A Fast Amplitude Approximation For Quadrature Pairs
01 October 1971
When a discrete Fourier transformation is applied to samples from a data segment the results are usually desired in the form of phase and amplitude estimates of the components into which the data is resolved. When F F T 1 algorithms are used to perform the transformation the information from which these estimates are obtained is usually produced in the form of quadrature pairs of numbers A cos 6, and A sin 6, where A is the amplitude and 9 the phase of the estimate. Obviously A = (A2 cos2 6 + A2 sin 2 0)h. 2849 (1)