PPP for Hydrography
Ashraf Abdallahvisibility
…
description
17 pages
link
2 files
Sign up for access to the world's latest research
checkGet notified about relevant papers
checkSave papers to use in your research
checkJoin the discussion with peers
checkTrack your impact
Abstract
A new high accuracy technique using one dual frequency GNSS receiver, precise point positioning (PPP) offers the possibility of cost effectively obtaining coordinates. This study investigates the accuracy of kinematic PPP for hydrographic applications on rivers, and shows results comparable to double-difference solutions.
Related papers
Kinematic Precise Point Positioning (PPP) Solution for Hydrographic Applications
Precise Point Positioning (PPP) has been one of the major research areas in surveying in recent years to obtain cost effectively coordinates using one dual frequency GNSS instrument. The purpose of this study is to investigate the accuracy of the kinematic PPP solution using Bernese software for hydrographic applications. This PPP solution was compared with the double-difference solution from Bernese software. The Virtual SAPOS (SAtellitenPOSitionierungsdienst der deutschen Landesvermessung) reference station was considered as a reference station. Two kinematic trajectories have been observed within project “HydrOs (Integrated Hydrographic Positioning System) on the Rhine River, Duisburg, Germany. This project is launched in co-operation of the department M5 (Geodesy) of the German Federal Institute of Hydrology (BfG) and the Institute of Engineering Geodesy at the University of Stuttgart (IIGS). The first kinematic trajectory shows a standard deviation for the kinematic PPP solution of 6 cm in East, 2.1 cm in North, and 6.8 cm in height. If the 5% of the measurements are eliminated as outliers, the standard deviation values for a confidence level of 95% (SD95%) are 5 cm in East, 1.2 cm in North and 5 cm in height. The second trajectory, which started with 40 minutes of quasi-static observation time (non-moving vessel), achieves a more precise solution. The standard deviation values of all measurement are 1.7 cm in East, 2.6 cm in North, and 4.9 cm in height. For a confidence level of 95%, the PPP solution provides a standard deviation (SD95%) of 1.5 cm for the East and North directions. Moreover, it delivers 3 cm for the height.
KINEMATIC-PPP USING SINGLE/DUAL FREQUENCY OBSERVATIONS FROM (GPS, GLONASS AND GPS/GLONASS) CONSTELLATIONS FOR HYDROGRAPHY
Journal of artificial satellites Vol. 53, No. 1, 2018
Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. Precise point positioning (PPP) is a technique used for position computation with a high accuracy using a single GNSS receiver. It relies on highly accurate satellite position and clock data that can be acquired from different sources such as the International GNSS Service (IGS). PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of observations among other factors. PPP offers comparable accuracy to differential GPS with safe in cost and time. For many years, PPP users depended on GPS (American system) which considered the solely reliable system. GLONASS's contribution in PPP techniques was limited due to fail in maintaining full constellation. Yet, GLONASS limited observations could be integrated into GPS-based PPP to improve availability and precision. As GLONASS reached its full constellation early 2013, there is a wide interest in PPP systems based on GLONASS only and independent of GPS. This paper investigates the performance of kinematic PPP solution for the hydrographic applications in the Nile river (Aswan, Egypt) based on GPS, GLONASS and GPS/GLONASS constellations. The study investigates also the effect of using two different observation types; single-frequency and dual frequency observations from the tested constellations.
Study on the Positioning Accuracy of GNSS/INS Systems Supported by DGPS and RTK Receivers for Hydrographic Surveys
Energies
Hydrographic surveys, in accordance with the International Hydrographic Organization (IHO) S-44 standard, can be carried out in the following five orders: Exclusive, Special, 1a, 1b and 2, for which minimum accuracy requirements for the applied positioning system have been set out. They are as follows, respectively: 1, 2, 5, 5 and 20 m, with a confidence level of 95% in two-dimensional space. The Global Navigation Satellite System (GNSS) network solutions (accuracy: 2–3 cm (p = 0.95)) and the Differential Global Positioning System (DGPS) (accuracy: 1–2 m (p = 0.95)) are now commonly used positioning methods in hydrography. Due to the fact that a new order of hydrographic surveys has appeared in the IHO S-44 standard from 2020—Exclusive, looking at the current positioning accuracy of the DGPS system, it is not known whether it can be used in it. The aim of this article is to determine the usefulness of GNSS/Inertial Navigation Systems (INS) for hydrographic surveys. During the resear...
