RT Conference Proceedings
T1 A direct sampling digital receiver for multiple GNSS signals
A1 Alonso, Asier
A1 Perre, Jean Michel
A1 Arizaga, Iñigo
AB The recent proliferation of different GNSS signals (GPS L2 & L5, Galileo, Glonass, etc.) offers new possibilities for designers, multiple constellations broadcasting interoperable open signals will result in improved geometry, increasing end user accuracy everywhere and improving service availability in environments where satellite visibility is often obscured. Receivers have to be adapted to be able to cope with different signals, but this may imply an increase of hardware elements. Using a SDR approach, the aim of this paper is to reduce the number of hardware components exploring the feasibility of a direct digitization wearable device, which can deal with different standards, concretely (GPS L1, L2 civilian signal & L5, and Galileo E5a, E5b, E6 & L1). A special digital signal processing had to be designed in order to employ a single front end for all the different frequency bands. Position awareness is fundamental for many pervasive computing applications. In an ubiquitous paradigm, mobile devices should know their location without the user telling them specifically and their behaviour may depend on where they are. Traditionally there have been different positioning techniques, concretely Global Navigation Satellite Systems (GNSS) systems, whose main representative is GPS L1, have been employed since more than twenty years. In recent years, the development of alternative GNSS signals, has open the way for advanced applications. The main advantage of this proliferation of standards, is the possibility of combining their capabilities, in order to obtain maximum coverage, creating a universal GNSS receiver. But there is an obvious inconvenient: such a device would require twice or three times more hardware than current GPS receivers, increasing considerably its size and reducing its flexibility. Software Defined Radio (SDR) is a technology which ideally aims to suppress all hardware elements in a radio receiver and replace them with software configurable elements such as FPGA's or DSP's. Due to GNSS low power signals, this is not feasible without RF amplification & filtering, and traditionally, an analog front-end has been used to move the signal from RF frequencies to one or two intermediate frequencies. The development of faster converters (up to 1Gsps) as well as high quality RF filters makes possible to suppress part of the analog system and bring the digital interface nearer to the aerial. The aim of this paper, is to present a Galileo-GPS receiver from the SDR point of view. The main problem of a conventional SDR receiver is that it requires an analog front-end and as the GNSS systems work in different bands, at least two RF channels are required for high accuracy receivers. In order to avoid this duplication of hardware a direct digitization approach will be used. The main idea is to choice an appropriate sampling frequency and signal processing algorithm, which will reduce the required input bandwidth to 50 MHz, so a single wideband front end will be required in order to condition GNSS signals. An specific digital signal processing is needed in order to separate and correctly acquire each different signal. In order to test the feasibility of such a receiver, different noisy signals will be used, also outband and inband jammering signals will be employed to test the tracking ability of the device in real conditions.
YR 2008
FD 2008-03-20
LK https://hdl.handle.net/11556/4705
UL https://hdl.handle.net/11556/4705
LA eng
NO Alonso , A , Perre , J M & Arizaga , I 2008 , ' A direct sampling digital receiver for multiple GNSS signals ' , Paper presented at European Navigation Conference, ENC-GNSS 2008 , Toulouse , France , 23/04/08 - 25/04/08 .
NO conference
DS TECNALIA Publications
RD 31 jul 2024