高动态信号高精度模拟技术研究

In order to efficiently help designers to comprehensively and fully validate the positioning and measurement performance of global navigation satellite system (GNSS) and telemetry, tracking, and command (TT&C) system under high-dynamics environments, signal simulation technology is required to be as realistic as possible to simulate the GNSS signal and the TT&C signal in different high-dynamics environments. Because of the difficulty in meeting the requirements of high dynamic, high precision, continuity, and applicability in common technologies, this project studies high-precision simulation technology of high-dynamics signals, and mainly focus on trajectory simulation and dynamic propagation delay simulation. For the problem of trajectory simulation, two trajectory simulation methods based on uniform sampling and nonuniform sampling are investigated; the former studies a spline approximation algorithm with high precision and continuity, which combines the concepts of spline interpolation and least squares fitting; the latter studies an adaptive sampling algorithm and a signal reconstruction algorithm, to solve the problem of poor accuracy of the trajectory simulation under high-dynamics environments. For the problem of dynamic propagation delay simulation, two dynamic propagation delay simulation methods based on the wideband variable fractional delay (VFD) filter and all-pass VFD filter, respectively, are investigated; in terms of finite impulse response filter and infinite impulse response filter respectively, the design algorithms of the VFD filters are studied and the corresponding filter structures are optimized, to improve the bandwidth of simulated signals and reduce the signal distortion caused by the dynamic propagation delay simulation, and therefore the applicability of the signal simulation technology is improved.

为了有效地帮助设计者全面、充分地验证全球卫星导航系统和航天测控系统在高动态场景下的定位和测量性能，要求信号模拟技术能够尽可能真实地模拟不同动态场景下的导航和测控信号。由于常规技术难以满足高动态、高精度、连续性和适用性等各方面需求，本项目将研究高动态信号高精度模拟技术，主要围绕轨迹模拟和动态传输延时模拟展开。针对轨迹模拟问题，研究基于等间隔采样和非等间隔采样的轨迹模拟方法：前者结合样条插值和最小二乘拟合思想，研究一种兼备高精度和连续性的样条近似算法；后者研究一种自适应采样和信号重构算法，解决高动态条件下轨迹模拟精度恶化的问题。对于动态传输延时模拟问题，研究基于宽带和全通可变小数延时（VFD）滤波器的动态传输延时模拟方法：分别基于有限长冲击响应和无限长冲击响应滤波器，研究VFD滤波器设计算法和结构优化，提升可模拟信号带宽并减小动态传输延时模拟引起的信号失真，从而提升信号模拟技术的适用性。

无线信道作为无线电信号的传输媒质，其传输特性对包括航天测控、卫星导航及5G移动通信在内的无线电系统的正常工作有着极大影响。信道模拟技术能够尽可能真实地模拟不同环境下的信道传输特性，充分验证无线电系统的功能、性能及可靠性。其中，为了充分验证无线电测量性能，开展高动态、高精度信号模拟技术研究具有重要意义。本项目的研究内容具体包括：.1. 常规轨迹模拟算法基于三阶分段多项式近似，对不同阶次开展一般性研究有望提升轨迹模拟精度。为此，提出了基于B样条近似的连续性轨迹模拟方法，完成对不同阶次的一般化。另外，提出了基于插值滤波器的轨迹模拟解算算法，有效解决了量化误差累积问题。理论分析与仿真结果表明，所提算法在轨迹模拟精度、连续性、复杂度、先验信息等方面各有优势。.2. 为了兼顾宽带信号延时技术与低复杂度，提出了基于多分段优化的宽带可变小数延时（VFD）滤波器设计方法。该算法对VFD参数的定义域进行分段，提出了多相-Farrow结构，推导了可变频率响应（VFR）误差，并基于最小最大准则，分别在各分段区间内对VFR误差进行优化，得到VFD滤波器系数。仿真结果表明，所提算法可实现宽带信号延时，并具有较低复杂度。.3. 基于均匀采样的轨迹模拟技术不区别低动态场景与高动态场景，动态适应性差。为此，提出了基于非均匀采样的高动态轨迹模拟方法。提出了分段密切插值算法，建立了轨迹模拟数学模型，并提出了基于Farrow结构的密切插值滤波器，可以高效完成基于非均匀采样的轨迹模拟解算。理论分析与仿真结果均表明，所提算法在不同动态场景下，具备较高的模拟精度，从而提升了动态适应性。.4. 为了实现全带宽信号延时技术，提出了基于导数采样的全通VFD滤波器设计方法。基于分段密切插值算法完成VFD滤波器的时域设计，为了提升频域性能，基于最小最大准则完成VFD滤波器的频域设计，使得最大VFR误差最小。仿真结果表明，所提算法实现了全通VFD滤波器，同时实现了低复杂度的均匀与非均匀采样信号的延时与重构。