Dissertations / Theses on the topic 'Frequency radar'
To see the other types of publications on this topic, follow the link: Frequency radar.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Frequency radar.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Geladakis, Dimitrios N. "Comparison of the step frequency radar with the conventional constant frequency radars." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA328272.
Full textAbstract:
Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, December 1996."December 1996." Thesis advisor(s): Gurnam S. Gill. Includes bibliographical references (p. 45). Also available online.
2
Aytun, Alper. "Frequency diverse array radar." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5113.
Full textAbstract:
Approved for public release; distribution is unlimitedElectronic scanning is the most desirable feature of state-of-the-art radar systems. With electronic scanning, it is possible to steer the main beam of an array antenna instantaneously into a desired direction where no mechanical mechanism is involved in the scanning process. Electronic scanning methods including phase scanning, time delay scanning, and frequency scanning have been used in various radar applications; however new and cheaper scanning methods are still being investigated. It is the purpose of this thesis to investigate an array configuration called frequency diverse array (FDA), which gives rise to range-, time-, and angle-dependent scanning without using phase shifters. In this thesis, first, frequency diverse array as a time-modulated array is presented. A general analysis and the theory of time domain scanning is given. Equations derived for a time-modulated frequency diverse array are simulated using MATLAB. Amplitude tapering and Fourier series expansion is implemented in MATLAB and the results are provided for comparison. Secondly, analysis of a frequency diverse array is presented. Time-, range-, and angle-dependent electronic scanning is achieved by applying a small amount of frequency shift among the antenna elements. The simulation results for radiation patterns with various excitation types are given. Lastly, the radar applications of FDA are considered. The received power from a target at a fixed range is simulated in MATLAB and the results are presented.
3
Mun, Kok Leong. "Stepped frequency imaging radar simulation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA379137.
Full text
4
Burger, Johann. "High frequency surface wave radar demonstrator." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29408.
Full textAbstract:
High Frequency Surface Wave Radar (HFSWR) is used around the globe for the mapping of sea currents and coastal monitoring of the Exclusive Economic Zone. Decision to build an HF radar at the University of Cape Town (UCT) was made by Daniel O’Hagan and Andrew Wilkinson in February 2015 immediately after seeing a demonstration of the CODAR system at IMT. Their intention was subsequently discussed at several meetings, including a South African Radar Interest Group (SARIG) meeting and one at IMT in order to gauge interest and raise funding. There was both interest (mainly for ocean current monitoring) and scepticism (expressed by CSIR and SARIG members) of the value of HF radar for ship monitoring. This reports the design, construction, test, and evaluation of the UCT HFSWR demonstrator. A modular approach was taken in its design and construction making it easy to replicate and upscale. A pillar of this work is to prove the feasibility of a software defined radar (SDR) based HF radar demonstrator. Every part of the demonstrator was designed and constructed from scratch as UCT had no prior HF activities, and therefore no legacy antennas or components to utilise. A low-cost RF frontend follows the HF antennas, which were also designed for this project. Combined with an SDR platforn known as the Red Pitaya (RP), a complete HF radar demonstrator was assembled and trials were conducted at the UCT rugby field and at the IMT facilities in Simon’s Town. A preliminary assessment of the results reveal the effects of Bragg resonance scatter and detection of two stationary targets (mountains) distinguishable by both range and azimuth. This assessment of the results indicates that the demonstrator is operational.
5
Heuschel, Eugene R. "Time-frequency, bi-frequency detector analysis of noise technology radar." Thesis, Monterey, California. Naval Postgraduate School, 2006. http://hdl.handle.net/10945/2636.
Full textAbstract:
Enemy integrated air defense systems (IADS) using low probability of intercept (LPI) emitters can cause significant problems for suppression of enemy air defense (SEAD) techniques. New threat emitter configurations using low-power random noise modulation have a significant processing gain unavailable to non-cooperative intercept receivers. Consequently, the detection of these emitters can not be accomplished with conventional intercept receiver detection methods. This thesis examines the use of time-frequency, bi-frequency signal detection techniques to identify the parameters of the four types of continuous waveform noise radar recently reported. These include: (a) random noise, (b) noise plus frequency modulation continuous wave (FMCW), (c) noise FMCW plus sine and (d) random binary phase modulation. Quadrature mirror filtering for wavelet decomposition is used to investigate the four types of noise signals in order to extract the signal parameters. The FFT accumulation method for estimating the spectral correlation density function is also used to examine the cyclostationary bi-frequency properties of the waveforms. In addition, the periodic autocorrelation function and periodic ambiguity function are studied to determine the waveform properties in the delay- Doppler offset domain. Results show that non-cooperative intercept receivers can increase their processing gain using these types of signal processing techniques providing a more efficient response time to the threat.
6
Middleditch, Andrew. "Spectral analysis in high frequency radar oceanography." Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/3590/.
Full textAbstract:
High Frequency radar systems provide a unique opportunity to measure evolving littoral oceanic dynamics at high temporal and spatial resolution. Backscattered electromagnetic signals from ocean waves are modulated by Bragg resonant scattering. A perturbation analysis yields an expression for the spectral content of radar signals which can be exploited to provide estimates of oceanographic parameters: the radial component of surface current can be extracted from the frequency locations of the first order peaks; the ocean wave directional spectrum is related to the second order continuum via a non-linear integral equation. The periodogram, based on a Fourier decomposition of radax data, is the standard method used to derive frequency spectra. Limitations in this approach, caused by inhomogeneities in the underlying ocean field, are investigated. An instantaneous frequency technique is proposed in this thesis which mitigates the spectral distortion by demodulating the backscattered radax signals -a filtering procedure is developed which measures the temporally varying Bragg components. Alternative spectral techniques are analysed in order to validate the filter: an autoregressive paxa, metric modelling approach and an eigendecomposition method. The filter is evaluated, using radar and in situ data, which establishes its potential for ocean remote sensing. Significant improvements in the quantity and accuracy of wave measurements are demonstrated. Properties and constraints of the filter are derived using simulated data. Finally, the generic structure of the extracted instantaneous frequency signals is investigated and related to oceanographic processes.
7
Ahmed, Atheeq. "Human Detection Using Ultra Wideband Radar and Continuous Wave Radar." Thesis, Linköpings universitet, Kommunikationssystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-137996.
Full textAbstract:
A radar works by radiating electromagnetic energy and detecting the reflected signal returned from the target. The nature of the reflected signal provides information about the target’s distance or speed. In this thesis, we will be using a UWB radar and a CW radar to help detect the presence and rough location of trapped survivors by detecting their motions. Range is estimated in the UWB radar using clutter removal with SVD and for the dual frequency CW Radar using STFT and median filtering. The effect of the algorithm parameters on their performance was analyzed. The performance of the implemented algorithms with regards to small motion detection, distance estimation and penetration capability was analyzed. Both systems are certainly capable of human detection and tracking.
8
Jones, Aaron M. "Frequency Diverse Array Receiver Architectures." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1323888275.
