Simultaneous two frequency observations of radio pulsars

Simultaneous two frequency single pulse observations for PRS 1133 + 16, PSR1929 + 10 and PSR2021 + 51 were carried out on 70-m Deep Space Network radio telescope near Evpatoria at frequencies 927 and 6000 MHz. Data analysis shows systematic time shift of the mean profiles between two frequencies when the known dispersion measures were taken into account. For PSR2021+51 this shift may be explained by the frequency dependence of the main profile. Cross-correlation level between single pulse intensity fluctuations at two frequencies was shown to be two times lower than the value obtained before at frequencies 102.5 and 1700 MHz