Resampling technique to correct for the Doppler effect in a search for gravitational waves

The frequency of any gravitational-wave signal received from a spinning neutron star will appear Doppler-shifted by the Earth's rotation and orbital motion. This frequency shift must be compensated to recover the signal energy as a spectral monochromatic peak with a high signal-to-noise ratio. Generally the correction depends on the source's position in the sky, spin, and spin-down rate. Here we propose a method of applying a single correction to the data which is valid for all the emission frequencies at a fixed position in the sky and for a given spin-down rate. We advance or retard the antenna proper time by removing (or repeating) single samples of the digitized output signal to keep the effective receiver and source clocks in accurate synchronization. The method, which requires just a few lines of code and little computational effort, appears to be very effective for "semitargeted" searches, where the source direction is known but the emission frequency is not.