65 research outputs found
Design and implementation of an SDR-based multi-frequency ground-based SAR system
Synthetic Aperture Radar (SAR) has proven a valuable tool in the monitoring of the Earth, either at a global or local scales. SAR is a coherent radar system able to image extended areas with high resolution, and finds applications in many areas such as forestry, agriculture, mining, structure inspection or security operations.
Although space-borne SAR systems can image extended areas, their main limitation is the long revisit times, which are not suitable for applications where the target experiments rapid changes, in the scale of minutes to few days. GBSAR systems have proven useful to fill this revisit time gap by imaging relatively small areas continuously, with extensions usually smaller than a few square kilometers. Ground Based SAR (GBSAR) systems have been used extensively for the monitoring of slope instability, and are a common tool in the mining sector.
The development of the GBSAR is relatively recent, and various developments have taken place since the 2000s, transitioning from the usage of Vector Network Analyzers (VNAs) to custom radar cores tailored for this application. This transition is accompanied by a reduction in cost, but at the same time is accompanied by a loss of operational flexibility. Specifically, most GBSAR sensors now operate at a single frequency, losing the value of the multi-band operation that VNAs provided.
This work is motivated by the idea that it is worth to use the value of multi-frequency GBSAR measurements, while maintaining a limited system cost. In order to implement a GBSAR with these characteristics, it is realized that Software Defined Radio (SDR) devices are a good option for fast and flexible implementation of broadband transceivers.
This thesis details the design and implementation process of an SDR-based Frequency Modulated Continuous Wave (FMCW) GBSAR system from the ground up, presenting the main issues related with the usage of the most common SDR analog architecture, the Zero-IF transceiver. The main problem is determined to be the behavior of spurs related to IQ imbalances of the analog transceiver with the FMCW demodulation process. Two effective techniques to overcome these issues, the Super Spatial Variant Apodization (SSVA) and the Short Time Fourier Transform (STFT) signal reconstruction techniques, are implemented and tested. The thesis also deals with the digital implementation of the signal generator and digital receiver, which are implemented on top of an RF Network-on-Chip (RFNoC) architecture in the SDR Field Programmable Gate Array (FPGA). Another important aspect of this work is the development of an radiofrequency front-end that extends the capabilities of the SDR, implementing filtering, amplification, leakage mitigation and up-conversion to X-band. Finally, a set of test campaigns is described, in which the operation of the system is verified and the value of multi-frequency GBSAR observations is shown.El radar d'obertura sintètica (SAR) ha demostrat ser una eina valuosa en el monitoratge de la Terra, sigui a escala global o local. El SAR és un sistema de radar coherent capaç d’obtenir imatges de zones extenses amb alta resolució i té aplicacions en moltes à rees com la silvicultura, l’agricultura, la mineria, la inspecció d’estructures o les operacions de seguretat. Tot i que els sistemes SAR embarcats en plataformes orbitals poden obtenir imatges d'à rees extenses, la seva principal limitació és el temps de revisita, que no són adequats per a aplicacions on l'objectiu experimenta canvis rà pids, en una escala de minuts a pocs dies. Els sistemes GBSAR han demostrat ser útils per omplir aquesta bretxa de temps, obtenint imatges d'à rees relativament petites de manera contÃnua, amb extensions generalment inferiors a uns pocs quilòmetres quadrats. Els sistemes SAR terrestres (GBSAR) s’han utilitzat à mpliament per al control de la inestabilitat de talussos i esllavissades i són una eina comuna al sector miner. El desenvolupament del GBSAR és relativament recent i s’han produït diversos desenvolupaments des de la dècada de 2000, passant de l’ús d’analitzadors de xarxes vectorials (VNA) a nuclis de radar personalitzats i adaptats a aquesta aplicació. Aquesta transició s’acompanya d’una reducció del cost, però al mateix temps d’una pèrdua de flexibilitat operativa. Concretament, la majoria dels sensors GBSAR funcionen a una única freqüència, perdent el valor de l’operació en múltiples bandes que proporcionaven els VNA. Aquesta tesi està motivada per la idea de recuperar el valor de les mesures GBSAR multifreqüència, mantenint un cost del sistema limitat. Per tal d’implementar un GBSAR amb aquestes caracterÃstiques, s’adona que els dispositius de rà dio definida per software (SDR) són una