Master thesis defence

“Robust Feature Extraction Algorithm for analysis of Radar Targets using Multi-Object Tracking on Range Doppler Space”

Nagesh, Saravanan

In this thesis, we propose, a Robust data extraction algorithm capable of extracting reliable target features of multiple moving targets of different classes over all channels of a S Band Doppler Polarimetric Radar – PARSAX. The proposed algorithm is capable of generating a time series data by tracking, clusters of detections - representing extended targets using a multi target tracker modified to track on sequential frames of Range Doppler Maps .The targets considered in this study are Automobiles of different classes (4 wheel drive and above). A performance analysis of the algorithm, for data extraction possibility with respect to target density has been presented. In addition the possibility to use the extracted features for Radar Classification has been investigated.

Master thesis defence

Deep Learning-based identification of human gait by radar micro-Doppler measurements

Vasileios Papanastasiuo

The radar micro-Doppler (m-D) signature of human gait has already been used successfully for a few classification tasks of human gait, for instance walking versus running and determining the number of humans under observation. How ever, the more challenging problem of personnel identification has not been solved yet. The aim of this study is to prove that the human walking gait differs between individuals and that it can be used for personnel identification using CW X-band radar measurements. This study investigates the effect of human walking gait characteristics such as speed and stride as well as the gender on leading to distinctive m-D signatures. Both simulated data and measurements of 22 subjects walking from and towards the radar were used. Unsupervised learning based on Adversarial Autoencoders was used to map the m-D signatures to a latent space. TDistributed Stochastic Neighbor Embedding and Uniform Manifold Approximation and Projection were then used for clustering and visualization. This study shows that even very slight changes in the walking gait characteristics mentioned above lead to distinctive m-D signatures mapped into closely located points in the latent space. A VGG-16 convolutional neural network was used to identify the walking subjects based on their measured m-D signature. Accuracy of above 93.5% was achieved, proving that CW X-band radar m-D signature of human walking gait can be used for accurate personnel identification which is reliable for 22 participants.

Master thesis defence

A X-Band Patch Antenna Array with Low Cross-pol for Weather Radar Applications

Vizcarro, Marc

Meaningful dual-polarized radar estimations suitable for radar meteorology require a cross-polarization discrimination (XPD) and isolation (XPI) in excess of 30 dB to reach a differential reflectivity accuracy of 0.1 dB. A planar dual-polarized patch antenna array featuring low cross-polarization is presented meeting this requirement via a simple implementation of imaged feeding and candidates as a cost-effective active electronically steerable array (AESA) for short-range X-band weather radars. In this M.Sc. Thesis a 4x4 sub-array tile has been conceived, designed, manufactured and validated. Using a feed rotation technique and carefully designing a feeding network, high isolation and low cross-polarization suppression are achieved up to scanning in elevation. Through this initial prototype, a low-cost AESA concept has been demonstrated, a crucial step that will enable further advancements leading to the final array design for Weather Radar applications at Fraunhofer FHR.

Master thesis defence

Super-resolution Algorithm for Target Localization using Multiple FMCW Automotive Radars

Jiadi Zhang

Master thesis defence

Detection of vital signs of auto driver and passengers using (distributed) radars inside auto

Guigeng Su

Master thesis defence

STEREOID data processor: Design and Performance analysis

Prithvi Laguduvan Thyagarajan

Abstract: Stereo Thermo-Optically Enhanced Radar for Earth, Ocean, Ice, and land Dynamics (STEREOID) is one candidate of the ESA , Earth Explorer 10 missions. The novel constellation system will consist of the active Sentinel-1 satellites and two passive spacecrafts , which can provide flexible baseline configurations. A huge added value is foreseen in monitoring the variation of ice sheets, the eruptions of earthquakes, the volcano activities, and the landslides, playing therefore an extremely important role in understanding the global climate dynamics and the geophysical processes involved. In order to evaluate the performance of STEREOID in providing estimates of the Level-2 geophysical observables (ocean currents, digital elevation models, surface displacement, etc) an end-to-end simulator is necessary for the different system configurations (i.e., the monostatic/multi-static SAR mode). A key component of the simulator is the SAR processing kernel, that entails the image formation/focusing functionalities in the different bistatic geometries. The design of a robust focusing strategy for the STEREOID squinted illumination is the main focus of the thesis. A prototype processing kernel is implemented which can handle atleast bistatic TOPS acquisition mode and also azimuth beamforming for dual antenna configuration as proposed for STEREOID. The evaluation and performance analysis of the focuser is assesed for different scenarios.

Master thesis defence

Multiple-input Multiple-output Grating Lobe Selection Scheme for Radar Applications

Nick Cancrinus

For radar applications, MIMO is often used. The problem is that the amount of available transmit- and receive channels is limited. For most MIMO systems, every channel is connected to a single antenna element. This means that the effective aperture is small, and therefore the directivity is limited. To circumvent this problem, a grating-lobe selection scheme is proposed. Using beamforming networks, the receive channels are connected to antenna beam patterns that have grating lobes. The transmit channels are connected to antenna beams that select different grating lobes of the receive beams. The result is an array that covers a reduced part of the visible space, with discrete beams that have improved directivity.

Master thesis defence

Multi-Channel Waveform Agile Radar: Experimental performance evaluation of Advanced Space-Time Adaptive Processing (ASTAP) radar system

Ahmed, Sheeraz

Recent advancements in Multiple Input Multiple Output (MIMO) radar techniques has created a paradigm shift in the overall radar technology to increase degrees of freedom in multi-function radar capabilities. The underlying principle of MIMO transmissions is to use colored transmission by simultaneously radiating specific waveforms from each antenna elements/sub-arrays in different directions to achieve ‘space-time coding’. This can be explained as colored spatial distribution (multiple coded beams to probe the radar environment) instead of the white spatial distribution (single wide beam), such that the transmitted signals are now function of time as well as space. Recently, a novel multi-channel waveform agile demonstrator namely ASTAP (Advanced Space-Time Adaptive Processing) radar system has been designed and developed in Microwave Sensing, Signals and Systems (MS3) group, capable of generating and transmitting independent arbitrary waveforms specific for each transmit channel simultaneously . It consists of eight transmit channels with a single receive channeland hence can also be called as co-located Multiple-Input Single Output (MISO) radar. However, the transmission of different coded waveforms with a radar system such as ASTAP demonstrator requires that the desired measurements exclude the unwanted system response as much as possible. This includes waveform amplitude distortion, RF channels cross-talk and phase-misalignment, microwave components gain/phase variations and antenna mutual coupling. These effects can disturb the transmission signal waveforms and the orthogonality between them severely. For system performance analysis and beamforming applications, Over-the-Air (OTA) measurements have been done to eliminate the ASTAP system response significantly and obtain the near-ideal waveform responses. Furthermore, it is investigated that to what extent it is possible to separate signals corresponding to each transmit channel from the composite received signal in a single receive channel. This study is extended further to generate and transmit two orthogonal beams occupying the same frequency band simultaneously and the corresponding transmit radiation patterns are recovered from the composite received signal matched filtering. Finally, conclusions along with future aspects and recommendations have been discussed.

Master thesis defence

Model-based Interference Mitigation for FMCW Radar System

Min DIng

MSc TC Thesis Presentation

Erkut Yiğit