  We present the results obtained from analysis of two AstroSat observations of
the high mass X-ray binary pulsar OAO 1657-415. The observations covered
0.681-0.818 and 0.808-0.968 phases of the $\sim$10.4 day orbital period of the
system, in March and July 2019, respectively. Despite being outside the
eclipsing regime, the power density spectrum from the first observation lacks
any signature of pulsation or quasi-periodic oscillations. However, during July
observation, X-ray pulsations at a period of 37.0375 s were clearly detected in
the light curves. The pulse profiles from the second observation consist of a
broad single peak with a dip-like structure in the middle across the observed
energy range. We explored evolution of the pulse profile in narrow time and
energy segments. We detected pulsations in the light curves obtained from
0.808--0.92 orbital phase range, which is absent in the remaining part of the
observation. The spectrum of OAO 1657-415 can be described by an absorbed
power-law model along with an iron fluorescent emission line and a blackbody
component for out-of-eclipse phase of the observation. Our findings are
discussed in the frame of stellar wind accretion and accretion wake at late
orbital phases of the binary.
