1. A signal classification system comprising: a training stage for receiving a plurality of training signals, wherein the training signals are associated respectively with predefined signal classes, wherein the training stage is operative to derive at least a first instance of a specified signal parameter from at least a first one of the training signals, and to associate the first instance of the specified signal parameter with at least one of the signal classes; and a classifying stage for receiving at least one input signal for classification, wherein the classifying stage is operative to derive at least a second instance of the specified signal parameter from the input signal, and for comparing the first and second instances of the specified signal parameters to determine whether to classify the input signal with the first training signal.