bona opció per a la implementació rà pida i flexible dels transceptors de banda ampla. Aquesta tesi detalla el procés de disseny i implementació d’un sistema GBSAR d’ona contÃnua modulada en freqüència (FMCW) basat en la tecnologia SDR, presentant els principals problemes relacionats amb l’ús de l’arquitectura analògica de SDR més comuna, el transceptor Zero-IF. Es determina que el problema principal és el comportament dels espuris relacionats amb el balanç de les cadenes de fase i quadratura del transceptor analògic amb el procés de desmodulació FMCW. S’implementen i comproven dues tècniques efectives per minimitzar aquests problemes basades en la reconstrucció de la senyal contaminada per espuris: la tècnica anomenada Super Spatial Variant Apodization (SSVA) i una tècnica basada en la transformada de Fourier amb finestra (STFT). La tesi també tracta la implementació digital del generador de senyal i del receptor digital, que s’implementen sobre una arquitectura RF Network-on-Chip (RFNoC). Un altre aspecte important d’aquesta tesi és el desenvolupament d’un front-end de radiofreqüència que amplia les capacitats de la SDR, implementant filtratge, amplificació, millora de l'aïllament entre transmissió i recepció i conversió a banda X. Finalment, es descriu un conjunt de campanyes de prova en què es verifica el funcionament del sistema i es mostra el valor de les observacions GBSAR multifreqüència
Low cost passive radar through software defined radio
Passive radars utilise existing terrestrial radio signals, such as those produced by radio or television stations, to track objects within their range. This project aims to determine the suitability of low cost USB TV tuners as hardware receivers for a Software Defined Radio (SDR) based passive radar receiver. Subsequently determining its effectiveness in producing inverse synthetic aperture radar images using data collected from Digital Television signals. Since the initial identification of passive radar, Militaries the world over have been using it as a part of electronic warfare. The evolution of SDR has enabled greater access to the technologies required to implement passive radar, with the greatest limitation being the cost of the required hardware. The availability of low cost hardware was therefore investigated to determine its suitability and subsequently the availability of passive radar to a wider audience.
Research was conducted into the available SDR receivers, and comparison of specifications was made against the low cost receiver used in the project. A functional hardware platform based around the Realtek RTL2832U chipset has been developed to determine its suitability as a low cost receiver verifying its ability to coherently receive radio signals for target identification. A complex ambiguity function was implemented to interpret sampled data windows, with the output of these windows to be compared to the requirements for an inverse synthetic aperture radar input, thus determining the suitability of the device. Interpretation of the received data has identified that although the hardware is capable, a real time implementation of data processing is not yet possible, impeding the ability to determine the suitability of the receiver as an inverse synthetic aperture receiver. The results of testing show that the hardware is capable of receiving and producing radar images, however due to the bandwidth of DVB-T signals , and the bandwidth limitations inherent in RTL-SDR dongles, they have proven not to be suitable for DVB-T based inverse synthetic aperture radar receivers
Concepts for Short Range Millimeter-wave Miniaturized Radar Systems with Built-in Self-Test
This work explores short-range millimeter wave radar systems, with emphasis on miniaturization and overall system cost reduction. The designing and implementation processes, starting from the system level design considerations and characterization of the individual components to final implementation of the proposed architecture are described briefly. Several D-band radar systems are developed and their functionality and performances are demonstrated
IMPLEMENTASI SISTEM RADAR FREQUENCY MODULATED CONTINUOUS WAVE UNTUK DETEKSI JARAK BERBASIS USRP
RADAR (Radio Detection and Ranging) merupakan sebuah sistem yang memancarkan gelombang yang dapat mengukur jarak, kecepatan dan posisi dari suatu objek. Sistem radar bekerja dengan memancarkan gelombang melalui transmitter ke arah objek kemudian objek memantulkan kembali gelombang yang ke receiver. Setelah gelombang diterima oleh receiver kemudian diolah untuk dapat melihat sinyal yang dihasilkan. Di Indonesia radar masih mengalami kendala terutama dalam segi harga yang dibutuhkan dalam membuat suatu sistem radar. Teknologi Software Defined Radio (SDR) dapat menjadi solusi untuk membangun suatu sistem radar.
