In this thesis, we compute the distance spectrum for non-causal generating signals and compare the different spectrum effects for different non-causal systems. The non-causal system is the system which the present output is determined by the future and the past. The distance spectrum is the list of the difference measures of any two signals and search through all the possible event paths by trellis as much as possible. We use the method of the line difference to compute the distance spectrum of non-causal generating signal systems by defining the line and the line difference to find the distance for every pair of signals. Using this method, we have computed the distance spectrum for non-causal generating signals. Finally, we compare the different spectrums for different non-causal systems of different coefficients.