Research On Channel Characteristic Emulating For Navigation Satellite Channel Emulator

Navigation satellite channel emulator can emulate the real environment transmission characteristics for satellite signal, to restore the space environment transmission dynamic changes of satellite signal, support the wired test between real satellite payload and receiver. Based on spread spectrum ranging, satellite navigation system achieves positioning, channel group delay characteristics directly affect the ranging accuracy, and is the key point of navigation satellite channel simulator research. Under this background, this paper focus on channel delay characteristics model and channel delay characteristics emulating, researched the following five aspects:This paper established the channel delay characteristics emulating model, established the complete signal transmission model. Through spread spectrum signal pseudo-orange measurements, proposed delay emulation accuracy measurement method, analysis the associated interval and the code rate.Traditional group delay optimal design methods can not meet the high precision, low complexity and fast convergence. The simulation analysis conclusion shows, channel group delay fluctuation is less than 0.8ns can meet the accuracy 0.1ns of channel delay emulating. In order to meet the design requirements of high precision, low complexity and fast convergence, this paper proposed the group delay optimization algorithm by combine the analog and digital domains, including the analog domain iterative step by step improvement optimization algorithm, digital domain maximum error minimization improvement algorithm, digital domain combined parameter optimization selection algorithm. The simulation results show that, the analog domain implementation complexity of improved algorithm is reduced by 43% when compared with the traditional algorithm, the digital domain convergence speed of improved algorithm is improved 7 times when compared with the traditional algorithm. The test results show that group delay error of optimal implementation is less than 0.7ns.For the dynamic continuous ionosphere channel dispersive delay characteristics, traditional methods can not meet the ionosphere TEC precision approach, and can not meet ionosphere model simplified and approximate for the limited accuracy loss and model equivalent decomposition for Easy-to-analog implementation. Analyze the demand of ionosphere channel real-time dynamic emulation, proposed the space-time domain combined for ionosphere TEC Kriging interpolation method. Then proposed that group delay dispersion characteristics separation and linear equivalent, phase delay dispersion characteristics equivalent carrier center frequency constant, ionosphere TEC discretely equivalent restrained by the carrier tracking error and time delay estimation error. The simulation results show that, compared with the traditional method, the error of this new model is reduced by 93%, emulated ionosphere channel dispersion group delay measurement results show that the implementation error is less than 3ns, navigation signal code correlation delay estimation bias effect is less than 0.1ns, the carrier tracking deviation is less than 0.01 rad.Aiming at the emulation of the dynamic continuous multipath channel delay characteristics, required to achieve a wide range of inter-signal delay, faster delay adjustment and increasing signal number, the traditional method is facing enormous consumption of resources, delay filter order is too high and the excessive dynamic parameter update. This paper analyze the delay range expansion between the multipath signal, established the multipath channel parallel delay model which meets the navigation satellite channel simulator multipath channel. With the constraint of low resource consumption, low parameter update and quick response, proposed the multiple level parallel multiplexing algorithm. The simulation results show that, compared with the method of traditional multipath shunt direct design and the method of multipath transmission function joint design, the delay range of multipath signals can be extended to multiple code width, the number of multipath signals can be extended. Algorithm resource consumption is hardly affected by delay range expansion or multipath number expansion. The resource consumption is only the 1/L times(L is the numbers of multipath channels), multipath channel delay characteristics parameters update quantity is only about 10%, when compared with the traditional algorithm.Navigation channel simulator in domestic research is still in its infancy, the field of foreign navigation related products embargo in China is still in the state. For navigation satellite channel simulator design and implementation, planned the system architecture and signal flow, designed an integrated hardware platform and mathematical simulation software platform, completed the system design and implementation, carried out the relevant tests to verify the test.Finally, we summarize the research contents, introduction the application fields of the research, and prospect the next step work. The research results of the paper have been applied in ground test verification system core equipment of China autonomous satellite navigation system.