Teknologi SDR menggunakan software sebagai pengganti dari hardware yang digunakan sebagai mixer, filter, modulator/demodulator dan sebagainya. Dengan demikian teknologi SDR dapat mempermudah dalam membangun suatu sistem radar. Salah satu implementasi dari teknologi SDR adalah sistem radar berbasis Universal Software Radio Peripheral (USRP). USRP merupakan hardware yang didukung dengan software GNU Radio Companion (GRC) untuk membuat konfigurasi dari sistem radar. Dalam penelitian tugas akhir ini menggunakan jenis sinyal Frequency Modulated Continuous Wave (FMCW). FMCW memiliki banyak keuntungan diantaranya memiliki desain yang sederhana dan memerlukan daya yang rendah untuk memancarkan sinyal dan memiliki resolusi sinyal yang tinggi sehingga lebih baik untuk mendeteksi sebuah objek yang diamati.
Pengujian implementasi sistem radar FMCW yang dibuat bekerja pada frekuensi 1 GHz dan bandwidth sebesar 10 MHz. Pada pengujian ini melakukan rekayasa jarak dengan menggunakan delay. Terdapat dua skema pengujian yang dilakukan pada penelitian ini. Skema pertama yang dilakukan adalah mengukur pergeseran kecil pada sebuah objek dengan range pergeseran sebesar 1 meter dan skema kedua adalah mengukur posisi objek dengan jarak 1 meter dan 2 meter
Potentialities of Usrp-Based Software Defined Radar Systems
International audienceSoftware Defined Radar is the latest trend in radar development. To handle enhanced radar signal processing techniques, advanced radars need to be able of generating various types of waveforms, such as frequency modulated or phase coded, and to perform multiple functions. The adoption of a Software Defined Radio system makes easier all these abilities. In this work, the implementation of a Software Defined Radar system for target tracking using the Universal Software Radio Peripheral platform is discussed. For the first time, an experimental characterization in terms of radar application is performed on the latest Universal Software Radio Peripheral NI2920, demonstrating a strongly improved target resolution with respect to the first generation platform
Software defined radar system
Software defined radar concept and simulation -- Signal processing methods of synthetic software defined radar -- Mixer-based synthetic software defined radar -- Six-port-based syunthetic software defined radar -- Performance study of synthetic software defined radar
Compressive Sensing and Its Applications in Automotive Radar Systems
Die Entwicklung in Richtung zu autonomem Fahren verspricht, künftig einen sicheren
Verkehr ohne tödliche Unfälle zu ermöglichen, indem menschliche Fahrer vollständig
ersetzt werden. Dadurch entfällt der Faktor des menschlichen Fehlers, der aus
Müdigkeit, Unachtsamkeit oder Alkoholeinfluss resultiert. Um jedoch eine breite
Akzeptanz für autonome Fahrzeuge zu erreichen und es somit eines Tages vollständig
umzusetzen, sind noch eine Vielzahl von Herausforderungen zu lösen. Da in einem
autonomen Fahrzeug kein menschlicher Fahrer mehr in Notfällen eingreifen kann,
müssen sich autonome Fahrzeuge auf leistungsfähige und robuste Sensorsysteme
verlassen können, um in kritischen Situationen auch unter widrigen Bedingungen
angemessen reagieren zu können. Daher ist die Entwicklung von Sensorsystemen
erforderlich, die für Funktionalitäten jenseits der aktuellen advanced driver assistance
systems eingesetzt werden können. Dies resultiert in neuen Anforderungen, die erfüllt
werden müssen, um sichere und zuverlässige autonome Fahrzeuge zu realisieren, die
weder Fahrzeuginsassen noch Passanten gefährden. Radarsysteme gehören zu den
Schlüsselkomponenten unter der Vielzahl der verfügbaren Sensorsysteme, da sie im
Gegensatz zu visuellen Sensoren von widrigen Wetter- und Umgebungsbedingungen
kaum beeinträchtigt werden. Darüber hinaus liefern Radarsysteme zusätzliche
Umgebungsinformationen wie Abstand, Winkel und relative Geschwindigkeit zwischen
Sensor und reflektierenden Zielen. Die vorliegende Dissertation deckt im Wesentlichen
zwei Hauptaspekte der Forschung und Entwicklung auf dem Gebiet der Radarsysteme
im Automobilbereich ab. Ein Aspekt ist die Steigerung der Effizienz und Robustheit
der Signalerfassung und -verarbeitung für die Radarperzeption. Der andere Aspekt ist
die Beschleunigung der Validierung und Verifizierung von automated cyber-physical
systems, die parallel zum Automatisierungsgrad auch eine höhere Komplexität
aufweisen.