Performance Comparison among Multi-GNSS Single Frequency Precise Point Positioning Techniques
Kartografija i geoinformacije, 2019
Precise Point Positioning (PPP) is a technique able to compute high accuracy positioning anywhere using a single GNSS receiver and without the need for corrections from reference stations. A wide range of possible PPP algorithms, using different correction models and processing strategies, exist for both post-processing and real-time applications. PPP relies on accurate satellite and clock data, with the use of precise carrier-phase measurements. Single Frequency-PPP (SF-PPP) is currently under investigation by the scientific community, owing to its cheap implementation with respect to classical differential positioning and multi-frequency un-differenced techniques. Unfortunately, the carrier-phase observable is ambiguous by an a priori unknown integer number of cycles, called ambiguity, which is difficult to resolve with SF receivers. The aim of this paper was to study the opportunity provided by the use of a multi-GNSS constellation applied to two widespread SF-PPP models, based on different carrier-phase and code observable combinations. The algorithms were tested using static data collection carried out in an opensky scenario. The results show decimeter level accuracy on the horizontal and vertical components of the position.
Precise Point Positioning (PPP) using Low- Cost and Ultra-Low-Cost GNSS Receivers
Institute of Navigation, 2017
He has a strong focus on the use of Global Navigation Satellite Systems (GNSSs) for a number of precise positioning and navigation applications such as satellite orbit determination and GNSS surveying. His Ph.D. research involves expanding York-PPP engine to provide an ambiguity resolved (AR) solution, utilization of the estimated slant ionospheric term for instantaneous re-convergence and examining the interoperability, as well as combination of the different PPP-AR products. ABSTRACT Few decimetre to metre level accuracy is possible using the cellphone grade GNSS hardware. Current low-cost and ultra-low-cost (cellphone) GNSS receivers have no dual-frequency observables to form linear combination, in-order to account for the ionospheric delay. Global Ionospheric Maps (GIM) are used to mitigate the ionospheric error. Signal-to-noise ratio (í µí° ¶ í µí± 0 ⁄) of cellphone antenna is on average 7.5 dB-Hz low compared to the geodetic-grade antenna which depicts that the quality of the raw observations from cellphone GNSS hardware is of low quality compared to the raw observables from geodetic-grade and u-blox hardware. Raw measurement analysis (í µí° ¶ í µí± 0 ⁄) and post-fit residuals show that signal from cellphones are more prone to multipath compared to signals from geodetic-grade and u-blox receivers. The primary reason for multipath is circular polarized antenna in the cellphones. Irregular gain pattern and poor multipath suppression of cellphone antenna is also the primary reason for the slow convergence of Precise Point Positioning (PPP) solution compared to PPP solution with geodetic-grade hardware. Positioning results from cellphone processing are inferior to the geodetic-grade hardware. However, horizontal and vertical RMS of 37 cm and 51 cm, respectively, is achieved using cellphone.
Precise Point Positioning (PPP): Method and its Geodetic Usage
Journal on Geoinformatics, Nepal
Combining the precise satellite positions and clocks correction with dual-frequency GNSS receiver, PPP is able to provide position solutions at centimeter- decimeter level. PPP can be regarded as a global positioning approach because its position solutions referred to a global reference frame. As a result, PPP provides much greater positioning consistency than the differential approach in which position solutions are relative to the local base station or stations. Due to this, today PPP has been the demand of large number of market.
