Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of... more Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. The horizontal position requirements for marine surveys vary between a few decimetres and several tens of metres. To meet these requirements, different observation and processing techniques using pseudo-ranges and/or carrier phases must be employed. 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 using high cost dual frequency receivers. PPP using low cost GPS ...
In this study, satellite image obtained from Spot-5 (2.5 m) sensor was rectified by means of PPP-... more In this study, satellite image obtained from Spot-5 (2.5 m) sensor was rectified by means of PPP-GPS (Precise Point Positioning using Global Positioning System) and DGPS (Differential Global Positioning System). Rectification of Spot image was carried out using 8 GCPs (Ground Control Points) covering an area of 9.15 km. The coordinates for GCPs were obtained using two techniques; PPP and DGPS. The accuracy of the image rectification using both techniques was evaluated using 3 GCPs as check points. A satellite image obtained from Geoeye (0.50 m) sensor covering the same area was rectified by using (PPP-GPS) 8 GCPs and its accuracy assessed using 3 check points.
Google Earth is a virtual globe, map and geographical information software. It maps the Earth by ... more Google Earth is a virtual globe, map and geographical information software. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. GoogleEarth® has become recently the ultimate source of spatial data and information for private and public decision-support systems. GoogleEarth is a strong tool for precision agriculture. It could be used for farm planning, field mapping, soil sampling, crop scouting, crop health monitoring, variable rate applications, and yield mapping. Also, Google Earth presents a base layer of an aerial photographic image that is geo-located. Different layers of information could be used with this base layer such as soil maps, mineral deposits and crop productivity. This research paper presents a small-scale accuracy assessment study of GoogleEarth’s derived elevations. The elevation profile for a 600 m path delivered by GoogleEarth was compared to combined dual frequency GPS/GLONASS Precise Point Po...
Digital Road Profile Using Kinematic GPS A Digital Road Profile (DRP) is a digital representation... more Digital Road Profile Using Kinematic GPS A Digital Road Profile (DRP) is a digital representation of road surface topography or terrain in the longitudinal direction. The need for accurate DRP is vital in two stages; before the road construction starts and after the road construction finished where the verification of its geometrical characteristics is essential for engineering safety purposes. Classical surveying techniques are traditionally used for the DRP generation with limitation of high-cost and time-waste. Kinematic DGPS or Real Time Kinematic DGPS positioning can provide accurate enough results for such application. This paper presents an assessment study of using kinematic GPS technique for DRP generation comparing with classical survey in south Egypt. The results shows that, vehicle-GPS system used in combination with post processing kinematic DGPS gave satisfactory accuracy for nearly all points for a distance of nearly 2 km. with max. and min. difference not more than 7...
Accuracy Assessment of Digital Elevation Models Using GPSA Digital Elevation Model (DEM) is a dig... more Accuracy Assessment of Digital Elevation Models Using GPSA Digital Elevation Model (DEM) is a digital representation of ground surface topography or terrain with different accuracies for different application fields. DEM have been applied to a wide range of civil engineering and military planning tasks. DEM is obtained using a number of techniques such as photogrammetry, digitizing, laser scanning, radar interferometry, classical survey and GPS techniques. This paper presents an assessment study of DEM using GPS (Stop&Go) and kinematic techniques comparing with classical survey. The results show that a DEM generated from…
Precise point positioning (PPP) is a GNSS positioning technique that saves cost and has an accept... more Precise point positioning (PPP) is a GNSS positioning technique that saves cost and has an acceptable accuracy for enormous applications. PPP proved its efficiency through two decades comparing with traditional differential positioning technique. PPP uses one receiver collecting observations at an unknown station without the need for a reference station with known coordinates. PPP-collected observations must undergo extensive mitigation of different GNSS errors. Static-PPP accuracy depends mainly on the observations type (dual or single frequency), used systems (GPS or GLONASS or mixed GPS/GLONASS), satellites geometry, and observations duration. Static-PPP using dual-frequency observations gives optimum accuracy with a high cost. Static-PPP using single-frequency observations gives acceptable accuracy with a low cost. Since the end of 2012, PPP users are able to depend on GLONASS system as an alternative. This research investigates singe-frequency/static-PPP accuracy variation on K...
