  A systematic study of ionospheric scintillation at the low-latitudes,
especially around the Equatorial Ionization Anomaly (EIA) and the magnetic
equator, is essential in understanding the dynamics of ionospheric variation
and related physical processes. Our study involves NavIC $S_{4_C}$ observations
over Indore and Hyderabad. Additionally, GPS $S_{4_C}$ observations over Indore
were analyzed, under disturbed as well as quiet time ionospheric conditions
from September 2017 through 2019, falling in the declining phase of the solar
cycle 24. The $S_{4_C}$ observations were further analyzed using proxy
parameters: ROT and ROTI. These results have been obtained from three
satellites of the NavIC constellation (PRNs 2, 5, and 6). The onset times of
scintillations \textbf{were} observed to be around 19:30 LT (h) and 20:30 LT
(h) for Hyderabad and Indore respectively, while the $S_{4_C}$ peak values
occurred between 22:00 LT (h) and 23:00 LT (h). The reliability of NavIC was
evaluated using scattering coefficients that revealed a good correlation across
the pair of signals during quiet time ionospheric conditions. The observations
clearly show that the amplitude scintillation of the NavIC signal follows the
Nakagami-m distribution along with the $\alpha-\mu$ distribution as a depiction
of the deep power fades caused by scintillation on these signals. This paper
shows the impact of such systematic studies near these locations for the first
time, in improving the understanding of the dynamic nature of low-latitude
ionosphere under low solar activity conditions.
