With the rapid increase in the number of automotive radars on the road, interference becomes unavoidable. This paper analyses the effectiveness of dithering or randomization of FMCW modulation (applying random idle time jitter) on... more
With the rapid increase in the number of automotive radars on the road, interference becomes unavoidable. This paper analyses the effectiveness of dithering or randomization of FMCW modulation (applying random idle time jitter) on reducing interference. This analysis is undertaken for various interference scenarios and modelling-based results are compared. The results show that the efficiency of interference reduction by employing random idle time jitter strongly depend on the radar waveform parameters and the achievable reduction in interference level is in the range of 0 to 27 dB.
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Spread spectrum (SS) systems are well known to have high immunity against narrowband interference. However, it has been shown that structural correlation exists between SS signal and continuous wave (CW) interference, which will degrade... more
Spread spectrum (SS) systems are well known to have high immunity against narrowband interference. However, it has been shown that structural correlation exists between SS signal and continuous wave (CW) interference, which will degrade the system performance. In particular, for a direct sequence SS (DS/SS) system with linear input structure, a maximum reduction of about 3–5 dB on SNR is observed [1]. The aim of this paper is to extend this study for systems with non-linearity. The introduction of non-linearity will redistribute the power among the signal and interference and destroy the time-determined structure of CW interference.
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The results of long-term clutter tests are presented for short-range ground-based bistatic radar sensor operating at different carrier frequencies in VHF and lower UHF bands. Measured clutter realizations are analyzed in time and spectral... more
The results of long-term clutter tests are presented for short-range ground-based bistatic radar sensor operating at different carrier frequencies in VHF and lower UHF bands. Measured clutter realizations are analyzed in time and spectral domains. Total clutter power is increased with wind speed and system carrier frequency increasing, but clutter dynamics in time (gust factor) and the shape of clutter power spectrum remain practically independent from wind and frequency. The results coincide well with known clutter measurement results obtained mostly by monostatic radars.
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The development of remote surface recognition systems is an important step in ensuring road safety. This paper examines the performance of surface classification algorithms, used for the analysis of backscattered microwave and ultrasonic... more
The development of remote surface recognition systems is an important step in ensuring road safety. This paper examines the performance of surface classification algorithms, used for the analysis of backscattered microwave and ultrasonic signals. The novelty of our research is the joint use of data obtained from sonar and multifrequency polarimetric radar. The results demonstrate the feasibility of reliable surface classification using the proposed methodology.
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This paper presents an experimental comparative study of the propagation of microwave signals in the frequency ranges of 300 GHz and 79 GHz through fire. The operation of Low Terahertz imaging radar was investigated in various real... more
This paper presents an experimental comparative study of the propagation of microwave signals in the frequency ranges of 300 GHz and 79 GHz through fire. The operation of Low Terahertz imaging radar was investigated in various real scenarios, including fire with strong flame, dense smoke, and water vapor. The ability of Low Terahertz radar to ensure visibility of objects in fire environments was proven. In all scenarios, radar signal absorption was measured and in the case of steam was compared with theoretical calculations; the results are in good agreement. The analysis of the experimental results allows us to conclude that there are good prospects for Low Terahertz radar in the field of firefighting equipment for vision and navigation.
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A unique graphical tool is presented in this paper that shows the severity of effects, in terms of signal to interference ratio, when receiving interference from various FMCW radars into one FMCW victim radar. The Heatmap tool is of... more
A unique graphical tool is presented in this paper that shows the severity of effects, in terms of signal to interference ratio, when receiving interference from various FMCW radars into one FMCW victim radar. The Heatmap tool is of importance as wide range of automotive radars are currently operating and more will be introduced in the future with plethora of new parameters. Understanding the effects on the functionality of the automotive radars in the presence of interference is crucial to aid development of mitigation strategies. The universal Heatmap tool can also be used to estimate the level of signal to interference ratio for any victim and interferer radars pair and road scenarios. The estimated signal to interference ratio value calculated by the described technique is compared and validated with simulation results and backed by laboratory experimental measurement results.
