Intensity autocorrelation functions (ACF) of pulses with structure for two pulsars. The uppermost panels present example pulses. The autocorrelations displayed in the middle panel correspond to the pulses above them. The two bottom panels display the averaged ACFs for 120 and 132 pulses for PSRs B0031−07 and B1133+16 respectively. The averaged ACF’s for two bands centred on 116.75 MHz and 173.25 MHz (dashed line) are shown.