The geometry of PSR B0031-07
  Here we present the results from an analysis of a multifrequency simultaneous observation of PSR B0031$-$07. We have constructed a geometrical model, based on an empirical relationship between height and frequency of emission, that reproduces many of the observed characteristics. The model suggests very low emission altitudes for this pulsar of only a few kilometers above the star's surface. 
R. Smits, D. Mitra, B. Stappers, J. Kuijpers, P. Weltevrede, A.   Jessner, Y. Gupta