综合卫星导航信号模拟器

综合卫星导航信号模拟器是一种高精度的标准信号源，可以模拟不同载体所需环境，精确发出其上接收机所需的卫星信号（GPS、BD2G、LONASS）。由于国内研究起步较晚，为了打破外国先进技术的垄断，我们研制自己的高动态模拟器具有重大意义。     

《全球导航卫星系统信号模拟器校准规范》即将实施 计量更准导航才能更准

日前从质检总局获悉,《全球导航卫星系统信号模拟器校准规范》即将于11月1日起实施。这一规范将对全球导航卫星系统（GNSS）信号模拟器相关指标进行科学校准,从而为运用广泛的GNSS接收机提供更多质量保证。很多人喜欢自驾出行旅游。在准备出行装备时,车辆定位导航设备成为很多司机自驾的必备装置。     

导航GPS接收机校准数据自动处理方法研究

基于校准过程一体化,设计一体化校准数据计算、精度评定、数据存储技术,实现导航型GPS接收机校准的一体化。实验证明,该自动处理方法能有效提高数据处理效率,克服校准数据处理过程冗余的缺点,提高导航型GPS接收机校准过程数据自动处理的性能,并能自动生成计量校准所需的数据表格,极大地简化了校准数据的处理工作,提高了试验采集系统校准数据处理的自动化程度。     

第十二届中国卫星导航年会召开

正2021年5月26日,第十二届中国卫星导航年会在江西南昌召开。年会以"时空数据,赋能未来"为主题,全面展示了卫星导航时空服务对未来发展的重要意义,推动北斗系统与各领域深入融合。本次年会集中展示了北斗系统融合应用成果。上海市计量测试技术研究院展示了国家时间频率计量中心上海实验室的技术能力和服务范围。其中,网约车计程计时检测、卫星信号模拟器校准、北斗船载接收机检测、北斗应急无线电示位标检测等特色服务项目以及标准化工作,受到了业内客户的好评。     

卫星导航接收机动态性能评估方法

根据卫星导航接收机的应用领域,利用卫星信号模拟器针对导航型接收机动态定位准确度、测速准确度、测向准确度三个主要指标制定了测试方法,并构建了一套评估工具。该工具能够在单次测试完成后输出上述三个指标的统计评估结果,统计评估结果包含均值、方差、圆概率误差等多项参数。研究结果表明,该测试方法及评估工具能够快速、有效地完成卫星导航接收机动态性能的校准。     

JJF1471-2014《全球导航卫星系统(GNSS)信号模拟器校准规范》解读

<正>一、规范制定背景及目的1.GNSS信号模拟器在和卫星导航相关的科研、应用等过程中,仅依靠全球导航卫星系统(GNSS)接收机(以下简称"接收机")来接收导航卫星信号的方式,会受到(如可视卫星数、天气、电磁环境等)诸多不可控因素影响科研、验证工作的进度和效率,并且受条件限制,无法得到多样化的导航卫星状态场景来满足需求。因此,利用GNSS信号模拟器来模拟各种导航卫星信号就成为首     

北斗高精度授时终端测试技术研究

针对北斗授时终端提出了基于模拟环境下的定时精度及守时精度性能测试方法,使用卫星导航信号模拟器、铷钟、计数器搭建了模拟环境下北斗授时终端测试系统,北斗授时终端通过解算卫星信号,解算出北斗时间后,输出秒脉冲1PPS信号,实现和北斗模拟时间同步。测试系统解算北斗授时终端和卫星导航信号模拟器输出的秒脉冲1PPS信号之间的时间间隔,获取终端定时精度,测试结果表明测试方法具有较好的一致性和可重复性,实现了纳秒级别的定时精度测试。     

关于北斗_GPS组合导航定位系统的设计与研究

北斗卫星定位系统是由中国建立的区域导航定位系统。它是覆盖中国本土的区域导航系统。全球卫星定位系统——GPS是最具有开创意义的高新技术之一,其全球性、全能性、全天侯性的导航定位、定时、测速优势必然会在诸多领域中得到越来越广泛的应用。但是我国单纯应用GPS存在风险的可能性,卫星导航走向系统兼容可达到最佳效果。提出北斗与GPS组合导航系统的总体框架并分析该系统的主要特点及应用范围。     

卫星导航接收机时延测定技术研究

利用卫星导航接收机进行高精度授时同步是一种简单有效的授时同步手段。导航接收系统时延的精确测量是进行高精度授时的前提,其输出秒脉冲信号的时延更是影响远距离授时、时间同步的关键。围绕卫星导航接收系统时延的测定,通过分析卫星导航接收机的时延构成及特点,建立了卫星导航接收机的时延构成模型,制定了便于操作的卫星导航接收机时延测定的方法,搭建了一套完整的卫星导航接收机时延测定系统,并对系统进行了标定和实验验证。     

