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Search Results: 1 - 10 of 833 matches for " Narrowband GNSS Receiver "
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Limited Bandwidths and Correlation Ambiguities: Do They Co-Exist in Galileo Receivers  [PDF]
Elena Simona Lohan
Positioning (POS) , 2011, DOI: 10.4236/pos.2011.21002
Abstract: Galileo is the Global Navigation Satellite System that Europe is building and it is planned to be operational in the next 3-5 years. Several Galileo signals use split-spectrum modulations, such as Composite Binary Offset Carrier (CBOC) modulation, which create correlation ambiguities when processed with large or infinite front-end bandwidths (i.e., in wideband receivers). The correlation ambiguities refer to the notches in the correlation shape (i.e., in the envelope of the correlation between incoming signal and reference modulated code) which happen within +/– 1 chip from the main peak. These correlation ambiguities affect adversely the detection probabilities in the code acquisition process and are usually dealt with by using some form of unambiguous processing (e.g., BPSK-like techniques, sideband processing, etc.). In some applications, such as mass-market applications, a narrowband Galileo receiver (i.e., with considerable front-end bandwidth limitation) is likely to be employed. The question addressed in this paper, which has not been answered before, is whether or not this bandwidth limitation can cope inherently with the ambiguities of the correlation function, to which extent, and which the best design options are in the acquisition process (e.g., in terms of time-bin step and ambiguity mitigation mechanisms).
Direct RF Sampling GNSS Receiver Design and Jitter Analysis  [PDF]
Guillaume Lamontagne, René Jr. Landry, Ammar B. Kouki
Positioning (POS) , 2012, DOI: 10.4236/pos.2012.34007
Abstract: This paper describes the design of a flexible Direct RF Sampling based GNSS receiver as well as its use for the verification of jitter effects on various performance metrics. The proposed architecture allows the sampling and the real-time digital signal processing of real GNSS signals. The analysis of the measurements obtained from this system validates theoretical formulations from which the sampling jitter limit is established in order not to impact the GNSS signal’s detection.
SDR Joint GPS/Galileo Receiver from Theory to Practice
International Journal of Aerospace Sciences , 2012, DOI: 10.5923/j.aerospace.20120101.01
Abstract: This paper deals with a Software Defined Radio (SDR) receiver capable to process GPS and Galileo signals jointly. A large set of possible solution can be implemented, with the main aim of assessing the performance of the receiver for the considered architectures. For this reason, software receivers, either real-time or non-real-time, are fundamental tools to enable research and new developments in the field of GNSSs. In this paper our intent is to discuss some of the choices one can face when implementing an SDR GNSS receiver, switching from the theory to the practice. We focus our attention on the pseudorange construction and the Position, Velocity and Time (PVT) estimation stage, discussing different algorithms to implement these blocks. Our aim is to offer an insight on the options to implement those stages of the receiving chain, in a practical vision which is difficult to find in the available literature.
Analysis of Multipath Mitigation Techniques with Land Mobile Satellite Channel Model
M. Z. H. Bhuiyan J. Zhang,E. S. Lohan,W. Wang,S. Sand
Radioengineering , 2012,
Abstract: Multipath is undesirable for Global Navigation Satellite System (GNSS) receivers, since the reception of multipath can create a significant distortion to the shape of the correlation function leading to an error in the receivers’ position estimate. Many multipath mitigation techniques exist in the literature to deal with the multipath propagation problem in the context of GNSS. The multipath studies in the literature are often based on optimistic assumptions, for example, assuming a static two-path channel or a fading channel with a Rayleigh or a Nakagami distribution. But, in reality, there are a lot of channel modeling issues, for example, satellite-to-user geometry, variable number of paths, variable path delays and gains, Non Line-Of-Sight (NLOS) path condition, receiver movements, etc. that are kept out of consideration when analyzing the performance of these techniques. Therefore, this is of utmost importance to analyze the performance of different multipath mitigation techniques in some realistic measurement-based channel models, for example, the Land Multipath is undesirable for Global Navigation Satellite System (GNSS) receivers, since the reception of multipath can create a significant distortion to the shape of the correlation function leading to an error in the receivers’ position estimate. Many multipath mitigation techniques exist in the literature to deal with the multipath propagation problem in the context of GNSS. The multipath