Multiple signal direction-finding and interference reduction techniques

Increasingly, airborne reconnaissance platforms are faced with multiple signals transmitting at the same frequency. Conventional direction finding (DF) and signal intercept methods are ineffective when processing frequency channels containing more than one signal. Modern DF and interference reduction techniques can effectively determine the number of active signals, estimate their angle-of-arrival (AOA) and extract individual signals. In this paper, an overview of several different solutions to the problem will be described including the multiple signal classification (MUSIC), multi-target modulus restoral (MT-MORE) and decision-directed techniques. The paper will conclude with DF and interference-reduction performance results for real data. The performance results demonstrate the promise of this technology. Moreover, the performance of the property-restoral techniques is especially promising due to the inherent robustness of these techniques.