Galileo Receiver Core Technologies

The modern satellite navigation system Galileo is developed by European Union. Galileo is a completely civil system that offers various levels of services especially for civil users including service with safety guarantee. Galileo system employs modern signal structure and modern BOC (Binary Offset Carrier) modulation. The Galileo Receiver is investigated in the frame of the GARDA project solved by consortium under leadership of Alenia Spacio – LABEN. The aim of Galileo Receiver Core Technologies subtask is to investigate the key problems of the Galileo receiver development. The Galileo code and carrier tracking subtask of the Galileo Receiver Core Technologies is carried out at the Czech Technical University. The problem was analysed and split to the particular tasks. The aim of this paper is focused on BOC correlator architecture. The correlation function of the BOC modulation is more complex with a plenty of correlation peaks. The delay discriminator characteristic of such signal has several stable nodes, which cause stability problem. The standard solutions of this problem like BOC non-coherent processing, very early – very late correlator and deconvolution correlator are analysed. The new correlator architecture for BOC modulation processing has been developed. The developed correlator has two outputs, one for fine tracking and the second one for correct node detection. The second output is based on comparison of the correlation function envelopes. The simplified method of correlation function envelope calculation is described in this paper. The correlator is planned to be tested in the GRANADA software simulator including a sophisticated method of correlator output combination.