What innovations does RF Payload Systems involve?
Payload Systems involves the technical development of new generations of specialised radio-based instrumentation and communication systems, as well as the industrial development of new technologies and subsystems.
On the instrument side that implies new types of payload capable of increased performance while reducing cost, employing radio signals to return data about various important aspects of the Earth environment, from surface characteristics to atmospheric patterns.
Examples of 'active' radio sensors include synthetic aperture radar (SAR), which fires a radar beam down to Earth and records signal bounce back while 'passive' sensors include radiometers which detect microwaves radiating out from Earth's surface or atmosphere.
The innovations involved on the signal side include novel algorithms for signal coding, modulation and processing, fade and interference mitigation techniques as well as the design of telecom system architectures and methodologies, plus networking techniques related to radio resource and network management. Concepts related to modulation and fade mitigation techniques developed in ESTEC are now part of commercial broadband standards such as DVB-S2. Security techniques for telecom networking is also important – covering means of assuring secure end-to-end communications – and the physical equipment required, including user terminals.
Telecom satellites are requiring more and more advanced on-board concepts involving the processing of very large bands as required by broadband multi-beam satellites. Techniques like frequency demultiplexing, switching and beam forming requires very powerful digital processors on-board the satellite. These technologies together with very complex RF front-ends able to support the generation of many satellite antenna beams with flexible power and bandwidth resource allocation to accommodate traffic requirements.
Another crucial area of activity is radio navigation systems, where work includes the development of ground receivers, the positioning and accuracy algorithms that underpin them and, increasingly, ways of integrating them with other telecommunication systems to further increase their reliability and utility.
And onboard receivers should not be overlooked: an increasing number of satellites already employ radio navigation systems as a tool for highly-accurate positioning. This application will only become more important once formation flying satellite constellations begin to enter service.
Future enabling technologies for radio frequency systems include more compact but higher power radio frequency systems, measurement and calibration systems and also enhanced accuracy time and frequency technologies such as more stable atomic clocks – among the most likely components to fail in current spacecraft.
Last update: 16 September 2009