Overview

In Chapter 1, Section 1.3, we referred to radar, the classic device for measuring distance and position of a target by wireless means. Here we are concerned with how the measurement accuracy is affected by basic system characteristics of bandwidth, noise, and measurement clock rate. A radar terminal transmitter sends a short pulse at a precisely known time. The pulse is reflected back and the terminal receiver measures time of arrival. The total distance traveled by the transmitted signal is the difference between the transmitted and received times multiplied by the propagation speed of the signal, which is the speed of light. The distance between the terminal and the target is one half of the measured distance, which was based on the total two way time of flight.

The radar provides location expressed as two-or three-dimension coordinates of the target with respect to the terminal. It uses a continuously rotating directional antenna whose bearing and elevation at the instant of receiving the reflected wave is recorded. The relative location of the target is specified, in degrees of elevation angle and azimuth, and the measured one-way distance.

In this book the targets don't passively reflect signals impinging upon them. A target is a terminal in a two-way or networked radio communication system whose principle function is exchange of data. However, from the point of view of distance and location, as in radar, operation must provide a specified accuracy within a given electromagnetic environment and with appropriate equipment and radio channel...