The ionospheric delay is the major current source of potential range delay for single-frequency G... more The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users. Single-frequency GNSS users are in utmost need of an ionospheric model to eliminate the ionospheric delay to a high degree of accuracy. GPS system uses the Klobuchar model for this task, which its coefficients are sent through the GPS navigation message to GPS users. Klobuchar model uses the Ionospheric Corrections Algorithm (ICA) designed to account for approximately 50% (rms) of the ionospheric range delay. The NeQuick is an ionospheric electron density model that has been adopted for single-frequency positioning applications in the frame work of the European Galileo project. A comparitive study between the behaviour of the GPS Single-frequency ionospheric modelling (Klobuchar model) and the Galileo proposed approach for this task (NeQuick model) is presented in this paper. The vertical range delay correction by the two models have been assessed using the highly accurate IGS...
The GNSS observations suffer from different types of errors that could affect the achieved positi... more The GNSS observations suffer from different types of errors that could affect the achieved positioning accuracy based on the receiver type used. Single-frequency receivers are widely used worldwide because of its low cost. The ionospheric delay considers the most challenging error for single-frequency GNSS observations. All satellite navigation systems, except GLONASS, are advising their users to correct for the ionospheric delay using a certain model. Those models’ coefficients are sent to users in the system’s navigation message. These models are different in their accuracy and behavior based on its foundation theory as well as the updating rate of their coefficients. The GPS uses Klobuchar model for mitigating the ionospheric delay. BeiDou system (BDS-2) adopts a slightly modified Klobuchar model that resembles GPS ICA (Ionospheric Correction Algorithm) with eight correction parameters but is formulated in a geographic coordinate system with different coefficients in origin and u...
Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of... more Global Positioning System (GPS) 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 improv...
Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satel... more Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Single-frequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-freq...
Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning... more 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-base...
Satellite navigation systems face different types of errors that affect the positioning accuracy.... more Satellite navigation systems face different types of errors that affect the positioning accuracy. The tropospheric delay considers one of the major sources of error for the transmitted signal that could face a tropospheric delay of over 2 m at zenith and 20 m at lower satellite elevation angles. A positioning error of 10 m could result from inaccurate mitigation of the tropospheric delay. Two types of models are available; surface meteorological models and global empirical models. Surface meteorological models use surface meteorological data to give accurate mitigation while the global empirical models use global standard atmospheres. Global empirical models are favorable for satellite based augmentation systems such as EGNOS model for the EGNOS augmentation system. Several hybrid neutral atmosphere delay models have been developed (UNB1 through UNB4). The IGGtrop model is initially developed to provide tropospheric delay corrections for the users of Chinese BeiDou Navigation Satell...
The range delay caused by the ionosphere layer is the major current source of error for GNSS user... more The range delay caused by the ionosphere layer is the major current source of error for GNSS users with single-frequency receivers. GNSS advice users to correct this type of error using ionospheric models whose coefficients are sent in their navigation messages. GPS-users use the Klobuchar model to correct this type of error. GPS navigation message contains the model’s eight coefficients which vary on the basis of seasonal ionospheric variations and average solar flux. The correction accuracy of Klobuchar model is about 50% (rms) of the ionospheric range delay. Beidou system calculates and broadcast 8 parameters of Klobuchar model based on continuous monitoring stations. BeiDou system updates the ionospheric coefficients every two hours. GPS-Klobuchar model uses completely different coefficients than BeiDou-Klobuchar model. This research demonstrates a comparison study between the Klobuchar model using the GPS broadcast coefficients and the same model using BeiDou-coefficients. The ...
Double-Difference Carrier-Phase Network Solution Using Nominal Gnss Constellations (Future Percep... more Double-Difference Carrier-Phase Network Solution Using Nominal Gnss Constellations (Future Perception)Global Navigation Satellite Systems (GNSS) have an endless number of applications in industry, science, military, transportation and recreation & sports. Two systems are currently in operation namely GPS (the USA Global Positioning System) and GLONASS (the Russian GLObal NAvigation Satellite System), and a third is planned, the European satellite navigation system GALILEO. The potential performance improvements achievable through combining these systems could be significant and expectations are high. The need is inevitable to explore the future of positioning accuracy using different nominal constellations. In this research paper, Bernese 5.0 software could be modified to simulate and process GNSS observations from three different constellations (GPS, Glonass and Galileo) using different combinations. This study presents results of double-difference carrier-phase solution for five s...
