scholarly journals Design and Simulation of a Fully Digitized GNSS Receiver Front-End

2011 ◽  
Vol 2011 ◽  
pp. 1-11
Author(s):  
Yuan Yu ◽  
Qing Chang ◽  
Yuan Chen
Keyword(s):  
Sampling Rate ◽  
Sampling Technique ◽  
Navigation Systems ◽  
Front End ◽  
Optimal Value ◽  
Gnss Receivers ◽  
Rate Selection ◽  
Near Future ◽  
Global Navigation Systems ◽  
Rf Sampling

In the near future, RF front-ends of GNSS receivers may become very complicated when multifrequency signals are available from at least four global navigation systems. Based on the direct RF sampling technique, fully digitized receiver front-ends may solve the problem. In this paper, a direct digitization RF front-end scheme is presented. At first, a simplified sampling rate selection method is adopted to determine the optimal value. Then, the entire spectrum of GNSS signal is directly digitized through RF sampling at a very fast sampling rate. After that, the decimation and filtering network is designed to lower the sampling rate efficiently. It also realizes the digital downconversion of the signal of interest and the separation of narrow band signals from different navigation systems. The scheme can be flexibly implemented in software. Its effectiveness is proved through the experiment using simulated and true signals.

DDC Design for Multi-Frequency Receiver Based on RF Sampling

2014 ◽  
Vol 651-653 ◽  
pp. 413-416
Author(s):  
Chun Yang Han ◽  
Wei Sun ◽  
Gui Xin Han
Keyword(s):  
Sampling Rate ◽  
Software Radio ◽  
Sampling Technique ◽  
High Sensitivity ◽  
Local Oscillator ◽  
High Signal ◽  
High Sampling Rate ◽  
Stable Performance ◽  
Down Conversion ◽  
Rf Sampling

Multi-frequency receivers rely on GNSS to achieve high-precision positioning, high sensitivity and other functions. GNSS signal frequencies are widely distributed around 1.1GHz to 1.6GHz. Good performance RF front-end receiver will provide high-quality acquisition and tracking environment, reducing the SER to ensure CNR. RF sampling technique is widely used in software radio for its simple structure, flexible configuration, and other advantages, but rarely used in satellite navigation, because the high signal carrier frequency and sampling rate, down-conversion based on RF sampling becomes a big challenge. So, to solve the problems of widely distributed we design three signal bands, using different local oscillator to implement signal down-conversion; to solve the problems of high sampling rate, we propose a down-conversion program of using a cascade of CIC filter’s ployphase and FIR compensation filter. Through the simulation of MATLAB after tracking tests, analysis of CNR and other indicators of programs. Ultimately, we implement the program with Verilog language on the multi-frequency GNSS receiver. The results show that this scheme can achieve digital down-conversion and stable performance of tracking loop with less consumption of resources.

The PPP data processing algorithm to create geodetic networks

2021 ◽  
pp. 464-468
Author(s):  
A.D. Tikhonov ◽  
A.A. Kochiev
Keyword(s):  
Data Processing ◽  
Processing Algorithm ◽  
Navigation Systems ◽  
Geodetic Networks ◽  
Data Processing Algorithm ◽  
Global Navigation ◽  
Global Navigation Systems

The article deals with determination of coordinates using global navigation systems, and application of the PPP data processing algorithm to obtain coordinates. The authors conducted an experiment illustrating the algorithm accuracy.

scholarly journals Assessment of the Implementation of GNSS into Gliding

2017 ◽  
Vol 5 (4) ◽  
pp. 6
Author(s):  
Tomáš Kubáč ◽  
Jakub Hospodka
Keyword(s):  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Navigation Systems ◽  
Satellite Systems ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
Global Navigation Systems ◽  
Usage Preference ◽  
Selection Of ◽  
Wide Usage

