Research And Implementation On Technique Of High Accuracy Signal Delay Simulation

In order to support the research, development and construction of the navigation system, various relevant research institutes in our country have established navigation signal simulation systems which are independent of each other. However, owing to these simulation systems’ incomplete functions and limited application scope, its performance cannot meet the needs of the system testing verification, and it cannot function as the advanced verification of the system and performance and fresh technique testing verification. The factors aforementioned lead to the current satellite navigation signal simulation systems in our country failing to satisfy demand for global navigation system testing verification. And overseas channel simulator is not only expensive but its safety is not guaranteed as well. So there is a need for us to develop our own channel simulator with high performance through self-innovation. Technique of High Accuracy and Huge Range Signal Delay Simulation is at the core of satellite signal channel simulation. Currently, very few channel simulators on the market can reach the delay accuracy of 0.01 ns, which has profound significance to investigate the Technique of High Accuracy and Huge Range Signal Delay Simulation building the channel simulation system of our own.The paper concentrates on the following aspects studying Technique of High Accuracy and Huge Range Signal Delay Simulation.Firstly, the paper introduces two models of high accuracy delay and analyzes the design and performance of the filters in the models when facing the request of high accuracy. When design interpolated filter, a new method which can reduce the length of the filter and simplify the structure was proposed. In the new method, a low accuracy filter is designed first, and then the coefficients of the filter are interpolated to get new coefficients to improve the accuracy. This method increases the accuracy to 0.01 ns and provides an algorithm for low order filters.Secondly, after comparing the two methods, the paper designs the physical structure of the two Algorithms, optimizes the interpolated filter by using pipeline structure, decreasing the amount of calculation to from 8000 to 60 and improving the utilization of multipliers. In order to reduce the cost of multiplier further, the paper optimizes variable delay filter by using Farrow structure. This design reduces the usage of multiplier from 60 to 30, and decouples the output and the coefficients of the filter. The output is only controlled by the delay and the accuracy can be increased to 0.01 ns.At last, the paper validates the filter in laboratory, feasibility and superiority have been verified by means of simulation. However, the accuracy of pseudo-range cannot be validated due to the restriction of signal receiver.