Analysis of magnetic fluctuations external to toroidal plasmas is important for understanding the Magneto-HydroDynamic (MHD) properties of the plasma, among other things. These properties affect nearly all aspects of behavior of magnetic confinement, and thus are of interest in topics ranging from gross global plasma stability, control, and disruption avoidance, to the more subtle areas such as are involved with passive and active MHD spectroscopy, to name a few examples. Mode number analysis is generally accomplished by interpreting signals from a finite number of external Mirnov coils, which typically are unevenly spaced in the toroidal and poloidal coordinates. The toroidal mode number, n, is usually easily determined in tokamaks because different modes generally oscillate at well separated and distinct frequencies, because of toroidal symmetry, and because n is often very low (n ≤ 2). On occasion however, multiple modes of various origins may overlap in frequency, and then the signals in the individual sensors are the result of a superposition of multiple modes, so that the task of spatial decomposition becomes a difficult problem. Previous efforts to resolve mode numbers involve phase fitting, singular value decomposition and/or Lomb periodogram techniques. We describe a new approach, based on the SparSpec method, and show that it may be superior in several respects. To illustrate the method, we apply SparSpec to data from externally driven, stable Alfvén Eigenmodes on the JET device.