VLBI reception system
The 9 metre antenna is used both for geodetic VLBI measurements and for satellite data reception. For the former, the signal path is diverted directly from the feed to the VLBI reception system, which can process signals in S-band (2.1 – 2.4 GHz) and X-band (8.1 – 8.9 GHz). The extremely weak signals coming from extragalactic radio sources are first boosted in low-noise amplifiers that have been cooled down to 20 Kelvin, then downmixed to intermediate frequencies from 100-500 MHz and forwarded to the data recording system. The reception system was completely reworked and modernized in 2013 and 2014 so that from 2015 high-quality data could again be generated.
During a 24 hour VLBI experiment about 1 TB of data are recorded and then transported on hard disks from O'Higgins to a correlator at the Max Planck Institute for Radio Astronomy in Bonn. There, the transit time differences are ascertained – the foundation for measuring the distance between different radio telescopes.
