Abstract: A system for determining whether a given phenomenon has occurred based on ltiple sensor decisions is provided. Each sensor samples input data and attempts to decide if the given phenomenon exists. These sensor decisions are provided to the data fusion processor. The data fusion processor uses a sum of the sensor decisions multiplied by a logarithmic gain indicating the relative reliability of each sensor to generate a test existence metric. The test existence metric is compared to two threshold limits. The results of this comparison are used to provide a final decision indicating the existence of the given phenomenon. An optimization is used to determine the threshold values used in the threshold table to guarantee that the false alarm rate and the data fusion processor is constant, even in cases where data from some sensor is missing.