Mitigation of the effects of the space environment on radio systems presents a wide range of challenges. These require research into the specification and forecasting of the ionosphere, the radio propagation impact, radio instrumentation, assimilative mathematics, and advanced computing techniques. The applications are as diverse as HF radar and corrections in low frequency astronomy exploring the origins of the universe.
Mitigation also includes engineering designs to overcome and even benefit from the ionosphere. Past examples include the dual frequency and differential approaches in GPS and Galileo navigation systems. Looking forward the challenges include designs for space-based low-frequency synthetic aperture radars and other novel space surveillance techniques.
SERENE is a new research group in the School of Electronic, Electrical and Systems Engineering at the University of Birmingham. It has been set up to develop a programme of internationally recognised, inter-disciplinary research to measure, model and mitigate the effects of the ionosphere on radio systems. SERENE is supported by a Chair that has been co-sponsored by DSTL and the Royal Academy of Engineering. It is expected that the group will grow the UK capability in this area and bridge the gap between academia and industry.
Space environment mitigation often requires the development of ground and space based instrumentation. SERENE is developing novel measurement techniques that take advantage of CubeSat technologies.
ESPAS – EU FP7
ESPAS (Near-Earth Space Data Infrastructure for e-Science) is an EU FP7 research infrastructures project. It will provide the e-Infrastructure necessary to support the access to observations and prediction of the Near-Earth Space environment. This includes the plasma and energetic particle environments that surround the Earth as well as the neutral atmosphere environment at altitudes above 60km. These environments are an important target for future research in areas such as space weather and Sun-climate studies.
EPSAS will provide access to a diverse set of databases that have been individually developed for the needs of different users. Thus a primary goal is to facilitate access to heterogeneous data from multiple providers; such data ranges from ground-based observations acquired with multiple instruments and techniques, to data from satellite experiments, using a mixture of in-situ and remotely sensed techniques. The ESPAS infrastructure will also be used as a test-bed for development of methodologies and standards for validation of models of the near-Earth environment.
Analytic Descriptions of the Ionospheric Impact on Space-Based Synthetic Aperture - EPSRC
The ionosphere is the dominant degrading factor in low-frequency (UHF) space-based synthetic aperture radar (SAR). The ionosphere controls the orbit choice, the selection of the transmitted waveforms and integration times together with signal and image post-processing. We are quantifying the effects of the ionosphere (total electron content and irregularities) on SAR to offer mitigation strategies. The ionospheric effects considered are those that affect SAR resolution, interferometry, polarimetry, radiometric calibration and image quality and focus.
We are developing analytical (as opposed to numerical) techniques to quantify the various ionospheric impacts on SAR images. Using these analytic expressions, the dependency of the SAR performance on the ionosphere will be established. This will enable the SAR design space to be searched, the performance optimized for a given task, and mitigation strategies developed. These analytic expressions will be validated against numerical simulation and against experimental L-band PALSAR imaging of calibrated targets located in the equatorial region. At the same time we will measure the background quiescent and disturbed ionosphere using GNSS equipment.
Wideband Ionospheric Sounder CubeSat Experiment (WISCER)
Low frequency (UHF) synthetic aperture radar (SAR) can be used to observe objects obscured by foliage. Such systems could be operated from space, but in this case the radar signals are susceptible to distortion by the ionosphere. This presents a considerable design challenge and the ionosphere is often the dominant degrading factor in these sorts of systems. The ionosphere controls the orbit choice, the selection of the transmitted waveforms and integration times, together with signal and image post-processing.
SERENE is designing the wideband ionospheric sounder CubeSat experiment (WISCER). WISCER will comprise a wideband (~100 MHz) beacon on a low cost CubeSat in order to measure and evaluate the ionospheric channel in anticipation of any future development of operational SAR systems.
- Professor Matthew Angling – Head of Group
Research interests: Ionospheric data assimilation, ionospheric propagation, CubeSat systems
- Dr. Sean Elvidge – Research Fellow
- Dr. Geoff de Villiers
- Dr. David Belcher
- Chris Mannix – Impacts of the ionosphere on space based radar
- Graham Kirkby – Development of CubeSat antenna systems for ionospheric sounding
- Victor Solea – Development of next generation ionospheric data assimilation techniques