LPI/LPD Detection Sensitivity Limitations

LPI/LPD (Low Probability of Intercept/Low Probability of Detection) analyses typically follow the original work of Urkowitz [1] to obtain probability of detection for a specified false alarm rate. Such analyses are based on a uniform time invariant noise background. However, when the noise background is not uniform, the detection performance is significantly reduced. The resulting loss in detection sensitivity is described, and typical measured background variability is illustrated. An example is the radiometric detection of a source in a terrestrial background and illustrates detection performance is roughly 25 dB less sensitive than if the radiometric background were uniform and time invariant. Low side lobe antenna technology is also shown to provide significant LPD and downlink jamming protection.