Cost-Effective GNSS Hardware for High-Accuracy Surveys and Its Prospects for Post-Processed Kinematic (PPK) and Precise Point Positioning (PPP) Strategies
2020
This dissertation determines for the first time the vertical accuracy achievable with low-cost mass-market multi-frequency, multi-GNSS (LM3GNSS) receivers, and antennas in the context of Ellipsoid Reference Survey (ERS), usually employed in bathymetric operations aboard survey platforms. LM3GNSS receivers are relatively new in the market, and their emergence is driven by the automobile industry and several mass-market applications requiring location-based solutions at high accuracies. It is foreseeable that emerging hydrographic survey platforms such as autonomous surface vehicles, small unmanned aircraft, crowd-sourced bathymetric platforms, and offshore GNSS buoy will find LM3GNSS receivers attractive since they are power- and cost-effective (often less than $1,000 per unit). Previous studies have shown that some mass-market GNSS receivers\u27 positioning accuracy is at the sub-meter level in some positioning strategies, but the authors rarely discussed the vertical accuracy. In r...
Comparative Study between Precise Point Positioning (PPP) Versus Relative Positioning
2018
With the development of the International GNSS Service, whose primary object is to provide highest quality data and products for research, education and multidisciplinary application, the concept of Precise Point Positioning began to receive more and more interest on the problem called “positioning”. Nowadays because of this development, the PPP technique it started to grow on the detriment of the relative GNSS positioning. PPP, it is able to offer point determination by processing undifferenced dual frequency receiver, combine with precise orbit and clock corrections offered by IGS to obtain centimeter accuracy. The aim of this paper is to make a comparative study between Precise Point Positioning (PPP) versus relative positioning under different conditions. The conditions or constrains used in this study are observation period and base line length. We apply base line technique in relative solution to spot the errors without adjustment that applied in network technique.
Accuracy Assessment Study of GNSS Precise Point Positioning for Kinematic Positioning
GNSS Precise Point Positioning (PPP) technique has received a great deal of attention from scientists in the last few years. The aim of this study is to evaluate the accuracy and the initialization time of PPP solutions compared to Precise Differential GPS (PDGPS) solutions. SAPOS stations were considered as reference solutions were estimated using GIPSY-OASIS software and CSRS-PPP online service. Two kinematic trajectories have been observed in Stuttgart, Germany. The observations started with 60 minutes static data acquisition as initialization time. The static data was followed by 30 minutes of kinematic measurement. PPP solutions were evaluated with different periods for the initialization time (zero to sixty minutes) to establish the OASIS software as well as CSRS-PPP online service achieved a RMSE in 3 dimensions of 10 cm from 10 minutes initialization time. The second data set had cycle slip problems during the observation process. CSRS-PPP provided a reliable solution beginning with 20 minutes initialization time. Regarding GIPSY-OASIS software different tropospheric models and approaches were tested in the study to improve the non-reliable service solution, provides a RMSE of 5 cm in horizontal directions and below 15 cm in height direction from 10 minutes initialization time.
Sub-Metre Accuracy for Stand Alone GPS Positioning in Hydrographic Surveying
The accuracy that can be achieved by a single GPS receiver in stand-alone mode is around 10 metres with SA switched off; this is not adequate for most hydrographic studies. This study aims to improve this level of accuracy using a single geodetic receiver in stand-alone mode by applying a phase smoothing algorithm. The algorithm described in this study requires that the measurements be started from a known point for initialisation. The test site selected for the study is Halic bay, Istanbul. After GPS data were collected on a geodetic point for initialisation, the receiver was moved to a hydrographic vessel and trial measurements were performed along several survey profiles. The position of the vessel was calculated at every epoch using the carrier phase smoothing algorithm. In order to analyse the accuracy of the results, a second receiver collected data on another known point on the seashore during the whole session. The position of the vessel was accurately determined using a kinematic positioning method considering the data collected by both receivers. The results produced show that an accuracy of less than a metre can be achieved using the approach considered in this study.
