A GNSS Software Receiver for Governmental Applications

R. Capua and A. Bottaro

Abstract:	The paper presents the work of the Sogei GNSS R&D Group for the development of a GNSS SDR receiver for institutional applications. Target applications are high accuracy GNSS Surveying for Land Registry, Customs Border Control and Tracing and Tracking. The objective of the project is to build a Real-Time GNSS SDR receiver running on a Notebook, based on COTS and internal developed source code. The GNSS SDR receiver is composed by an RF Front-End and four software modules: Data Dispatcher, Acquisition, Tracking and PVT. The Software has been written in C++, using SIMD primitives. Communication is performed through TCP/IP sockets. Look-Up tables are used for Code and Carrier replicas and logic operations. The RF Front-End was developed using a reconfigurable commercial IC sampler and is connected to the Notebook through USB. IF is 1.023 MHz and undersampling is performed at 4.092 MHz. A Data Dispatcher spools samples to the processing modules. The Parallel Search Acquisition provides results in about 300 ms for 32 GPS and 4 SBAS channels, using FFT and zero-padding. Code matching ambiguities are avoided. Tracking loop works on bit-parallelized samples through a second order PLL and a first order FLL. Correlation is performed using logical tables, while a Dot product DLL discriminator is used. The Tracking processes 1s of samples in less than 50 ms per channel. PVT is implemented through an Extended Kalman Filter and outputs NMEA. A DSP GNSS SDR, developed for achieving high performance processing, provides results comparable to the PC platform. At the end of the First Phase of the Project, the GNSS SDR receiver implements Real-Time GPS, GIOVE-A/B and SBAS Acquisition and Tracking, with an accuracy of 5 m. The Second Phase will implement a Multi-Carrier/Multi-Constellation Code/Phase SDR receiver based on Multi-Core programming, including Hybridization with external sensors and indoor positioning capabilities.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	813 - 823
Cite this article:	Capua, R., Bottaro, A., "A GNSS Software Receiver for Governmental Applications," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 813-823.
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