Ground Moving Target Indication with Synthetic Aperture Radar - General and Millimeter Wave Applications

Contact Persons

Maurice Rüegg

Erich Meier

Keywords

SAR Signal Processing, SAR Ground Moving Target Indication, GMTI, MTI, Millimeter Wave Radar
Quick Reference

Ground moving target indication (GMTI) for synthetic aperture radar (SAR) provides information on non-static objects in radar imagery of a static ground scene. While general applications cover a wide area of topics from ocean current measurements to glacier ice flow, millimeter wave (mmW) SAR is well suited for traffic monitoring, reconnaissance, and identifcation of special target movements including vibration and rotation. Through a thorough motion analysis in a standard SAR system model, one may show the effects of constant target motion, acceleration, vibration, and rotation in mmW SAR theoretically and in simulated and real data.

An effcient approach for GMTI is the use of multi-channel SAR systems for a space- and time-variant analysis of moving targets. This allows the indication, correction of position displacement, and estimation of radial velocity components of moving targets in a SAR image. The small radar wavelength of mmW SAR offers very sensitive movement detection and measurements. Work at RSL includes theoretical considerations specific to mmW SAR GMTI, adaptive algorithms to collect velocity and position information on moving targets with mmW amplitude-comparison monopulse radar, and discussions on GMTI blind speed elimination and target velocity ambiguity resolving by dual-frequency SAR. To determine the capabilities of both, system and algorithm, four large-scale experiments with the FGAN MEMPHIS mmW system in different environments have been conducted between 2004 and 2006 as well as a preliminary experiment in 2000 with the AeroSensing AeS-1 X-Band sensor to gain experiences in SAR GMTI.

Partnerships

Research has been conducted in cooperation with the following organizations:

• Forschungsgesellschaft für angewandte Naturwissenschaften (FGAN)
• AeroSensing GmbH (now a unit of Intermap)

Some Results

X-Band Along-Track Interferometry

The images below show the measurement of the surface water current flow of the river Reuss near the city of Emmen, Lucerne. The experiment was conducted in the year 2000 with the purpose to gain prelimimary experiences with SAR GMTI. Classic along-track interferometry was used to evaluate flow velocities of the river. The left image shows the amplitude image of the master channel (AeS-1, X-band) while the right image shows the flattened interferogram between master and slave channel with distinct phase derivations of non-static surface areas, i.e. the river Reuss.

mmW Monopulse GMTI

The image below shows three indicated moving targets on a field path. The data was collected during a flight campaign in western Switzerland in November 2005. A red pixel in the image indicates a moving target in the SAR image. Green pixels are position corrected true target positions.

The data was obtained with FGAN MEMPHIS at 35 GHz and with a resolution of 0.75 m. The algorithm to automatically indicate the shown targets is based on monopulse processing and is described in detail in the published works below.

Rotating Targets in SAR

Theoretical analyses of special target motion like vibration and rotation may be found in the published works below. There, it is shown that a rotating radar dish on the ground causes a large smeared signature in a SAR image.

Publications

• Maurice Rüegg, Erich Meier, and Daniel Nüesch. Capabilities of Dual-Frequency Millimeter Wave SAR with Monopulse Processing for Ground Moving Target Indication. IEEE Transactions on Geoscience and Remote Sensing, vol. 45, nr. 3, pp. 539-553, March 2007. [pdf] (PDF, 0.9 Mb)
• Maurice Rüegg, Erich Meier, and Daniel Nüesch. Vibration and Rotation in Millimeter Wave SAR. IEEE Transactions on Geoscience and Remote Sensing, vol. 45, nr. 2 pp. 293-304, February 2007. [pdf] (PDF, 0.9 Mb)
• Maurice Rüegg, Manfred Hägelen, Erich Meier, and Daniel Nüesch. High Resolution Millimeter Wave SAR for Moving Target Indication. Proceedings of EUSAR, 1-4, May 2006. [pdf] (PDF, 572 Kb)
• Maurice Rüegg, Manfred Hägelen, Erich Meier, and Daniel Nüesch. Moving Target Indication with a Dual Frequency Millimeter Wave SAR. Proceedings of IEEE RADAR, 350-357, April 2006. [pdf] (PDF, 472 Kb)
• Maurice Rüegg, Erich Meier, and Daniel Nüesch. Constant Motion, Acceleration, Vibration, and Rotation of Objects in SAR Data. SPIE Proceedings Vol. 5980(05):48-59. SAR Image Analysis, Modeling and Techniques X. October 2005. [pdf] (PDF, 1.0 Mb)
• Maurice Rüegg, Manfred Hägelen, Erich Meier, and Daniel Nüesch. Moving Target Indication with a Millimeter Wave Monopulse SAR. Proceedings of the International Radar Symposium, 105-110, September 2005. [pdf]
  (PDF, 386 Kb)