TABLE OF CONTENTS Electromagnetic wave theory is fundamental to all navigation and detection systems. Global positioning system (GPS) applications have brought an added dimension to this area and in many applications works with radar systems in more sophisticated applications. The basic operation of the radar system has not changed in years; however, computers and digital technology have significantly enhanced the way data are processed.
Underwater sound systems are nothing more than radar systems at lower frequencies. We can work with underwater systems like we do for the higher-frequency electromagnetic systems to communicate, navigate, detect, track, classify, and so on. We are just working with substantially longer wavelengths. C.A.
In This Section:
David K. Barton
Radar is an acronym for radio detection and ranging, and is defined7 as a device for transmitting electromagnetic signals and receiving echoes from objects of interest (targets) within its volume of coverage. The signals may be in the frequency range from the high-frequency radio band (3 to 30 MHz) to light (10 15 Hz), although most systems operate between 300 MHz and 40 GHz. The target is a passive reflecting object in primary radar, while in secondary radar a beacon (transponder) is used to reinforce and identify the echo signal.
A radar system in its environment is shown in Fig. 23.1.1. Transmission is typically through a directional antenna, whose beam can either scan...
