1. In a system having a data source, providing a data stream, at least one transmission path, providing a path for transmission of the data stream, and a data receiver, receiving the data stream, a method for determining the type of a data corrupting interference, which causes bit errors in the data stream, comprising steps of: a) emitting test data from the data source; b) determining bit errors in data received; c) deriving a bit error function for the bit errors determined in step (b); d) dividing the bit error function into sections; e) performing a section by section autocorrelation of the bit error function to obtain an autocorrelation function, a length of an autocorrelation section at any one time being rated to contain a plurality of bit errors; f) checking the periodicity of the bit-error function based on the autocorrelation performed in step (e); g) determining the type of interference to be stochastic whenever the autocorrelation function obtained in step (e) exhibits a significant maximum without further pronounced maxima, and determining the type of interference to be deterministic whenever the autocorrelation function obtained in step (e) exhibits several maxima of an equidistant distribution.