| GPS satellites roam high above in very precise | | | | convey relevant information about the observed |
| orbits of around 16,000 km up (to use the space | | | | satellites, such as maneuvers or maintenance. GPS |
| shuttle as an example, orbits at about 320km and | | | | navigational systems have tremendous benefits |
| geosynchronous satellites orbit at about | | | | over other positioning systems in that these |
| 38,600km). Because the satellites are so far | | | | systems do not rely upon visual, magnetic, or |
| away, their radio signals are fairly weak. GPS | | | | other points of reference. However, conventional |
| satellites play an important role in many navigation | | | | GPS navigational systems can experience blackout |
| systems produced today, and is beginning to play | | | | areas or regions when line-of-site is broken with |
| an increasing role in providing accurate time signals | | | | the satellites. |
| for many industries. | | | | GPS is regarded by most governments as a utility |
| Applications Include: Land surveying, autonomous | | | | on a par with mobile telephony. When mobile |
| vehicle control including the smart highway | | | | telephones first started appearing in the early |
| system, marine navigation, air traffic control, | | | | 1980s, they were regarded as a luxury item. |
| satellite navigation, and power signal time | | | | Nowadays they are considered commonplace and |
| synchronization. GPSnet) system under various | | | | necessary items for everyone. Similarly GPS |
| ionospheric conditions, this paper investigates both | | | | systems will experience the same rise in |
| temporal and spatial variations of the ionospheric | | | | acceptance from people and governing parties. |
| total electrons content (TEC) through analysing | | | | The benefits of this type of technology is difficult |
| GPS dual frequency data from the GPSnet or | | | | to realize until ownership and constant use has |
| similar network over a period of two years. | | | | provided the user with experiential viewpoints. |
| Diurnal and seasonal ionospheric variations, and | | | | GPS technologies are often used and are working |
| winter anomaly of the ionosphere in Victoria are | | | | in many areas that we do not normally consider. |
| investigated based on GPS-derived TEC values. | | | | GPS satellites fly in circular orbits at an altitude of |
| GPS satellites precise orbits are derived using 24 | | | | 20,100 km (12,500 mi) and with a period of 12 |
| hour data segments from the global GPS | | | | hours. The orbits are tilted to Earth's equator by |
| network. An informational summary file is | | | | 55 degrees to ensure coverage of polar regions. |
| provided to document the computation and to | | | | |