FALSE ALARM ANALYSIS OF THE ENVELOPE DETECTION GO-CFAR PROCESSOR

The greatest of constant false alarm rate processor (GO CFAR) is a use ful architecture for adaptively setting a radar detection threshold in the presence of clutter edges. The GO CFAR input is often the envelop e detected in-phase (I) and quadrature (Q) channels of the baseband si gnal (x(e) = square-root I2 + Q2). This envelope detection can also be approximated using x = a max{Absolute value of I, Absolute value of Q } + b min {Absolute value of I, Absolute value of Q} which requires le ss complex hardware (a and b are simple multiplying coefficients). The envelope GO CFAR processor and several envelope approximation GO CFAR processors are compared in terms of the probability of false alarm (P FA) performance. Closed-form expressions which describe the PFA perfor mance are given and their accuracy evaluated. It is shown that for all cases, the PFA is proportional to the number of reference cells n for small threshold multiplier T and inversely proportional to n for larg e T. A region of intersection occurs where the PFA is the same for two different values of n. For example, at T' = 1.68 in the Absolute valu e of I + Absolute value of Q GO CFAR (a = 1, b = 1) the PFA for n = 1 is equal to the optimal n = infinity fixed-threshold PFA (PFA = 0.112) .