  We present experimental studies of the power spectrum and other fluctuation
properties in the spectra of microwave networks simulating chaotic quantum
graphs with violated time reversal in- variance. On the basis of our data sets
we demonstrate that the power spectrum in combination with other long-range and
also short-range spectral fluctuations provides a powerful tool for the
identification of the symmetries and the determination of the fraction of
missing levels. Such a pro- cedure is indispensable for the evaluation of the
fluctuation properties in the spectra of real physical systems like, e.g.,
nuclei or molecules, where one has to deal with the problem of missing levels.
