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This paper proposes a corner reflector and Luneburg ball reflector group. The omnidirectional radar cross-sectional (RCS) distribution characteristics of a fighter are simulated using the sharp and smooth RCS distribution features of the corner and the Luneburg ball reflectors, respectively. A new type of Doppler signal generation principle is proposed to design a Doppler frequency simulator to transmit frequency signals by connecting in parallel with the metal layer of the corner reflector and the Luneburg sphere ball, and then transmit through their other end. The existing radar target aircraft cannot simulate the RCS and speed of the targets that are less than 0.005 m2 by enhancing the echo intensity of the target location, which makes it impossible for the military to conduct practice drills and evaluate the effectiveness of the air defense systems. The experimental results show that the Doppler frequency simulator successfully simulates the target speed of 0-80 km/h and when the speed is greater than 20 km/h, the error of the simulation frequency is less than 1.5%. The proposed method can provide guidance and a theoretical basis for simulating the speed of various types of aircraft in future work.

This paper proposes a corner reflector and Luneburg ball reflector group. The omnidirectional radar cross-sectional (RCS) distribution characteristics of a fighter are simulated using the sharp and smooth RCS distribution features of the corner and the Luneburg ball reflectors, respectively. A new type of Doppler signal generation principle is proposed to design a Doppler frequency simulator to transmit frequency signals by connecting in parallel with the metal layer of the corner reflector and the Luneburg sphere ball, and then transmit through their other end. The existing radar target aircraft cannot simulate the RCS and speed of the targets that are less than 0.005 m2 by enhancing the echo intensity of the target location, which makes it impossible for the military to conduct practice drills and evaluate the effectiveness of the air defense systems. The experimental results show that the Doppler frequency simulator successfully simulates the target speed of 0-80 km/h and when the speed is greater than 20 km/h, the error of the simulation frequency is less than 1.5%. The proposed method can provide guidance and a theoretical basis for simulating the speed of various types of aircraft in future work.

This paper proposes a corner reflector and Luneburg ball reflector group. The omnidirectional radar cross-sectional (RCS) distribution characteristics of a fighter are simulated using the sharp and smooth RCS distribution features of the corner and the Luneburg ball reflectors, respectively. A new type of Doppler signal generation principle is proposed to design a Doppler frequency simulator to transmit frequency signals by connecting in parallel with the metal layer of the corner reflector and the Luneburg sphere ball, and then transmit through their other end. The existing radar target aircraft cannot simulate the RCS and speed of the targets that are less than 0.005 m2 by enhancing the echo intensity of the target location, which makes it impossible for the military to conduct practice drills and evaluate the effectiveness of the air defense systems. The experimental results show that the Doppler frequency simulator successfully simulates the target speed of 0-80 km/h and when the speed is greater than 20 km/h, the error of the simulation frequency is less than 1.5%. The proposed method can provide guidance and a theoretical basis for simulating the speed of various types of aircraft in future work.

Стаття присвячена дослідженню систем звуколокації безпілотних літальних апаратів для моніторингу терористичних загроз, які є захищеними від засобів радіоелектронної боротьби. В роботі запропоновано звуколоційну систему щодо виявлення рухомих об’єктів, яка побудована за допомогою мережі датчиків, що розміщені в просторі. Основною відмінністю від існуючих звуколокаційних систем є визначення часової затримки не за взаємною кореляційною функцією, а за взаємною функцією невизначеності сигналів між датчиками. Однак застосування методу взаємної функції невизначеності обмежено лише визначенням характеристик для одноцільової ситуації, тобто неможливо оцінити координати у випадку двох цілей, і відповідно, у багатоцільовій ситуації, при атаці великої кількості безпілотних літальних апаратів. Також існує обчислювальна складність обробки широкосмугових сигналів у часовій, спектральній та допплерівській областях. Якщо для нерухомих цілей досить обробки в спектрально-часової області на основі швидкого перетворення Фур’є, то для рухомих цілей потрібна додаткова багатоканальна обробка в області допплерівських частот. Так як число допплерівських каналів порівнянне з розміром вибірки, то обчислювальні витрати суттєво зростають, на кілька порядків, тому для роботи системи звуколокації в реальному часі доцільна розробка програмного забезпечення із застосуванням паралельного програмування, бібліотеки Openmp, відеокарти з векторною та матричною обробкою даних, GPU NVIDIA на основі технології CUDA. Це дозволить прискорити виконання операцій приблизно в 30 разів та забезпечити реалізацію систем на портативних комп’ютерах. Проведений аналіз системи звуколокації показав потенційні можливості визначення координат безпілотних літальних апаратів та інших рухомих об’єктів у тривимірному просторі з точністю, достатньою для подальшого супроводу цілей засобами візуального спостереження.

