SoftGNSS 2 - A Dual Frequency Software-based GNSS Receiver
Within the last decade, a significant trend towards the development of software-based Global Navigation Satellite System (GNSS) receivers has evolved, because since that time, the necessary computation power has been available. Software- based GNSS receivers are highly flexible concerning the adaptation to several applications. They serve as a development platform investigating new algorithms and techniques and have the advantage of only few necessary hardware parts. Thus, a small overall size is achievable and hence makes it easy to implement those receivers into mobile devices, e.g. cell phones. Due to the flexible architecture they can be easily integrated into those devices with other sensors for the purpose of position determination and are therefore excellently applicable to a wide range of applications.
The main focus of current developments is the single frequency approach, aiming at mass market applications. However, the resulting position accuracy is not sufficient for many applications. Nowadays the automotive domain or security relevant applications for example strongly demand a higher position accuracy (≤ 1m).
Beside the errors introduced by the satellites (orbit, clock, etc.), the troposphere and the receiver clock, the ionosphere is one of the biggest error sources. Adding a second measurement, using a different carrier frequency, the error due to the ionosphere can be eliminated. Furthermore, integrity can be increased, which is inevitable for a wide range of applications as well.
To fulfil the mentioned accuracy requirements within the project SoftGNSS 2, a software-based dual frequency GNSS receiver has been developed.
In a first step the receiver is only capable of processing GPS code measurements but makes use of both currently available civilian signals. The second civilian signal L2C, available on the second carrier frequency L2, is under construction at the moment, but eight satellites already transmit this signal. For the future, the adaptation to other GNSS, especially Galileo, has been planned and thus availability and position accuracy can be further increased.
TeleConsult Austria GmbH - Philipp Berglez
- Graz University of Technology, Signal Processing and Speech Communication Laboratory - Christian Vogel
- Graz University of Technology, Institute of Navigation and Satellite Geodesy - Christoph Abart