Full text
9
Paulose, Abraham Thomas. "High radar resolution with the step frequency waveform." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA284611.
Full text
10
Huang, Jen-Chih. "The ambiguity function of the stepped frequency radar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA289533.
Full textAbstract:
Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering) Naval Postgraduate School, September 1994.Thesis advisor(s): G. S. Gill. "September 1994." Includes bibliographical references. Also available online.
11
Kalkan, Yilmaz. "Target Localization Methods For Frequency-only Mimo Radar." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614805/index.pdf.
Full textAbstract:
This dissertation is focused on developing the new target localization and the target velocity estimation methods for frequency-only multi-input, multi-output (MIMO) radar systems with widely separated antennas. If the frequency resolutions of the transmitted signals are enough, only the received frequencies and the Doppler shifts can be used to find the position of the target.
In order to estimate the position and the velocity of the target, most multistatic radars or radar networks use multiple independent measurements from the target such as time-of-arrival (TOA), angle-of-arrival (AOA) and frequency-of-arrival (FOA). Although, frequency based systems have many advantages, frequency based target localization methods are very limited in literature because of the fact that highly non-linear equations are involved in solutions. In this thesis, alternative target localization and the target velocity estimation methods are proposed for frequency-only systems with low complexity.
One of the proposed methods is able to estimate the target position and the target velocity based on the measurements of the Doppler frequencies. Moreover, the target movement direction can be estimated efficiently. This method is referred to as "Target Localization via Doppler Frequencies - TLDF"
and it can be used for not only radar but also all frequency-based localization systems such as Sonar or Wireless Sensor Networks. Besides the TLDF method, two alternative target position estimation methods are proposed as well. These methods are based on the Doppler frequencies, but they requires the target velocity vector to be known. These methods are referred to as "
Target Localization via Doppler Frequencies and Target Velocity - TLD&
V methods"
and can be divided two sub-methods. One of them is based on the derivatives of the Doppler Frequencies and hence it is called as "
Derivated Doppler - TLD&
V-DD method"
. The second method uses the Maximum Likelihood (ML) principle with grid search, hence it is referred to as "
Sub-ML, TLD&
V-subML method"
. The more realistic signal model for ground based, widely separated MIMO radar is formed as including Swerling target fluctuations and the Doppler frequencies. The Cramer-Rao Bounds (CRB) are derived for the target position and the target velocity estimations for this signal model. After the received signal is constructed, the Doppler frequencies are estimated by using the DFT based periodogram spectral estimator. Then, the estimated Doppler frequencies are collected in a fusion center to localize the target. Finally, the multiple targets localization problem is investigated for frequency-only MIMO radar and a new data association method is proposed. By using the TLDF method, the validity of the method is simulated not only for the targets which are moving linearly but also for the maneuvering targets. The proposed methods can localize the target and estimate the velocity of the target with less error according to the traditional isodoppler based method. Moreover, these methods are superior than the traditional method with respect to the computational complexity. By using the simulations with MATLAB, the superiorities of the proposed methods to the traditional method are shown.
12
Kenny, Owen Patrick. "Theory of radar imaging using time-frequency distribution." Thesis, Queensland University of Technology, 1992. https://eprints.qut.edu.au/36211/6/36211_Digitised%20Thesis.pdf.
Full textAbstract:
The concept of radar was developed for the estimation of the distance (range) and velocity of a target from a receiver. The distance measurement is obtained by
measuring the time taken for the transmitted signal to propagate to the target and return to the receiver. The target's velocity is determined by measuring the Doppler
induced frequency shift of the returned signal caused by the rate of change of the time- delay from the target. As researchers further developed conventional radar systems
it become apparent that additional information was contained in the backscattered signal and that this information could in fact be used to describe the shape of the target itself. It is due to the fact that a target can be considered to be a collection of individual point scatterers, each of which has its own velocity and time- delay. DelayDoppler parameter estimation of each of these point scatterers thus corresponds to a mapping of the target's range and cross range, thus producing an image of the target. Much research has been done in this area since the early radar imaging work of the 1960s. At present there are two main categories into which radar imaging falls. The
first of these is related to the case where the backscattered signal is considered to be deterministic. The second is related to the case where the backscattered signal is of a stochastic nature. In both cases the information which describes the target's scattering
function is extracted by the use of the ambiguity function, a function which correlates the backscattered signal in time and frequency with the transmitted signal. In practical situations, it is often necessary to have the transmitter and the receiver of the radar system sited at different locations. The problem in these situations is 'that a reference signal must then be present in order to calculate the ambiguity function. This causes an additional problem in that detailed phase information about the transmitted signal is then required at the receiver. It is this latter problem which has led to the investigation of radar imaging using time- frequency distributions. As will be shown in this thesis, the phase information about the transmitted signal can be extracted from the
backscattered signal using time- frequency distributions.
The principle aim of this thesis was in the development, and subsequent discussion into the theory of radar imaging, using time- frequency distributions. Consideration is
first given to the case where the target is diffuse, ie. where the backscattered signal has temporal stationarity and a spatially white power spectral density. The complementary situation is also investigated, ie. where the target is no longer diffuse, but some degree
of correlation exists between the time- frequency points. Computer simulations are presented to demonstrate the concepts and theories developed in the thesis. For the proposed radar system to be practically realisable, both the time- frequency distributions and the associated algorithms developed must be able to be implemented in a timely manner. For this reason an optical architecture is proposed. This architecture is specifically designed to obtain the required time and frequency resolution when using
laser radar imaging. The complex light amplitude distributions produced by this architecture have been computer simulated using an optical compiler.
13
Akhanli, Deniz. "Radar Range-doppler Imaging Using Joint Time-frequency Techniques." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608325/index.pdf.
Full textAbstract:
Inverse Synthetic Aperture Radar coherently processes the return signal from the target in order to construct the image of the target. The conventional methodology used for obtaining the image is the Fourier transform which is not capable of suppressing the Doppler change in the return signal. As a result, Range-Doppler image is degraded. A proper time-frequency transform suppresses the degradation due to time varying Doppler shift.
In this thesis, high resolution joint-time frequency transformations that can be used in place of the conventional method are evaluated. Wigner-Ville Distribution, Adaptive Gabor Representation with Coarse-to-Fine search algorithm, and Time-Frequency Distribution Series are examined for the target imaging system.
The techniques applied to sample signals compared with each other. The computational and memorial complexity of the methods are evaluated and compared to each other and possible improvements are discussed. The application of these techniques in the target imaging system is also performed and resulting images compared to each other.
14
Warren, Craig. "Numerical modelling of high-frequency ground-penetrating radar antennas." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4074.
