scholarly journals GNSS Practice in Survey Department

2019 ◽  
Vol 17 (1) ◽  
pp. 55-60
Author(s):  
Sushmita Timilisina ◽  
Bibek Nepal
Keyword(s):  
Global Navigation Satellite System ◽  
Service Providers ◽  
Single Point ◽  
Control Point ◽  
Satellite System ◽  
Geodetic Survey ◽  
Navigation Satellite ◽  
Control Points ◽  
Global Navigation ◽  
Global Navigation Satellite

Control Networks for Nepal was originally defined through the use of conventional measurements. Conventional mapping methods have led to a static and inactive networks of control point. This network of control served us very well until the devastating earthquake hit Nepal and disturbed it. Determination of precise ground locations is essential for various tasks such as engineering works, earth observation, location-based technologies, emergency service providers, etc. Global Navigation Satellite System plays a very important role in providing quick and reliable positioning/navigation data. The term ‘global navigation satellite system’ (GNSS) refers to a constellation of satellites providing signals from space transmitting positioning and timing data. These systems use the principle of trilateration to calculate the location of a user, through the information obtained from a number of satellites. Each satellite transmits coded signals at precise intervals. In principle, three satellites must be available to determine a three-dimensional (x,y,z) position , additional fourth signal is necessary for precise location of a single point. This helps in eliminating the time differences between satellite’s atomic clocks and the receiver's clocks. USA in around 1970’s started the use of Global Positioning System(GPS). Geodetic Survey Division under Survey Department commenced the use of GPS technology in 1991 A.D as a method for survey technology. Survey Department initiated the use of GPS for carrying out survey of the previously established high order control points. Transformation Parameters (TP) between the National Co-ordinate System and WGS-84 System was derived using the initial Control points co-ordinate and co-ordinate of the same Control points obtained from GNSS survey. GNSS has been used for establishing, updating and rehabilitation of Control Network, measure shift in location produced by earthquake and for various survey task carried out by Survey Department.

Aircraft positioning using GPS/GLONASS code observations

2019 ◽  
Vol 92 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Kamil Krasuski ◽  
Janusz Cwiklak ◽  
Marek Grzegorzewski
Keyword(s):  
Global Navigation Satellite System ◽  
Single Point ◽  
Satellite System ◽  
Least Square ◽  
Navigation Satellite ◽  
Navigation Systems ◽  
Protection Level ◽  
Content Type ◽  
Global Navigation ◽  
Global Navigation Satellite

Purpose This paper aims to present the problem of the integration of the global positioning system (GPS)/global navigation satellite system (GLONASS) data for the processing of aircraft position determination. Design/methodology/approach The aircraft coordinates were obtained based on GPS and GLONASS code observations for the single point positioning (SPP) method. The numerical computations were executed in the aircraft positioning software (APS) package. The mathematical scheme of equation observation of the SPP method was solved using least square estimation in stochastic processing. In the research experiment, the raw global navigation satellite system data from the Topcon HiperPro onboard receiver were applied. Findings In the paper, the mean errors of an aircraft position from APS were under 3 m. In addition, the accuracy of aircraft positioning was better than 6 m. The integrity term for horizontal protection level and vertical protection level parameters in the flight test was below 16 m. Research limitations/implications The paper presents only the application of GPS/GLONASS observations in aviation, without satellite data from other navigation systems. Practical implications The presented research method can be used in an aircraft based augmentation system in Polish aviation. Social implications The paper is addressed to persons who work in aviation and air transport. Originality/value The paper presents the SPP method as a satellite technique for the recovery of an aircraft position in an aviation test.

Performance Evaluation of the CNAV Broadcast Ephemeris

2019 ◽  
Vol 72 (5) ◽  
pp. 1331-1344
Author(s):  
Ahao Wang ◽  
Junping Chen ◽  
Yize Zhang ◽  
Jiexian Wang ◽  
Bin Wang
Keyword(s):  
Global Navigation Satellite System ◽  
Single Point ◽  
Satellite Orbit ◽  
Satellite System ◽  
Single Frequency ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Navigation Message ◽  
Global Navigation ◽  
Global Navigation Satellite

The new Global Positioning System (GPS) Civil Navigation Message (CNAV) has been transmitted by Block IIR-M and Block IIF satellites since April 2014, both on the L2C and L5 signals. Compared to the Legacy Navigation Message (LNAV), the CNAV message provides six additional parameters (two orbit parameters and four Inter-Signal Correction (ISC) parameters) for prospective civil users. Using the precise products of the International Global Navigation Satellite System Service (IGS), we evaluate the precision of satellite orbit, clock and ISCs of the CNAV. Additionally, the contribution of the six new parameters to GPS Single Point Positioning (SPP) is analysed using data from 22 selected Multi-Global Navigation Satellite System Experiment (MGEX) stations from a 30-day period. The results indicate that the CNAV/LNAV Signal-In-Space Range Error (SISRE) and orbit-only SISRE from January 2016 to March 2018 is of 0·5 m and 0·3 m respectively, which is improved in comparison with the results from an earlier period. The ISC precision of L1 Coarse/Acquisition (C/A) is better than 0·1 ns, and those of L2C and L5Q5 are about 0·4 ns. Remarkably, ISC correction has little effect on the single-frequency SPP for GPS users using civil signals (for example, L1C, L2C), whereas dual-frequency SPP with the consideration of ISCs results have an accuracy improvement of 18·6%, which is comparable with positioning accuracy based on an ionosphere-free combination of the L1P (Y) and L2P (Y) signals.

scholarly journals A dynamic localization network for regional navigation under global navigation satellite system denial environments

