Published online by Cambridge University Press: 12 April 2016
Results from an analysis of polarization data, at three different frequencies, for PSR B1133+16, show a clear systematic phase shift between the mode separated profiles for the two orthogonal modes. It is found that the shift has opposite signs for the two components of the profile. Further, the shift shows a tendency to increase at lower frequencies. The implications of these results for the origin of orthogonal modes and the location of pulsar emission regions are discussed.