Page 36 - Fundamentals of Radar Signal Processing

laid for the successful development of radar at the microwave frequencies that
have predominated ever since.
Each of the other countries mentioned also carried out CW radar
experiments, and each fielded operational radars at some time during the course
of World War II. Efforts in France and Russia were interrupted by German
occupation. On the other hand, Japanese efforts were aided by the capture of

U.S. radars in the Philippines and by the disclosure of German technology. The
Germans themselves deployed a variety of ground-based, shipboard, and
airborne systems. By the end of the war, the value of radar and the advantages of
microwave frequencies and pulsed waveforms were widely recognized.
Early radar development was driven by military necessity, and the military
is still a major user and developer of radar technology. Military applications
include surveillance, navigation, and weapons guidance for ground, sea, air, and

space vehicles. Military radars span the range from huge ballistic missile
defense systems to fist-sized tactical missile seekers.
Radar now enjoys an increasing range of applications. One of the most
common is the police traffic radar used for enforcing speed limits (and
measuring the speed of baseballs and tennis serves). Another is the “color
weather radar” familiar to every viewer of local television news. The latter is

one type of meteorological radar; more sophisticated systems are used for large-
scale weather monitoring and prediction and atmospheric research. Another
radar application that affects many people is found in the air traffic control
systems used to guide commercial aircraft both en route and in the vicinity of
airports. Aviation also uses radar for determining altitude and avoiding severe
weather, and may soon use it for imaging runway approaches in poor weather.
Radar is commonly used for collision avoidance and buoy detection by ships,

and is now beginning to serve the same role for the automobile and trucking
industries. Finally, spaceborne (both satellite and space shuttle) and airborne
radar is an important tool in mapping earth topology and environmental
characteristics such as water and ice conditions, forestry conditions, land usage,
and pollution. While this sketch of radar applications is far from exhaustive, it
does indicate the breadth of applications of this remarkable technology.

This text tries to present a thorough, straightforward, and consistent
description of the signal processing aspects of radar technology, focusing
primarily on the more fundamental functions common to most radar systems.
Pulsed radars are emphasized over CW radars, though many of the ideas are
applicable to both. Similarly, monostatic radars, where the transmitter and
receiver antennas are collocated (and in fact are usually the same antenna), are
emphasized over bistatic radars, where they are significantly separated, though

again many of the results apply to both. The reason for this focus is that the
majority of radar systems are monostatic, pulsed designs. Finally, the subject is
approached from a digital signal processing (DSP) viewpoint as much as
practicable, both because most new radar designs rely heavily on digital