Full textAbstract:
Ground-Penetrating Radar (GPR) is a non-destructive electromagnetic investigative tool used in many applications across the fields of engineering and geophysics. The propagation of electromagnetic waves in lossy materials is complex and over the past 20 years, the computational modelling of GPR has developed to improve our understanding of this phenomenon. This research focuses on the development of accurate numerical models of widely-used, high-frequency commercial GPR antennas. High-frequency, highresolution GPR antennas are mainly used in civil engineering for the evaluation of structural features in concrete i. e., the location of rebars, conduits, voids and cracking. These types of target are typically located close to the surface and their responses can be coupled with the direct wave of the antenna. Most numerical simulations of GPR only include a simple excitation model, such as an infinitesimal dipole, which does not represent the actual antenna. By omitting the real antenna from the model, simulations cannot accurately replicate the amplitudes and waveshapes of real GPR responses. Numerical models of a 1.5 GHz Geophysical Survey Systems, Inc. (GSSI) antenna and a 1.2 GHz MALÅ GeoScience (MALÅ) antenna have been developed. The geometry of antennas is often complex with many fine features that must be captured in the numerical models. To visualise this level of detail in 3d, software was developed to link Paraview—an open source visualisation application which uses the Visualisation Toolkit (VTK)—with GprMax3D—electromagnetic simulation software based on the Finite-Difference Time-Domain (FDTD) method. Certain component values from the real antennas that were required for the models could not be readily determined due to commercial sensitivity. Values for these unknown parameters were found by implementing an optimisation technique known as Taguchi’s method. The metric used to initially assess the accuracy of the antenna models was a cross-corellation of the crosstalk responses from the models with the crosstalk responses measured from the real antennas. A 98 % match between modelled and real crosstalk responses was achieved. Further validation of the antenna models was undertaken using a series of laboratory experiments where oil-in-water (O/W) emulsions were created to simulate the electrical properties of real materials. The emulsions provided homogeneous liquids with controllable permittivity and conductivity and enabled different types of targets, typically encountered with GPR, to be tested. The laboratory setup was replicated in simulations which included the antenna models and an excellent agreement was shown between the measured and modelled data. The models reproduced both the amplitude and waveshape of the real responses whilst B-scans showed that the models were also accurately capturing effects, such as masking, present in the real data. It was shown that to achieve this accuracy, the real permittivity and conductivity profiles of materials must be correctly modelled. The validated antenna models were then used to investigate the radiation dynamics of GPR antennas. It was found that the shape and directivity of theoretically predicted far-field radiation patterns differ significantly from real antenna patterns. Being able to understand and visualise in 3d the antenna patterns of real GPR antennas, over realistic materials containing typical targets, is extremely important for antenna design and also from a practical user perspective.
15
Svensson, Johan. "High Resolution Frequency Estimation in an FMCW Radar Application." Thesis, Linköpings universitet, Reglerteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-148526.
Full textAbstract:
FMCW radars are widely used in the process industry for range estimation, usu- ally for estimating the liquid level in a tank. Since the tank system, often is an automatically controlled system, reliable estimates of the surface level are re- quired, e.g. to avoid the tank from pouring over or become empty. The goal of this thesis is to investigate methods which can distinguish fre- quencies closer to each other than the FFT resolution limit. Two properties are of interest, the accuracy and the resolution performance. Three such methods have been evaluated: one that tries to compensate for the leakage and interference of close frequencies, one subspace-based method and one deconvolution method. The deconvolution is performed with the iterative Lucy Richardson algorithm. The methods are evaluated against each other and against a typical FFT based algorithm. The methods sensitivity to amplitude differences is examined together with the robustness against noise and disturbances which appear due to imperfections in the radar unit. The deconvolution algorithm is the one that performs the best. The subspace-based method SURE requires prior knowledge of the number of ingoing frequencies which is difficult to know for real data from an FMCW radar. The leakage compensation method main weakness is the influence of the phase difference between close frequencies. The deconvolution algorithm is evaluated on some real data, and it is proven that it has better resolution performance than the FFT. However, the accuracy of the estimates are dependent on the number of iterations used. With a large num- ber of iterations, the algorithm finds peaks with small amplitude nearby the large peaks and they will thus interact and hence contribute to a worse accuracy even in the undisturbed case. If too few iterations are used in the deconvolution algo- rithm the resolution performance is about the same as the FFT algorithm. With a suitable choice of iterations about 40–50 mm, extra of continuous measurements are achieved. However, the estimation error of the gained resolution can in the worst case be about 40–50 mm.
16
Trevithick, Jacob D. "Millimeter Wave Radar Object Detection Through Frequency Selective Surfaces." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2077.
Full textAbstract:
Millimeter wave (mmWave) radar systems are a leading technology in autonomous vehicle object sensing. The radar’s ability to detect surrounding objects is critical to its performance. One method of increasing object detection performance is to enhance object visibility. Frequency selective reflectors can increase object visibility. This work examines the performance of a mmWave 77 GHz radar system developed by Texas Instruments in conjunction with frequency selective surfaces. Two bandpass frequency selective surfaces are designed and fabricated using a loaded cross aperture configuration to analyze their application to object detection. The chosen design frequencies are 8 GHz and 79 GHz. The frequency selective surfaces are designed and simulated in 3-D electromagnetic simulation software, High Frequency Structure Simulator (HFSS). The frequency selective surfaces are fabricated on 127μm thick FR4 dielectric. The 8 GHz frequency selective surface demonstrates bandpass center frequency at 8.12 GHz. The 8 GHz and 79 GHz frequency selective surface reflection characteristics are compared to a copper sheets with the same physical cross section as each respective design. Although different testing methodology is used for each design, both frequency selective surfaces demonstrate bandpass characteristics at their respective design frequencies.
17
Bailey, Eric Stanton. "Sparse Frequency Laser Radar Signal Modeling and Doppler Processing." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1271937372.
Full text
18
Jones, William John. "Direct frequency synthesis using combined digital and analogue techniques." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336118.
Full text
19
Crescitelli, David M., and Patrick B. Kistner. "Enhanced detection of orthogonal radar waveforms using time-frequency and bi-frequency signal processing techniques." Thesis, Monterey, California. Naval Postgraduate School, 2008. http://hdl.handle.net/10945/3931.
Full textAbstract:
Approved for public release; distribution is unlimitedThis thesis investigates the periodic autocorrelation function (PACF) and periodic ambiguity function (PAF) for orthogonal continuous waveform (CW) modulations used in netted low probability of intercept (LPI) radar. Three orthogonal polyphase sequences and one frequency coding sequence are examined and their PACF and PAF characteristics are quantified. The Wigner-Ville distribution (WVD) and quadrature mirror filter bank (QMFB) timefrequency signal processing techniques and the cyclostationary bi-frequency technique (often used in non-cooperative intercept receivers) are used to detect the orthogonal CW signals and extract their parameters. The results shows that a combination of the techniques used were able to extract the basic signal parameters of bandwidth and code period from the polyphase waveforms and also the frequency hop slots and code length from the frequency coding sequence. The concept of using a swarm of unmanned aerial vehicles (UAV) is examined from the viewpoint of a coordinated group of netted intercept receivers in search of an LPI radar network.
