Discrimination Gain to Optimize Detection and Classi cation

A method for managing agile sensors to optimize detection and classi cation based on discrimination gain is presented. Expected discrimination gain is used to determine threshold settings and search order for a collection of discrete detection cells. This is applied in a low signal-tonoise environment where target-containing cells must be sampled many times before a target can be detected or classi ed with high con dence. The goal of sensor management is interpreted to be to direct sensors to optimize the probability densities produced by a data fusion system that they feed. The use of discrimination is motivated by its interpretation as a measure of the relative likelihood for alternative probability densities. This is studied in a problemwhere a single sensor can be directed at any detection cell in the surveillance volume for each sample. Bayes rule is used to construct a recursive estimator for the cell target probabilities. The expected discrimination gain is predicted for each cell using its current target probability estimates. This gain is used to select the optimal cell for the next sample. For thresholded data, the expected discrimination gain depends on the threshold which is selected to maximize the gain for each sample. The expected discrimination gains can be maintained in a binary search tree structure for computational e ciency. The computational complexity of this algorithm is proportional to the height of the tree which is logarithmic in the number of detection cells. In a test case for a single 0 dB Gaussian target, the error rate for discrimination directed search was similar to the direct search result against a 6 dB target. Supported by the Institute for Mathematics and Its Applications under Air Force O ce of Scienti c Research contract AFOSR/F49620-94-1-0275