Abstract: The decoder is a real time electronic device for processing, decoding and classifying data whose optimally achievable format of encoding is not known a prioristically but is desired to become known for either future optimal encoding, transmission, decoding for classificational discrimination or for storage. The decoder operates on rawdata inputs.The decoder may be manifested in either of two forms, namely a complete decoder for use as a laboratory research tool or an incomplete decoder which consists of all and only that subset of a complete decoder which is relevant for decoding a particular class of inputs whose application limits are well defined in the information theoretic sense. In general, the input to be processed is a non-stationary signal in analog form. The output of the decoder is usually sampled at most twice the cut-off frequency of the highest frequency component contained within the signal being analyzed. In the complete decoder form, the 2.sup.