The ionospheric delay is the major current source of potential range delay for single-frequency G... more The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users. Different ionospheric delay mitigation methods have been developed to mitigate the ionospheric delay effects for single-frequency users. The NeQuick is a quick-run ionospheric electron density model particularly designed for trans-ionospheric propagation applications developed at the Aeronomy and Radio propagation Laboratory of the Abdus Salam International Centre for Theoretical Physics (ICTP), Italy. NeQuick2 is the latest version of the NeQuick ionosphere electron density model. NeQuick model been used by the European Space Agency (ESA) European Geostationary Navigation Overlay Service (EGNOS) project for assessment analysis and has been adopted for single-frequency positioning applications in the frame work of the European satellite navigation system (Galileo). NeQuick2 model adopted modifications related to the modeling of the F1 layer peak electron density, height and th...
Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy... more Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.
Tropospheric delay is the second major source of error after the ionospheric delay for satellite ... more Tropospheric delay is the second major source of error after the ionospheric delay for satellite navigation systems. The transmitted signal could face a delay caused by the troposphere of over 2m at zenith and 20m at lower satellite elevation angles of 10 degrees and below. Positioning errors of 10m or greater can result from the inaccurate mitigation of the tropospheric delay. Many techniques are available for tropospheric delay mitigation consisting of surface meteorological models and global empirical models. Surface meteorological models need surface meteorological data to give high accuracy mitigation while the global empirical models need not. Several hybrid neutral atmosphere delay models have been developed by (University of New Brunswick, Canada) UNB researchers over the past decade or so. The most widely applicable current version is UNB3m, which uses the Saastamoinen zenith delays, Niell mapping functions, and a look-up table with annual mean and amplitude for temperature...
Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of... more Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of its high accuracy and the short observation time required for a position fix. The horizontal position requirements for marine surveys vary between a few decimetres and several tens of metres. To meet these requirements, different observation and processing techniques using pseudo-ranges and/or carrier phases must be employed. 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 using high cost dual frequency receivers. PPP using low cost GPS ...
In this study, satellite image obtained from Spot-5 (2.5 m) sensor was rectified by means of PPP-... more In this study, satellite image obtained from Spot-5 (2.5 m) sensor was rectified by means of PPP-GPS (Precise Point Positioning using Global Positioning System) and DGPS (Differential Global Positioning System). Rectification of Spot image was carried out using 8 GCPs (Ground Control Points) covering an area of 9.15 km. The coordinates for GCPs were obtained using two techniques; PPP and DGPS. The accuracy of the image rectification using both techniques was evaluated using 3 GCPs as check points. A satellite image obtained from Geoeye (0.50 m) sensor covering the same area was rectified by using (PPP-GPS) 8 GCPs and its accuracy assessed using 3 check points.
Google Earth is a virtual globe, map and geographical information software. It maps the Earth by ... more Google Earth is a virtual globe, map and geographical information software. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. GoogleEarth® has become recently the ultimate source of spatial data and information for private and public decision-support systems. GoogleEarth is a strong tool for precision agriculture. It could be used for farm planning, field mapping, soil sampling, crop scouting, crop health monitoring, variable rate applications, and yield mapping. Also, Google Earth presents a base layer of an aerial photographic image that is geo-located. Different layers of information could be used with this base layer such as soil maps, mineral deposits and crop productivity. This research paper presents a small-scale accuracy assessment study of GoogleEarth’s derived elevations. The elevation profile for a 600 m path delivered by GoogleEarth was compared to combined dual frequency GPS/GLONASS Precise Point Po...
Digital Road Profile Using Kinematic GPS A Digital Road Profile (DRP) is a digital representation... more Digital Road Profile Using Kinematic GPS A Digital Road Profile (DRP) is a digital representation of road surface topography or terrain in the longitudinal direction. The need for accurate DRP is vital in two stages; before the road construction starts and after the road construction finished where the verification of its geometrical characteristics is essential for engineering safety purposes. Classical surveying techniques are traditionally used for the DRP generation with limitation of high-cost and time-waste. Kinematic DGPS or Real Time Kinematic DGPS positioning can provide accurate enough results for such application. This paper presents an assessment study of using kinematic GPS technique for DRP generation comparing with classical survey in south Egypt. The results shows that, vehicle-GPS system used in combination with post processing kinematic DGPS gave satisfactory accuracy for nearly all points for a distance of nearly 2 km. with max. and min. difference not more than 7...