studies in the literature are often based on optimistic assumptions, for example, assuming a static two-path channel or a fading channel with a Rayleigh or a Nakagami distribution. But, in reality, there are a lot of channel modeling issues, for example, satellite-to-user geometry, variable number of paths, variable path delays and gains, Non Line-Of-Sight (NLOS) path condition, receiver movements, etc. that are kept out of consideration when analyzing the performance of these techniques. Therefore, this is of utmost importance to analyze the performance of different multipath mitigation techniques in some realistic measurement-based channel models, for example, the Land Mobile Satellite (LMS) channel model [1]-[4], developed at the German Aerospace Center (DLR). The DLR LMS channel model is widely used for simulating the positioning accuracy of mobile satellite navigation receivers in urban outdoor scenarios. The main objective of this paper is to present a comprehensive analysis of some of the most promising techniques with the DLR LMS channel model in varying multipath scenarios. Four multipath mitigation tech
Processing the GPS reflected signals for wind speed estimation during the GEOHALO mission
Danijela Ignjatovi？ Stupar
Geonauka , 2013,
Abstract: This paper is devoted to a research performed during a full-time work experience at the German Aerospace Center (DLR). I was investigating GNSS-Reflectometry techniques in order to provide detailed information about sea state including wind speed from reflected GPS signals recorded during some experimental flight part of the GEOHALO project. Moreover, investigation of direct and reflected microwave signals and methods were used to process the collected data for monitoring geophysical parameters about sea state and wind interface during the flight and compared with other in-situ measurements such as data from buoys network and Earth observation satellites. This paper discusses theory, methodology and application of acquisition and post-processing of scattered signals over the Mediterranean Sea surface during the GEOHALO-GNSS-Reflectometry flight mission flown on June 2012.
GNSS Multipath Reduction Using GPS and DGPS in the Real Case  [PDF]
Salem Titouni, Khaled Rouabah, Salim Atia, Mustapha Flissi, Oussama Khababa
Positioning (POS) , 2017, DOI: 10.4236/pos.2017.84004
Abstract: In Global Navigation Satellite System (GNSS) like Global Positioning System (GPS) and future Galileo, space signal reception in urban environment seems to be one of most significant. The urban environment is characterized by the presence of an excessive number of obstacles that produce Multiple Path (MP) in positioning the receiver. Consequently, it is of primary importance to characterize and ameliorate the performances of GNSS receiver for this type of application. In this paper, a method to mitigate MP in GNSS applications was proposed. Its principle is based on the addition, to the geographic map of a city or a neighborhood, of a supplementary information that consists of the correction of error caused by the MPs. The latter one was carried out by the comparison of the measurements, realized by Differential GPS (DGPS) and GPS, between two different sites with the same form. The first one was characterized by the presence of the MPs and the second one was completely clear of any type of obstacle. As a consequence, the measurements comparison has allowed us to deduce the GNSS MPs errors. This information can subsequently be used to make the corrections of the errors caused by MPs and it can be generalized by a measurement company to any entire city in order to identify errors in any neighborhood.
Study of Ionospheric Variability Using GNSS Observations  [PDF]
Jouan Taoufiq, Bouziani Mourad, Azzouzi Rachid, Christine Amory-Mazaudier
Positioning (POS) , 2018, DOI: 10.4236/pos.2018.94006
Abstract: With the increasing number of applications of Global navigation satellite system, the modeling of the ionosphere is a crucial element for precise positioning. Indeed, the ionosphere delays the electromagnetic waves which pass through it and induces a delay of propagation related to the electronic density (TEC) Total Electronic Content and to the frequency of the wave. The impact of this ionospheric error often results in a poor determination of the station’s position, particularly in strong solar activity. The first part of this paper focuses on a bibliographic study oriented first of all on the study of the ionosphere in relation to solar activity and secondly on the determination of the total electron content using GNSS measurements from the IGS network reference stations. Measurements were made on two permanent stations “RABT”, “TETN”. We selected years of GNSS measurements to evaluate the geomagnetic impact on the ionosphere, 2001, 2009 and 2013. A description of the ionospheric disturbances and geomagnetic storms was analyzed by determination of TEC, especially in high solar activity. The results show a strong dependence of the ionospheric activity with the geomagnetic activity.
