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Abstract: |
Currently trends towards GNSS receivers require that the receivers need to be compatible with multi GNSS systems, like GPS/GLONASS/BD2(which is developed by China) or Galileo. Accuracy, reliability, integrity, and usability of the receiver can be improved by using the multi GNSS solution. The multi GNSS receiver will replace the single GPS receiver in many applications in the future. In this paper, we introduced a module-based multi GNSS baseband chip design structure and its implementation. Two GNSS baseband chips, the “NavCore-S” and the “OTrack-32”, have been produced successfully based on this structure by OlinkStar cooperation, Ltd. The NavCore-S baseband chip is a single GNSS baseband processor and the OTrack-32 is a Multi-GNSS baseband processor, the OTrack-32 can process BD2/GPS and GLONASS signals concurrently while the NavCore-S can switch to process one of them by configuration. In this paper, the most updated acquisition and tracking structure of GNSS baseband processor is introduced at first. And implementation in ASIC is also presented. This efficient structure can acquire several satellites quickly and track them reliably. By using the innovative circuit architecture design in the ASIC, power consumption and die size are greatly reduced. And power and cost requirement can be satisfied for mass products. There are more than 140,000 equivalent correlators implemented in the acquisition block and up to 32 tracking channels in the tracking block, both of them are parameterized and can be upgraded easily. In the end, the complete performance comparison between our receivers based on the two chips and same kind of foreign receivers is presented. As the result, all the performance of our receivers is as good as other receivers developed by some famous GNSS companies, including start time, sensitivity, power, dynamics, and so on.
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