舰载飞机着舰最佳甲板风初步分析

主要依据美国海军航空兵试验地各种舰载飞机实际飞行试验研究结果，阐述舰载飞机着舰最佳甲板风研究的意义、方法及其大小。经初步分析认为：对于喷气式舰载飞机着舰甲板风为２５ｋｎ，对于螺旋桨式舰载飞机着舰甲板风 １５ｋｎ是最佳的。但通过计算喷气式飞机甲板风值在２５ｋｎ和３５ｋｎ的结果比较，在甲板风为２５ｋｎ时，由于接地速率增加近１０％，这将会带来一些不利的结果。     

舰载飞机飞行品质规范编制的原则,依据和设想

根据我国航空事业发展的需要，以及现行国军标（ＧＪＢ１８５－８６）所存在的不足之处，论述了编制舰载飞机飞行品质规范的必要性。进而提出了编制此规范应遵循的基本原则和主要依据，最后阐述了舰载飞机飞行品质规范的初步设想。     

Preliminary analysis of the quality and positioning performance of BDS-3 global interoperable signal B1C&B2a

BeiDou-3 Navigation Satellite System (BDS-3) satellites are equipped with the new generation GNSS signals B1C and B2a, which support the interoperability with GPS and Galileo systems. In this study, the pseudo-range multipath error and carrier phase observation noise of the BDS-3 B1C and B2a signals were evaluated based on zero baseline measurements from the day of year (DOY) 113 to 116, 2020. Further, the precision and performance of the single point positioning (SPP) and precise point positioning (PPP) are assessed at 9 stations. This assessment manifests that the standard deviations (STDs) of the pseudo-range multipath error are about 0.09 ~ 0.22 m, while STDs of the carrier phase observation noise are about 0.075 mm. For the single-frequency SPP, its positioning precision is about 2.03 ~ 4.85 m and 3.29 ~ 10.73 m at the 99.99% confidence level in horizontal and vertical directions, respectively, while the dual-frequency SPP precision is about 1.92 ~ 8.02 m and 4.81 ~ 12.77 m in horizontal and vertical directions, respectively. For the daily static PPP, the convergence time is about 20 ~ 30 min, while the daily positioning precision can reach 1.38 ~ 4.42 cm and -1.31 ~ 4.34 cm in horizontal and vertical directions, respectively. In general, the quality and the SPP and PPP performance of the BDS-3 B1C&B2a signals are comparable to the GPS and Galileo.     

基于可变带宽数字锁相环的快速载波同步

锁相环的环路带宽和捕获时间是两个相互制约的因素。提出一种基于最小均方误差准则的自适应调整环路带宽的数字锁相环,能将锁相环的入锁时间缩短为常规锁相环需要时间的1/10,同时在稳态下达到很小的环路带宽以抑制相位噪声。     

CPAFC辅助判决反馈环的一种具体实现方案

对叉积自动频率控制算法(CPAFC)进行了研究,该算法常用来辅助载波抑制环来实现对大频偏信号的跟踪,而叉积自动频率控制算法在频偏估计的过程中,往往会造成一定的系统时延。针对这个问题,本文给出了一种解决方法,在此基础上提出了一种CPAFC辅助判决反馈环的具体实现方案。仿真结果表明,这种方案在保持一定同步精度的同时,极大地缩短了系统延时。     

Galileo L1F信号载波跟踪环中鉴别器组合研究

为了更好地进行载波相位跟踪,Galileo L1F信号相比于GPS信号增加了没有导航数据的导频信道,使数据信道能够使用不受导航数据限制的鉴别器。但是Galileo L1F信号载波相位跟踪环中传统的鉴别器组合方式仍有不足。基于适用于单一导频信道的鉴别器性能优于适用于单一数据信道的鉴别器的原理,提出了新的鉴别器组合方式,并通过仿真实验对比在不同热噪声环境下传统组合方式的两种鉴别器组合和新组合方式的两种鉴别器组合的性能。研究结果表明新的鉴别器组合在Galileo L1F接收信号的抑制噪声和防止失锁控制方面比传统鉴别器组合有明显优势。     

一种改进的GNSS整周模糊度解相关算法

GNSS整周模糊度解相关算法的性能直接影响到整周模糊度的搜索速度和解算成功率。为了在不降低GNSS整周模糊度解相关算法解相关程度的前提下,提高解相关算法的计算效率,在深入分析典型解相关方法优缺点的基础上,提出基于对角线预排算的解相关算法。该方法源于对直接对角线排序解相关算法的预排序思想,采用矩阵分解后对角线元素中最小值并将其转换到对应对角线位置的方式,用更少的迭代次数达到比直接对角线排序更好的解相关效果。将新算法与其他算法进行仿真比较得出,其性能优于直接对角线排序算法,解相关功能与联合解相关算法等效,且计算效率略占优势。     

GNSS carrier phase ambiguity resolution based on integrity restriction in ambiguity domain

Carrier phase ambiguity resolution of Global Navigation Satellite System (GNSS) is a key technology for high-precision navigation and positioning, and it is a challenge for applications which require both high accuracy and high integrity. This paper proposes efficient ambiguity resolution methods based on integrity restriction using Fixed Failure rate Ratio Test (FF-RT) and Doubly Non-central F-distribution Ratio Test (DNF-RT), and derives the related processing models and numerical algorithms compared with the traditional Ratio Test (RT) method. Firstly, the integer ambiguity resolution and validation procedures, especially the Least squares AMBiguity Decorrelation Adjustment (LAMBDA) estimation and RT validation are analyzed. Then the quality evaluation using success rate, the FF-RT method using Integer Aperture (IA) estimation and the NDF-RT method are proposed. Lastly, the simulation and analysis for LAMBDA using RT, FF-RT and DNF-RT methods are performed. Simulation results show that in case of unbiased scenario FF-RT and DNF-RT have similar performances, which are significantly better than RT. In case of biased scenario it is difficult for FF-RT to predict the biased success rate thus it should not be used for bias detection, while DNF-RT can detect biases in most cases except for the biases are approximate or equal to integer, which has the important benefit for early detection of potential threat to the position solution.     

火箭垂直起飞段漂移变化的建模与分析

垂直起飞段是火箭靶场试验过程中最容易发生故障的时段之一,并且起飞段发生故障带来的后果往往是灾难性的。因此,分析运载火箭起飞段的运行情况,测量箭体起飞漂移和分析漂移量变化规律,对于航天工程具有极为重要的意义。在系统分析某一型号火箭起飞段漂移情况的基础上,建立了火箭垂直起飞段漂移模型．查明了箭体漂移量服从自回归模型AR(5),并采用D—W典型检验方法,对数学模型实际情况的吻合性进行了检验。大量实测数据计算结果证实,该箭体漂移的运动学模型是可靠的,很好地刻画了火箭在垂直起飞段漂移量的变化规律。     

卫星双向时间传递调制解调器跟踪环路设计CSCD

精密跟踪技术是高精度伪码测距系统中的关键技术,根据卫星双向时间比对调制解调器的工作特点,对解调器的跟踪环路进行了研究,并利用Matlab进行环路设计与仿真,分析了不同载噪比、不同环路带宽条件下跟踪环路的性能;根据软件仿真结果,在DSP+FPGA硬件平台上加以实现,给出测试结果,并最终应用到自主开发的卫星双向时间比对调制解调器上,测量不确定度优于1ns。