Intra-channel dispersion smearing at 39 MHz as a function of frequency resolution (ranging from 0.5 to 195 kHz). The five coloured lines correspond to five different DM values: (from the bottom to the top) 1, 20, 50, 70, and 100 pc cm⁻³ . The red dashed-dotted line corresponds to the median of the periods of all the non-MSP pulsars according to the ATNF catalogue (Manchester et al. 2005). The black dotted line corresponds to the frequency resolution of 1.529 kHz used for the NPBS and the associated smearing for the five DM values.