For multipath mitigation of loops,the technologies like EML and HRC are usually adopted in receivers at present. However,different correlator spaces should be selected for new navigation signals of different modulation systems by HRC technology in practical application. In light of the problems above,and based on the analysis of phase discrimination and multipath mitigation performance,a modified design method for correlator space of HRC discriminator in new navigation signals is proposed. Simulation results show that different optimizations are selected for HRC correlator space in different new OS navigation signals. When baseband is wide enough,the phase discrimination scope is enlarged with the increase of correlator space,and the performance of multipath mitigation is enhanced as the correlator space decreases.When baseband is narrow and correlator space is small,no multipath mitigation performance of new navigation signal would be improved with the decrease of correlator space in a certain phase discrimination scope.The proposed optimization method for correlator space is innovative,research result is of significant theoretical value,and thus this method is already applied to the engineering practice.

本文首先介绍了南太平洋大学卫星远程教育网络USPnet的发展历史及现状,重点分析了网络由最初只能提供单向语音通信到目前支持交互式多媒体通信的发展历程;然后分析了USPnet的VSAT网络架构,主校区作为主站,各分校区作为远端站;最后介绍了USPnet提供的应用,包括交互式数据、语音通信和视频会议等。

本文主要对俄罗斯卫星远程教育的发展现状进行了简要介绍。着重从Radio—MSU．RUNNET及卫星教育网这三大卫星远程教育体系的结构、业务及应用进行阐述。

To improve the bidirectional timing accuracy of the BD receiver,the bidirectional timing of the BD system and the error model of TCXO was studied.A novel closed loop method of Adaptive Kalman filtering was proposed to estimate the clock offset and clock shifting,so as to predict the clock bias and its rate between the user time and the system time at the next sampling.Moreover,an adaptive update method of noise covariance and the design of Kalman filtering was given.The bidirectional timing data of the BD receiver was collected and then simulated by computer.The result indicates that the bidirectional timing accuracy of the BD receiver could be increased by Adaptive Kalman Filter.Furthermore,the timing accuracy increased with the estimate intervals getting longer,and at the same time the Allan covariance was stabled at 10-15.Finally,the reason of this conclusion was analysed.

Locating user’s position only by the communication constellation’s one LEO satellite has some drawbacks,such as low accuracy and long waiting time.This is related with the larger PDOP.The scheme of pseudorange equation assisted by height equation is proposed in this paper.The scheme’s performance with the algorithm is evaluated by simulations and it is proved that this scheme can effectively improve the positioning accuracy and reduce the waiting time.Hence it satisfies the con-stellation communication system’s demand.This paper also studies the positioning error caused by the height error.

在国家智能交通系统(ITS)的发展战略和产业化方向的指引下,GPS技术在ITS的发展中得到广泛的应用与发展,随着交通运输规模的不断扩大,它在交通运营中的应用也得到广泛地推广。本文着重介绍了GPS系统在交通运输中的应用,包括在车辆交通管理、军事交通、奥运车辆监控等方面的作用,最后做了总结和展望。

The history of GNSS was introduced firstly.Then the applications in civil and military were discussed and the development of its techniques was summarized.

为提高卫星资源的利用率,充分利用卫星通信系统的设计备余量,讨论了利用窄带系统的备余量来传输类似于噪声的宽带扩频信号的有关问题,并为宽带扩频信号的传输建立了相应的系统模型.分析了在给定窄带系统备余量,当窄带信号占用不同卫星资源时该宽带扩频系统的容量,得到了窄带信号传输不受影响的情况下该系统能容纳的最大宽带用户数及相应各宽带用户信号的功率上限,为卫星通信系统的组网提供了一定的理论依据.