20
Holder, Sade A. "Linear frequency modulated signals vs orthogonal frequency division multiplexing signals for synthetic aperture radar systems." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42647.
Full textAbstract:
Approved for public release; distribution is unlimitedThe goal of this thesis is to investigate the effects of an orthogonal frequency-division multiplexing (OFDM) signal versus a linear frequency modulated or chirp signal on simulated synthetic aperture radar (SAR) imagery. Various parameters of the transmitted signal, such as pulse duration, transmitted signal energy, bandwidth, and (specifically for the OFDM signal) number of subcarriers and transmission scheme were examined to determine which parameters are most important to reconstructing a SAR image. Matched filtering and interpolation are two techniques used to reconstruct the SAR image. SAR systems are used in various military and civilian sector applications. Some SAR application examples include ground surveillance, reconnaissance and remote sensing. These applications demand high resolution imagery; therefore, knowledge of exactly which parameters of the transmitted radar signal are more important in producing fine resolution imagery is worth investigating. This research will also aid in providing flexibility in terms of what type of signal and signal parameters are best suited for a particular SAR application and associated military missions. In addition to improving the method attaining high resolution images, SAR process improvement can potentially reduce military SAR system design cost.
21
Kistner, Patrick B. Crescitelli David M. "Enhanced detection of orthogonal radar waveforms using time-frequency and bi-frequency signal processing techniques." Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FKistner.pdf.
Full textAbstract:
Thesis (M.S. in Information Warfare Systems Engineering)--Naval Postgraduate School, September 2008.Thesis Advisor(s): Pace, Phillip E. "September 2008." Description based on title screen as viewed on November 5, 2008. Includes bibliographical references (p. 115-116). Also available in print.
22
Middleton, Robert. "Techniques for homodyne dechirp-on-receive linearly frequency modulated radar." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1843.
Full textAbstract:
This thesis presents work done to extend and improve the operation of homodyne dechirp-on-receive linearly frequency modulated radars. First, an investigation of the effect of common phase errors on the point response function of the radar is described. The dependence on the window function of the degradation due to phase errors is investigated, and a simple, precise, and general approach for calculating the degraded Point Spread Function (PSF) is described and demonstrated. This method is shown to be particularly useful when investigating the effect of chirp nonlinearity on the PSF. Next, a method for focussing range profiles that are degraded by chirp nonlinearity is described. This method is based on two established methods, the Phase Gradient Algorithm (PGA) and a time-domain re-sampling technique. The technique is entirely hardware independent, allowing any homodyne dechirp-on-receive linearly frequency modulated radar to be focussed. Where suitable archive signal data exists, focussed imagery can even be produced from radars that no longer exist. The complete algorithm and details of the implementation are described, and the technique is demonstrated on three representative radar cases: extreme chirp nonlinearity, typical chirp nonlinearity, and a retrospective case. In all of the cases, it was shown that the PSF was dramatically improved. A technique based on down conversion by aliasing for reducing the required sampling rate is described, and a simple technique for calculating suitable sampling rates is presented. This method is demonstrated for a typical application in which sampling rate reduction might be required, namely Moving Target Indication (MTI). The MTI application is described and quantified, including a simple technique for choosing suitable radar operation parameters. The MTI technique with subsampling was demonstrated in software simulations and in a simple radar experiment. A Synthetic Aperture Radar (SAR) test bench for researching component performance and scatterer properties in the context of SAR was developed. An appropriate image formation processing algorithm was found and modified to better suit the task of a short data collection baseline and drifting centre frequencies, both of which are present in the test bench situation. Software was written to collect data, to control the hardware, and to process the signals into SAR images. A data simulator was written to test the image formation algorithm implementation; it also served as a useful tool for investigating the effect of signal errors on the quality of the resultant SAR imagery. A suitable oscillator was chosen for the task, based on phase noise and centre frequency stability considerations, both of which are quantified and discussed. Preliminary SAR imagery was produced, indicating that the system operates correctly and in agreement with comparable systems.
23
Ma, Chung-Hsiu. "Stepped-frequency pulse train waveforms for improved radar range resolution." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41030.
Full textAbstract:
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996."June 1996."
Includes bibliographical references (leaves 87-89).
The traditional approach of improving radar range resolution using a linear frequency modulated chirp signal requires the full width of the frequency spectrum, which is not feasible in the UHF band due to interference or frequency allocation for other purposes. In this study a linear frequency modulated chirp signal is approximated using two stepped-frequency pulse train waveforms, a continuous wave pulse train and a linear frequency modulated pulse train. The continuous wave pulse train consists of a series of single frequency pulses, each at a different frequency. It is found to be susceptible to corruption due to target motion. The linear frequency modulated pulse train consists of linear frequency modulation within pulses, each at a different center frequency. Simulations are used to demonstrate that both approaches approximate a linear frequency modulated chirp signal, and performance is degraded when there is a gap in the frequency band or if there is phase distortion due to target motion. However, it is shown that a linear frequency modulated pulse train with frequency overlaps between pulses can be used to reduce or eliminate phase distortions resulting from target motion provided the target is moving with constant velocity. The validity of the technique is demonstrated by non-coherently processing radar data from an internal moving target simulator and data from actual planes to resolve targets from their reflected image in order to estimate target height.
by Chung-Hsiu Ma.
S.B.and M.Eng.
24
Park, James. "Multi-Frequency Radar Signatures of Human Motion: Measurements and Models." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354228912.
Full text
25
Green, Sean David. "Improving the range information of high frequency over-the-horizon skywave radar." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268265.
Full text
26
Park, Joongsuk. "Development of microwave and millimeter-wave integrated-circuit stepped-frequency radar sensors for surface and subsurface profiling." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/1588.
Full textAbstract:
Two new stepped-frequency continuous wave (SFCW) radar sensor prototypes, based on a coherent super-heterodyne scheme, have been developed using Microwave Integrated Circuits (MICs) and Monolithic Millimeter-Wave Integrated Circuits (MMICs) for various surface and subsurface applications, such as profiling the surface and subsurface of pavements, detecting and localizing small buried Anti-Personnel (AP) mines and measuring the liquid level in a tank. These sensors meet the critical requirements for subsurface and surface measurements including small size, light weight, good accuracy, fine resolution and deep penetration. In addition, two novel wideband microstrip quasi-TEM horn antennae that are capable of integration with a seamless connection have also been designed. Finally, a simple signal processing algorithm, aimed to acquire the in-phase (I) and quadrature (Q) components and to compensate for the I/Q errors, was developed using LabView. The first of the two prototype sensors, named as the microwave SFCW radar sensor operating from 0.6-5.6-GHz, is primarily utilized for assessing the subsurface of pavements. The measured thicknesses of the asphalt and base layers of a pavement sample were very much in agreement with the actual data with less than 0.1-inch error. The measured results on the actual roads showed that the sensor accurately detects the 5-inch asphalt layer of the pavement with a minimal error of 0.25 inches. This sensor represents the first SFCW radar sensor operating from 0.6-5.6-GHz. The other sensor, named as the millimeter-wave SFCW radar sensor, operates in the 29.72-35.7-GHz range. Measurements were performed to verify its feasibility as a surface and sub-surface sensor. The measurement results showed that the sensor has a lateral resolution of 1 inch and a good accuracy in the vertical direction with less than 0.04-inch error. The sensor successfully detected and located AP mines of small sizes buried under the surface of sand with less than 0.75 and 0.08 inches of error in the lateral and vertical directions, respectively. In addition, it also verified that the vertical resolution is not greater than 0.75 inches. This sensor is claimed as the first Ka-band millimeter-wave SFCW radar sensor ever developed for surface and subsurface sensing applications.
