  Suppression of interference from narrowband frequency signals play vital role
in many signal processing and communication applications. A transform based
method for suppression of narrow band interference in a biomedical signal is
proposed. As a specific example Electrocardiogram (ECG) is considered for the
analysis. ECG is one of the widely used biomedical signal. ECG signal is often
contaminated with baseline wander noise, powerline interference (PLI) and
artifacts (bioelectric signals), which complicates the processing of raw ECG
signal. This work proposes an approach using Ramanujan periodic transform for
reducing PLI and is tested on a subject data from MIT-BIH Arrhythmia database.
A sum ($E$) of Euclidean error per block ($e_i$) is used as measure to quantify
the suppression capability of RPT and notch filter based methods. The
transformation is performed for different lengths ($N$), namely $36$, $72$,
$108$, $144$, $180$. Every doubling of $N$-points results in $50{\%}$ reduction
in error ($E$).
