The signal processing chain of the Low Frequency Aperture Array

The SKA LOW telescope is an interferometer composed of 512 stations. Each station consists of 256 electronically steered antennas. The Low Frequency Aperture Array is the portion of the SKA-LOW telescope including the antennas and the related electronics. The LFAA signal processing chain amplifies, transports and combines the signals from the antennas composing each station into a coherent beam. Beamforming is performed in the frequency domain, with stringent requirements on bandpass flatness, linearity in a RFI contaminated spectral region, and allowed signal degradation. We adopted an architecture including a highly optimized oversampled polyphase filterbank for channelization, and a distributed network beamformer. The system has been validated as part of the Aperture Array Verification System, a single station operating at the SKA site in Western Australia.