27
Delgado, Raymond R. "Mapping coastal surface winds in Monterey Bay using high frequency radar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA362924.
Full textAbstract:
Thesis (M.S. in Meteorology and M.S. in Physical Oceanography) Naval Postgraduate School, March 1999."March 1999". Thesis advisor(s): Jeffrey D. Paduan, Carlyle H. Wash. Includes bibliographical references (p. 121-122). Also available online.
28
Abd, Rashid Nur Emileen Binti. "Automatic vehicle classification in a low frequency forward scatter micro-radar." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3018/.
Full textAbstract:
Forward Scattering Radar (FSR) is a special case of bistatic radar configuration where the desired radar signal is formed via the shadowing of the direct (transmitter-to-receiver) signal by the target body. FSR offers a number of interests including an inherent ability to detect stealth target, absence of signal fluctuations, reasonably simple hardware, enhanced target radar cross-section (RCS) compared to traditional radar and capability to use Inverse Synthetic Aperture algorithms for Automatic Target Classification (ATC). Of course as any system FSR has its own drawbacks and limitations. This thesis presents the research results on development of ATC algorithm under a variety of external factors such as clutter and target's trajectories uncertainties. The peculiarity of this research are that the FSR operates at a low (VHF and UHF) frequency bands that in a strict sense does not correspond to an optical region for vehicles like targets and the system operate with omnidirectional antennas. There is no previous research considered this practically important case. The algorithm is developed based on Fourier transform, Principal Component Analysis (PCA) and K-Nearest Neighbour (KNN) classifier - for features extraction, transformation and classification, respectively. The ATC system is integrated with coherent signal processing algorithm in order to estimate target’s motion parameters (i.e speed) prior to spectra normalisation process. The analytical and modelling results are experimentally confirmed. As ATC performance degraded when high level of clutter is present, cluttercompensated ATC model is introduced and its classification performance is analysed using measured signals with added simulated clutter.
29
Metwally, Mohamed. "OFDM Coupled Compressive Sensing Algorithm for Stepped Frequency Ground Penetrating Radar." ScholarWorks @ UVM, 2014. http://scholarworks.uvm.edu/graddis/274.
Full textAbstract:
Dating back to as far as 1940, the US road and bridge infrastructure system has garnered quite the status for strategically connecting together half a continent. As monumental as the infrastructure's status, is its rate of deterioration, with the average bridge age coming at a disconcerting 50 years. Aside from visual inspection, a battery of non-destructive tests were developed to conduct structural fault assessment and detect laminations, in order to preemptively take preventive measures.
The mainstream commercially favored test is the impulse time domain ground penetrating radar (GPR). An extremely short, high voltage pulse is used to visualize cross-sections of the bridge decks. While effective and it does not disturb traffic flow, impulse radar suffers from major drawbacks. The drawbacks are namely, its limited dynamic range and high cost of system manufacturing. A less prominent yet highly effective system, stepped frequency continuous wave (SFCW) GPR, was developed to address the aforementioned drawbacks. Mostly developed for research centers and academia, SFCW boasts a high dynamic range and low cost of system manufacturing, while producing comparable if not identical results to the impulse counterpart. However, data procurement speed is an inherent problem in SFCW GPR, which seems to keep impulse radar in the lead for production and development.
I am proposing a novel approach to elevate SFCW's data acquisition speed and its scanning efficiency altogether. This approach combines an encoding method called orthogonal frequency division multiplexing (OFDM) and an emerging paradigm called compressive sensing (CS). In OFDM, a digital data stream, the transmit signal, is encoded on multiple carrier frequencies. These frequencies are combined in such a way to achieve orthogonality between the carrier frequencies, while mitigating any interference between said frequencies. In CS, a signal can be potentially reconstructed from a few samples below the standardized Nyquist rate. A novel design of the SFCW GPR architecture coupled with the OFDM-CS algorithm is proposed and evaluated using ideal channels and realistically modelled bridge decks.
30
Moes, Henderikus Jan. "A low noise PLL-based frequency synthesiser for X-band radar." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1337.
Full text
31
Clarke, Bryan Russell. "Frequency Modulated Continuous Waveform Radar for Collision Prevention in Large Vehicles." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14034.
Full textAbstract:
The drivers of large vehicles can have very limited visibility, which contributes to poor situation awareness and an increased risk of collision with other agents. This thesis is focused on the development of reliable sensing for this close proximity problem in large vehicles operating in harsh environmental conditions. It emphasises the use of in-depth knowledge of a sensor’s physics and performance characteristics to develop effective mathematical models for use in different mapping algorithms. An analysis of the close proximity problem and the demands it poses on sensing technologies is presented. This guides the design and modelling process for a frequency modulated continuous waveform (FMCW) radar sensor for use in solving the close proximity problem. Radar offers better all-weather performance than other sensing modalities, but its measurement structure is more complex and often degraded by noise and clutter. The commonly used constant false alarm rate (CFAR) threshold approach performs poorly in applications with frequent extended targets and a short measurement vector, as is the case here. Therefore, a static detection threshold is calculated using measurements of clutter made using the radar, allowing clutter measurements to be filtered out in known environments. The detection threshold is used to develop a heuristic sensor model for occupancy grid mapping. This results in a more reliable representation of the environment than is achieved using the detection threshold alone. A Gaussian mixture extended Kalman probability hypothesis density filter (GM-EK-PHD) is implemented to allow mapping in dynamic environments using the FMCW radar. These methods are used to produce maps of the environment that can be displayed to the driver of a large vehicle to better avoid collisions. The concepts developed in this thesis are validated using simulated and real data from a low-cost 24GHz FMCW radar developed at the Australian Centre for Field Robotics at the University of Sydney.
32
Chang, Paul Chinling. "Near zone radar imaging and feature capture of building interiors." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1197399599.
Full text
33
Streed, Daniel H. "High-frequency meteorological phenomena observed with the Naval Postgraduate School's UHF Doppler Wind Profiler." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA243762.