Accuracy Assessment of Digital Elevation Models Using GPSA Digital Elevation Model (DEM) is a dig... more Accuracy Assessment of Digital Elevation Models Using GPSA Digital Elevation Model (DEM) is a digital representation of ground surface topography or terrain with different accuracies for different application fields. DEM have been applied to a wide range of civil engineering and military planning tasks. DEM is obtained using a number of techniques such as photogrammetry, digitizing, laser scanning, radar interferometry, classical survey and GPS techniques. This paper presents an assessment study of DEM using GPS (Stop&Go) and kinematic techniques comparing with classical survey. The results show that a DEM generated from…
Precise point positioning (PPP) is a GNSS positioning technique that saves cost and has an accept... more Precise point positioning (PPP) is a GNSS positioning technique that saves cost and has an acceptable accuracy for enormous applications. PPP proved its efficiency through two decades comparing with traditional differential positioning technique. PPP uses one receiver collecting observations at an unknown station without the need for a reference station with known coordinates. PPP-collected observations must undergo extensive mitigation of different GNSS errors. Static-PPP accuracy depends mainly on the observations type (dual or single frequency), used systems (GPS or GLONASS or mixed GPS/GLONASS), satellites geometry, and observations duration. Static-PPP using dual-frequency observations gives optimum accuracy with a high cost. Static-PPP using single-frequency observations gives acceptable accuracy with a low cost. Since the end of 2012, PPP users are able to depend on GLONASS system as an alternative. This research investigates singe-frequency/static-PPP accuracy variation on K...
The ionospheric delay is the major current source of potential range delay for single-frequency G... more The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users. Single-frequency GNSS users are in utmost need of an ionospheric model to eliminate the ionospheric delay to a high degree of accuracy. GPS system uses the Klobuchar model for this task, which its coefficients are sent through the GPS navigation message to GPS users. Klobuchar model uses the Ionospheric Corrections Algorithm (ICA) designed to account for approximately 50% (rms) of the ionospheric range delay. The NeQuick is an ionospheric electron density model that has been adopted for single-frequency positioning applications in the frame work of the European Galileo project. A comparitive study between the behaviour of the GPS Single-frequency ionospheric modelling (Klobuchar model) and the Galileo proposed approach for this task (NeQuick model) is presented in this paper. The vertical range delay correction by the two models have been assessed using the highly accurate IGS...
The GNSS observations suffer from different types of errors that could affect the achieved positi... more The GNSS observations suffer from different types of errors that could affect the achieved positioning accuracy based on the receiver type used. Single-frequency receivers are widely used worldwide because of its low cost. The ionospheric delay considers the most challenging error for single-frequency GNSS observations. All satellite navigation systems, except GLONASS, are advising their users to correct for the ionospheric delay using a certain model. Those models’ coefficients are sent to users in the system’s navigation message. These models are different in their accuracy and behavior based on its foundation theory as well as the updating rate of their coefficients. The GPS uses Klobuchar model for mitigating the ionospheric delay. BeiDou system (BDS-2) adopts a slightly modified Klobuchar model that resembles GPS ICA (Ionospheric Correction Algorithm) with eight correction parameters but is formulated in a geographic coordinate system with different coefficients in origin and u...
Global Positioning System (GPS) is ideally suited for inshore and offshore positioning because of... more Global Positioning System (GPS) 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 improv...
Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satel... more Nowadays, Precise Point Positioning (PPP) is a very popular technique for Global Navigation Satellite System (GNSS) positioning. The advantage of PPP is its low cost as well as no distance limitation when compared with the differential technique. Single-frequency receivers have the advantage of cost effectiveness when compared with the expensive dual-frequency receivers, but the ionosphere error makes a difficulty to be completely mitigated. This research aims to assess the effect of using observations from both GPS and GLONASS constellations in comparison with GPS only for kinematic purposes using single-frequency observations. Six days of the year 2018 with single-frequency data for the Ethiopian IGS station named “ADIS” were processed epoch by epoch for 24 hours once with GPS-only observations and another with GPS/GLONASS observations. In addition to “ADIS” station, a kinematic track in the New Aswan City, Aswan, Egypt, has been observed using Leica GS15, geodetic type, dual-freq...
Global Positioning System (GPS) technology is ideally suited for inshore and offshore positioning... more 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-base...
Satellite navigation systems face different types of errors that affect the positioning accuracy.... more Satellite navigation systems face different types of errors that affect the positioning accuracy. The tropospheric delay considers one of the major sources of error for the transmitted signal that could face a tropospheric delay of over 2 m at zenith and 20 m at lower satellite elevation angles. A positioning error of 10 m could result from inaccurate mitigation of the tropospheric delay. Two types of models are available; surface meteorological models and global empirical models. Surface meteorological models use surface meteorological data to give accurate mitigation while the global empirical models use global standard atmospheres. Global empirical models are favorable for satellite based augmentation systems such as EGNOS model for the EGNOS augmentation system. Several hybrid neutral atmosphere delay models have been developed (UNB1 through UNB4). The IGGtrop model is initially developed to provide tropospheric delay corrections for the users of Chinese BeiDou Navigation Satell...
