Zainal Fitry M Amin’s scientific contributions

This study is aimed at evaluating the trade-off between Global Positioning System (GPS) accuracy and power saving from reduction of number of channels. The study is conducted for number of GPS receiver channels of 4 to 12 for two scenarios: (1) normal scenario with full range of available GPS satellites and (2) obstruction scenario with GPS satellite elevation cutoff of 20°. It is observed that increase of power saving from reducing the number of channels causes increase of probable error values. This is due to increasing position dilution of precision (PDOP) of the reducing number of GPS satellites tracked. However, reduction of number of channels to match the number of available GPS satellites does not cause degradation of accuracy, as there is no reduction in number of trackable GPS satellites. For the obstruction scenario, with significantly fewer available GPS satellites due to the GPS satellite elevation cutoff, significant power saving can be achieved without degradation of accuracy. An effective power saving system would require the management of minimum number of channels required to achieve the user’s minimum required accuracy.

In this study, Global Positioning System (GPS) simulation is employed to evaluate the accuracy of GPS speed measurements. The two methods of GPS speed measurement, trackpoints and Doppler shift, are compared for two conditions of tests: 1) Normal scenario with the full range of available GPS satellites; 2) Obstruction scenario with only six GPS satellites available. For the trackpoints method, significant errors are observed, due to positioning errors caused by the GPS receiver's user equivalent ranging error (UERE). The errors increased with increasing speed due to increasing length of zigzag lines connecting the trackpoints, which is caused by the receiver's positioning errors. The Doppler shift method generated much smaller errors for the normal scenario (maximum of 0.238 km/h for speeds of up to 1,800 km/h), as it is insensitive to the UERE of GPS receivers. Decrease of available GPS satellites in the obstruction scenario also caused increase of error for the trackpoints method due to increased position dilution of precision (PDOP) and thus, increased UERE. For the Doppler shift method, the increase of error was much smaller (maximum of 0.254 km/h for speeds of up to 1,800 km/h), indicating that change in GPS satellite geometry has limited effect on this method.

This study is aimed at evaluating the trade-off between Global Positioning System (GPS) accuracy and power saving from reduction of number of channels. The study is conducted for number of GPS receiver channels of 4 to 12 for two scenarios: 1) Normal scenario with full range of available GPS satellites; 2) Obstruction scenario with GPS satellite elevation cutoff of 20°. It is observed that increase of power saving from reducing the number of channels causes increase of probable error values, due to increasing position dilution of precision (PDOP) of the reducing number of GPS satellites tracked. However, reduction of number of channels to match the number of available GPS satellites does not cause degradation of accuracy, as there is no reduction in number of trackable GPS satellites. For the obstruction scenario, with significantly fewer available GPS satellites due to the GPS satellite elevation cutoff, significant power saving can be achieved without degradation of accuracy. An effective power saving system would require the management of minimum number of channels required to achieve the user's minimum required accuracy.