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Work on the Aperture Array Verification System (AAVS) in Australia and
Italy has focussed on the deployment, simulation, measurement,
calibration and commissioning of prototype low-frequency stations.
AAVS0.5, deployed circa 2014, was an array of 16 log-periodic dipole "SKALA" antennas.
AAVS1.0, completed in 2018, deployed 256 SKALA2.0 antennas.
AAVS1.5, initially deployed 48 SKALA4.1 antennas (as pictured above) in 2019, and this was
later expanded with an additional 208 antennas to form a full tile of
256 antennas for AAVS2.0.
In AAVS2.0, each antenna has a Low Noise
Amplifier (LNA) located at the top of the antenna. Signals from
the LNA are carried through coaxial cables (one per
polarization) to a SMART (Small Modular Aggregation and RFoF Trunk,
where RFoF stands for Radio Frequency over Fibre)
Box, where the corresponding Front-End Module (FEM) is located. Each
FEM contains an RF amplifier and RF-to-optical transducer which
amplitude-modulates and transmits the two RF signals onto optical
fibres. Each SMART Box supports a "tile" of 16
antennas, so 16 SMART Boxes are needed to handle all 256 antennas.
The AAVS arrays have
allowed the consortium to validate key enabling technologies and
performance requirements, gather production knowledge, test interfaces
and assess prototypes in a realistic operating environment.
(Image credit: ICRAR)
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