Detecting Potential Performance Improvements in Cognitive Radar Systems

As a cognitive radar system adapts to interference in real time by adjusting its transmission characteristics, such as operating frequency and bandwidth, the optimal load impedance for the transmit power amplifier will also change. A search algorithm and tunable matching network on the output of the transmit power amplifier optimizes the amplifier for improved system performance, such as increased transmit power and resultant radar range. However, later changes in interference will cause the cognitive radar to change its transmission frequency again, affecting the optimal impedance and potentially requiring reoptimization. In order to determine when reoptimization is needed, this work demonstrates use of the earth mover distance (EMD) applied to utilized transmit frequencies over time to determine when reoptimization may provide meaningful output power improvement.