See discussions, stats, and author profiles for this publication at: http://www.researchgate.net/publication/287771154
PPP for Hydrpgraphy
ARTICLE in GPS WORLD · DECEMBER 2015
READS
6
2 AUTHORS:
Ashraf Talaat Abdallah
Volker Schwieger
9 PUBLICATIONS 2 CITATIONS
36 PUBLICATIONS 98 CITATIONS
Universität Stuttgart
SEE PROFILE
Universität Stuttgart
SEE PROFILE
Available from: Ashraf Talaat Abdallah
Retrieved on: 30 December 2015
16.12.2015
PPP for Hydrography : GPS World
Follow Us
Search the Site...
subscribe
OEM
UAV
Survey
Mapping
GNSS
Defense
Mobile
Machine Control/Ag
Transportation
More
The Almanac
Buyers Guide
Events
Innovation
Magazine Archive
Opinions
Upcoming GNSS Satellite Launches
Webinars
Navigate to ...
http://gpsworld.com/pppforhydrography/
1/16
16.12.2015
PPP for Hydrography : GPS World
PPP for Hydrography
December 15, 2015 By GPS World staff
Share this:
Facebook
Twitter
Google
LinkedIn
0 Comments
A new highaccuracy technique using one dualfrequency GNSS receiver, precise point positioning (PPP)
offers the possibility of costeffectively obtaining coordinates. This study investigates the accuracy of
kinematic PPP for hydrographic applications on rivers, and shows results comparable to double
difference solutions.
By Ashraf Abdallah and Volker Schwieger
Duisburg Harbor, Germany: site of the PPP
survey.
Precise Point Positioning (PPP) is a challenging surveying technique for highaccuracy results. It offers the
advantage of using one dualfrequency GNSS instrument. Estimation of a PPP solution is based on the
ionospherefree linear combination for code data and carrierphase data.
http://gpsworld.com/pppforhydrography/
2/16
16.12.2015
PPP for Hydrography : GPS World
Bernese Software. Bernese software V. 5.2 is a GNSS postprocessing software, using GNSS measurement
data for static and kinematic surveying. It processes the data in doubledifference (differential GNSS) and zero
difference (PPP solution) techniques. The software was developed at the Astronomical Institute of the
University of Bern.
Bernese software contains a group of different tools or programs to complete the processing for double
difference or zerodifference mode. The estimation of the two techniques has the same processing schedule in
most of the preprocessing stages. The change appears later within the parameter estimations section.
As shown in Figure 1, the processing starts with downloading the related orbits from the CODE (Center for
Orbit Determination in Europe) FTP server. The orbit tools include the updating of the Earth orientation
parameters to be in Bernese format, converting the satellite data to a specific format and generating the standard
orbit format for Bernese software. A preprocessing program contains the smoothing of the RINEX data from
outliers and cycle slips.
Figure 1. Bernese software processing schedule.
This smoothing step is following by converting the RINEX into Bernese binary format. The receiver clock is
synchronized with respect to the GPS time and stored to observation files using clock synchronization tools.
Using the code solution, a kinematic file is written to be inserted in the next parameter estimation procedure.
For doubledifference solution, a baseline is created, and this baseline is corrected from cycle slips for phase
data. Parameter estimation is carried out by leastsquare estimation for the phase and code GNSS observations.
Kinematic PPP Solution. Bernese software provides the possibility to obtain the PPP solutions in automatic
script (Bernese Protocol Engine [BPE]). The satellite orbit and clock ephemeris data from CODE center were
used with intervals of 5 seconds to obtain highly accurate results. Satellite and receiver phase center offsets are
considered. Tropospheric correction is applied using the Global Mapping Function (GMF) model for the
hydrostatic and wet delay estimation. Regarding ionospheric correction, the estimation of the PPP solution is
based on the linear ionosphericfree combination, with highorder ionospheric parameters to improve the
estimation.
The ocean tidal loading correction is considered in the PPP estimation. Atmosphere tidal loading is also
http://gpsworld.com/pppforhydrography/
3/16
16.12.2015
PPP for Hydrography : GPS World
corrected.
Figure 2 gives the analysis flowchart. Some outputs of the PPP solution could be visualized, such as the satellite
phase and code residuals. The high residuals might come from the lower elevation angles of the satellites.
Moreover, the residuals appear because of the effect of the remaining observation errors, such as atmospheric
delay, multipath, or even the satellite orbit and clock residuals.
Figure 2. Flowchart of analysis strategy.
