Dynamic spectra I(f, t) from four observations with different scintle sizes in the left panels and their normalized autocorrelation functions in the right panels. The horizontal and vertical axes correspond to the time (or time lag) and frequency (or frequency lag), respectively. In the two smaller side plots, the sky blue points are the 1D autocorrelation functions at zero time and frequency lag, the black lines are the best Gaussian fits, the red lines indicate the values for v_d and τ_d. The pulsar name, telescope, epoch of observation, v_d and τ_d are given above the dynamic spectra.