### phase dispersion minimization

**(PDM)**
(particular method of finding periodic components in signal)

**Phase dispersion minimization** (**PDM**)
is a time series analysis mathematical technique
used astronomy for finding periodically repeating
components of a signal, especially measurements made over time
such as those of light curves.
PDM is a particular method used in **data folding**, a means of
dealing with time-series data in which each measurement has some
source(s) of randomness that obscures any pattern (such as variations
in the instrument's sensitivity).

The Fourier transform can also be used for finding repeating
components but it is best suited to signals collected periodically
rather than with varying time gaps.

*Data folding* consists of trying out a possible period by mapping
the data from an absolute time to phases of the proposed period,
then evaluating it for plausibility.
PDM is a formula to assign a score to such a trial, so candidate
periods can be compared. PDM also allows the such a candidate
period to be compared with the presumption that the signal
is random and has no period.

(*mathematics,method*)
**Further reading:**

http://en.wikipedia.org/wiki/Phase_dispersion_minimization

https://hea-www.harvard.edu/~swolk/thesis/period/node2.html

http://www.britastro.org/vss/BAA%20VSS%20Star%20Meeting.htm

**Referenced by pages:**

data folding

Index