Regarding kinematic PPP solution, the error values in the east, north and ellipsoidal height are calculated with
respect to the doubledifference solution from Bernese software. The rootmeansquare (RMS) error, which
refers to the doubledifference solution, and the standard deviation (SD), which is related to the mean value of
the PPP solution error, are calculated, and the frequency histogram is plotted.
An antenna and a receiver were mounted on the
surveying vessel to collect the GNSS data with an
interval of 1 second during two days.
Experimental Work. Two kinematic trajectories were observed on the Rhine River in Duisburg, Germany, as a
part of the project “HydrOs — Integrated Hydrographical Positioning System.” The project was launched in
cooperation with Department M5 (Geodesy) of the German Federal Institute of Hydrology (BfG) and the
http://gpsworld.com/pppforhydrography/
4/16
16.12.2015
PPP for Hydrography : GPS World
Institute of Engineering Geodesy at the University of Stuttgart (IIGS) .
An antenna and a receiver were mounted on the surveying vessel (inset photo, opener) to collect the GNSS data
with an interval of 1 second during two days. The virtual SAPOS (SAtellitenPOSitionierungsdienst der
deutschen Landesvermessung) reference station was considered as a reference station, provided from the
SAPOSNRW team. SAPOS is a continuously operating reference station (CORS) GNSS service collecting
data throughout Germany.
Results and Discussions
The layout of the first trajectory, which was observed for more than three hours, is presented in Figure 3. The
measurements started from the inner harbour in Duisburg. The left figure shows the overview layout, and the
right figure illustrates a zoomin of the trajectory below two bridges. The white line refers to the kinematic PPP
trajectory; the crosshatched white line shows interpolated points between two solved points from the PPP
solution. Because of loss of GNSS signals from the bridges, the yellow line indicates the actual vessel trajectory
below bridges.
http://gpsworld.com/pppforhydrography/
5/16
16.12.2015
PPP for Hydrography : GPS World
Figure 3. Layout of the first trajectory [DOY: 2014/126], zoomin on bottom. (Photos: Google Earth)
As mentioned before, the doubledifference solution of the Bernese software is considered as the reference
solution for the PPP solution. The PPP residuals for phase and code observations (not using doubledifference
solution) are presented in Figure 4. Here the residual values in phase and code have a gap because of the loss of
GNSS signals, which starts from epoch 438 to 486 [GPS week second = 199845: 200115]. Additionally, there
are some cycle slips from epoch 883 to 892 [GPS week second = 202105: 202150].
Figure 4. Satellite residuals for the first trajectory [DOY: 2014/126].
http://gpsworld.com/pppforhydrography/
6/16
16.12.2015
PPP for Hydrography : GPS World
To assess the accuracy of the PPP solution for this hydrographic trajectory, Figure 5 illustrates the analysis
results for this trajectory between the doubledifference and PPP solutions. The Xaxis refers to the number of
observations (one epoch/5 seconds), and the Yaxis indicates the error value in meters. Figure 5.1 shows the
error plot (m) in east, north and height. As shown previously, the error values have a gap in the solution because
of the loss of lock below the bridges. Moreover, there are some cycle slips later on, which decrease the
estimated kinematic PPP accuracy.
Figures 5.2 and 5.3 provide the error plot for the east and north and east and height directions. The blue points
refer to the errors, and the red cross refers to the mean value. Table 1 summarizes the PPP results.
Table 1. Statistical results of the first trajectory [DOY: 126/2014].
Five percent of the PPP errors are eliminated to get outlierfree results. The SD (95%) of the kinematic PPP
solution is obviously improved to reach 5.0 cm, 1.20 and 5.0 cm in east, north and height directions,
respectively.
To distinguish between the standard deviation and the standard deviation based on 95 percent of the data, Figure
5 shows additionally the histogram of SD in Figures 5.4, 5.5 and 5.6 for east, north and height respectively.
Figures 5.7, 5.8 and 5.9 provide the error with 95 percent of the results. Absolutely, the error range is improved
by eliminating 5 percent of the data including outliers.
http://gpsworld.com/pppforhydrography/
7/16
16.12.2015
http://gpsworld.com/pppforhydrography/
PPP for Hydrography : GPS World
8/16
16.12.2015
PPP for Hydrography : GPS World
Figure 5. Analysis results for the first trajectory. Standard deviations shown in plots on the left, with
outliers excluded, right.
