  Transit photometry is perhaps the most successful method for detecting
exoplanets to date. However, a substantial amount of signal processing is
needed since the dip in the signal detected, an indication that there is a
planet in transit, is minuscule compared to the overall background signal due
mainly to its host star. In this paper, we put forth a doable and
straightforward method to enhance the signal and reduce noise. We discuss how
to achieve higher planetary signals by subtracting equal halves of the host
star - a folded detection. This results in a light curve with a double
peak-to-peak signal, 2R_p^2/R_s^2, compared to the usual transit. We derive an
expression of the light curve and investigate the effect of two common noises:
the white Gaussian background noise and the noise due to the occurrences of
sunspots. We show that in both simulation and analytical expression, the folded
transit reduces the effective noise by a factor of 1/sqrt(2). This reduction
and the doubling of the signal enables (1) less number of transit measurements
to get a definitive transiting planet signal and (2) detection of smaller
planetary radii with the usual transit with the same number of transit data.
Furthermore, we show that in the presence of multiple sunspots, the estimation
of planetary parameters is more accurate. While our calculations may be very
simple, it covers the basic concept of planetary transits.
