  Dead time is a common instrumental effect of X-ray detectors which would
alter the behavior of timing properties of astronomical signals, such as
distorting the shape of power density spectra (PDS), affecting the
root-mean-square of potential quasi-periodic oscillation signals, etc. We
revisit the effects of the dead time of Medium Energy X-ray telescope (ME)
onboard Insight-HXMT, based on the simulation of electronic read-out mechanism
that causes the dead time, and the real data. We investigate dead time effects
on the pulse profile as well as the Quasi-Periodic Oscillation (QPO) signals.
The dead time coefficient suggests a linear correlation with the observed count
rate in each phase bin of the pulse profile according to the simulation of
periodic signal as well as the real data observed on Swift J0243.6+6124. The
Fourier-amplitude-difference (FAD) method could well recover the intrinsic
shape of the observed PDS in the case that the PDS is from two identical
detectors. We apply this technique on ME, by splitting the 9 FPGA modules into
2 groups. The results indicate that the FAD technique suits the case when two
groups of detectors are not largely different; and the recovered PDS of Sco X-1
observed by ME slightly enhances the significance of the previously known QPO
signal, meanwhile the root-mean-square of QPO is significantly improved. We
provide the FAD correction tool implemented in HXMTDAS for users in the future
to better analyze QPO signals.
