脉冲多卜勒引信实时校准技术初步研究

脉冲多卜勒引信实时校准技术主要对引信回波模拟源的无线电引信技术指标进行准确评定,以达到校准的目的。目前对该类专用测试设备的校准仍停留在分项校准的状态,无法全面地对整个专用测试设备进行评定,本文利用"宽带数字接收+软件无线电"技术和解调算法,实现对引信回波模拟源的系统级校准的目的。     

Multi-wavelength coordinated observations of ionospheric irregularity structures from an anomaly crest location during unusual solar minimum of the 24th cycle

The present paper reports coordinated ionospheric irregularity measurements at optical as well as GPS wavelengths. Optical measurements were obtained from Tiny Ionospheric Photometer (TIP) sensors installed onboard the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. GPS radio signals were obtained from a dual frequency GPS receiver operational at Calcutta (22.58°N, 88.38°E geographic; geomagnetic dip: 32.96°; 13.00°N, 161.63°E geomagnetic) under the SCIntillation Network Decision Aid (SCINDA) program. Calcutta is located near the northern crest of Equatorial Ionization Anomaly (EIA) in the Indian longitude sector. The observations were conducted during the unusually low and prolonged solar minima period of 2008–2010. During this period, four cases of post-sunset GPS scintillation were observed from Calcutta. Among those cases, simultaneous fluctuations in GPS Carrier-to-Noise ratios (C/N_o) and measured radiances from TIP over a common ionospheric volume were observed only on February 2, 2008 and September 25, 2008. Fluctuations observed in measured radiances (maximum 0.95 Rayleigh) from TIP due to ionospheric irregularities were found to correspond well with C/N₀ fluctuations on the GPS links observed from Calcutta, such effects being noted even during late evening hours of 21:00–22:00 LT from locations around 40° magnetic dip. These measurements indicate the existence of electron density irregularities of scale sizes varying over several decades from 135.6 nm to 300–400 m well beyond the northern crest of the EIA in the Indian longitude sector during late evening hours even in the unusually low solar activity conditions.     

Thermal and nonthermal flare emission observed with the Nobeyama Radio Heliograph

The early phases of three flares, observed by the Nobeyama Radio Heliograph, are studied. Nonthermal and thermal radio sources are identified by comparison with soft X-ray images taken by the Soft X-ray Telescope onboard the Yohkoh satellite. Two of the flares are mainly of nonthermal origin and their location coincides with one of the footpoints of soft X-ray loops. Another flare has both thermal and nonthermal components which start to brighten simultaneously. This suggests that particle acceleration and plasma compression develop simultaneously.     

电离层对普通GPS和位置差分GPS定位误差的影响

在没有选择可用性条件下，差分ＧＰＳ定位精度完全取决于电离层的空间不相关性，为了改进差分ＧＰＳ的校正算法，本文在月平均电离层时延等值图的基础上，建立了一个简单而又逼真的电离层模型，并分析了普通ＧＰＳ和位置差分ＧＰＳ仅电离层单一因素引入的定位误差。     

毫微秒脉冲雷达高度表的超低空静态模拟测高及其结果分析

本文主要介绍一种新型脉冲雷达高度表,装于CK1E超低空靶机模型上静态测高的试验方法和结果。结果分析表明该高度表适用于CK1E靶机的飞行控制系统,作为高度传感器,在超低空进行精确而稳定的测高成功。     

基于飞机平台的北斗救生信标机 的性能测试技术研究

从北斗系统组成、功能及原理入手,分析了北斗救生信标机在飞机平台上进行性能测试的特点,介绍了性能测试和评判方法,分析并研究了验证结果.应用结果表明,本文设计的试飞和测试评估方法科学可行,测试结果准确,充分体现了被测设备的功能性能,暴露了设计缺陷,给出了使用限制建议.研究结果具有重要的工程实际应用价值,能够为用户提供使用参考.     

某型直升机超短波电台互相干扰的问题分析

某型直升机装备的两超短波电台在使用中出现某些频点下的互相干扰现象,尽管地面采取了相应措施却均未改善。本文在常规修理方法的基础上,采用了一些新方法找到了此故障的根源,并为类似电台干扰问题提供参考。     

利用通信和广播电视卫星定位干扰源的技术

简要介绍了利用通信和广播电视卫星对地面干扰辐射源进行定位的必要性和基本工作原理、技术难点及解决方法,以及提高定位精度的主要技术途径。     

雷达-电子战-通信的一体化

为充分发挥武器系统的作战效能，对作战平台上的雷达-电子战-通信一体化技术进行了研究。阐述了雷达与电子战、雷达与通信一体化的必要性和特点，并对一体化的关键技术，如以线性调频与伪随机编码信号的组合为共用信号、共用孔径及其波束控制技术等进行了分析。最后给出了一个采用软件无线电技术的雷达-无线电-通信一体化系统的方案。     

差分编码OQPSK调制解调器设计

OQPSK调制性能大大优于 QPSK,但由于 OQPSK调制的特殊性 ,其差分编解码相应比较复杂 ,文中对DOQPSK的差分编解码和调制解调原理进行了深入的分析 ,针对传统 DOQPSK相干解调和解码方法存在的问题 ,给出一种简单高效的改进 DOQPSK解调和解码方法。该方法不仅结构简单 ,同时消除了与 DQPSK解调相比存在的 3 d B解调损失问题 ,大大提高系统的解调性能