This chapter contains a brief overview of the basic results of detection and estimation theory as well as optimum filtering related to radar applications. In this chapter, we introduce and develop the basic concepts of decision and estimation, both of fundamental importance in all analyses and activities related to random phenomena. For example, decision theory is used to establish whether a '1' or a '0' was sent on a digital communication channel, but also to detect a radar target, by examining the signal received by the radar itself, where not only thermal noise, but also unwanted echoes such as the 'clutter' are present and corrupt the target echo.

This chapter discusses: linear and logarithmic constant false-alarm rate (CFAR) techniques and receivers; CFAR loss; the log CFAR technique for Weibull clutter; Weibull CFAR; the error in the estimation of the parameter from a finite number of samples; computer simulation of Weibull CFAR; weather clutter (with and without targets); window Weibull CFAR; and smoothing.

This chapter deals with Doppler techniques and their different applications for surveillance radar, multifunction radar and synthetic aperture radar. The chapter presents: an analysis of a simple pulse Doppler radar [fixed station, low pulse repetition frequency (PRF), no range ambiguity] (radar characteristics, power and spectra of clutter and target, basic block diagram of the radar, practical considerations and implementation); a similar radar with range ambiguity (medium PRF); shipborne surveillance pulse Doppler radar; airborne surveillance radar (general description; low, medium and high PRF modes); combat aircraft radar (radar characteristics; look-up and look-down operation in low, medium and high PRF modes; examples and comparison of the modes); solving range ambiguities in medium PRF (MRF) and high PRF (HRF) modes; and synthetic aperture radars.

This chapter deals with the rejection of active interference (jamming) in the space domain (antennas) and in the frequency domain, as well as with the simultaneous rejection of clutter and jamming. It is well known that the most effective measure of electronic countermeasures (ECM) is active noise jamming. Therefore, this chapter discusses the rejection of active interference as a main topic of radar electronic counter-countermeasures (ECCM). The strategy of active interference rejection prevents the interference from entering the radar detector as far as possible. Since there are many nonlinear components in the radar receiver, such as mixer, envelope detector etc., a weak signal will be suppressed by the strong interference in these nonlinear components. Therefore, the most effective measures to reject interference are spatial selectivity and frequency selectivity, since spatial selectivity rejects the interference at the antenna, and frequency selectivity rejects the interference before the mixer. Two types of jamming are often used: standoff jamming (SOJ) and self-screening jamming (SSJ). SOJ interferes with the radar receiver mainly through the sidelobe of the radar antenna, while SSJ interferes with the radar receiver mainly through the main lobe of the antenna. It is evident that the best way to reject SOJ is by spatial selectivity, and the best way to reject SSJ is by frequency selectivity. Therefore these two methods are discussed in detail in this chapter.

This chapter summarises the requirements, architectural options and trends of radar signal processing. Target identification methodologies may be separated into three broad categories: (i) signal generation and feature extraction methods, (ii) algorithmic procedures, and (iii) theoretical approaches. This chapter emphasises the first one. It looks at theoretical approaches to target identification based on polarisation and pole extraction, and discusses target identification (a) based on natural resonance; (b) with multifrequency radar; (c) with impulse radar; (d) based on spatial processing of coherent echoes; (e) based on spectral estimation; (f) based on non-coherent signal processing; and (g) based on millimetre-wave radar.

This chapter refers to bistatic radars, which are described and analysed in terms of operational requirements and advantages, design aspects and constraints, deployment options, current programmes and future trends. A bistatic radar is one in which the transmitter and the receiver are deployed at two separate locations; either or both of these locations can be changing with time.

This chapter concludes the book with a glance at the evolution and trends of radar systems and technologies. Aspects discussed include: emerging technologies (silicon and III-V components, microwave tubes and others); high resolution in range and in angle; the use of new frequencies; and advanced system concepts.