Ionospheric critical frequency observation from ionosonde data for GPS positioning improvement over Malaysia

This research work was done to determine the critical frequency, fc, variation over Advanced Telecommunication Research Center (ATRC) UTHM by identifying the variability of the ionosphere from Ionosonde. The ionospheric variability was analyzed on diurnal variation basis at Low Solar Activity (LSA) and High Solar Activity (HSA). Ionosonde that was placed in ATRC was used to detect the fc of the ionosphere. Observation data in the form of Ionogram than was used to identify the fc and then the plotted using Matlab. The comparison was done for 2 diurnal solar activity variation data for 2 consecutive months from the year 2011. The results then was compared with the International Reference Ionosphere’s (IRI) fc. Overall, the solar activity has direct effect to the fc during daytime than after Sun set over the equatorial region. By knowing the ionospheric condition, this will be helpful to improve the position of train when applying the European Rail Traffic Management System (ERTMS) in Malaysia late

Ionospheric Drift Motions and Velocities at UTHM’s Parit Raja Station During Periods of Low Solar and Geomagnetic Activities

Measurements relating to ionospheric plasma drift have been made by the Wireless and Radio Science Centre (WARAS) at Universiti Tun Hussein Onn Malaysia (UTHM) Parit Raja station in Batu Pahat, Johor, since 2004. This is done using a digital doppler interferometer which allows investigations into the dynamics of the ionosphere at this equatorial station to be carried out. These measurements include Doppler shifts and angles of arrival of the reflected HF signals that also allows simultaneous determination of plasma drift directions, drift distance covered and velocities as well as virtual heights of reflection, from ionospheric scattering point sources embedded within the moving plasma. By employing Doppler inteferometry reception technique at four receivers connected to four square array antennas nearby, it is possible to identify the locations, movements and velocities of the bulk scattering points reflected from the ionospheric F-region from the vertically incident HF waves. These waves are transmitted at frequencies of 6MHz, 7MHz, and 8MHz which cover the local F-layers since the critical frequencies lie between 5.9MHz and 8MHz. This work is based on data collected from the F2-layer of this local station at about 300km of virtual height during the measurement period of 2005

Ionospheric Drift Motions and Velocities at UTHM's Parit Raja Station During Periods of Low Solar and Geomagnetic Activities

Measurements relating to ionospheric plasma drift have been made by the Wireless and Radio Science Centre (WARAS) at Universiti Tun Hussein Onn Malaysia (UTHM) Parit Raja station in Batu Pahat, Johor, since 2004. This is done using a digital doppler interferometer which allows investigations into the dynamics of the ionosphere at this equatorial station to be carried out. These measurements include Doppler shifts and angles of arrival of the reflected HF signals that also allows simultaneous determination of plasma drift directions, drift distance covered and velocities as well as virtual heights of reflection, from ionospheric scattering point sources embedded within the moving plasma. By employing Doppler inteferometry reception technique at four receivers connected to four square array antennas nearby, it is possible to identify the locations, movements and velocities of the bulk scattering points reflected from the ionospheric F-region from the vertically incident HF waves. These waves are transmitted at frequencies of 6MHz, 7MHz, and 8MHz which cover the local F-layers since the critical frequencies lie between 5.9MHz and 8MHz. This work is based on data collected from the F2-layer of this local station at about 300km of virtual height during the measurement period of 2005

Improved Ionospheric Correction for Dual Frequency and Differential GPS Positioning Methods