Full textAbstract:
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Nuss, Wendell A. Second Reader: Wash, C. H. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Descriptor(s): Marine Meteorology, Meteorological Radar, Wind, Specifications, Comparison, Doppler Radar, Accuracy, Theses, Meteorological Data, Time, Short Range(Time), Reliability, Profiles, Scale, Data Acquisition, California, Inversion, Statistical Analysis, Meteorological Phenomena, Radiosondes, Schools, Ultrahigh Frequency, High Frequency, Contracts. DTIC Identifier(s): Wind Profilers. Author(s) subject terms: Doppler Wind Profiler, Wind Profiler, Doppler Radar. Includes bibliographical references (p. 115-117). Also available in print.
34
Kim, Kyung Cheol. "Calibration and validation of high frequency radar for ocean surface current mapping." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FKim.pdf.
Full text
35
Brinkman, Wade H. "Focusing ISAR images using fast adaptive time-frequency and 3D motion detection on simulated and experimental radar data." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FBrinkman.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2005.Thesis Advisor(s): Michael A. Morgan, Thayananthan Thayaparan. Includes bibliographical references (p. 119-120). Also available online.
36
Sova, Markus Gintas. "The sampling variability and the validation of high frequency radar measurements of the sea surface." Thesis, University of Sheffield, 1995. http://etheses.whiterose.ac.uk/12786/.
Full textAbstract:
Remote sensing is becoming an increasingly important tool for ocean wave measurement, and over the past decade much progress has been made in the development of the wave measuring capabilities of HF (High Frequency) radar. This system is able to make detailed and near continuous observations of the sea surface over a wide area. However, because the mathematics of the data extraction process is rather difficult, the statistical properties of the observed data have to date been poorly understood. In this study, the approximate sampling distributions of a variety of measurements from HF radar (including significant waveheight, mean wave period, wind direction, and various spectral parameters) are derived in terms of quantities that are either known or estimable. The resulting confidence intervals are, in the case of significant waveheight and mean wave period, of comparable width to those obtained from the corresponding NURWEC2 (Netherlands UK Radar Wave buoy Experimental Comparison) wave buoy measurements, and in the case of spectral power, they are narrower. Furthermore, methods are derived by which such radar measurements may be compared with their corresponding wave buoy measurements in a statistically valid manner, and their relative biases estimated. These methods are then applied to data taken during the NURWEC2 field trial, which suggest that the radars and the wave buoy show good correspondence for measurements of significant waveheight and of spectral power (over 85 - 125mHz - the frequencies with most wave power, and hence those of most importance). There is also a fair correspondence for mean period measurements in the range 6.8 - 11.0secs. Spectral mean direction shows good correspondence over 85 - 155mHz over the somewhat limited directional range (i. e. as observed during the NURWEC2 storm) of the data.
37
Everaere, Etienne. "Polarimetry in Bistatic Configuration for Ultra High Frequency Radar Measurements on Forest Environment." Palaiseau, Ecole polytechnique, 2015. https://theses.hal.science/tel-01199522/document.
Full textAbstract:
Les systèmes radar permettent de couvrir de larges zones et grâce à la capacité qu’ont les ondes électromagnétiques qu’ils utilisent de passer à travers les milieux, le radar est un des outils les plus approprié pour la télédétection dans la forêt. Mais pour une utilisation efficace, il est important de choisir de bonne configuration d’acquisition. À trop haute fréquence l’onde ne pénètre pas, c’est pourquoi nous limitons notre étude aux bandes UHF, P et L. De plus, un système radar qui utilise une diversité de polarisations d’émission et de réception peut récolter plus d’information de la scène, car la polarisation est sensible à la structure de la forêt. Avec un récepteur radar dissocié de l’émetteur, la polarimétrie a encore plus de potentiel car la symétrie entre les trajets aller et retour du monostatique est évité. Le but de cette thèse est d’anticiper des mesures réelles bistatiques en bande P sur la forêt. Cela permet de donner des paramètres clés pour choisir la meilleure configuration que ce soit pour une application dans l’inversion des paramètres physiques de la forêt ou la détection d’objets artificiels dans la forêt. La solution que nous proposons consiste en l’utilisation d’un polarimètre à l’échelle optique et qui permet de faire des mesures sur un ensemble de configurations bistatiques à la fois. Les scènes utilisées sont constituées de nanotubes de carbone qui reproduisent les caractéristiques structurelles et diélectriques de forêts de troncs à l’échelle radar. Nous démontrons que ces mesures peuvent être utilisées pour anticiper la mesure bistatique radar mais elles permettent également la validation des codes de simulation existants. Le code COBISMO développé pour le radar peut reproduire les mesures de nanotubes. En utilisant les résultats de comparaison, le code de simulation est ensuite appliqué pour étudier les configurations et les polarisations les plus à même de retrouver l’orientation des branches et pour la détection sous le couvert forestierDue to penetration capabilities of electromagnetic waves and the possibility to cover large areas, radar is one of the most appropriate tool for remote sensing of forest. To use radar images for forestry, it is crucial to select and optimize the best configurations of acquisition. If the frequency is too high, no penetration occurs and only the top leafs will play a role in the scattering events. Large wavelengths used in radar are more able to penetrate the forest elements and to interact also with the ground below. For this reason, we limit this thesis to the use of UHF, P-band and L-band. By emitting and receiving several couples of polarizations, several images can be collected. The polarimetry is sensitive the structure information and consequently, it can bring a diversity of information. A radar system which comprises a transmitter and receiver which are spatially separated is an opportunity to supply additional information to classical polarimetric radar, because it breaks symmetry observed in the monostatic case. The aim of the thesis is to anticipate real P-band bistatic radar measurements on forest and to give keys to choose more appropriate configuration for a given application: physical parameter retrieval or target detection. The solution we propose is to construct an optical scale device that is full polarimetric and that handle the bistatic configurations, and to measure scene having a structure comparable to a real forest. We demonstrate that the optical scale measurement can be used to anticipate polarimetric behavior of forest and jointly to validate our simulation code. Polarization and configuration are studied to discriminate branch orientation and to detect man-made objects in the forest
38
Haider, Ammar. "Design of a metal detector." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-26452.
Full textAbstract:
Electromagnetic wave propagation is a well-known phenomenon in the scientific world and when the first telescope was built method of sensing objects excelled afterwords. Research in optical system and infrared is growing day by day but radar system still dominates the world in object sensing. One of the benefits of using electromagnetic waves in a Radar system is that they can create images of areas which cannot be observed with optical light. Radars work on the basic phenomena of an extremely short burst of radio energy which transmit energy that reflects from the object as an echo. This principle is also known as ECHO Principal [13]. This thesis presents a Coffee Can radar system which gives detection of a stationary and moving object. Objects detection is performed on the oscilloscope using a triangular wave transmitted from an antenna, that gets reflected from an object and received on the second antenna. The prototype consists of two antennas one of which is used for transmitting signal and other is used for receiving signal. Voltage control oscillator is used to generate the RF frequency signal and power amplifiers are used before transmitting and receiving the RF signal. The signals are down-converted using a mixer the output of which is observed on an oscilloscope. Detection of the reflected signal can be performed using Doppler shift which can be determined from the velocity of electromagnetic radiation and angular displacement of the reflected waves. The wavelength of the Doppler shift is then used to indicate the detection and ranging of the object. Coffee Can radar operates at 2.4GHz with the output power of 10mW. Triangular wave signal is generated with the help of a wave generator. The radar prototype built in this thesis is used for detection and ranging of two different types of materials. First, is a metal sheet and secondly an aluminum foil. The detection process is completed by noting the Vpp values reflected from these sheets. Vpp values are measured on the oscilloscope when the signal reflected from aluminum sheet. With the help of a commercial software, aluminum foil presence is detected under the snow. For the future work if the video amplifier is built then the aluminum foil presence can be detected on MATLAB without the help of any commercial software. In future Coffee Can Radar can also be used for surveillance purposes like smart homes, autonomous vehicles and as a jammer. This Radar system can also be used as a data logging system.
