  A new digital backend has been developed for the BEST-2 array at
Radiotelescopi di Medicina, INAF-IRA, Italy which allows concurrent operation
of an FX correlator, and a direct-imaging correlator and beamformer. This
backend serves as a platform for testing some of the spatial Fourier transform
concepts which have been proposed for use in computing correlations on
regularly gridded arrays. While spatial Fourier transform-based beamformers
have been implemented previously, this is to our knowledge, the first time a
direct-imaging correlator has been deployed on a radio astronomy array.
Concurrent observations with the FX and direct-imaging correlator allows for
direct comparison between the two architectures. Additionally, we show the
potential of the direct-imaging correlator for time-domain astronomy, by
passing a subset of beams though a pulsar and transient detection pipeline.
These results provide a timely verification for spatial Fourier transform-based
instruments that are currently in commissioning. These instruments aim to
detect highly-redshifted hydrogen from the Epoch of Reionization and/or to
perform widefield surveys for time-domain studies of the radio sky. We
experimentally show the direct-imaging correlator architecture to be a viable
solution for correlation and beamforming.
