CrossCorr Resampling: integrates the resampling code used in the F-statistic into the CrossCorr_v2 search pipeline
F-stat resampling code, using an API written by Reinhard Prix and already merged into master, converts input data into the binary system reference frame, removing the need to barycenter Short Fourier Transform (SFT) frequency bins into both the solar system frame and the binary orbital frame. Because the resampled data is constant-frequency, the cross-correlation method written in master by John Whelan and Yuanhao Zhang is modified.
The rho-statistic is redefined in terms of the Fourier transforms of antenna-function-weighted timeseries. Sinc-interpolation is replaced with zero-padded integration. Durations Tshort and Tcoh specify the padding. Because Tlag (the user argument '--maxLag') already specifies the cross-correlation coherence time-scale, these durations have optimal values. These optimal integration times are chosen by default when '--resamp' is requested by the user. A 'test' set of functions is provided, with associated input arguments, to validate the consistency of the pipeline under all regimes. When '--resamp' is NOT specified, functionality has been tested to be identical to the pipeline as used in the O1 Scorpius X-1 search.
In general, resampling provides an advantage over the previous 'demod' search for long coherence times, O(1000 s) and above. C code in final form 2017-10-04. The performance and timing model of this resampled CrossCorr code are detailed in Meadors, Krishnan, Papa, Whelan, and Zhang, 'Resampling to accelerate cross-correlation searches for continuous gravitational waves from binary systems', Physical Review D 97, 044017 (published 12 February 2018) [DOI: 10.1103/PhysRevD.97.044017] [DCC-P1600327] [arXiv:1712.06515].
Grant David Meadors, 02018-09-20 (JD 2458381).
API Changes and Justification
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Backwards Incompatible Changes
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