39
Pichler, Markus. "Phase-locked-loop-based signal synthesis for frequency-modulated continuos wave radar /." Linz : Trauner, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=9783854993889.
Full text
40
Brooks, William Allen. "Ultra-wideband radar transient signal detection using time-frequency and wavelet transforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School; Available from the National Technical Information Service, 1992. http://edocs.nps.edu/npspubs/scholarly/theses/1992/Dec/92Dec_Brooks.pdf.
Full text
41
Moraitakis, Ioannis. "Feature extraction of intra-pulse modulated radar signals using time-frequency analysis." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA371390.
Full textAbstract:
Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, September 1999."September 1999". Thesis advisor(s): Monique P. Fargues, Ralph D. Hippenstiel. Includes bibliographical references (p. 103-104). Also Available online.
42
Loza, Artur. "Image processing and time-frequency transform methods for radar characterisation and recognition." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500445.
Full textAbstract:
This thesis covers research into radar target characterisation and recognition with the use of joint time-frequency representations and image processing techniques. Specifically, the recognition of the scatterers of ballistic missiles is of particular interest. The complex motion and composite structure of the targets result in highly nonstationary signal, and therefore its characteristics are investigated both in time and frequency. A novel method for time-frequency analysis of nonstationary radar signals is proposed facilitating formulation of a feature space suited to the problem at hand. This signal-adaptive procedure allows unsupervised computation of the Smoothed Wigner-Ville Distribution based on time and frequency moments of the time-segmented signal.
43
Schmid, Robert L. "High-frequency silicon-germanium reconfigurable circuits for radar, communication, and radiometry applications." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54838.
Full textAbstract:
The objective of the proposed research is to create new reconfigurable RF and millimeter-wave circuit topologies that enable significant systems benefits. The market of RF systems has long evolved under a paradigm where once a system is built, performance cannot be changed. Companies have recognized that building flexibility into RF systems and providing mechanisms to reconfigure the RF performance can enable significant benefits, including: the ability support multiple modulation schemes and standards, the reduction of product size and overdesign, the ability to adapt to environmental conditions, the improvement in spectrum utilization, and the ability to calibrate, characterize, and monitor system performance. This work demonstrates X-band LNA designs with the ability to change the frequency of operation, improve linearity, and digitally control the tradeoff between performance and power dissipation. At W-band frequencies, a novel device configuration is developed, which significantly improves state-of-the-art silicon-based switch performance. The excellent switch performance is leveraged to address major issues in current millimeter-wave systems. A front-end built-in-self-test switch topology is developed to facilitate the characterization of millimeter-wave transceivers without expensive millimeter-wave equipment. A highly integrated Dicke radiometer is also created to enable sensitive measurements of thermal noise.
44
Kabutz, Marten Herbert. "RF hardware design of a stepped frequency continuous wave ground penetrating radar." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/18227.
Full textAbstract:
Bibliography: pages 86-88.Research into stepped frequency continuous wave ground penetrating radar (SFCW GPR) at UCT has been carried out since 1990. A first generation system comprising of Hewlett-Packard test equipment controlled by a PC was assembled. Cavity-backed log spiral antennas were designed and built by the University of Stellenbosch for the specific use of ground penetrating radar. Measurements with the first generation system proved the concept of SFCW GPR and thus a dedicated second generation system was planned. A SFCW GPR system was designed to replace the first generation system. Various designs for transmitter and receiver configurations were investigated and those found most suitable were used for the implementation. The SFCW radar consists of a wideband CW transmitter and a coherent receiver. A 300-1000 MHz transmitter was constructed using varactor-tuned oscillators as frequency sources. A double-sideband, low-IF receiver was constructed for the 300- 1000 MHz signal, to mix it to an IF of 10.7 MHz and I-Q demodulate it. The transmitter was found to operate according to specifications. The receiver was found to operate satisfactorily, but the dynamic range was less than expected. A limiting problem encountered in the first generation GPR was the large direct coupling signal from the transmitter into the receiver. This large signal reduced the effective receiver dynamic range. A method of cancelling this large direct coupling signal was implemented, using a bi-phase modulator to generate the cancelling signal in antiphase to the coupling signal. A 20 dB reduction in coupling was shown. The system was used to measure cable lengths to within the inherent accuracy of the system. A metal plate target was detected by the system feeding two antenna and a concrete floor was detected under 1 m of sand. It was thus shown that the SFCW system could be used as a second generation GPR.
45
Edman, Sebastian. "Radar target classification using Support Vector Machines and Mel Frequency Cepstral Coefficients." Thesis, KTH, Optimeringslära och systemteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214794.
Full textAbstract:
In radar applications, there are often times when one does not only want to know that there is a target that reflecting the out sent signals but also what kind of target that reflecting these signals. This project investigates the possibilities to from raw radar data transform reflected signals and take use of human perception, in particular our hearing, and by a machine learning approach where patterns and characteristics in data are used to answer the earlier mentioned question. More specific the investigation treats two kinds of targets that are fairly comparable namely smaller Unmanned Aerial Vehicles (UAV) and Birds. By extracting complex valued radar video so called I/Q data generated by these targets using signal processing techniques and transform this data to a real signals and after this transform the signals to audible signals. A feature set commonly used in speech recognition namely Mel Frequency Cepstral Coefficients are used two describe these signals together with two Support Vector Machine classification models. The two models where tested with an independent test set and the linear model achieved a overall prediction accuracy 93.33 %. Individually the prediction resulted in 93.33 % correct classification on the UAV and 93.33 % on the birds. Secondly a radial basis model with a overall prediction accuracy of 98.33 % where achieved. Individually the prediction resulted in 100% correct classification on the UAV and 96.76 % on the birds. The project is partly done in collaboration with J. Clemedson [2] where the focus is, as mentioned earlier, to transform the signals to audible signals.I radar applikationer räcker det ibland inte med att veta att systemet observerat ett mål när en reflekted signal dekekteras, det är ofta också utav stort intresse att veta vilket typ av föremål som signalen reflekterades mot. Detta projekt undersöker möjligheterna att utifrån rå radardata transformera de reflekterade signalerna och använda sina mänskliga sinnen, mer specifikt våran hörsel, för att skilja på olika mål och också genom en maskininlärnings approach där med hjälp av mönster och karaktärsdrag för dessa signaler används för att besvara frågeställningen. Mer ingående avgränsas denna undersökning till två typer av mål, mindre obemannade flygande farkoster (UAV) och fåglar. Genom att extrahera komplexvärd radar video även känt som I/Q data från tidigare nämnda typer av mål via signalbehandlingsmetoder transformera denna data till reella signaler, därefter transformeras dessa signaler till hörbara signaler. För att klassificera dessa typer av signaler används typiska särdrag som också används inom taligenkänning, nämligen, Mel Frequency Cepstral Coefficients tillsammans med två modeller av en Support Vector Machine klassificerings metod. Med den linjära modellen uppnåddes en prediktions noggrannhet på 93.33%. Individuellt var noggrannheten 93.33 % korrekt klassificering utav UAV:n och 93.33 % på fåglar. Med radial bas modellen uppnåddes en prediktions noggrannhet på 98.33%. Individuellt var noggrannheten 100 % korrekt klassificering utav UAV:n och 96.76% på fåglar. Projektet är delvis utfört med J. Clemedson [2] vars fokus är att, som tidigare nämnt, transformera dessa signaler till hörbara signaler.