Global navigation satellite systems are increasingly part of our lives and many industries including aviation. Glider flying is no exception in this trend. Global navigation satellite systems were part of gliding since the early 1990s. First as official recording devices for simple evidence of sporting performances, then as navigation systems, anti-collision systems and emergency location transmitters. Development of recording application was initiated and supported by International Gliding Commission of World Air Sports Federation in way of certifications for flight recorders. The use of navigation and other modern instruments in gliders has brought many benefits but also risks. However, the advantages outweigh the disadvantages and these systems are now integral part of gliding. With this wide usage of global navigation satellite systems devices, there is great many possibilities how and in which way one can use these systems. Pilots must orient themselves in varied selection of products, which they can use to choose one solution, that fits him. Therefore, to find out how and if pilots use these devices, we created questionnaire survey among 143 Czech glider pilots. We found out, that 84% of them are using global navigation satellite systems devices for official record of flight and for navigation as well. More than half of pilots is using free, not built-in devices. Most common devices are mobile phones up to 5 inches of screen diagonal in combination with approved flight recorder without display. If pilots use mobile device for navigation, 52% of them is using one with Windows Mobile operating system, 33% use Android. Navigational software on these mobile devices is then almost tied between SeeYou Mobile, XCSoar and LK8000. Knowledge about usage preference of global navigation systems devices should help pilots with selection and overall orientation in subject.

Increasing the Resistance of GPS Receivers by Using a Fuzzy Smart Estimator in Weak Signal Conditions

2020 ◽  
Vol 73 (5) ◽  
pp. 991-1013
Author(s):  
M. A. Farhad ◽  
M. R. Mosavi ◽  
A. A. Abedi ◽  
K. Mohammadi
Keyword(s):  
Kalman Filter ◽  
Simulated Data ◽  
Real Data ◽  
Navigation Systems ◽  
Weak Signal ◽  
Signal Tracking ◽  
Advantages And Disadvantages ◽  
Vector Tracking ◽  
Gnss Receivers ◽  
Satellite Navigation Systems

Global satellite navigation systems (GNSS) are nowadays used in many applications. GNSS receivers experience limitations in receiving weak signals in a degraded environment. Hence, tracking weak GNSS signals is a topic of interest to researchers in this field. Different methods have been proposed to address this issue, each of which has advantages and disadvantages. In this paper, a method based on the vector tracking method is proposed for weak signal tracking. This method has been developed based on a strong Kalman filter instead of the extended Kalman filter used in conventional vector tracking methods. In order to adjust important parameters of this filter, the fuzzy method is used. The results of tests performed with both simulated data and real data demonstrate that the proposed method performs better than previous ones in weak signal tracking.

Improvement of Reception and Transmission Performance on Early Warning System for Multi Country with QZSS Augmentation Signal

2015 ◽  
Vol 10 (2) ◽  
pp. 373-385
Author(s):  
Daisuke Iwaizumi ◽  
◽  
Shota Iino ◽  
Hiroki Satoh ◽  
Mitsuaki Takaishi ◽  
...  
Keyword(s):  
Large Scale ◽  
Warning System ◽  
Satellite Orbits ◽  
Navigation Systems ◽  
Common Information ◽  
Information Infrastructures ◽  
Disaster Information ◽  
Gnss Receivers ◽  
System Prototype ◽  
System Effectiveness

Information blackout may occur in which it becomes difficult to obtain required information because information infrastructures have been destroyed. Infrastructures for providing disaster information are vulnerable in some Asian regions, so it is vital to cover such blanks to minimize damage. Much attention has been given to a method for communicating disaster information to GNSS receivers installed on cell phones and in car navigation systems. Augmentation of signals from quasi-zenith satellite (QZS) are used independent of terrestrial information infrastructures. Information capacity using QZS augmentation signals is low, however, and elevation angles in some Asian countries varies due to satellite orbits, meaning that the methods of the distribution and reception performance of disaster information should be investigated. This study has the objective of formulating a system for distributing disaster information using augmentation signals from QZS, the system prototype. This prototype was designed for large-scale disasters across multiple Asian and Oceanic regions such as Indian Ocean tsunamis. The system’s effectiveness is evaluated in distribution and receiving performance, so the designed message formats and resulting distribution schedule show system effectiveness in of distribution performance. In simultaneous receiving experiments in two countries, common information and area- and country-based information were received, indicating the effectiveness of the system in receiving performance across multiple countries.

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