Reaching for the STARx A Software-Defined All-GNSS Solution

J A N U A R Y / F E B R U A R Y 2 0 1 4 www.insidegnss.com GNSS modernization includes not only the global coverage capabilities of GPS, GLONASS, Galileo, and BeiDou, but also regional GNSS enhancement systems such as Japan’s Quasi-Zenith Satellite System (QZSS), the Indian Regional Navigation Satellite System (IRNSS), and the European Geostationary Navigation Overlay Service (EGNOS). GNSS systems transmit a variety of signals on different frequencies as allocated by the International Telecommunication Union (ITU). Moreover, new signal processing methods for these signals are continuously emerging. Both the actual performance of signals and their processing methods need to be evaluated and confirmed. During the evolutionary period of several of the GNSSs, some of the transmitted signals may be changed during construction, ground operation, and maintenance, evaluation, and testing. Thus, the need arises to ensure the ability to monitor, evaluate, and modify a diverse set of signals and/or processing algorithms. The major objective of Tsinghua University’s Software-defined Tunable All-GNSS Receiver (STARx) project is to support a new generation of GNSS signal processing capabilities. STARx could be used to optimize system design and algorithm development, including design activities such as signal performance analysis and comparison, processing algorithms development, multisystem concurrent processing, field test, and signal quality monitoring. Because STARx will need to be able to handle evolving signal design and processing algorithms, it must have a f lexible and scalable architecture to facilitate easy integration, replacement, and updating of processing algorithms. The more challenging requirement for STARx is to simultaneously receive all civil signals from the existing and emerging GNSSs in order to support multi-system joint processing research and performance evaluation. Additionally, all of the pertinent intermediate results in the signal processing need to be outputted, displayed, and stored in real-time. Traditional GNSS receiver architectures that have a high integration density cannot meet the requirement of adaptability and flexibility that would facilitate multi-GNSS signal processing. However, the recent advent of software defined radios (SDRs) offers a great level of flexibility in data processing as well as a low-cost of implementation, requirReaching for the STARx A Software-Defined All-GNSS Solution