1. A method for detecting a dispersed pulse in a received signal that has been dispersed by a dispersive medium, the method comprising: obtaining an input array of cells, the value of each cell being indicative of an intensity of a frequency component of the signal during a time period at a representative time, a time coordinate of each cell within the array being indicative of the representative time, and a frequency coordinate of each cell being indicative of a frequency of the frequency component; applying a fast dispersion measure transform (FDMT) to the input array to concurrently sum the values of subsets of the cells of the input array, the coordinates of the cells of each subset lying along one of a plurality of different dispersion curves, each dispersion curve being defined by a known non-linear functional form of dispersion in the dispersive medium and being uniquely characterized by a time coordinate of one of the cells of the subset of cells that is included in that dispersion curve, said one of the cells having a preselected frequency coordinate, and by a value of a dispersion measure, the summing to produce an output array of the sums, wherein a position of each sum in the array is indicated by a coordinate that is indicative of said time coordinate of one of the cells and by a coordinate that is indicative of the dispersion measure value, the application of FDMT including: initially generating a plurality of sub-arrays of the input array, each sub-array representing a frequency sub-band of an initial frequency range of the frequency coordinates of cells of the input array, the value of each cell of each of the sub-arrays being a summation over each of the different dispersion curves that includes a cell of that sub-array; and iteratively combining pairs of adjacent sub-arrays in accordance with an addition rule until all of the initially generated plurality of sub-arrays are combined into said output array of the sums; and identifying a cell of the output array that is indicative of a transmitted pulse.