1. A method of assessing a signal, the method comprising: repetitively sampling the signal from at least two tap points to retrieve a single successive sample set at each sampling, the at least two tap points being separated by a fixed time delay, the sampling being asynchronous relative to the signal, each sample set having a single distinct value of the sampled signal from each and every tap point; retrieving a plurality of such sample sets over time that define a probability density; building an at least two dimensional histogram of the probability density of the plurality of sample sets; and passing the at least two dimensional histogram to a machine learning algorithm trained to predict a value of at least one characteristic of the signal.