  We study the mean profiles of the multi--component pulsars PSRs B1839+09,
B1916+14 and B2111+46. We estimate the emission height of the core components,
and hence find the absolute emission altitudes corresponding to the conal
components. By fitting Gaussians to the emission components, we determine the
phase location of the component peaks. Our findings indicate that the emission
beams of these pulsars have the nested core--cone structures. Based on the
phase location of the component peaks, we estimate the aberration--retardation
(A/R) phase shifts in the profiles. Due to the A/R phase shift, the peak of the
core component in the intensity profile and the inflection point of the
polarization angle swing are found to be symmetrically shifted in the opposite
directions with respect to the meridional plane in such a way that the core
shifts towards the leading side and the polarization angle inflection point
towards the trailing side. We have been able to locate the phase location of
the meridional plane and to estimate the absolute emission altitude of both the
core and the conal components relative to the neutron star centre, using the
exact expression for the A/R phase shift given by Gangadhara (2005).