基准站观测数据加密方法及其在差分GNSS后处理中的应用
A Densification Method for Base Station Observation Data and its Application to Post Processing of Differential GNSS
石波, 王云鹏, 李太恒
SHI Bo, WANG Yunpeng, LI Taiheng
- , 2018, DOI: 10.13203/j.whugis20160339
Abstract: 当基准站采样率低于流动站时，不能用常规差分全球卫星导航系统（Global Navigation Satellite System，GNSS）后处理方法得到流动站所有历元坐标。针对此问题，给出了基于精密单点定位（precise point positioning，PPP）模型构造基准站非采样点上虚拟观测值的方法。该方法将接收机钟差、对流层天顶湿延迟从观测值误差中分离出来，同消电离层模糊度一起进行估计，利用基准站真实坐标获得卫地距，在此基础上计算相邻两个观测历元的残差进而拟合历元间非采样点残差，与卫地距、各项估计误差一起生成虚拟观测值。该方法保持了虚拟观测值的误差特性，尤其是基准站与流动站间的共性误差。该方法仅加密基准站数据，对流动站没有影响。算例结果表明，基准站在采样间隔30 s范围内，使用该方法加密的虚拟观测值与真实值有较好的一致性，采样间隔分别为30 s、15 s、5 s的虚拟测码伪距和载波相位观测值偏差的标准中误差分别在0.2 m和1.2周左右、0.1 m和0.7周左右、0.05 m和0.2周左右；在30 s采样间隔情况下，按照该方法处理后仍能满足厘米级定位精度的要求
低轨卫星星载GNSS反射事件模拟分析
Simulation Study of Spaceborne GNSS-R Events
柳聪亮, 白伟华, 夏俊明, 孙越强, 孟祥广, 杜起飞
LIU Congliang, BAI Weihua, XIA Junming, SUN Yueqiang, MENG Xiangguang, DU Qifei
- , 2018, DOI: 10.13203/j.whugis20160161
Abstract: 基于低轨（low earth orbit，LEO）卫星星载GNSS反射事件的数学判据，分别用BDS、GPS、Galileo、GLONASS和4系统耦合GNSS星座模拟信号源，仿真分析了LEO卫星轨道高度、轨道倾角、下视天线视场角等参量对反射事件数量和时空分布的影响；进而研究了用上述4大GNSS系统进行GNSS反射信号遥感技术（GNSS reflectometry，GNSS-R）探测对接收机通道数量的需求。统计结果表明：LEO卫星轨道越高，天线视场越大，反射事件越多，镜面反射点分布越稠密；轨道倾角越小，反射事件镜面点越趋于赤道地区分布；GNSS-R接收机所需通道数随LEO卫星轨道高度和下视天线视场范围增大而增加；而LEO卫星轨道倾角变化对通道数需求影响不明显。研究结果对GNSS-R低轨卫星系统设计具有一定的理论参考价值
强信号下GNSS接收机前端处理引起的相关损耗
Correlation loss caused by GNSS receiver front-end processing for strong signals
潘虹臣,寇艳红
- , 2016, DOI: 10.13700/j.bh.1001-5965.2015.0518
Abstract: 摘要 在全球导航卫星系统（GNSS）信号质量监测及GNSS射频（RF）信号模拟器测试等应用中，有用信号功率往往远高于噪声功率。针对二进制相位移位键控（BPSK）和二进制偏移载波（BOC）调制信号，首次研究了这种强信号条件下接收机带限滤波、采样和量化（BSQ）引起的相关损耗。首先分析了不考虑量化作用时由滤波和采样引起的损耗；然后分析了不考虑前端滤波时由量化和采样引起的损耗，推导了相关损耗的解析表达式并得到了量化器的最佳量化间隔；最后，对于滤波、采样、量化共同作用引起的损耗，采用蒙特卡罗方法仿真分析了GPS L1 C/A信号在不同滤波带宽和量化比特数下的归一化相关功率，探讨了根据仿真结果拟合相关损耗解析表达式的方法以简化分析。
Abstract：In the applications of global navigation satellite system (GNSS) signal quality monitoring and GNSS radio frequency (RF) signal simulator test, the power of the desired GNSS signal usually goes much higher above the noise floor. This paper investigates the correlation power loss of binary phase shife keying (BPSK) and binary offset carrier (BOC) signals caused by band-limiting, sampling and quantization (BSQ) processing under strong signal conditions. Firstly, the correlation power loss caused by band-limiting and sampling without quantization is studied, and then the loss caused by quantization and sampling without band-limiting is analyzed. Consequently the desired signal correlation loss under corresponding conditions is theoretically derived, and the optimal step size of the uniform quantizer with different quantization bit numbers is determined. Finally, for the combined effect of BSQ on the signal correlation power, Monte Carlo simulations are conducted to analyze the normalized correlator power with the configurations of different bandwidths and quantization bit numbers of a GPS L1 C/A receiver, from which a method of fitting an analytical expression of correlation power loss by using the simulation results is explored to simplify the analysis.
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