Polar signal averaging

Signals suffering from phase noise, such as spin echoes from NMR experiments in a fluctuating magnetic field, can be underestimated by traditional signal averaging. Averaging in the polar rather than in the Cartesian domain can solve this problem. However, because of background noise, there is an inherent drawback in the polar averaging technique: polar averaging under conditions of a low initial signal to noise will cause these same signals to be overestimated. We studied this problem with both numerical simulations and experiments. The quantitative results allow not only an assessment of the applicability of polar averaging for a given experiment but also possible corrections of the overestimate. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 359–364, 2002