Nach der Analyse zahlreicher möglicher Compressive Sensing Methoden, die im
Bereich Fahrzeugradarsysteme angewendet werden können, wird ein rauschmoduliertes
gepulstes Radarsystem vorgestellt, das kommerzielle Fahrzeugradarsysteme in
seiner Robustheit gegenüber Rauschen übertrifft. Die Nachteile anderer gepulster
Radarsysteme hinsichtlich des Signalerfassungsaufwands und der Laufzeit werden
durch die Verwendung eines Compressive Sensing-Signalerfassungs- und Rekonstruktionsverfahrens
in Kombination mit einer Rauschmodulation deutlich verringert.
Mit Compressive Sensing konnte der Aufwand für die Signalerfassung um 70% reduziert
werden, während gleichzeitig die Robustheit der Radarwahrnehmung auch für signal-to-noise-ratio-Pegel nahe oder unter Null erreicht wird. Mit einem validierten
Radarsensormodell wurde das Rauschradarsystem emuliert und mit einem
kommerziellen Fahrzeugradarsystem verglichen. Datengetriebene Wettermodelle
wurden entwickelt und während der Simulation angewendet, um die Radarleistung
unter widrigen Bedingungen zu bewerten. Während eine Besprühung mit Wasser die
Radomdämpfung um 10 dB erhöht und Spritzwasser sogar um 20 dB, ergibt sich die
eigentliche Begrenzung aus der Rauschzahl und Empfindlichkeit des Empfängers. Es
konnte bewiesen werden, dass das vorgeschlagene Compressive Sensing Rauschradarsystem
mit einer zusätzlichen Signaldämpfung von bis zu 60 dB umgehen kann
und damit eine hohe Robustheit in ungünstigen Umwelt- und Wetterbedingungen
aufweist.
Neben der Robustheit wird auch die Interferenz berücksichtigt. Zum einen wird
die erhöhte Störfestigkeit des Störradarsystems nachgewiesen. Auf der anderen
Seite werden die Auswirkungen auf bestehende Fahrzeugradarsysteme bewertet und
Strategien zur Minderung der Auswirkungen vorgestellt.
Die Struktur der Arbeit ist folgende. Nach der Einführung der Grundlagen
und Methoden für Fahrzeugradarsysteme werden die Theorie und Metriken hinter
Compressive Sensing gezeigt. Darüber hinaus werden weitere Aspekte wie Umgebungsbedingungen,
unterschiedliche Radararchitekturen und Interferenz erläutert.
Der Stand der Technik gibt einen Überblick über Compressive Sensing-Ansätze und
Implementierungen mit einem Fokus auf Radar. Darüber hinaus werden Aspekte
von Fahrzeug- und Rauschradarsystemen behandelt. Der Hauptteil beginnt mit
der Vorstellung verschiedener Ansätze zur Nutzung von Compressive Sensing für
Fahrzeugradarsysteme, die in der Lage sind, die Erfassung und Wahrnehmung von
Radarsignalen zu verbessern oder zu erweitern. Anschließend wird der Fokus auf
ein Rauschradarsystem gelegt, das mit Compressive Sensing eine effiziente Signalerfassung
und -rekonstruktion ermöglicht. Es wurde mit verschiedenen Compressive
Sensing-Metriken analysiert und in einer Proof-of-Concept-Simulation bewertet. Mit
einer Emulation des Rauschradarsystems wurde das Potential der Compressive Sensing
Signalerfassung und -verarbeitung in einem realistischeren Szenario demonstriert.
Die Entwicklung und Validierung des zugrunde liegenden Sensormodells wird ebenso
dokumentiert wie die Entwicklung der datengetriebenen Wettermodelle. Nach der
Betrachtung von Interferenz und der Koexistenz des Rauschradars mit kommerziellen
Radarsystemen schließt ein letztes Kapitel mit Schlussfolgerungen und einem
Ausblick die Arbeit ab.Developments towards autonomous driving promise to lead to safer traffic, where fatal
accidents can be avoided after making human drivers obsolete and hence removing
the factor of human error. However, to ensure the acceptance of automated driving
and make it a reality one day, still a huge amount of challenges need to be solved.
With having no human supervisors, automated vehicles have to rely on capable and
robust sensor systems to ensure adequate reactions in critical situations, even during
adverse conditions. Therefore, the development of sensor systems is required that
can be applied for functionalities beyond current advanced driver assistance systems.
New requirements need to be met in order to realize safe and reliable automated
vehicles that do not harm passersby.
Radar systems belong to the key components among the variety of sensor systems.
