TABLE OF CONTENTS The discussion of active devices in Chapter 8 did not examine probability of detection. Unsaturated radar target enhancers act as passive point targets whose fluctuation characteristics are governed by the antenna radiation patterns, which are usually smooth enough for the RTE to become a Swerling Case 0 non-fluctuating target, even when not ground-fast. The RTE receiver noise component of output adds a generally insignificant component to system noise.
Receivers within saturated RTEs can be regarded as detecting all interrogations; P D1 = 1, subscript 1 denoting interrogate leg.
Racon receivers contribute noise but pick up no clutter, and see radar transmitters as non-fluctuating Swerling Case 0 sources. Because quite low sensitivity suffices to detect the one-way interrogation, receiver noise of superhet racons is small, their SNR usually being very high even when the interrogation is only marginally above receiver threshold, causing a rather sharp increase in P D1 from 0 to almost 1. Because of the numerous interrogating radars within range, pulse to pulse integration is not normally possible, or indeed necessary. These racons have Ricean probability distribution as for non-coherent radar receivers, Section 12.3. Unless the manufacturer's data sheet indicates otherwise, one may assume the racon receiver threshold is set for no more than one false interrogation per 20 s, with P FA ~ 10 -8 (Eq. (12.1), F = -8, bandwidth ~5 MHz). The low false alarm rate provides a margin against deterioration in...
