We discuss the cross-correlation analysis of single pulses in the emission of PSR 0329+54 observed simultaneously at 102.5 and 1700 MHz. We have found that the observed correlations between the two frequencies are consistent with the model in which the subpulses in single pulses correspond to plasma excitations flowing from the neutron-star surface along dipolar magnetic field lines. The peaks of strongly correlated subpulses at the two frequencies correspond to the same field line at two different emission radii. We have found that the core (central) and the conal (outer) components of the pulse profile of PSR 0329+54 originate at the same distance from the neutron star.