46
Chauhan, Ruchir. "A Platform for False Data Injection in Frequency Modulated Continuous Wave Radar." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3964.
Full textAbstract:
Radar is an acronym for RAdio Detection And Ranging. In general terms, it is a machine that uses radio waves for object-detection in its near periphery. It transmits radio waves in a known direction, which when intercepted by an obstruction/object are reflected by its surface and are received back at the radar system. The round trip delay time along with the known velocity of radio waves gives an accurate measurement of the distance of the object from the radar system. In a somewhat similar fashion, some radars are even capable of measuring the velocity of this object. Frequency-modulated continuous-wave (FMCW) radar is one such radar system, which is a subclass of continuous wave (CW) radars, where a continuous sinusoidal radio energy is transmitted, reflected, and received back at the radar system. These radar systems are widely used in vehicle automation technologies such as adaptive cruise control (ACC) and collision avoidance systems (CAS) to measure the distance from the nearest vehicles and maintain a safe following distance. But in designing these systems, little attention has been given to security, and these systems have vulnerabilities that are capable of compromising the whole purpose of making such systems.
In this work one such vulnerability in FMCW radar was exploited to design an attack that was capable of decreasing the apparent distance, as measured by a radar system. The attack was designed in such a way that there was no tampering with the radar system being attacked. Instead, false distance information was introduced in the return path of the transmitted radio wave by absorbing the original victim transmission and sending out a modified radio wave on the It was shown that the distance could be decreased to alarming values, which at the level of the vehicle automation system results in decreasing the speed of the automobile when actually it should have increased.
47
Frost, Shaun W. "Performance Analysis of Radar Waveforms for Congested Spectrums." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1323183379.
Full text
48
Green, Ryan K. "Scaled Synthetic Aperture Radar System Development." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1498.
Full textAbstract:
Synthetic Aperture Radar (SAR) systems generate two dimensional images of a target area using RF energy as opposed to light waves used by cameras. When cloud cover or other optical obstructions prevent camera imaging over a target area, SAR can be substituted to generate high resolution images. Linear frequency modulated signals are transmitted and received while a moving imaging platform traverses a target area to develop high resolution images through modern digital signal processing (DSP) techniques. The motivation for this joint thesis project is to design and construct a scaled SAR system to support Cal Poly radar projects. Objectives include low-cost, high resolution SAR architecture development for capturing images in desired target areas. To that end, a scaled SAR system was successfully designed, built, and tested. The current SAR system, however, does not perform azimuthal compression and range cell migration correction (image blur reduction). These functionalities can be pursued by future students joining the ongoing radar project. The SAR system includes RF modulating, demodulating, and amplifying circuitry, broadband antenna design, movement platform, LabView system control, and MATLAB signal processing. Each system block is individually described and analyzed followed by final measured data. To confirm system operation, images developed from data collected in a single target environment are presented and compared to the actual configuration.
49
Seybert, Audrey, Jay Fuller, and Bryan Townley. "Detect Sense and Avoid Radar for UAV Avionics Telemetry." International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595802.
Full textAbstract:
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaThis paper describes the development and test results of a Frequency Modulated Continuous Wave (FMCW) L-Band radar testbed designed to detect obstacles in the proximity of an Unmanned Aerial Vehicle (UAV). From laboratory loopback tests, it was calculated that with pulse compression and a transmit power of 150 mW (22 dBm), the radar is capable of detecting an object with a 0.014-m2 radar cross-sectional area at ranges between 500 ft to 1 mi. Analysis shows that post processing of the collected data would reveal information about the obstacle such as its range and location relative to the aircraft. Design and testing procedures are discussed.
50
Eriksson, Oscar. "Filterdesign och hårdvarukonstruktion för FMCW-radar." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7988.
Full textAbstract:
Den här högskoleavhandlingen beskriver designen av ett IF-filter samt hårdvarukonstruktion av en ny 77 GHz FMCW-radar demonstrator. Syftet med demonstratorn är att illustrera hur kisel germanium-, SiGe, teknologi kan användas istället för den mer vedertagna men dyrare gallium arsenik-, GaAs, teknologin. Den gamla radar-prototypen vilken Acreo AB utvecklat är funktionell men behöver konstrueras om för att bättre kunna utvärdera radarprestandan. I avhandlingen presenteras grundläggande radarteori och ekvationer för att underlätta förståelsen av de olika systemblocken. Rapporten beskriver också systemarkitekturen och hur dess funktionalitet kommer att testas. Det omdesignade IF-filtret har simulerats i en PSpice-simulator och ett prototypkort av detta har tillverkats för mätningar. Ett 4-lagers kretskort av hela systemet har tagits fram i Orcad Layout. Slutligen innehåller rapporten förslag på förbättringar till nästa demonstratorversion.
This bachelor thesis describes the design of an IF-filter and the hardware construction of a new version of a 77 GHz FMCW-radar demonstrator. The purpose of the demonstrator is to illustrate how the silicon germanium-, SiGe, technology could be used instead of the more conventional but also much more expensive gallium arsenide-, GaAs, technology. The old radar prototype that Acreo AB has developed is fully functional but needs to be redesigned to be able to evaluate the radar performance in a better way. The thesis presents the basic radar theory and equations to help understanding the construction of the system blocks. The report also describes the system architecture and how its functionality should be tested. The redesigned IF-filter has been simulated in a PSpice simulator and a prototype has been manufactured and measured. A 4-layer PCB-board of the whole system was done in Orcad Layout. Finally the report is concluded with suggestions on improvements for the next demonstrator version.