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A pulsar's pulse profile gets broadened at low frequencies due to dispersionalong the line of sight or due to multi-path propagation. The dynamic nature ofthe interstellar medium makes both of these effects time-dependent andintroduces slowly varying time delays in the measured times-of-arrival similarto those introduced by passing gravitational waves. In this article, we presenta new method to correct for such delays by obtaining unbiased dispersionmeasure (DM) measurements by using low-frequency estimates of the scatteringparameters. We evaluate this method by comparing the obtained DM estimates withthose, where scatter-broadening is ignored using simulated data. A bias is seenin the estimated DMs for simulated data with pulse-broadening with a largervariability for a data set with a variable frequency scaling index, $\alpha$,as compared to that assuming a Kolmogorov turbulence. Application of theproposed method removes this bias robustly for data with band averagedsignal-to-noise ratio larger than 100. We report, for the first time, themeasurements of the scatter-broadening time and $\alpha$ from analysis of PSRJ1643$-$1224, observed with upgraded Giant Metrewave Radio Telescope as part ofthe Indian Pulsar Timing Array experiment. These scattering parameters werefound to vary with epoch and $\alpha$ was different from that expected forKolmogorov turbulence. Finally, we present the DM time-series after applicationof the new technique to PSR J1643$-$1224.

Using low-frequency scatter-broadening measurements for precision estimates of dispersion measures