Probability of detection for objects with low radar cross section

Based on an earlier work, that investigated how the received radar signal from a generic tactical ballistic missile (TBM) can be modelled statistically to include random fluctuations in the attitude angles of the platform, the present work describes how the probability of detection, Pd, can be calculated. Calculations for a given flight trajectory are made by first deriving the expression for the so called ROC-curve (Receiver Operation Characteristic). Simulations at L- and S-band show that the frequently used Swerling 1-2-results overestimates Pd at low SNR values and vice versa underestimates the same at high values. This is in comparison with results obtained using a Rice distribution, which in an earlier work was found to be a more relevant description of the fluctuations of the target RCS.