BOOK_CONTENT
From Radar System Analysis, Design and Simulation

10.1 Introduction

One of most important signal processing objectives in target detection in locally varying homogeneous noise or clutter is to maintain the false-alarm rate as a constant. Constant false-alarm rate (CFAR) processing is one of maybe half a dozen indispensable types of signal processing for the successful operation of a radar system.

The classic theory of target detection assumes that the noise is distributed as Gaussian with unknown power. When an antenna sweeps the surveillance sectors, the radar receives noise and clutter returns, and they may not be distributed as Gaussian; clutter may be distributed as lognormal, Weibull, gamma or K distribution, or the like. We shall investigate a few CFAR processing methods in Gaussian noise and Weibull clutter.

10.2 Cell-Averaged CFAR (CA-CFAR)

Finn and Johnson [1] have reported a CFAR processing method for use when the target signal received is embedded in Gaussian noise of unknown power level. The probability density function of noise is Gaussian; the unknown is the locally varying noise power. We follow their analysis.

When the input to a square-law detector is narrowband Gaussian noise with zero mean and unknown variance (noise power), the output is distributed as exponential with unknown variance [2-4]. (See Figure 10.1.)



Figure 10.1: Probability density functions: Gaussian and exponential

We note that the mean of the exponential is E{y}= ? y, and the average of the random variable y is equal to the standard deviation of y. In radar literature we call f y(y) the probability density...

Copyright Artech House, Inc. 2008 under license agreement with Books24x7

Products & Services
Active Band Pass Filters
Active band pass filters are used to attenuate frequencies below and above a range of frequencies (i.e., the bandwidth or passband of the filter).
Active Band Reject Filters
Active band reject filters are tuned circuits that prevent the passage of signals within a specified band of frequencies. These devices are also known as bandstop or notch filters.
Active High Pass Filters
Active high pass filters pass signals from high frequencies and reject signals from low frequencies.
Active Low Pass Filters
Active low pass filters pass signals from low frequencies and reject signals from high frequencies.
Noise Figure Meters
RF noise figure meters measure the noise contribution of an amplifier relative to a noise-free amplifier at a reference temperature. Usually expressed in dB for Ku-band amplifiers.

Topics of Interest

11.1 Introduction The object of moving target detection and indication is to reject returned signals from stationary objects such as buildings, hills, and islands and detect the signal from moving...

a auxiliary channel vector a noise-to-clutter ratio ABF adaptive beamforming ACP auxiliary channel processor ACE adaptive coherence estimator ADC analogue-to-digital conversion AEP...

AMTI Airborne moving target indication APU Auxiliary power unit A Scope A type of radar display that shows signal amplitude vs. time AWACS Airborne Warning and Control System CCM...

William L. Melvin 10.1 Introduction Aerospace radar systems must detect a variety of target types in the presence of severe, dynamic clutter and jamming signals. Signal diversity -the exploitation of...

Glossary A a noise-to-clutter ratio a auxiliary channel vector ABF adaptive beamforming ACP auxiliary channel processor AEP auxiliary eigenvector processor AEW airborne early warning ASEP...