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The exploitation of sub-terahertz technology (200 GHz–700 GHz) is proposed for imaging and the recognition of an object's state from a space-based sensor using inverse synthetic aperture radar, benefiting from wide bandwidth and... more
The exploitation of sub-terahertz technology (200 GHz–700 GHz) is proposed for imaging and the recognition of an object's state from a space-based sensor using inverse synthetic aperture radar, benefiting from wide bandwidth and enhanced sensitivity to surface texture of signals in this band. An initial technical analysis of the system is presented with the calculation of expected resolutions and of the power budget. Initial experimental results from measurements in a scaled environment are presented.
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This chapter is an introduction to passive synthetic aperture radar (SAR) using global navigation satellite systems (GNSS), as illuminators of opportunity. Such systems include the global positioning system (GPS), the Russian GLONASS... more
This chapter is an introduction to passive synthetic aperture radar (SAR) using global navigation satellite systems (GNSS), as illuminators of opportunity. Such systems include the global positioning system (GPS), the Russian GLONASS system, or the forthcoming Galileo constellation. Apart from the traditional benefits of a passive radar system, which include cost efficiency, license-free and covert operation, GNSS-based systems have a number of relative merits compared to passive systems based on terrestrial illuminating sources. One of its most prominent features is the potential for persistent monitoring anywhere in the world due to the global GNSS coverage. In addition, as GNSS guarantee a number of satellites illuminating the same point on Earth from multiple aspect angles simultaneously, this provides an opportunity to enhance radar information space. This can be done either by comparing individual passive SAR images obtained from multiple satellite perspectives, or combining them using multistatic SAR techniques. On the other hand, the relatively low power flux density near the Earth's surface restricts the field of view of applications for such a system to monitoring local areas. At the same time, and partially due to its rather broad scope, this technology has not yet reached the maturity of terrestrial-based systems. As such, the purpose of this chapter is to present methods and results on the fundamental science and technology behind GNSS-based SAR, as a stepping stone to realizing its full potential. This includes an introduction to the system concept and its fundamental parameters (power budget/resolution), signal processing algorithms for signal synchronization and image formation, as well as proof-of-concept results for advanced techniques such as change detection, multi-perspective and multistatic imaging.
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This paper presents an overview of the latest research results towards the development of a coherent change detector based on passive, bistatic SAR imagery. The proposed system uses navigation satellites as transmitters, while the... more
This paper presents an overview of the latest research results towards the development of a coherent change detector based on passive, bistatic SAR imagery. The proposed system uses navigation satellites as transmitters, while the receiver is fixed on the ground. Potential problems in using such a configuration are briefly described, and a conceptual description of how they were tackled is given. Experimental results are provided where appropriate. Finally, an experimental test-bed designed to confirm the system feasibility is presented.
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ABSTRACT The work described in this paper is a continuation of previous analytical work that has progressed to an experimental phase. The paper discusses the development of an ultra-wideband (UWB), forward-scatter radar (FSR) system for... more
ABSTRACT The work described in this paper is a continuation of previous analytical work that has progressed to an experimental phase. The paper discusses the development of an ultra-wideband (UWB), forward-scatter radar (FSR) system for the detection and (ultimately) automatic recognition of low reflectivity maritime targets. Here we present the concept, developed hardware and selected initial experimental results. A number of novel ideas have been developed to reduce cost, size, prime power requirement, complexity and utilise the advantages of FSR operation. System benefits include increased target cross section (over conventional bi/monostatic radar), increased target detection capability, robustness to stealth targets, decrease in sea clutter effects from synthesis of extremely narrow beams whilst using omni directional antennas and sub-Hertz Doppler frequency measurement capability. The experimental work investigates the use of an UWB FSR fence for security, UWB propagation measurements, UWB sea clutter measurements at very low grazing angles, UWB spectral coverage and the synthesis of narrow beamwidth antennas using forward scatter pulse transmission.
