The Research Of GPS Weak Signal Acquisition Technology

With the number of urban construction growing and the gradually improvement of userlocation requirements, acquisition technology research under the environment of weak signalhas played a very important role.This paper launched research to this topic, the main contentbrief description of the paper are as follows:First of all, modernization GPS signals’ peculiarity is analyzed in the article, at the sametime a high sensitivity acquisition algorithm is proposed based on single GPS L1C/A code,based on BIT correction technology as well as the superposition of data pretreatmenttechnology, this paper puts forward a algorithm using a long integration time can effectivelyrestrain the navigation data under the condition of transition, at the same time reduce thecapture computational complexity, the algorithm theoretical analysis results show that underthe conditions the input SNR of-29dB, integration time when selecting20ms, false-alarmprobabilityPf a10-3,detection probability can achieve Pd0.99,comparing with the delaymultiplication algorithm, signal compression algorithm, non-coherent capture algorithm, FFTparallel code search algorithm respectively, the computational complexity proportion of themare26.1%,21.4%,10.5%,8.07%, therefore the new algorithm has great advantage.Secondly, combined the resources from the same satellite to improve the sensitivity ofthe algorithm is studied, in this paper, GPS L1C/A code signal and L2CM code signalcombined capture technology is studied, using the double combined generalized differenceacquisition technology to improve the single code sensitivity, solve the data bits jumpproblem due to the cyclic of satellite navigation data.On the basis of traditional technology atthe same time introduced the multiplicative measurement methods, used to improve thedouble code combined satellite signal acquisition correlation detection ratio of the first mainpeak and the second peak, and also improve the detection probability, to make it more suitableto achieve a normal positioning under weak environment. The experimental results show thatthis technology improves the sensitivity of3dB than single frequency technology, at the sametime, the improved algorithm when under the condition of the input SNR is-24dB, existingnavigation data jump, it can captured signal successfully, the ratio of the first main peak andthe second peak is5.23, increased by4.25times than the traditional algorithm.At last, the focus is on utilizing the single channel to achieve combined acquisitionmethod from the different frequency but the same satellite. In view of the dual-frequencysignal acquisition, different doppler residual will lead to the distortion or fission problem ofcomposite SINC function, this paper proposes a combined GPS dual-frequency signal capture algorithm with single channel. The algorithm makes good use of correction factor weightedlocal carrier frequency offset generator of two-frequency signal carrier, and then use localcomplex code to finish PRN code stripping, to repair compound SINC function into unimodal.The performance results show that the improved algorithm is better than traditional combinedcapture algorithm for saving80%operation time. In the premise that input SNRselects-27dB,chooses false alarm probabilityP-3f a10,the detection probability of theimproved algorithms is90.29%,and the detection probability of traditional combined capturealgorithm is37.19%, so the improved capture algorithm has a great significance in combinedprocessing technology.