Glossary

?: absorptance
?: difference channel of a monopulse radar
? f: frequency interval or difference
?: emissivity; also a general measure of precision
? _B: width at half-power (-3 dB) beam (i.e., angle within which the power of the transmitted signal is more than half its maximum level)
? _q: squint angle
?: wavelength: distance between two adjacent peaks on a sinusoidal wave; for an electromagnetic wave the wavelength is given by c/f where c is the velocity of light and f is the frequency of the wave
?: reflectance or reflection coefficient
? _r: reflection coefficient of a rough surface
? _s: specular reflection coefficient
?: sum channel of a monopulse radar
?: Stefan-Boltzmann constant
?: equivalent area
?: standard deviation (i.e., square root of the variance of a probability distribution; a quantity whose values have a Gaussian distribution has a 67% probability of being within ? of the mean; 90% probability of being within 2 ?; 97% probability of being within 3 ?)
? _p: standard deviation of a quantity with zero mean
?: pulse duration, pulsewidth (PW)
? _a: atmospheric transmittance
? ₀: transmittance of optical system
?: phase or phase shift angle
?: field of view, measured as a solid angle
?: angular velocity or angular frequency of a signal

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Introduction to Electronic Defense Systems, Second Edition