A precorrelation DiLL scheme based on antenna array for GNSS receivers

In this paper, we propose a precorrelation direction lock loop (DiLL) scheme and a new modification factor estimation method for the global navigation satellite system (GNSS) receivers. The proposed scheme executes spatial correlation before code demodulator and does not need to do code demodulation for every antenna element. It can decrease the number of code demodulator to 3 regardless of the array element number while the postcorrelation DiLL scheme requires as many as array elements. Moreover, performance can be improved for immunity of undesired signals, multipath and interference, for example, from other different direction of arrivals compared with the postcorrelation DiLL scheme. The new modification factor estimation method is based on the prompt code branch and estimated angle outputs, which are suitable for reality environments. Theory analysis and simulation results show that two schemes are equivalent when the code tracking loop is working on the ideal tracking state under interference-free environment. The proposed scheme can also be used for DS/CDMA systems.