Computer Simulation of Speckle in a Synthetic Aperture Radar Image Pixel

Images of a uniform scene produced with a synthetic aperture radar will frequently appear nonuniform. This phenomenon, called "speckle," is attributed to the coherency of the radar signal and intrapixel interferometry. Speckle is generally regarded as image contrast or response variation between adjacent pixels of a uniform scene. The same type of variation can be observed by imaging just one such pixel when viewed from different azimuthal heading angles. A computer program described in this paper was written to simulate the radar return from a single pixel containing numerous scatterers. The phase and amplitude of the signal reflected from the pixel generally varies from pulse to pulse due to intrapixel interference. After integration, the pixel response usually differs with each "azimuth look," and this speckle variation between azimuth looks may be as much as 20 dB or more. Speckle variation can be significantly reduced by averaging or median filtering multiple azimuth looks per pixel.