Phasing out speckle

It is demonstrated that the instantaneous frequency of a backscattered echo sequence can be used to pinpoint the location of destructive interference effects. These interference artefacts, which are generally interpreted as speckle in the image, are generally removed by stochastic averaging or filtering methods applied to the acquired image. The method proposed here can detect such artefacts within individual A-lines, and thus differs from conventional techniques. Where speckle is recognised within each A-line, the artefact can be corrected on a local basis by the application of the frequency diversity technique. Because it relies only on A-line processing, the approach points the way towards a speckle reduction technique which can realistically be implemented on a real-time basis. In this paper, the principles of the technique are illustrated using a simple two-reflector model.