Research On Direct Position Determination Technology Of Frequency Hopping Signal

Location-based Services(LBS)is widely used in production and life,therefore positioning technology has become a hot topic in the research.The traditional positioning method,which first estimates the parameters of the collected data and then calculates the target position according to the specific geometric relationship,inevitably results in the loss of information,which leads to the limitation of improvement of positioning error accuracy,especially in the low SNR environment.Direct position determination technology which can realize the positioning by using the collected information without data association can make up this disadvantage.And direct position determination technology has been proven to have obvious advantages in a variety of systems.However,there are few types of research on direct position determination technology of frequency hopping signals.Because of this,this thesis will systematically research the direct position determination technology of frequency hopping signals.The main research work of this thesis is listed as follows:Firstly,the research status of the passive location of frequency hopping signals and direct position determination is summarized by searching and reading-related domestic and foreign literature.The passive location of frequency hopping signals mainly focuses on the estimation and location of frequency hopping signal parameters and the sorting of frequency hopping network station.Direct position determination mainly focuses on time difference estimation and direction finding based on space spectrum estimation,and with the improvement of computer computing power,direct position determination which as a better positioning method began to penetrate various systems.Secondly,the existing direct position determination algorithm researches are analyzed,and the narrow-band TOA direct position determination algorithm is established.The simulation of frequency hopping signals is carried out to analyze the time-frequency characteristics of frequency hopping signals.And the variation on the positioning error between direct position determination and traditional positioning is compared with the change of SNR,and the influence of grid division of positioning performance is analyzed.The simulations show that the positioning performance of direct position determination is better than that of traditional positioning in the low SNR environment.Thirdly,the model of frequency hopping signal is studied,and the direct position determination model of frequency hopping signal TDOA estimated is established based on the time-frequency characteristics of frequency hopping signals.Under the assumption of gaussian white noise,the time difference direct position determination algorithm of single frequency hopping signal is studied from the two directions of maximum likelihood estimate and least square estimate.And the theoretical analysis of their consistency under the gaussian white noise is given.In order to solve the problem of large computation cost of maximum likelihood direct position determination,the maximum correlation cumulative direct position determination based on complex ambiguity function is introduced.And then the CRLB expression of the TDOA direct position determination of the frequency hopping signal is analyzed.Simulation and analysis of the direct position determination cost function search principle.The TDOA direct position determination performance of frequency hopping signal and the influence of base station’s layout and number on the positioning performance are compared and analyzed.The direct location of frequency hopping signal TDOA is realized.Then,a DOA-based direct position determination model of frequency hopping signal is established in the synchronous observation environment,which based on the characteristics of frequency hopping signal,and the single-target and multi-target direct position determination algorithms for frequency hopping signals are studied respectively.For single target,CBF direct position determination algorithm and MVM direct position determination algorithm are analyzed and derived.The MUSIC direct location algorithm expression is derived from multi-target environment.The direct location of multiple frequency hopping signals is realized.In the end,the research contents of this thesis are sorted out and summarized,and some suggestions for the follow-up research are given.