Second Data Set. The second trajectory on the Rhine River was observed [DOY: 127] for more than 5 hours
(see Figure 6). Sixteen satellites were observed during the measurement time.
Figure 6. Layout of the second trajectory [DOY: 127/2014]. (Photo: Google Earth)
In Figure 7, the phase and code residuals are plotted. Some outliers are reported in this graph, which refers to
cycle slips during the observations.
http://gpsworld.com/pppforhydrography/
9/16
16.12.2015
PPP for Hydrography : GPS World
Figure 7. Satellite residuals for the second trajectory [DOY: 127/2014].
Figure 8 illustrates the PPP results for this kinematic trajectory. Figure 8.1 shows the PPP error values in the
east, north and height directions with respect to the doubledifference solution from Bernese software.
http://gpsworld.com/pppforhydrography/
10/16
16.12.2015
PPP for Hydrography : GPS World
Figure 8. Kinematic PPP solution for the second trajectory. Standard deviations shown in plots on the
http://gpsworld.com/pppforhydrography/
11/16
16.12.2015
PPP for Hydrography : GPS World
left, with outliers excluded, right.
The first 40 minutes of that trajectory were realized in a quasistatic observation technique (nonmoving vessel)
from GPS week second 281660: 284060. The result obtained from this solution is more accurate due to the high
number of satellites, and the trajectory did not include the bridges area. Figure 8.2 and 8.3 show errors in east
and north, and east and height.
As shown in Table 2, the maximum and minimum values for the error range, which are presented in detail in
Figure 8.4, 8.5 and 8.6, are reported in the east, north and height directions. These figures show the frequency
histogram for the PPP errors. The RMS error from the solution is 2.10 cm and 2.90 cm in east and north
respectively, with an RMS error of 5.60 cm in height. The standard deviation is definitely improved after
eliminating 5 percent of the PPP errors as outliers. The standard deviation for 95 percent of the results shows
1.5 cm in east and north and 3 cm in height. The error histograms for 95 percent of the data are provided in
Figures 8.7, 8.8 and 8.9.
Table 2. Statistical results of the second trajectory [DOY: 127/2014].
The second trajectory clearly provides a higher accuracy than the first. Its data has a higher number of satellites
and lower outliers than the first. Figure 8 shows the histogram of the second trajectory is similar to the Gaussian
distribution curve.
Acknowledgments
The authors would like to thank Annette Scheider for receiving the GNSS measurements through the HydrOs
project, our BfG partners Harry Wirth and Marc Breitenfeld, and Bernhard Galitzki form SAPOSNRW for
providing us with the reference stations.
This article is based on a peerreviewed paper presented at the FIG Working Week, May 2015, in Sofia,
Bulgaria.
Manufacturers
A Leica 1203+ antenna and GX1230+ GNSS receiver collected the data shown here.
Ashraf Abdallah is an assistant lecturer in engineering, Aswan University, Egypt, and a Ph. D. student at the
Institute of Engineering Geodesy (IIGS), Stuttgart University, Germany. He received a master’s degree from
Aswan University in applications of singlefrequency GNSS.
Volker Schwieger is a full professor at the University of Stuttgart and director of the IIGS. He received a Ph.D.
from the University of Hannover, focusing on GPS for monitoring applications.
Share this:
http://gpsworld.com/pppforhydrography/
12/16
16.12.2015
PPP for Hydrography : GPS World
Facebook
Twitter
Google
LinkedIn
Related Articles
SP80 under cover in Chile’s rainforests
GNSS monitoring scrapes the sky
NVS Technologies Releases L1 RTK Receiver
ComNav Releases Receiver and GNSS OEM Board
Satlab Offers Hydrographic Echo Sounder for GNSS Rover
This article is tagged with GNSS receiver, hydrography, postprocessing, PPP, precise point positioning, rivers
and posted in Featured Stories, From the Magazine, Survey
About the Author: GPS World staff
GPS World covers all aspects of the GPS and GNSS industry for our readers. To submit news, please send your
release to [email protected].
