scholarly journals A New High-Resolution GPS Multipath Mitigation Technique Using Fast Orthogonal Search

2016 ◽  
Vol 69 (4) ◽  
pp. 794-814 ◽  
Author(s):  
Mohamed Tamazin ◽  
Aboelmagd Noureldin ◽  
Michael J. Korenberg ◽  
Ahmed M. Kamel
Keyword(s):  
High Resolution ◽  
Global Navigation Satellite Systems ◽  
Multipath Mitigation ◽  
Gps Receivers ◽  
Satellite Systems ◽  
Delay Locked Loop ◽  
Orthogonal Search ◽  
Fast Orthogonal Search ◽  
Global Navigation Satellite ◽  
Mitigation Technique

The Delay Locked Loop (DLL) tracking algorithm is one of the most widely used in GPS receivers. It uses different correlators such as the Early-Late Slope (ELS) correlator and High-Resolution Correlator (HRC) to mitigate code phase multipath. These techniques are effective for weak multipath environments but they may not be suitable for challenging multipath environments. The Multipath Estimating Delay Lock Loop (MEDLL) shows better performance than the classical methods. However, MEDLL still has limited capabilities in severe multipath environments. This paper introduces a robust multipath mitigation technique based on fast orthogonal search to obtain better delay estimation for GPS receivers. This research utilised a SPIRENT Global Navigation Satellite Systems (GNSS) simulator to compare the performance of the proposed method with other multipath mitigation techniques. Experimental results demonstrated that the performance of the proposed algorithm was better than the classical and advanced techniques under the multipath scenarios tested.

scholarly journals Suitability of Unmanned Aerial Vehicles for Cadastral Surveys

2019 ◽  
Vol 19 (1) ◽  
pp. 1-8
Author(s):  
S. Mantey
Keyword(s):  
High Resolution ◽  
Unmanned Aerial Vehicles ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Aerial Vehicles ◽  
High Resolution Images ◽  
The Difference ◽  
Cadastral Surveying ◽  
Difficult Terrain ◽  
Global Navigation Satellite

Cadastral surveys in Ghana often employ well known surveying equipment such as Total Station andGNSSreceivers or a combination of both. These survey techniques are well-established and widely accepted. However, there are limitations in certain areas. In situations where difficult terrain and inaccessible areas and dense vegetation are encountered or when surveyor’s life may be at risk, Unmanned Aerial Vehicles (UAVs) could be used to overcome the limitations of these well-established survey instruments. This research used high resolution images from UAV (DJI Phantom 4) to survey plots within the University of Mines and Technology land area. Coordinates of the boundary points were extracted using Agisoft Photoscan.GNSSreceivers were also used to survey the land and the same boundary point coordinates obtained and compared. This enabled the establishment of accurate ground control points for georeferencing. The coordinates obtained from both UAV andGNSSSurveys were used to prepare cadastral plans and compared. The difference in Northings and Eastings from UAV andGNSSsurveys were +0.380 cmand +0.351 cmrespectively. These differences are well within tolerance of +/-0.9114 m(+/-3 ft) set by the Survey and Mapping Division (SMD) of the Lands Commission for cadastral plans production. This research therefore concludes that high resolution images from UAVs are suitable for cadastral surveying. Keywords: Unmanned Aerial Vehicles, Drones, Global Navigation Satellite Systems, Cadastral Surveys

scholarly journals A Chip Scale Atomic Clock Driven Receiver for Multi-Constellation GNSS

2013 ◽  
Vol 66 (3) ◽  
pp. 449-464 ◽  
Author(s):  
Alper Ucar ◽  
Yacine Adane ◽  
Burak Bardak ◽  
Carlo Paparo ◽  
Reuben Berry ◽  
...  
Keyword(s):  
Rapid Development ◽  
Atomic Clock ◽  
Global Navigation Satellite Systems ◽  
Dual Band ◽  
Easy Access ◽  
Signal Acquisition ◽  
Multipath Mitigation ◽  
Satellite Systems ◽  
Dual Channel ◽  
Global Navigation Satellite

