Page 68 - Fundamentals of Radar Signal Processing

frequency bandwidth, and leads to the synthetic aperture techniques of Chap. 8.

Improving velocity (equivalently, Doppler) resolution requires a long time
observation and is accomplished with multipulse waveforms. Because the
antenna far-field pattern is the Fourier transform of the aperture current
distribution, improved angular resolution can be obtained with larger apertures,
i.e., bigger antennas.

1.5 A Preview of Basic Radar Signal Processing
There are a number of instances where the design of a component early in the

radar signal processing chain is driven by properties of some later component.
For example, in Chap. 4 it will be seen that the matched filter maximizes SNR;
but it is not until the performance curves for the detectors that follow the
matched filter are derived that it will be seen that maximizing SNR also
optimizes detection performance. Until the detector is considered, it is hard to
see exactly how performance depends on SNR. Having seen the major

components of a typical pulsed coherent radar system, the most common signal
processing operations in the radar signal processing chain are now described
heuristically. By sketching out this preview of the “big picture” from beginning
to end, it may be easier to understand the motivation for and interrelation of
many of the processing operations to be described in later chapters.
Figure 1.18 illustrates one possible sequence of operations in a generic
radar signal processor. The sequence shown is not unique, nor is the set of

operations exhaustive. In addition, the point in the chain at which the signal is
digitized varies in different systems; it might occur as late as the output of the
clutter filtering step. The operations can be generally grouped into signal
conditioning and interference suppression; imaging; detection; and
postprocessing. Radar signal phenomenology must also be considered. In the
next few subsections the basic purpose and operation of each block in this

signal processing chain is described.