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This paper presents research results on passive bistatic SAR. It discusses various system parameters, problems (e.g. parameter estimation, motion compensation), and signal processing algorithms (imaging, synchronization) required for... more
This paper presents research results on passive bistatic SAR. It discusses various system parameters, problems (e.g. parameter estimation, motion compensation), and signal processing algorithms (imaging, synchronization) required for bistatic SAR imaging. An experimental set-up for the verification of our system is described and an experimentally obtained image using Galileo satellite transmitter is analyzed.
This paper presents a new topology for a sub-class of bistatic SAR, called Space-Surface Bistatic SAR (SS-BSAR). This new topology comprises Global Navigation Satellite Systems (GNSS) as transmitters of opportunity and a stationary... more
This paper presents a new topology for a sub-class of bistatic SAR, called Space-Surface Bistatic SAR (SS-BSAR). This new topology comprises Global Navigation Satellite Systems (GNSS) as transmitters of opportunity and a stationary receiver on the ground. It is shown that such a system is promising for local area monitoring, and its very basic radar performance (power budget, resolution) is assessed.
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ABSTRACT There is a lack of published experimental forward-scattering radar sea clutter data at very low (almost zero) grazing angle over the sea. This data is necessary to provide a fundamental understanding of the operating environment... more
ABSTRACT There is a lack of published experimental forward-scattering radar sea clutter data at very low (almost zero) grazing angle over the sea. This data is necessary to provide a fundamental understanding of the operating environment for the development of forward-scatter radar systems for maritime applications. Experimental data has therefore been recorded at frequencies of 7.5 GHz, 9.3 GHz, 24 GHz, and 37.5GHz using Forward Scatter Radar with static, medium gain antennas for low sea states 1–3. Results of clutter power spectral density measurements are presented and conclusions drawn from the results.
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There is a certain relationship between the delay spread and the received signal strength of multipath waves. This paper describes the geometrical interpretation for spread delay in urban areas. An analytical approach for relative... more
There is a certain relationship between the delay spread and the received signal strength of multipath waves. This paper describes the geometrical interpretation for spread delay in urban areas. An analytical approach for relative receivedpower as a funetion of excess delay is ...
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... M. Cherniakov, Result of a space surface bistatic sar image formation algorithm, IEEE Transactions on GRS, Vol.45,2007,pp3359-3371 [6] M. Cherniakov, R. Saini, R. Zuo, M. Antoniou, Space-surface bistatic synthetic aperture radar... more
... M. Cherniakov, Result of a space surface bistatic sar image formation algorithm, IEEE Transactions on GRS, Vol.45,2007,pp3359-3371 [6] M. Cherniakov, R. Saini, R. Zuo, M. Antoniou, Space-surface bistatic synthetic aperture radar with global navigation satellite system ...
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This paper presents an overview of the research conducted at University of Birmingham. It highlights and briefly discusses various systems parameters (e.g., resolution, power budget), problems (e.g., interference, heterodyne channel... more
This paper presents an overview of the research conducted at University of Birmingham. It highlights and briefly discusses various systems parameters (e.g., resolution, power budget), problems (e.g., interference, heterodyne channel Doppler compensation), and signal processing algorithms (imaging, synchronization) required for successfully obtaining an image. The GLONASS satellite is used for experiential confirmation of the main results. All these results are presented and briefly discussed.
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Multipath fading and human body influence affect the performance of a Low Earth Orbit Satellite (LEOS) handheld terminal. In this research, the effectiveness of optimum combining is compared with selection diversity and omni-directional... more
Multipath fading and human body influence affect the performance of a Low Earth Orbit Satellite (LEOS) handheld terminal. In this research, the effectiveness of optimum combining is compared with selection diversity and omni-directional antenna systems. By using the electric field and magnetic field antennas, zero correlation can be provided. In the presence of interference, adaptive antennas can nullify the interference. In the absence of interference, adaptive antennas can maximise the final Signal to Noise Ratio (SNR). In this case, an adaptive antenna is the same as a maximum ratio combiner. An adaptive antenna system provides a 2.0dB gain on average when its performance is compared with the selection diversity system. The adaptive antenna system also provides a 9.5dB gain on average when its performance is compared with the omni-directional antenna system. Finally, adaptive antennas can automatically resolve the phase ambiguity effect, so that differential coding is not required. Therefore, an extra 3dB gain can be obtained.
