Radar and electronic warfare systems

Published research highlights

	Toward everywhere, all the time monitoring using radar Engineers at the CSIR are working hard to develop and produce a series of South African innovations that can be used by departments and agencies of the state to enhance national security. The CSIR has embarked on a programme, the Awarenet programme, in support of persistent, ubiquitous surveillance systems.

	How best can we support our local defence and industry? CSIR engineers probe progress made with establishing a radar capability in support of the South African National Defence Force, defence related industry and R&D partners.

	Quaternion-Based Transformation for Extraction of Image-Generating Doppler for ISAR CSIR researcher Yunus Abdul Gaffar proposes a new mathematical transformation that extracts the component of the rotational motion that leads to the imaging of sea vessels using the inverse synthetic aperture radar (ISAR) techniques.

	ISAR image distortion This paper investigates and characterises the effect of a time-varying Doppler generating axis of rotation on inverse synthetic aperture radar image distortion.

	Analysis of calibrated sea clutter and boat reflectivity data at C- and X-band in South African coastal waters Dr Paul Herselman records datasets of sea clutter returns to validate the state-of-the-art sea clutter models of South African coastal seawaters.

	Helicopter parameter extraction using joint time-frequency and tomographic techniques CSIR engineers show that it is possible to extract parameters about the main rotor blades of a helicopter from the measured Radar Doppler spectra of the helicopter. The work shows that engineers can accurately extract both blade length, number of blades and main rotor rotation rate. The work is shown both in simulation and on measured radar data, and the technique is shown to be very accurate.

	Improved covariance matrix estimation in spectrally inhomogeneous sea clutter with application to adaptive small boat detection CSIR researchers show empirically that the assumption of spectrally homogeneous sea clutter is the exception rather than the rule. Alternative methods of choosing the reference cells used to estimate the clutter covariance matrix in spectrally inhomogeneous sea clutter is suggested. It is shown that these methods results in a lower detection threshold for fixed false alarm rates.

	Quaternion-based transformation for extraction of image-generating Doppler for ISAR In radar imaging of sea vessels, it is only a component of a vessel's 3-D rotational motion that is useful to the imaging process. CSIR engineers have developed a new mathematical transformation that extracts the useful component of motion for radar imaging of coopertive vessels. This research is useful for radar imaging of military vessels for the purpose of identifying hotspots for electromagnetic signature management.

	Range Doppler dynamic range considerations for dechirp on receive radar CSIR radar experts present detailed analysis on how imperfections in the analogue front-end of the radar, influence the achievable spurious-free dynamic range of dechirp on receive radar measurements. Dechirp on receive is a technique to perform high range-resolution radar measurements. This research is based on experimental measurements conducted with an X-band Dechirp on receive concept demonstrator, implemented using the CSIR’s Fynmeet radar facility.

	X-band high range resolution radar measurements of sea surface forward scatter at low grazing angles Radar engineers measured the forward scatter characteristics of the ocean at X-band with a resolution of less than 15 cm. From these measurements the direct and reflected signals can be isolated. The temporal correlation of the single bounce component is extracted and a filter is designed to emulate this correlation. A temporal correlation extension to an existing low-angle propagation model is proposed and the results are compared to the measured results.