GLONASS卫星L1信号接收机的设计

基于高频电路设计的原理,设计了GLONASS接收机的方案。电路分为信号放大、中频分离和相干载波产生这三个部分。主要使用了微波集成电路放大器BGA2001,高频滤波器TA0676A,宽带正交解调器AD8347和集成压控振荡射频合成器Si4123。设计出的接收机能够接收GLONASS L1信号。     

GPS/GLONASS同步的可编程逻辑实现

给出了一种用于第三代移动通信系统(3G)CDMA2000基站的时钟同步方案。由一个双星接收卡接收GPS/GLONASS标准秒信号作为整个时钟同步系统的参考,分两级锁相环实现:第一级锁相环采用软件锁相,输出10MHz信号作为第二级锁相环的参考源,第二级锁相环为2个模拟锁相环,分别输出16fc和48fc(fc=1.2288MHz)。2S信号由16fc分频得到。这种设计保证了输出时钟的长期稳定性和短期稳定性,满足协议所规定的同步精度。详细介绍了数字鉴相器、2S产生电路、相差检测及控制电路的电路设计和有关仿真结果。     

多模卫星信号仿真器上位机软件设计与实现

运用面向对象和多线程的技术,在VC++6.0环境下对GPS/GLONASS/BD1三模卫星信号仿真器上位机软件进行了设计与开发,重点分析并完成了多导航系统时空统一、导航电文生成、卫星与用户的伪距仿真和用户轨迹计算等功能模块,实现了统一时基模式下三模卫星信号的高逼真仿真.商业接收机的实验结果表明,该仿真软件操控灵活,与下位机连接合成的信号逼真度高,为各类接收机的性能检测提供了有益支持.     

Preprocessing of GNSS signals subject to interference

Increasingly, interference effects on GNSS receivers are becoming important as more safety-critical applications such as civil aviation are employing the system. The inherent interference rejection capability of the GNSS spread spectrum modulating technique is now no longer considered adequate to remove the effects of very strong jammers. These can be generated intentionally, as in jamming situations, or unintentionally by systems such as mobile satellite systems. Continuous satellite tracking through this interference is essential for high-integrity applications. This study describes a new hardware-based GNSS interference mitigation scheme which is particularly effective against CW and pulsed CW interference. Interferers with some degree of frequency or amplitude modulation can also be reduced. The core hardware can remove two CW interferers from anywhere within the GPS P code bandwidth or the GLONASS frequency spectrum and further interferers can be removed by cascading modules. Simulation and actual data are shown. Owing to the wideband nature of the signal processing, the module introduces very little additional phase distortion and thus group delay to the GLONASS band, which has been shown to be advantageous to differential GLONASS processing. © 1997 John Wiley & Sons, Ltd.     

Compact Circularly Polarized Antenna with a Capacitive Feed for GPS/GLONASS Applications

This letter presents a novel compact circularly polarized patch antenna for Global Positioning System/Global Navigation Satellite System (GPS/GLONASS) applications. The proposed antenna is composed of a simple square radiating patch fed by a capacitive dual‐feeder to increase the impedance bandwidth and a lumped element hybrid coupler to achieve the broadband characteristic of the axial ratio (AR). The realized antenna dimensions are 28 mm × 28 mm × 4 mm, which is the most compact size among the dual‐band GPS/GLONASS antennas reported to date. The measured results demonstrate that the proposed antenna has a gain of 2.5 dBi to 4.2 dBi and an AR of 0.41 dB to 1.51 dB over the GPS/GLONASS L1 band (1.575 GHz to 1.61 GHz).     

新思考：北斗导航卫星系统的发展与思考

本文结合美国新一代全球定位系统卫星GPSBLOCK—IIF的技术特点,分析了GPS卫星导航系统的发展特点,总结了开展我国北斗全球导航定位系统的必要性以及建设未来北斗导航卫星的思路。     

On the inclusion of geographic information systems (GIS) in global navigation satellite systems (GNSS)

The latest innovation of the global navigation satellite systems (GNSS) technologies plays an important role in improving the quality and safety of modern life. Most of the applications evolved from the integration between GNSS, geographical information systems (GIS) and wireless communications and networking (WCN) systems. The wide spread applications that are using these technologies include: the automatic vehicle location (AVL), tracking systems, navigation systems, pedestrian navigation systems, intelligent transportation systems, precise positioning, and emergency callers, among others. The location‐based services (LBS) are possible only by the combination of GNSS, GIS and WCN. The growing need for commercial LBS has forced cellular‐phone and network manufacturers to concentrate on positioning solutions, which are even more precise than the regulatory mandates for positioning of emergency callers and other user services and applications. In this paper, we will present a literature review of the GNSS, the three satellite systems GPS, GLONASS and Galileo, which are aimed to support GNSS services, and a comparison between them and their role in creating a GIS. Copyright © 2006 John Wiley & Sons, Ltd.     

Understanding signals from glonass navigation satellites

In late 1986 details of the radio-frequency signal structure currently employed by the pre-operational GLONASS satellite navigation system were revealed by the Satellite Communications Group at Leeds University. Since then further investigation has resulted in a successful interpretation of most of the data message transmitted on the civil code, sufficient to allow the design and construction of a GLONASS receiver capable of the same level of performance as can now be achieved with NAVSTAR GPS. Details of the message content relating to location of GLONASS satellites for the purposes of position-fixing and time-referencing are presented for the first time.     

Introducing relativity in global navigation satellite systems

Today, the Global Navigation Satellite Systems, used as global positioning systems, are the GPS and the GLONASS. They are based on a Newtonian model and hence they are only operative when several relativistic effects are taken into account. The most important relativistic effects (to order 1/c²) are: the Einstein gravitational blue shift effect of the satellite clock frequency (Equivalence Principle of General Relativity) and the Doppler red shift of second order, due to the motion of the satellite (Special Relativity). On the other hand, in a few years the Galileo system will be built, copying the GPS system unless an alternative project is designed. In this work, it will be also shown that the SYPOR project, using fully relativistic concepts, is an alternative to a mere copy of the GPS system. According to this project, the Galileo system would be exact and there would be no need for relativistic corrections.     

欧洲"伽利略"导航卫星

卫星导航系统用途广泛。目前全球主要的卫星导航系统有美国的GPS和俄罗斯的GLONASS。GLONASS因俄罗斯经济等方面的问题,无力补网,系统降效运行,主要用于军事;GPS军民两用,市场规模大,但由于是军方控制,对用户的安全使用具有潜在威胁。“伽利略”卫星导航系统组网布局更加合理先进,采用开放的市场运作模式,具有非常诱人的应用前景。