The junior researcher of the GRC-UPM group, David Dima, recently has successfully defended his final Bachelor thesis in the School of Telecommunication Systems Engineering at UPM. His work has lead to the design and implementation of an architecture to receive and register the Galileo E1 (1575.42 MHz), E5-a (1176.45 MHz) and E5-b (1207.14 MHz) IQ baseband signals in real time.
The system in operation consists on a three-band active antenna placed on the roof of the School, a feeder to connect to an indoor unit with a bias-tee as a first stage, a power splitter as a second stage, and a commercial dual-channel Software-Defined Radio (SDR) with a maximum bandwidth of 56 MHz as a third stage. The output of the SDR is injected to a Workstation, equipped with a CPU Intel i9-12900, through a USB 3.0 connection and processed by a software specifically developed in GNU-Radio, running under an Ubuntu Linux operative system.
This Galileo GNSS station operates for 24 hours-a-day in an autonomous way, having the possibility to be self-recovered in the event of a network failure or a power outage. The output IQ samples of the baseband Galileo signal are all saved in binary files duly compressed to make the most of the storage drive unit installed in the Workstation.
IQ data so obtained can be remotely accessed via Internet through a Secure File Transfer Protocol (SFTP) access. This information will be employed for researching purposes on preventing GNSS spoofing attacks, for supporting GNSS academic activities in-class, and for detecting abnormal situations of the Galileo signal received in this university campus of Madrid.
This thesis was co-supervised by Prof. Antonio Pérez Yuste from UPM and by the PhD candidate Francisco Gallardo López from DLR-GfR, both active members of the GRC-UPM research group.