  Double white dwarfs could be important sources for space based gravitational
wave detectors like OMEGA and LISA. We use population synthesis to predict the
current population of double white dwarfs in the Galaxy and the gravitational
waves produced by this population. We simulate a detailed power spectrum for an
observation with an integration time of 10^6 s. At frequencies below ~3 mHz
confusion limited noise dominates. At higher frequencies a few thousand double
white dwarfs are resolved individually. Including compact binaries containing
neutron stars and black holes in our calculations yields a further few hundred
resolved binaries and some tens which can be detected above the double white
dwarf noise at low frequencies. We find that binaries in which one white dwarf
transfers matter to another white dwarf are rare, and thus unimportant for
gravitational wave detectors. We discuss the uncertainties and compare our
results with other authors.
