DTU Space has developed radiometer systems for many years, in particular airborne systems for demonstrating methods and for scientific campaigns.
In recent years, DTU Space has been closely involved in ESA’s SMOS (Soil Moisture and Ocean Salinity) satellite mission. The Institute has carried out several ESA-supported campaigns with its airborne radiometers and conducted research into digital radiometers. DTU Space was represented in the SMOS Science Advisory Group and now in the Quality Working Group. The Institute’s expertise in radiometers and radiometry provides a solid platform for further development, for example, developing digital radiometers designed to operate at high frequencies, and including algorithms for detecting man made interference from active services.
Radiometers, like on SMOS, are very sensitive microwave receivers, that measure the natural radiation from the Earth’s surface. Thus active services (radars, radio and TV, communication) potentially disturb or even render radiometer measurements impossible (trough so-called radio frequency interference – RFI). Even if the radiometer is designed to only receive in a protected band, where active services are not allowed, there are oftentimes locations infested by RFI. This is due to illegal or poorly designed/maintained sources. DTU Space are leading within the development of special methods for detection of RFI, using advanced radiometers featuring special signal analysis made possible by means of fast digital data processing.
Radiometer calibration has become an increasingly important task in line with the more stringent resolution and precision requirements. DTU Space is already involved in ESA projects regarding the above. Special calibration objects have been developed and tested. The Institute will continue to pursue these activities – both in general and more specifically with the objective of increasing the accuracy of airborne campaigns in connection with SMOS calibration and validation.