Subscribe to GPS World
If you enjoyed this article, subscribe to GPS World to receive more articles just like it.
Post a Comment
Name ( required )
Email ( required; will not be published )
Website
Submit Comment
http://gpsworld.com/pppforhydrography/
13/16
16.12.2015
PPP for Hydrography : GPS World
Notify me of followup comments by email.
Notify me of new posts by email.
Today's News
more news
Galileos in the zone for Thursday’s launch News from the European Space Agency Galileos 11 and 12...
Read more» Dec 15, 2015 | 0 Comments
Septentrio introduces nextgeneration GNSS reference receiver — PolaRx5 Septentrio has launched its
nextgeneration GNSS receiver for precise scientific and geodetic... Read more» Dec 14, 2015 | 0
Comments
FAA unveils UAS rule, begins drone registry Dec. 21 The Federal Aviation Administration announced on
Dec. 14 an official... Read more» Dec 14, 2015 | 0 Comments
FLYPRO announces smartwatchcontrolled XEagle drone Shenzhen FLYPRO Aerospace Tech Co. has
officially released the XEagle, an unmanned... Read more» Dec 11, 2015 | 3 Comments
http://gpsworld.com/pppforhydrography/
14/16
16.12.2015
PPP for Hydrography : GPS World
About Us
Contact Us
Advertise
Digital Edition
Subscriber Services
http://gpsworld.com/pppforhydrography/
15/16
16.12.2015
PPP for Hydrography : GPS World
© 2015 North Coast Media LLC, All Rights Reserved.
Terms of Use
Privacy Policy
http://gpsworld.com/pppforhydrography/
16/16
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.
Related papers
Grammar and Syntax of Primary Art an Enquiry in Conceptual Anthropology
EXPRESSION quarterly journal, 2023
In the Search for a Precise Objective and True Definition of Systems
In the Search for a Precise Objective and True Definition of Systems, 2020
EU Enlargement in the Western Balkans: Strategies of Borrowing and Inventing
Journal of Balkans and Middle Eastern Studies 10 (3): 293-307., 2008
Can Online Instructional Strategies Improve Emotional Intelligence of Students in Basic Science? A Quasi Experimental Study
International Centre for Science, Humanities & Education Research Journal, 2024
A Critical Investigation of English Language Teaching in Bangladesh
English Today, 2018
Electrocortical and ocular indices of attention to fearful and neutral faces presented under high and low working memory load
Biological Psychology, 2012
CRM application in agricultural management in the Mekong delta
International Journal of Multidisciplinary Research and Management, 2019
Pohřby jedinců s postižením pohybového aparátu na pohřebišti kultury zvoncovitých pohárů v Kolíně, střední Čechy
Archeologické rozhledy
The Influence of Humor on the Attitudes and Behavior of Interns
Academy of Management Learning and Education (forthcoming)
Identity for sale: Construction of a national identity for the needs of tourism
Glasnik Etnografskog instituta SANU, 2008
Phytochemical, Antimicrobial and Heavy Metals Analyses of Sarcocephalus Latifolius Leave Extract
Applied Chemistry, 2018
Impact of Competition on the Financial Performance of Listed Deposit Money Banks in Nigeria
Journal of economics and sustainable development, 2015
Guayaquilia gen. nov., typified by Idriella cubensis
Mycotaxon, 2020
Characterization of Ventricular Tachycardia and Fibrillation Using Semantic Mining
Computer and Information Science, 2012
Does a Fundamentalist Mindset Predict a State or Trait Anxiety? The Covariate Role of Dogmatism
Journal of Religion and Health, 2020
Associations of physical activity levels and screen time with oral glucose tolerance test profiles in Singaporean women of reproductive age actively trying to conceive: the S‐PRESTO study
Diabetic Medicine, 2019
Improving the Management of Hypertension in Pediatric Hematopoietic Stem Cell Transplantation
Biology of Blood and Marrow Transplantation, 2013