Conference Presentations by André Løfaldli
The NTNU Test Satellite (NUTS-1) is an educational CubeSat project aiming to launch a student des... more The NTNU Test Satellite (NUTS-1) is an educational CubeSat project aiming to launch a student designed and manufactured satellite. The project is one of three participants in the Nor-wegian CubeSat program ANSAT. The current primary goal is to have an engineering model ready by August of 2016. Communication with the ground segment will be in the VHF and UHF bands, allowing for full duplex transmission. The ground segment will be based upon a Software Defined Radio (SDR) to enable an easier and more flexible configuration. The SDR-platform used is the Ettus Research USRP, supported by a GNU Radio implementation on a computer. The link layer packet protocol implemented in the prototype is NGHam, a link protocol partly inspired by AX.25. In order to improve the link reliability, it features Reed Solomon codes for Forward Error Correction (FEC). This makes the data transmission more robust compared to i.e. AX.25, which does not implement FEC on the link layer directly. The required GNU Radio modules have been designed and implemented. An end-to-end communication between the USRP and the NUTS VHF module has been proved. A ground station based on traditional HAM radio equipment requires several bits of hardware, such as a radio, TNC or third part modems in order to enable packet transmission. By replacing this with a SDR setup the ground station will be more flexible; it will be easier to receive data from different satellites that might be using different link protocols and message formats. Utilising open source software, such as GNU Radio, gives radio amateurs around the world the opportunity to receive data from NUTS using cheap SDR hardware such as the RTLSDR USB dongles. Finally, as an SDR system can support a wide range of frequency bands, it will be easy for other project groups to implement support for their satellite mission using such an SDR based system. Support for other link protocols can easily be implemented. Messages received from the satellite(s) can easily be made available online.
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Conference Presentations by André Løfaldli