χ2time-frequency discriminator for gravitational wave detection

Searches for known waveforms in gravitational wave detector data are often done using matched filtering. When used on real instrumental data, matched filtering often does not perform as well as might be expected, because nonstationary and non-Gaussian detector noise produces large spurious filter outputs (events). This paper describes a ${\chi }^2$ time-frequency test which is one way to discriminate such spurious events from the events that would be produced by genuine signals. The method works well only for broadband signals. The case where the filter-template does not exactly match the signal waveform is also considered, and upper bounds are found for the expected value of ${\chi }^2$.