Arcetri Technical Report 2/2015
SKA Project Series
LFAA Tile Beamformer structure
G. Comoretto, C.Belli
INAF Osservatorio Astrofisico di Arcetri
Abstract
The LFAA tile processing modules (TPM) combine the signals from 256 dual-polarization antennas, in the frequency range 50-350 MHz, into a single station beam. Beamforming is done hyerachically, with the TPM first combining the 16 antennas that are processed in the module, using the Tile Beamformer described here, and then combining these partial beams into the station beam, using a daisy chain structure.
The Tile Beamformer receives antenna samples already channelized, with a channel spacing of 750 KHz, and align each antenna in the frequency domain using a phasor computed in real time from delay and delay rate informations. It is possible to select up to 16 idependent portions of the input frequency range, each one pointing in a different direction.
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