We present the measurements of scatter broadening time-scales (τ sc ) for 124 pulsars at 327 MHz, using the upgraded Ooty Radio Telescope (ORT). These pulsars lie in the dispersion measure range of 37 -503 pc cm −3 and declination (δ) range of −57 • < δ < 60 • . New τ sc estimates for 58 pulsars are presented, increasing the sample of all such measurements by about 40% at 327 MHz. Using all available τ sc measurements in the literature, we investigate the dependence of τ sc on dispersion measure. Our measurements, together with previously reported values for τ sc , affirm that the ionized interstellar medium upto 3 kpc is consistent with Kolmogorov spectrum, while it deviates significantly beyond this distance.Subject headings: ISM :scattering -pulsars: general IntroductionFree electrons in the interstellar medium (ISM) affect the pulsar signal in three different ways: cold plasma dispersion, free-free absorption and scattering. The broadband pulsar signal gets dispersed in the ISM resulting in delay in pulse arrival time, which is a function of wavelength, λ, and its magnitude is described by the quantity known as dispersion measure DM =

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We present multi-wavelength scatter broadening observations of 47 pulsars, made with the Giant Metre-wave Radio Telescope (GMRT), Ooty Radio Telescope (ORT) and Long Wavelength Array (LWA). The GMRT observations have been made in the phased array mode at 148, 234, and 610 MHz and the ORT observations at 327 MHz. The LWA data sets have been obtained from the LWA pulsar data archive. The broadening of each pulsar as a function of observing frequency provides the frequency scaling index, α. The estimations of α have been obtained for 39 pulsars, which include entirely new estimates for 31 pulsars. This study increases the total sample of pulsars available with α estimates by ∼50%. The overall distribution of α with the dispersion measure (DM) of pulsar shows interesting variations, which are consistent with the earlier studies. However, for a given value of DM a range of α values are observed, indicating the characteristic turbulence along each line of sight. For each pulsar, the estimated level of turbulence, C 2 ne , has also been compared with α and DM. Additionally, we compare the distribution of α with the theoretically predicated model to infer the general characteristics of the ionized interstellar medium (ISM). Nearly 65% of the pulsars show a flatter index (i.e., α < 4.4) than that is expected from the Kolmogorov turbulence model. Moreover, the group of pulsars having flatter index is typically associated with an enhanced value of C 2 ne than those with steeper index.