“国家级卫星导航产业基地”落户龙岗并投产

据广州日报,"国家级卫星导航产业基地"赛格导航新基地近日落户龙岗宝龙工业区并于近日正式投入使用。昨日,记者实地探访了这个在中国卫星导航应用领域的领军企业基地。作为北斗代/GPS兼容的国家级卫星导航基地,占地面积3万平方米,位于龙岗宝龙工业区,毗邻比亚迪宝龙工厂。记者看到,业内领先的北斗/GPS卫星导航设备生产线     

A Methodology for the Evaluation of a GPS Receiver Performance in Telematics Applications

This paper presents a methodology to evaluate the position availability of automotive grade global positioning system (GPS) receivers intended for Telematics applications utilizing a multichannel GPS satellite signal simulator in a controlled laboratory environment. Initially, field testing of two distinct GPS receivers was conducted in an urban canyon environment and a foliage environment to assess each receiver's position availability performance. Test scenarios were then developed on a multichannel GPS satellite signal simulator in order to create controlled and repeatable stimuli to the GPS receivers. The scenarios take into account the actual satellite constellations at the same day, time, and locations of the field data collections. Furthermore, the number of visible satellites and power levels was adjusted in order to stimulate the hardware tracking sensitivity, hardware acquisition sensitivity, dynamic range, and navigation filter design, all of which impact position availability for GPS receivers. Quantitative results demonstrated good correlation between the results obtained using the developed test scenarios and the results from the field testing. The proposed methodology will result in reducing validation cost and time to market for automotive Telematics products     

The performance comparison between GPs and BeiDou‐2/compass: A perspective from Asia

Abstract

The next decade promises drastic improvements to global navigation satellite systems. The USA is modernizing GPS, Russia is refreshing GLONASS, Europe is moving ahead with its own Galileo system, and The People's Republic of China is expanding its BeiDou‐1 system from a regional navigation system to a full constellation global navigation satellite system known as BeiDou‐2/Compass, which consists of thirty five satellites including geostationary satellites, MEO satellites and geosynchronous satellites in the coming year. Extra satellites will make possible improved performance for all applications, and especially where satellite signals can be obscured, such as in urban canyons, under tree canopies or in open‐pit mines. The benefits of the expected extra satellites and their signals can be evaluated in terms of availability, accuracy, continuity, and reliability issues.

The advent of a hybrid GNSS constellation has drawn a lot of attention to study compatibility and interoperability. A number of performance analyses have been conducted on a global scale with respect to availability, reliability, accuracy and integrity in different simulated scenarios (such as open sky and urban canyons) for each system individually as well as for combined systems with all the possible combinations. Since the BeiDou‐2/Compass has gained more attention from GNSS communities, the main objective of this paper is to study the performance of BeiDou‐2/Compass comparied to GPS in the greater Asia region; and also to explore whether the combination of BeiDou‐2/Compass with GPS would yield performance improvements in this region.

The performance analysis can be analyzed by either the signal or the geometrical conditions. However, the scope of this study is limited to investigating the impact of current and future GNSS based on geometrical conditions. Therefore, the satellite visibility and DOP (Dilution of Precision) values of each system or possible combinations between them are used as the major indices for performance evaluation with the emphasis on the addition of Compass. In addition, those indices are further analyzed in terms of their spatial and temporal distributions with the emphasis on the greater Asia region. Moreover, the spatial performance analyses are conducted on both global and regional scales to provide more insightful comparisons to illustrate the importance of future Compass for users in the greater Asia region.     

GPS接收机天线相位中心一致性差异分析研究

在GPS接收机枪定过程中发现,按校准规范JJF1118-2004中所述的检定方法所测出的同一台GPS接收机天线相位中心一致性都不尽相同,有时这种差异达到3 mm以上.导致这种差异的因素有很多,包括一些随机误差,如:基座整平误差、卫星质量的影响、数据采集时间长短的影响和解算误差等.通过对检定方法的分析得知,规程所述的枪定方法对检定结果的差异有较大的影响.从理论上对GPS天线相位中心一致性差异进行了推导,并进行了试验验证.结果表明,GPS天线相位中心一致性检定结果应在一定范围内变化.     