The range delay caused by the ionosphere layer is the major current source of error for GNSS user... more The range delay caused by the ionosphere layer is the major current source of error for GNSS users with single-frequency receivers. GNSS advice users to correct this type of error using ionospheric models whose coefficients are sent in their navigation messages. GPS-users use the Klobuchar model to correct this type of error. GPS navigation message contains the model’s eight coefficients which vary on the basis of seasonal ionospheric variations and average solar flux. The correction accuracy of Klobuchar model is about 50% (rms) of the ionospheric range delay. Beidou system calculates and broadcast 8 parameters of Klobuchar model based on continuous monitoring stations. BeiDou system updates the ionospheric coefficients every two hours. GPS-Klobuchar model uses completely different coefficients than BeiDou-Klobuchar model. This research demonstrates a comparison study between the Klobuchar model using the GPS broadcast coefficients and the same model using BeiDou-coefficients. The ...
Double-Difference Carrier-Phase Network Solution Using Nominal Gnss Constellations (Future Percep... more Double-Difference Carrier-Phase Network Solution Using Nominal Gnss Constellations (Future Perception)Global Navigation Satellite Systems (GNSS) have an endless number of applications in industry, science, military, transportation and recreation & sports. Two systems are currently in operation namely GPS (the USA Global Positioning System) and GLONASS (the Russian GLObal NAvigation Satellite System), and a third is planned, the European satellite navigation system GALILEO. The potential performance improvements achievable through combining these systems could be significant and expectations are high. The need is inevitable to explore the future of positioning accuracy using different nominal constellations. In this research paper, Bernese 5.0 software could be modified to simulate and process GNSS observations from three different constellations (GPS, Glonass and Galileo) using different combinations. This study presents results of double-difference carrier-phase solution for five s...
The ionospheric delay is the major current source of potential range delay for single-frequency G... more The ionospheric delay is the major current source of potential range delay for single-frequency GNSS users. Different ionospheric delay mitigation methods have been developed to mitigate the ionospheric delay effects for single-frequency users. The NeQuick is a quick-run ionospheric electron density model particularly designed for trans-ionospheric propagation applications developed at the Aeronomy and Radio propagation Laboratory of the Abdus Salam International Centre for Theoretical Physics (ICTP), Italy. NeQuick2 is the latest version of the NeQuick ionosphere electron density model. NeQuick model been used by the European Space Agency (ESA) European Geostationary Navigation Overlay Service (EGNOS) project for assessment analysis and has been adopted for single-frequency positioning applications in the frame work of the European satellite navigation system (Galileo). NeQuick2 model adopted modifications related to the modeling of the F1 layer peak electron density, height and th...
Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy... more Precise Point Positioning (PPP) is a technique used for position computation with a high accuracy using only one GNSS receiver. It depends on highly accurate satellite position and clock data rather than broadcast ephemeries. PPP precision varies based on positioning technique (static or kinematic), observations type (single or dual frequency) and the duration of collected observations. PPP-(dual frequency receivers) offers comparable accuracy to differential GPS. PPP-single frequency receivers has many applications such as infrastructure, hydrography and precision agriculture. PPP using low cost GPS single-frequency receivers is an area of great interest for millions of users in developing countries such as Egypt. This research presents a study for the variability of single frequency static GPS-PPP precision based on different observation durations.
Tropospheric delay is the second major source of error after the ionospheric delay for satellite ... more Tropospheric delay is the second major source of error after the ionospheric delay for satellite navigation systems. The transmitted signal could face a delay caused by the troposphere of over 2m at zenith and 20m at lower satellite elevation angles of 10 degrees and below. Positioning errors of 10m or greater can result from the inaccurate mitigation of the tropospheric delay. Many techniques are available for tropospheric delay mitigation consisting of surface meteorological models and global empirical models. Surface meteorological models need surface meteorological data to give high accuracy mitigation while the global empirical models need not. Several hybrid neutral atmosphere delay models have been developed by (University of New Brunswick, Canada) UNB researchers over the past decade or so. The most widely applicable current version is UNB3m, which uses the Saastamoinen zenith delays, Niell mapping functions, and a look-up table with annual mean and amplitude for temperature...
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Papers by Ashraf Farah