digital satellite

Recently, with the escalating cost of large satellite missions, attention has turned to smaller satellites. Their advantages of low overall cost in construction and launch, and short time span between conception and launch has given a new impetus to the further study of the geosphere. By using a combination of space-based and ground-based receivers, The ionised part of the atmosphere, the ionosphere, causes distorting effects or errors in satellite communications, navigation and altimetry. In order to understand these effects and improve our knowledge of the ionosphere, the various regions of the ionosphere have been monitored to different degrees on a long-term basis. Even instruments such as incoherent scatter radars, while providing profiles of both the topside and bottom side ionosphere, do not operate on a continuous basis and provide poor resolution for the lower ionosphere. The ground-based ionosondes provide non-homogeneous coverage of the bottom side ionosphere, as they are limited to observations from land. This is particularly true in the Southern Hemisphere where the oceans cover most of the Hemisphere. FedSat, the first Australian satellite to be launched in over 30 years, will be a microsatellite of around 58 kg launch mass. It is planned to launch into a sun synchronous polar orbit at a height of 800 km. FedSat’s mission is basically a science and engineering one. The planned scientific payloads include a fluxgate magnetometer for monitoring the Earth's magnetic field and solar -terrestrial interactions as well as a dual frequency GPS receiver for ionospheric and atmospheric research. The aims of the program are to conduct basic research on the structure and dynamics of the ionosphere, plasmasphere and magnetosphere. The results will be applied to the forecasting of space weather. The space-qualified dual-frequency GPS receiver and patch antenna, supplied by NASA, are being built by Spectum Astro of Arizonia, USA. Using the two coherently connected frequencies f₁ = 1575.42 MHz and f₂ = 1227.60 MHz,