Principles of Modern Radar - Volume 2 1891121537

632 CHAPTER 14 Automatic Target Recognitionother parts of ATR literature sometimes refer to classification as the assignment of atarget to a broad class of targets (e.g., military aircraft vs. commercial aircraft), while discrimination,identification, and target recognition are used interchangeably to refer to theassignment of a target to a more specific target class (e.g., F-4 vs. F-15). For consistency’ssake, we have chosen to adopt the terminology associated with SAR literature.14.1.1 OrganizationA single chapter cannot possibly address the entire aforementioned body of ATR research.Hence, in keeping with the theme of this overall textbook, this chapter limits the scope toradar-based ATR schemes using sources found in open literature. Section 14.2 providesa unified framework for understanding basic ATR functionality; metrics for scoring ATRalgorithms are presented in Section 14.3. The unified framework for ATR is then appliedin Section 14.4 to SAR, in Section 14.5 to ISAR, in Section 14.6 to passive radar, and inSection 14.7 to high-resolution range profiles. Section 14.8 concludes with a summary.14.1.2 Key Points• Regardless of the application, most ATR algorithms can be decomposed into four mainsteps, which we have named the unified framework for ATR. The four steps include(1) identify the target set, (2) select the feature set, (3) observe the feature set, and(4) test the feature set.• Although academic papers often focus on the last two steps, the algorithm will not berobust if the feature set does not adequately segregate the desired target set.14.1.3 AcronymsATR automatic target recognitionCFAR constant false alarm rateDOA direction-of-arrivalDCCF distance classifier correlation filterEO/IR electro-optical/infraredFOA focus of attentionHDVI high-definition vector imagingHMM hidden Markov modelHRR high-resolution radarHRRP high-resolution range profileICA independent component analysisIPR image point responsesISAR inverse synthetic aperture radarKF Kalman filterLDA linear discriminant analysisMACH maximum average correlation heightMRA multi-resolution analysisMSE mean-squared errorMSTAR moving and stationary target acquisition and recognitionMTI moving target indicationPCA principal component analysis