This paper presents the design and implementation of a Chip Scale Atomic Clock (CSAC) driven dual-channel Digitally Configurable Receiver (DCR) for Global Navigation Satellite Systems (GNSS). The receiver is intended to be used for research applications such as; multipath mitigation, scintillation assessment, advanced satellite clock and spatial frame transformation modelling, Precise Point Positioning (PPP) as well as rapid development and assessment of novel circuits and systems for GNSS receivers. A novel sub-Nyquist sampling (subsampling) receiver architecture incorporating dual-band microstrip RF filters is employed in order to minimize the complexity of the multi-frequency Radio Frequency (RF) front-end. Moreover, the digital receiver incorporates a novel and complexity-reduced Fast Fourier Transform (FFT) core for signal acquisition as well as COordinate Rotation DIgital Computer (CORDIC) cores for the code/carrier discriminators in order to minimize the resource allocation on the FPGA. The receiver also provides easy access to enable adjustment of its internal parameters such as; RF gain, position update rate, tracking channel correlator spacing and code/carrier loop noise bandwidth. Correlator outputs, code/carrier error, Carrier-to-Noise Ratio (C/N0), navigation and RINEX data are provided to the end-user in real-time. This paper collectively highlights and reports on the implementation, test and validation of the novel techniques, elements and approaches in both the RF and digital part of the DCR that comprise the multi-constellation receiver.

Modified High-Resolution Correlator Technique for Short-Delayed Multipath Mitigation

2009 ◽  
Vol 62 (3) ◽  
pp. 523-542 ◽  
Author(s):  
Hyoungmin So ◽  
Ghangho Kim ◽  
Taikjin Lee ◽  
Sanghoon Jeon ◽  
Changdon Kee
Keyword(s):  
High Resolution ◽  
Tracking Error ◽  
Satellite System ◽  
Test Results ◽  
Multipath Mitigation ◽  
Error Sources ◽  
Gnss Positioning ◽  
Multipath Signals ◽  
Global Navigation Satellite ◽  
Mitigation Technique

Multipath is one of the main error sources in global navigation satellite system (GNSS) positioning. The high-resolution correlator (HRC) is a multipath mitigation technique well known for its outstanding performance for mid-delayed multipath, but still has a remaining error for the short-delayed multipath. This paper proposes a modified HRC scheme that can remove or reduce the error for short-delayed multipath signals. It estimates the HRC tracking error and augments the conventional HRC with the estimates. The method was implemented with a software receiver and the test results show short-delayed multipath-induced errors were reduced to about one third of those from the conventional HRC.

scholarly journals QUICK 3D WITH UAV AND TOF CAMERA FOR GEOMORPHOMETRIC ASSESSMENT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 259-264
Author(s):  
A. Masiero ◽  
G. Sofia ◽  
P. Tarolli
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Low Cost ◽  
Wide Band ◽  
Global Navigation Satellite Systems ◽  
3D Reconstructions ◽  
Satellite Systems ◽  
Close Range ◽  
Tof Camera ◽  
Global Navigation Satellite

Abstract. Most of the high resolution topographic models are currently obtained either by means of Light Detection and Ranging (LiDAR) or photogrammetry: the former is usually preferred for producing very accurate models, whereas the latter is much more frequently used in low cost applications. In particular, the availability of more affordable Unmanned Aerial Vehicles (UAVs) equipped with high resolution cameras led to a dramatic worldwide increase of UAV photogrammetry-based 3D reconstructions. Nevertheless, accurate high resolution photogrammetric reconstructions typically require quite long data processing procedures, which make them less suitable for real-time applications.This work aims at investigating the use of a low cost Time of Flight (ToF) camera, combined with an Ultra-Wide Band (UWB) positioning system, mounted on a drone, in order to enable quasi real time 3D reconstructions of small to mid-size areas, even in locations where Global Navigation Satellite Systems (GNSSs) are not available.The proposed system, tested on a small area on the Italian Alps, provided high resolution mapping results, with an error of few centimeters with respect to a terrestrial close-range photogrammetry survey conducted on the same day.

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