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General Global Navigation Satellite System (GNSS) receiver is an equipment for the process of signal acquisition, tracking and positioning using signals from GNSS satellites to the ground user. GNSS receiver is mainly composed of RF front-end, Correlator, and Navigation. RF front-end processes the signals from satellite, Correlator does digital processing using intermediate frequency, and Navigation functions include acquisition, tracking, and positioning algorithms.
Ordinary GNSS receiver is hardware based, meaning that RF front-end and Correlator are hardware-based. And navigation algorithms are performed using processor setting on the receiver. In Software Receiver (or Software Defined Radio), however, all processes after RF front-end including correlator and navigation are executed by processor.
Fig. 1 Hardware Receiver and Software Receiver
Our laboratory's works include both Hardware and Software receivers, which are mainly manufactured in laboratory by ourselves. For H/W receiver, PCB design and manufacturing, and algorithm implementation using FPGA have been researched, and software based GPS/Galileo receivers are implemented using MATLAB, Labview and C++.
The future GNSS environments are not only based on GPS but also modernize GPS (include L1C, L5..), Galileo, GLONASS, and COMPASS. Therefore, researches using various GNSSs are widely progressed all over the world. Our laboratory also makes efforts on studying for new kinds of GNSS technologies.
Specific topics of GNSS technologies in our laboratory are rapid signal acquisition method, implementation of robust signal tracking, multi-path process, vector tracking loop, attitude determination, pseudolites, and GPS/Galileo integration.
Various papers based on GNSS technologies are presented in Institute Of Navigation conferences, and also published in Journals. And there are a number of patents which are registered.
Below figures are about receivers and their operations.
Fig. 2. Hardware Receiver (PCB manufacturing)
Fig. 3. FPGA-based Hardware Receiver (manufactured by TELACE Inc.)
Fig. 4. C++ based Software Receiver
Fig. 5. MATLAB based Software Receiver
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