Method for the automatic classification of digitally modulated signals, and apparatus to carry out the method

摘要

The invention relates to a method for the automatic classification of digitally modulated signals, in which a complex information signal derived from the digitally modulated signal and modulated in accordance with a type of a modulation which is initially still unknown is transformed into several intermediate signals, the information signal and the intermediate signals being processed further independently of one another; the complex envelope of the information signal only assumes a limited number of states in the state diagram of the complex plane. To achieve the highest possible reliability in the detection of the type of modulation, it is proposed in accordance with the invention that the transformations are selected which, in the state diagram, transform the states which are symmetric with respect to the origin of the complex plane into a lower number of states which are asymmetric to the origin, that from the information signal and, respectively, the intermediate signals, the in each case associated power density spectra are generated which are examined for the existence of lines, and the number, frequency and amplitude of which are determined and forwarded to a classifier which determines from these the type of modulation. IMAGE