammer-to-signal noise ratio increased, the depth of the notch also increased.