Other than visual sensors, radar is less vulnerable towards adverse weather and
environment conditions. In addition, radar provides complementary environment
information such as target distance, angular position or relative velocity, too. The
thesis ad hand covers basically two main aspects of research and development in the
field of automotive radar systems. One aspect is to increase efficiency and robustness
in signal acquisition and processing for radar perception. The other aspect is to
accelerate validation and verification of automated cyber-physical systems that
feature more complexity along with the level of automation.
After analyzing a variety of possible Compressive Sensing methods for automotive
radar systems, a noise modulated pulsed radar system is suggested in the thesis at
hand, which outperforms commercial automotive radar systems in its robustness
towards noise. Compared to other pulsed radar systems, their drawbacks regarding
signal acquisition effort and computation run time are resolved by using noise modulation
for implementing a Compressive Sensing signal acquisition and reconstruction
method. Using Compressive Sensing, the effort in signal acquisition was reduced by
70%, while obtaining a radar perception robustness even for signal-to-noise-ratio
levels close to or below zero. With a validated radar sensor model the noise radar
was emulated and compared to a commercial automotive radar system. Data-driven
weather models were developed and applied during simulation to evaluate radar performance
in adverse conditions. While water sprinkles increase radome attenuation
by 10 dB and splash water even by 20 dB, the actual limitation comes from noise
figure and sensitivity of the receiver. The additional signal attenuation that can be
handled by the proposed compressive sensing noise radar system proved to be even up to 60 dB, which ensures a high robustness of the receiver during adverse weather
and environment conditions.
Besides robustness, interference is also considered. On the one hand the increased
robustness towards interference of the noise radar system is demonstrated. On
the other hand, the impact on existing automotive radar systems is evaluated and
strategies to mitigate the impact are presented.
The structure of the thesis is the following. After introducing basic principles
and methods for automotive radar systems, the theory and metrics of Compressive
Sensing is presented. Furthermore some particular aspects are highlighted such as
environmental conditions, different radar architectures and interference. The state of
the art provides an overview on Compressive Sensing approaches and implementations
with focus on radar. In addition, it covers automotive radar and noise radar related
aspects. The main part starts with presenting different approaches on making use
of Compressive Sensing for automotive radar systems, that are capable of either
improving or extending radar signal acquisition and perception. Afterwards the focus
is put on a noise radar system that uses Compressive Sensing for an efficient signal
acquisition and reconstruction. It was analyzed using different Compressive Sensing
metrics and evaluated in a proof-of-concept simulation. With an emulation of the
noise radar system the feasibility of the Compressive Sensing signal acquisition and
processing was demonstrated in a more realistic scenario. The development and
validation of the underlying sensor model is documented as well as the development
of the data-driven weather models. After considering interference and co-existence
with commercial radar systems, a final chapter with conclusions and an outlook
completes the work
Development of a K-band FMCW flexible radar prototype for detection and classification of nano-drones
© Cranfield University 2020. All rights reserved. No part of this
publication may be reproduced without the written permission of the
copyright ownerNano-drones of the size of an insect can be used to perform stealthy
surveillance or to gather intelligence crucial to attack roles at a relatively short
range and within enclosed spaces and buildings. Conventional radar systems
have been optimised to detect and classify bigger targets and are not
specifically designed to detect nano-targets of less than 5 cm in size. Hence,
this project aims to develop a radar system to detect and classify an insect-like
size drone that corresponds to a low RCS. This will exhibit challenges due to
the nature of the weak echoed signal that will be masked by an uninterested
target with a stronger echoed signal. To tackle this sort of problem, micro Doppler extraction is applied for better target detection. This type of target that
consists of a bladed propeller will give rise to a significant micro-Doppler
signature that will contribute to the discernment of the interested target.
An ad-hoc S-band FMCW radar prototype using off-the-shelf components An ad-hoc S-band FMCW radar prototype using off-the-shelf components has
been successfully delivered. This prototype act as a groundwork for the next
research phase of design and development for a higher frequency. Then, with
the strong foundation of the S-band demonstrator, a flexible K-band FMCW
radar prototype has successfully delivered aiming to meet the research
purpose. The radar prototype offers a wide range of flexibility for the user to
select the radar parameters (like operating frequency, ramp duration, bandwidth
and integration time) and configure its performance. It will collect the signatures
of real targets (nano-drone model) so that their performance can be assessed
on experimental data. The results demonstrated that a nano-drone, a small size
of less than 5 cm can be detected with the radar prototype developed.Ph
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