2019 ◽  
Vol 15 (3) ◽  
pp. 155014771983442
Author(s):  
Hongwei Zhao ◽  
Yue Yan ◽  
Xiaozhu Shi
Keyword(s):  
Global Navigation Satellite System ◽  
Single Point ◽  
Satellite System ◽  
Navigation Satellite ◽  
Positioning Accuracy ◽  
Dynamic Localization ◽  
Localization System ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
Regional Augmentation

Global navigation satellite system signals are easily distorted by the interferences or disturbances, and global navigation satellite system receivers cannot offer continuous effective navigation results in challenging environments. As a representative regional augmentation technology, pseudolite has the potential to provide accurate positioning service to satisfy specific performance requirements in various applications. In this article, we developed a dynamic localization network based on pseudolite technology for regional augmentation navigation purpose. First, the collaborative positioning algorithm is given, and the architecture of localization system is proposed. Then the error sources of localization system are analyzed for performance evaluation. Finally, the proposed system is verified by experiments conducted in both static and kinenatic scenarios. The experiment results demonstrate that the positioning accuracy of the proposed localization system is nearly 10 m, which is close to the global navigation satellite system single-point positioning accuracy. Therefore, it can be used for emergency dynamic positioning of critical areas under the global navigation satellite system denial environments.

scholarly journals OutFin, a multi-device and multi-modal dataset for outdoor localization based on the fingerprinting approach

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Fahad Alhomayani ◽  
Mohammad H. Mahoor
Keyword(s):  
Global Navigation Satellite System ◽  
Urban Areas ◽  
Satellite System ◽  
Reference Points ◽  
Navigation Satellite ◽  
Data Types ◽  
Entry Barrier ◽  
Promising Alternative ◽  
Global Navigation ◽  
Global Navigation Satellite

AbstractIn recent years, fingerprint-based positioning has gained researchers’ attention since it is a promising alternative to the Global Navigation Satellite System and cellular network-based localization in urban areas. Despite this, the lack of publicly available datasets that researchers can use to develop, evaluate, and compare fingerprint-based positioning solutions constitutes a high entry barrier for studies. As an effort to overcome this barrier and foster new research efforts, this paper presents OutFin, a novel dataset of outdoor location fingerprints that were collected using two different smartphones. OutFin is comprised of diverse data types such as WiFi, Bluetooth, and cellular signal strengths, in addition to measurements from various sensors including the magnetometer, accelerometer, gyroscope, barometer, and ambient light sensor. The collection area spanned four dispersed sites with a total of 122 reference points. Each site is different in terms of its visibility to the Global Navigation Satellite System and reference points’ number, arrangement, and spacing. Before OutFin was made available to the public, several experiments were conducted to validate its technical quality.

Implementation of a Dual-Frequency GLONASS and GPS L1 C/A Software Receiver

2010 ◽  
Vol 63 (2) ◽  
pp. 269-287 ◽  
Author(s):  
S. Abbasian Nik ◽  
M. G. Petovello
Keyword(s):  
Global Navigation Satellite System ◽  
Critical Role ◽  
Satellite System ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Software Receiver ◽  
The Public ◽  
Global Navigation ◽  
Global Navigation Satellite

These days, Global Navigation Satellite System (GNSS) technology plays a critical role in positioning and navigation applications. Use of GNSS is becoming more of a need to the public. Therefore, much effort is needed to make the civilian part of the system more accurate, reliable and available, especially for the safety-of-life purposes. With the recent revitalization of Russian Global Navigation Satellite System (GLONASS), with a constellation of 20 satellites in August 2009 and the promise of 24 satellites by 2010, it is worthwhile concentrating on the GLONASS system as a method of GPS augmentation to achieve more reliable and accurate navigation solutions.

scholarly journals Computation Approach for Quantitative Dielectric Constant from Time Sequential Data Observed by CYGNSS Satellites

2021 ◽  
Vol 13 (11) ◽  
pp. 2032
Author(s):  
Junchan Lee ◽  
Sunil Bisnath ◽  
Regina S.K. Lee ◽  
Narin Gavili Kilane
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Global Navigation Satellite System ◽  
Measurement Data ◽  
Satellite System ◽  
Computation Method ◽  
Navigation Satellite ◽  
Local Soil ◽  
Global Navigation ◽  
Global Navigation Satellite

This paper describes a computation method for obtaining dielectric constant using Global Navigation Satellite System reflectometry (GNSS-R) products. Dielectric constant is a crucial component in the soil moisture retrieval process using reflected GNSS signals. The reflectivity for circular polarized signals is combined with the dielectric constant equation that is used for radiometer observations. Data from the Cyclone Global Navigation Satellite System (CYGNSS) mission, an eight-nanosatellite constellation for GNSS-R, are used for computing dielectric constant. Data from the Soil Moisture Active Passive (SMAP) mission are used to measure the soil moisture through its radiometer, and they are considered as a reference to confirm the accuracy of the new dielectric constant calculation method. The analyzed locations have been chosen that correspond to sites used for the calibration and validation of the SMAP soil moisture product using in-situ measurement data. The retrieved results, especially in the case of a specular point around Yanco, Australia, show that the estimated results track closely to the soil moisture results, and the Root Mean Square Error (RMSE) in the estimated dielectric constant is approximately 5.73. Similar results can be obtained when the specular point is located near the Texas Soil Moisture Network (TxSON), USA. These results indicate that the analysis procedure is well-defined, and it lays the foundation for obtaining quantitative soil moisture content using the GNSS reflectometry results. Future work will include applying the computation product to determine the characteristics that will allow for the separation of coherent and incoherent signals in delay Doppler maps, as well as to develop local soil moisture models.

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