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This paper describes a computer model for the radio wave propagation channel of Low Earth Orbit Satellites (LEOS) communication systems. The model assumes that the user receives the satellite-transmitted signal either in an outdoor or... more
This paper describes a computer model for the radio wave propagation channel of Low Earth Orbit Satellites (LEOS) communication systems. The model assumes that the user receives the satellite-transmitted signal either in an outdoor or indoor environment. The paper describes the equations of Doppler shift, elevation angle, and distance between satellite and the user at different times. It discusses how the frequency implementation of the Doppler filter in a fading channel can be improved by using a zero-packing technique. It also addresses the fact that delay spread power distribution can be approximated by the square of the ratio between the shortest time delay and the time delay.
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A handset for a Low Earth Orbit Satellite (LEOS) system is a new type of terminal. In comparison with terrestrial communication systems, LEOS link budget is essentially limited due to the distance between satellites and handsets. This can... more
A handset for a Low Earth Orbit Satellite (LEOS) system is a new type of terminal. In comparison with terrestrial communication systems, LEOS link budget is essentially limited due to the distance between satellites and handsets. This can be partly compensated by utilizing two-element antenna diversity systems at handsets. Antenna diversity systems utilized with and without the coding and interleaving
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In this study, the attenuation of 300 GHz signal propagating through a layer of leaves which can built upon the antenna radome is investigated. Three set of leaves (Lauren, Birch, Willow) are chosen in this measurement as likely... more
In this study, the attenuation of 300 GHz signal propagating through a layer of leaves which can built upon the antenna radome is investigated. Three set of leaves (Lauren, Birch, Willow) are chosen in this measurement as likely obscurants which can stick to automotive radar radome and cause signal degradation. Transmissivity through uniform layer of the leaves with different water contents is measured. The water content is estimated in leaves drying gradually. The complex permittivity of the leaves with different water contents is estimated and these values are used to calculate the transmissivity through the uniform layer of leaves. Comparison of transmissivity in equivalent water layer with that of leaves having the same water content is made. Measured transmissivity through leaves is compared with that obtained by theoretical model.
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In this paper it is described a universal experimental set-up to investigate a sub-THz communication channels performance and its preliminary testing results. The experimental set up at 300 GHz is described in the paper but the authors... more
In this paper it is described a universal experimental set-up to investigate a sub-THz communication channels performance and its preliminary testing results. The experimental set up at 300 GHz is described in the paper but the authors has 670 GHz version of this test bed which will be described in forthcoming papers.
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The development of automotive remote surface identification system is an important step in ensuring road safety. In this paper we shall discuss a novel approach which addresses the road surface classification process. This method is based... more
The development of automotive remote surface identification system is an important step in ensuring road safety. In this paper we shall discuss a novel approach which addresses the road surface classification process. This method is based on polarimetric radar and sonar data fusion and surface identification using artificial neural network. A modular artificial neural network, which is considered in the paper, allows an overall increase in classification accuracy in the presence of a large number of surface types and a large number of signal features. We shall discuss the techniques involved and present classification results that have been achieved using modular neural network.
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An underwater imaging system was investigated for automotive use in highly scattered underwater environments. The purpose of the system is the driver’s information about hidden obstacles, such as stones, driftwood, open sewer hatches. A... more
An underwater imaging system was investigated for automotive use in highly scattered underwater environments. The purpose of the system is the driver’s information about hidden obstacles, such as stones, driftwood, open sewer hatches. A comparison of various underwater vision methods was presented by the way they are implemented, the range reached, and the cost of implementation. It has been experimentally shown that a conventional active system can provide a maximum visibility range of up to three light attenuation lengths. In most practical cases of turbid waters during floods, this corresponds to distances of about 1 meter. From the presented analysis it follows that advanced extended range imaging methods allow increasing of the visibility range up to 2 meters.