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tokens: f dif – decorrelation bandwidth, t dif – scintillation time, τ sc – scattering time, θ H – angular diameter of the scattering disc, d s – distance to the scattering screen, ρ dif – scale of diffraction pattern, n – spectral index of ISM inhomogeneities. Dynamic spectra of observations conducted in 2014 and 2015 show clearly distinguishable inclined structures that indicate the presence of angular refraction in a given direction. Time and frequency structure functions obtained from analysis of the dynamic spectrum in 2015 showed their power-law character with an equal index of α = 1.13 ± 0.01, which corresponds to n = 3.13 ± 0.01. The similarity of their inclinations indicates strong refraction in the direction to the pulsar. In the 2014 observation, we had a strong modulation in frequency and time, so a quality structure function could not be obtained. Such a modulation is well known as time and frequency ripples caused by the interference of diffracted and direct rays in dual-reflector radio telescopes. It was found that the diffracted rays from the sub-reflector edge can interfere with the main beam to produce a gain ripple of sinusoidal form for the dual reflector system. Analysis of the dynamic spectrum for 2012 gave the same slope of the structure functions, α = 0.83 ± 0.04. For 2014 and 2015 observations, the drift of diffraction spots in the dynamic spectrum is clearly visible. In Bhat et al. ( 1999 ), it was noted that such drift behaviour is typical for this pulsar. Such a drift can last for quite a long time. This effect was observed during the entire series of observations conducted in 1993–1994 (110 days). This suggests that the structure leading to the refraction of radiation passes the line of sight for a time longer than 110 days. Analysis of the complex covariation function module for the space–ground interferometer yielded the scale of the diffraction pattern. In Fig. 6 , this function is shown for the 2015 observation for the RadioAstron–Arecibo (RA–AR) baseline. Applying equation ( 8 ), we found a value of the spatial coherence function B u = 0.25 ± 0.04. Using the values α = 1.1 and , we obtained ρ dif = (6.0 ± 0.9) × 10 9 cm. The distance from the observer to the screen d s was estimated using ( 10 ). Since the tangential velocity of the pulsar is , we neglected the velocity of the Earth and the screen. Accordingly, d s / D = 0.64 ± 0.06, . Using ( 11 ), we calculated , . We estimated the scattering time to be 0.76 μs. Figure 6. PSR B0834+06. Average covariation function from complex cross-spectra (observation 08.04.2015, baseline RadioAstron–Arecibo). The dashed line corresponds to the OFF-pulse window. For 2014, we did not obtain a qualitative covariation function, because of the influence from frequency ripples. In the observation of 2012, the baseline projection of the space–ground interferometer was 2.05 × 10 10 cm. For this day, we found the value B u = 0.38 ± 0.09 and, using α = 0.83, we determined the diffraction