1. A method for specific emitter identification, comprising: using a processor in performing the steps of: generating a computer-readable representation of a signal received from an emitter, the received signal being indicative of a hardware characteristic of the emitter; computing a plurality of gradients for each partition of a plurality of partitions of the computer-readable representation, each gradient indicative of at least the angular orientation of a respective portion of the computer-readable representation; for each partition, computing a histogram by assigning each computed gradient to a bin based at least in part on the magnitude of the computed gradient; extracting one or more Histogram of Oriented Gradient (HOG) features from a concatenation of the bins of all of the computed histograms; comparing the one or more HOG features to one or more corresponding HOG features stored on a computer-readable medium; and determining, based at least in part on the comparison, whether the emitter has a particular identification.