北斗在国际海事组织开展标准化工作初探

本文依据北斗卫星导航系统在航海领域应用的规划和考虑,介绍了国际海事组织（IMO）卫星导航标准现状以及对GNSS的政策与发展规划,阐释了航海领域制定GNSS相关标准现状及发展趋势,分析了北斗卫星导航系统开展IMO国际标准化工作的机遇与挑战,并给出了北斗卫星导航开展在IMO国际标准化工作的初步考虑与建议。     

北斗标准化发展战略思考

鉴于全球卫星导航系统（GNSS）在军事和民用领域的巨大促进作用,世界主要国家已将卫星导航产业上升为国家战略。标准化作为抢占技术前沿、引领科技创新、开拓国际市场、谋求经济利益的有效手段,在推动卫星导航技术飞速发展和提高国际竞争力等方面的地位和作用日趋突出,促使北斗对其标准化战略的需求日益迫切。本文介绍了国内外标准化战略现状及卫星导航标准化工作情况,深入分析了北斗对标准化发展战略的需求,系统阐述了北斗标准化发展战略的重点方向和主要任务,进而提出相应的战略举措建议,为北斗标准化发展战略的研究提供借鉴。     

一种新型GPS冗余授时方法

大量采用GPS授时的网络存在安全隐患,而采用其它授时方法则难以在现有设备增加外部时钟接口.介绍了基于GPS射频信号模拟的外部授时方法,对原有设备无需作任何改动,从外部授时模块中获得外部同步的1 pps(pulses per second)和时间信息,仿真产生固定点接收到GPS信号的导航电文和观测数据,并将GPS导航电文的时间信息实时修改;GPS射频信号基于仿真数据产生,使设备内嵌的GPS接收机正常定位授时,恢复出外部同步的1 pps,从而实现外部授时.论文介绍了采用大规模FPGA的实现方法,实验结果验证了对于固定位置该授时方法的有效性.     

伽利略导航系统若干关键技术分析

分析了目前最新的卫星导航定位系统——伽利略系统所采用的若干关键技术．从卫星轨道布置方式、信号与频率设计方法、伪卫星技术及信号服务等几个方面与GPS进行了对比研究．研究结果表明，Galileo系统具有定位精度高、兼容性好、功能全等优点，在新一代导航系统中具有重要地位．     

Support Vector Machine Assisted GPS Navigation in Limited Satellite Visibility

This paper investigates performance improvement via the incorporation of the support vector machine (SVM) into the vector tracking loop (VTL) for the Global Positioning System (GPS) in limited satellite visibility. Unlike the traditional scalar tracking loop (STL), the tracking and navigation modules in the VTL are not independent anymore since the user’s position can be determined by using the information from other satellites and can be predicted on the basis of the states of the user. The method proposed in this paper makes use of the SVM to bridge the GPS signal and prevent the error growth due to signal outage. Similar to the neural network, the SVM is motivated by its ability to approximate an unknown nonlinear input-output mapping through supervised training. The SVM is employed for predicting adequate numerical control oscillator (NCO) inputs, i.e., providing better prediction of residuals for the Doppler frequency and code phase in order to maintain regular operation of the navigation system. When the navigation processing is in good condition, the SVM is at the training stage, and the output information from the discriminator and navigation filter is adopted as the inputs. Other machine learning (ML) algorithms such as the radial basis function neural network (RBFNN) and the Adaptive Network-Based Fuzzy Inference System (ANFIS) are employed for comparison. Performance evaluation for the SVM assisted architecture as compared to the RBFNN- and ANFIS-assisted methods and the un-assisted VTL will be carried out and the performance evaluation during GPS signal outage will be presented. The proposed design is very useful for navigation during the environment of limited satellite visibility to effectively overcome the problem in the environment of GPS outage.     

Fast acquisition implementation for high sensitivity global positioning systems receivers based on joint and reduced space search

In Global Positioning Systems (GPS), unique pseudorandom codes allow different satellites to share available frequency spectra without interference. In receivers, the locally generated codes (replicas) are correlated with received signals to extract a particular satellite?s signal and wipe-off its pseudorandom code. The signals received are generally misaligned with replicas. As a result, receivers search for signals using different codes, code phases, and additional residual sinusoidal demodulations at several possible frequencies. This search is called acquisition and it is computationally challenging for receivers operating under weak signal conditions. Software GPS receivers have been developed over the past several years and continue to be an area of extensive research. Faster, less complex, and more efficient algorithms are required for software GPS receivers. We present a fast algorithm for accelerating acquisition. Several frequency domain approaches proposed by authors earlier are combined to reduce computational complexity. These are (i) joint code, code delay and frequency search; (ii) limited code-phase search; and (iii) a shifting replica approach. Significant gains in arithmetic complexity are achieved. A novel method for restoring correlation degradation introduced by limited code phase search is also presented in this paper. Overall performance of the acquisition is illustrated on different platforms.