At sub-GHz frequencies, the ionosphere has a profound effect on the electromagnetic signals that are passing through it. Radio Interferometers like Gaint Meter Wave Telescope (GMRT) and others like it can observe total electron content (TEC) fluctuations in the ionosphere on a much broader scale. Due to the positional advantage and configuration of the array, this interferometer is best suited to study sensitive regions between the magnetic equator and the northern crest of the Equatorial Ionization Anomaly (EIA). We have obtained a relatively long observation of a cosmic bright radio source (3C68.2) using GMRT at the sub-GHz frequencies to detect small-scale fluctuations in the ionosphere around the EIA region. Here, we present very preliminary results from our detailed study of the ionosphere using the GMRT. Our results reveal that this instrument is capable of measuring differential TEC between antenna elements with an accuracy of a few mTEC, which is more sensitive than current GPS-based TEC measurements. Furthermore, the TEC gradient is also computed along each antenna arms in which small scale fluctuations are detected in the two dimensional TEC surface. These fluctuations are best suited to study the unanticipated changes in the ionosphere during the nighttime.