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Anthropogenic radio frequency interference (RFI) within microwave radiometer bands is a serious problem in remote sensing. The problem is ever-increasing and thus, future spaceborne microwave radiometers will require efficient methods to mitigate the effects of RFI. In this paper, we present a solution: an RFI processor to detect and blank the RFI in real time. The processor was designed to be compatible with the 18.7-GHz channel of the Microwave Imager Instrument onboard the European MetOp Second Generation satellite system. The RFI processor developed here applies the following complementary detection algorithms: 1) anomalous amplitude detection; 2) kurtosis; and 3) two different cross-frequency algorithms. In the processing, the data are divided into subsamples with fine temporal and frequency resolution. The RFI processor detects and filters out RFI with this fine resolution in real time and then integrates the clean (noncontaminated) subsamples over time and frequency. Thus, a cleaned version of the radiometer data can be downlinked at a traditional low data rate. The processing is implemented in a reprogrammable field programmable gate array with high processing capacity, which provides high flexibility. The processing bandwidth that is applied is 200 MHz (+ 25-MHz transition bands on both sides). The detection limits of the system vary between various kinds of RFI but are in line with simulations. The power consumption of the RFI processor is ∼12 W (at room temperature), and its mass is ∼1.1 kg. [ABSTRACT FROM AUTHOR]

A 350\,\textkm \times 350\,\textkm area near the Concordia station on the high plateau of Dome-C in Antarctica has been mapped by an airborne L-band radiometer system. The area was expected to display a rather uniform brightness temperature (TB) close to the yearly mean temperature—well suited for calibration checks for spaceborne instruments like SMOS, Aquarius, and SMAP. The measured TBs show unexpected variations like 8-K variation over 240 km on an east–west profile through Concordia, and in certain local cases, a slope of about 0.7 K/km. Comparing the measured TB map with bottom topography reveals a convincing correlation. Simulations show that variations in bedrock topography can indeed modulate the TB appropriately to explain the observed variations. It is concluded that use of the Dome-C area for calibration check of spaceborne radiometers is indeed viable, but with caution—especially when comparing instruments with different spatial resolutions. [ABSTRACT FROM PUBLISHER]

Two semiconductor active cold loads (ACLs) to be used as cold references in spaceborne microwave radiometers have been developed. An X-band frequency was chosen, and the target noise temperature value was in the 50-100-K range. The ACLs are characterized in the operating temperature range of 0 °C-50 °C and long-term stability is assessed. To this end, a test bed has been developed. This test bed is actually a stable radiometer, and its design and performance are discussed. The test setup is described, and test campaign results indicate output temperatures of 77 and 56 K for the two ACLs. The temperature sensitivity is slightly below 0.4 K/°C for the units, and long-term stability within 2 K/year is observed. [ABSTRACT FROM AUTHOR]

Presents information on a study which outlined the capabilities and the performance of EMISAR, a high-resolution synthetic aperture radar (SAR) system. Operation of the system and various possibilities in mapping geometry and polarization; Requirements driving the design and the actual performance of the system; Performance verification; Processing and applications of the system.

Describes how antenna reflector losses in the calibration budget for a microwave radiometer are carried out. What is used as incident radiation; Use of main reflector of European Space Agency's MIMR system to demonstrate principle.