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tokens: 2 ) are subtracted from the DM values to produce this plot. The DMs obtained with only using BAND5 data are not shown in the plot as their uncertainties are large. The four pulsars presented in this work have different frequency evolution of their parameters like flux density, profile shapes, scintle sizes and scatter broadening. To illustrate this, frequency-resolved profiles for all four pulsars are shown in Fig. 1 . As a result, we had to obtain ToAs with different frequency resolution for each of them as described in Sect. 4 . 4. Results and discussions The DM time series obtained using the methods described in Sect. 4 for the four pulsars are shown in Fig. 3 . The left panel shows the DM measured using METHOD1 and the right panel shows DM obtained using METHOD2 . The median DM values and their uncertainties for the four pulsars are listed in Table 2 . We have only reported the measurements for which a reduced χ 2 10 is obtained with TEMPO2 . Some epochs show reduced χ 2 values worse than 10, but looking at each of them individually showed that they were affected by heavy RFI. Although we put a higher limit on χ 2 for getting the good measurements, most of them have reduced χ 2 much less than 10 and close to 1. The median value of the DMs estimated using METHOD1 and METHOD2 differs slightly for PSRs J1713+0747 and J1909−3744, while there is a clear offset between the DMs for PSRs J1939+2134 and J2145−0750. The possible cause of this difference is the underlying difference in the profile alignment methods used. Table 2. Median values of ToA uncertainties and DM. Notes. The ToA uncertainty for each pulsar is shown using the frequency and time averaged profiles with the analytic template created in METHOD2 for both bands. The median DM and DM uncertainty obtained from the DM time series of each pulsar using METHOD1 and METHOD2 are also given. In the present work, we have used the data obtained by observing simultaneously at both BAND3 and BAND5 using a 100 MHz bandwidth. The fractional bandwidth at BAND5 is a factor of ∼4−5 smaller than those used by most of the other PTAs, which reduces the precision with which we can obtain DM at BAND5. But a better fractional bandwidth at BAND3 enables us to get a good handle on the DM. The DM precision we can obtain in general by using this dataset with the BAND3 data alone is ∼10 −3 and while combining the two bands it gets better by an order of magnitude to ∼10 −4 . In particular, we achieve an order of magnitude better precision of 10 −4 with BAND3 and 10 −5 with BAND3 and BAND5 for PSR J1939+2134. Combining the two widely separated bands for measuring DM can create a bias due to the slightly different IISM the rays of these two bands pass through ( Cordes et al. 2016 ). Comparing our results obtained using the two methods described in this work to that of the recently published ones by Alam et al. (2021) and Donner et al. (2020) show interesting trends. For two pulsars, J1713+0747 and J2145−0750, we