Research Of Acquisition Technology In Multi‐mode GNSS Receiver

Global Navigation Satellite System(GNSS), is composed of the satellite navigation systems from a number of countries, such as the United States, Russia, the European Union, China and other countries.Currently GNSS has penetrated the fields of defense, industry, transportation, urban construction, agriculture and so on, and it plays an extremely important role, Therefore it has received more and more attention of domestic enterprises, universities and institutes. For receiving satellite navigation positioning signals accurately and interpret navigation message, acquisition technology has become the key technology of the user terminal.This paper focuses on the working principle and acquisition algorithms of acquisition module in user terminal. This paper also separately does the simulation experiment of time domain serial acquisition algorithm, parallel frequency acquisition algorithm, and parallel code phase acquisition algorithm in Matlab software platform. Through the analysis of simulation results, this paper finds out that there are two issues in the traditional acquisition algorithm, namely the large amount of computation and low accuracy of carrier frequency. Aimed at the large amount of computation, this paper do improvement based on the parallel code phase acquisition algorithm, process the baseband signal of stripping carrier wave based on reducing sampling. This method can reduce the number of points involved in the Fourier transform and maintain the pseudo-random code correlation properties, so as to reduce the amount of computation and complexity; Aimed at the low accuracy of carrier frequency, this paper has carried on the elaboration to the results of carrier frequency, a long period of time the input signal was despread according to the results of code phase, carrier frequency are obtained by Fourier transform. This paper carries out simulation experiments for these two methods in Matlab software platform, the simulation result verifies improved parallel code phase acquisition algorithm, reduces amount of computation and refines the carrier frequency in the case of ensuring that the accuracy of the code phase could meet the demands of tracking loop, so as to achieve the purpose to reduce the average capture time and improve the accuracy of the carrier frequency.