A new three dimensional (3-D) electron density model has been developed that can give a very accurate description of the real ionospheric variation; latitudinally,longitudinally and altitudinally. An important advantage of this model is that the electron density and all its spatial derivatives are continuous as required for high accuracy in a ray tracing program. This model was then incorporated in the Jones 3-D ray-tracing program in order to determine the effect of ionospheric horizontal gradient on Global Positioning System (GPS) ray paths. This was used to investigate the accurate mapping of slant to vertical in the presence of horizontal gradient. In differential GPS (DGPS), the effect of the ionosphere is assumed to be the same for two closely spaced Earth receiving stations (e. g. 10km baseline distance). However, the presence of ionospheric horizontal gradient, especially for receivers in the equatorial and polar regions and the difference in elevation angle at these two spaced receivers, that are observing the same satellite, do introduce some range errors. These range errors need to be considered when the ionospheric error is corrected in the single difference approach. Some mathematical expressions have been developed to show the significance of these errors in final DGPS user positioning by performing ray tracing calculations between a reference station and a user station using a simple block ionospheric model incorporating a linear horizontal gradient. The baseline distance between the stations was 10km. Then, these models have been used to show the improvement in DGPS positioning by taking into account the error due to the effect of an ionospheric horizontal gradient and the difference in the elevation angle at the reference and user receivers observing the same satellite. Final positioning improvement of about 10cm has been obtained. Additionally, methods have been proposed to determine the magnitude of the ionospheric gradient from real data (e. g. from GPS satellites). It has been found that the Rutherford Appleton Laboratory United Kingdom's (RAL UK's) Total Electron Content (TEC) online map (updated at every 10 minutes) can give a gradient magnitude and direction which can be applied in DGPS horizontal gradient correction. This determined gradient, which is 1.6853/rad (in all direction), was then used in the ray tracing program (linear gradient approach) to show the improvement possible in the user positioning. Further, since it has been found that the RAL UK's TEC map correlates very well with the vertical TEC from International Reference Ionosphere (IRI), the gradient was then obtained from IRI for GPS receiving stations in the equatorial region, such as Malaysia. 15cm of improvement in the user positioning was then obtained showing the importance of correcting for the effect of the horizontal gradient for GPS stations in the region like Malaysia. The amount of improvement was also investigated for different Geometrical Dilution of Precision(GDOP) factors to see for what satellite configurations there would be the most positional improvement. In addition, the component of the gradient in the satellite direction was approximated by using a simple mathematical relation taking account of the elevation angle and the azimuths of the satellite from the navigation data. Then, these `corrections' were applied to the carrier phase measurements of GPS observation data to show positional improvement at the user in DGPS using GPSurvey. The resolution of the ambiguity 3 minutes and 30 seconds earlier than for the case before corrections, shows the improvement in the user positional when the magnitude and direction of the gradients was taken into account. The dual frequency correction scheme uses the dispersive nature of the ionosphere to eliminate the ionospheric range error. Nevertheless, the dual frequency model cannot totally remove the effect of the ionosphere as it does introduce some approximations. For an example, it does not take into account the presence of the higher order terms in the phase refractive index equation's expansion (in the power of X-1). Though the higher order terms are about two orders of magnitude lower than the first order term at L-band frequencies, in applications such as geophysics and surveying which require millimetre level positioning accuracy, these terms need to be considered. In this work, these higher order terms have been obtained by using a program based on an analytical perturbation method (which required as input the azimuth and elevation angle of the satellite and an approximate electron density profile), which is much less numerically intensive than using the numerical ray tracing method based on the Haselgrove equations. Then, about 4cm of improvement in the final positioning using a dual frequency receiver has been shown to be possible by correcting for these higher order terms

Ionospheric horizontal gradients effect and estimation from observations

Global Navigation Satellite System (GNSS) is the standard generic term for satellite navigation systems that provides autonomous geospatial positioning with global coverage. GNSS allows the earth-based receivers to determine their location using time signals transmitted along a line of sight by radio signals form satellites.

Role of engineering technologist to solve the impact of COVID-19 to the society

The aim of this work is to study on the impact of COVID-19 to society and the role of engineering technologists to resolve the issue. Coronavirus disease (COVID-19) is an irresistible infection induced by a newly discovered coronavirus. The virus disseminated immediately from a person when a COVID-19 case coughs or exhales producing droplet that reaches the nose, mouth or eyes of another person. The outbreak of coronavirus is a front and leading a human buskin affecting hundreds of thousands of people. This disease also becomes a severe growing impact on society, the global economy, and education. This paper will discuss the impact of COVID-19 on society. Social reciprocities, interactions, and relations between the people have become united into our life. COVID 19 had changed the daily behavior of humans and the surrounding ecological system. So, if such an interaction is absent leads to stressful states of isolation, anxiety, panic, mental disorders, health hazards, and many other issues that impact the life of the person and the cooperative society as a whole. This paper also dedicated to presenting the role of engineering technologist with a perspective on the evolving situation and implications for the world. The technologist should come up with a design solution that would give guidance to solve the Impact of COVID-19 on the Society. They need to find out the solution to relative well in tackling the virus. Technologist can help share rightful knowledge and information that can help with COVID-19 responses. Technologist’ response to the virus has been providing information, research, and assistance that will have an immeasurable impact on the pace and efficiency of our response to the COVID-19. The outbreak is going fast, and some of the perspectives in this paper may fall rapidly out of date. However, the data analysis of COVID-19 in the world will be given in this paper