On Friday, January 31st, Michael Truong-Le, an intern working under supervision of IABG's Drs Stadler and Baumann, achieved the tracking of all four Galileo IOV's long enough to decode full almanac and ephemerides data and to get a position fix.
"To support our future GNSS research, our intern Michael Truong-Le was assigned the task of building up an SDR based GNSS workplace ‘on a budget'", reports Dr Stadler.
The equipment didn't however require lots of funds nor resources.
"In terms of hardware we decided on a software defined radio ‘USRP N210’ from National Instruments / Ettus Research.", says Dr Stadler.
"This SDR is equipped with a HF daughter card covering 50-2200 MHz, so it includes the L1 band at 1.5 GHz. Onto the daughter card we connect a consumer level GPS antenna from Navilock.
As this is an active antenna originally intended for car navigation, we had to improvise a bias-tee to supply it with external DC power.
The SDR is connected via LAN to a desktop PC, powered by an Intel Core i7 running under Ubuntu Linux."
"Regarding software we use the generic Ettus UHD driver together with the open source ‘GNU radio library’. This setup provides us with general HF signal processing capacity.
As the actual Galileo receiver we use the open source software package ‘GNSS SDR’ by CTTC. This software packet readily includes receiver functionality for GPS-C/A as well as Galileo-OS."
"Using the GNU radio library, GNSS SDR can work with live HF signals received by the SDR."
"The open source software ‘GPredict’ enabled us to predict the times when all four IOVs are visible over our Ottobrunn lab."
"The antenna was placed on an outside window sill facing our lab’s atrium, which is covered by a inflated plastic roof. We admit, that this antenna location is sub-optimal for satellite reception - but it worked.
Thus, a fully functional Galileo-OS receiver has been put together from free, open source software and rather affordable hardware.
The buildup of this versatile SDR-based GNSS workplace, which can host e.g. future master theses, supports IABG’s longstanding cooperation with universities and other research facilities."
The whole Galileo team wishes to express its warmest congratulations to the talented young intern, who brilliantly earned this way his virtual QSL card !!!
IABG was founded in 1961 as a central analysis and testing organisation for the aerospace industry and the Ministry of Defence as part of an initiative by the German government. Today, IABG is a leading European technology and science service provider.
IABG mbH has been involved in various national and international Galileo projects – especially related to Galileo’s Public Regulated Service (PRS) – for more than six years.
As a consulting & testing company, IABG’s contribution focusses on the robustness and security of GNSS signals, which, despite their vulnerability to accidental or intentional interference, have gained widespread use even in safety critical applications.
A QSL card is a written confirmation of either a two-way radiocommunication between two amateur radio stations or a one-way reception of a signal from an AM radio, FM radio, television or shortwave broadcasting station. It can also confirm the reception of a two-way radiocommunication by a third party listener (Wikipedia).