Whenever more than one target exist, the most important problem is associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the other unknown target parameters.

Whenever more than one target exist, the most important problem is associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the other unknown target parameters.

Whenever more than one target exist, the most important problem is associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the other unknown target parameters.

Whenever more than one target exist, the most important problem is associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the other unknown target parameters.

Whenever more than one target exist, the most important problem is associating the received signals to the correct targets. This problem appears for all multiple target applications such as multiple target tracking and it is known as "Data Association". For frequency-based systems, Multiple-Input Multiple-Output (MIMO) configuration together with the frequency diversity of the system enable us to determine the number of moving targets by using the Doppler frequencies. These frequencies include all relevant information about the location, velocity and direction of the targets and hence, they can be used efficiently to estimate the other unknown target parameters.

We demonstrate a novel method that makes an efficient use of laser nonlinear dynamics when subject to optical self-injection for subwavelength displacement sensing purposes. The proposed methodology combines two different phenomena taking place inside the laser cavity: optical self-injection, which results in optical feedback interference, and laser continuous wave frequency modulation, giving rise to a wavelength sweeping effect in the laser's emission. We present a combination of these phenomena to measure vibration amplitudes below lambda/2 with the resolutions of a few nanometers, bandwidth dependent upon the distance of external target, amplitude, and frequency of current modulation. The basic theoretical details and a mathematical model are presented for the developed measurement principle. Experimental results with the system working as a vibrometer to measure a target vibration of amplitude lambda/5 (137.5 nm) with a mean peak-to-peak error of 2.4 nm just by pointing the laser diode onto the target and applying some signal processing are also demonstrated., Postprint (author's final draft)

This work presents an improvement of the P2EPS end-to-end simulator to assess the performances of Global Navigation Satellite System Reflectometry (GNSS-R) space missions over land. Beyond the single specular reflection model, topography effects are included. In order to avoid the computational burden of facet approach based on the bi-static radar model, the Phong reflection model is employed. By calculating the delay, Doppler frequency, and relative intensity of scattered points, the topography effects can be accounted for as a sort of impulse response in the delay, and Doppler domains to be convolved with the Woodward Ambiguity function., Peer Reviewed, Postprint (published version)

Проаналізовано потенційні роздільні здатності за дальністю та радіальною швидкістю імпульсних складних сигналів із симетричною лінійною частотною модуляцією, трикутною, трапецеїдальною, квадратичною, кубічною частотною модуляцією та псевдовипадкових сигналів. Зроблені висновки щодо переваг відповідних складних сигналів з кнопкоподібною діаграмою невизначеності. Розроблено рекомендації для визначення числа доплерівських каналів. Оцінено складність реалізації багатоканальних трактів виявлення сигналу відбиття у вигляді багатоканального за доплерівською частотою тракту на базі узгоджених фільтрів або кореляторів з наданням відповідних структурних схем.

In this paper, the performance of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels is evaluated using measurement data. We consider the multi-user MIMO system using a block diagonalization (BD) scheme and an eigenbeam-space division multiplexing (E-SDM) technique. In an ideal case, the BD scheme eliminates inter-user interference, and the E-SDM technique suppresses inter-stream interference. In actual radio environments, however, channels change over time. This causes interference in the multi-user MIMO system even though the BD scheme and the E-SDM technique are used. To overcome this problem, the authors have developed a simple channel prediction scheme on the basis of a linear extrapolation and have demonstrated its effectiveness by computer simulations assuming the Jakes' model. To verify the performance of the channel prediction scheme in actual environments, we conducted a measurement campaign in indoor environments and measured a large amount of channel data. Using these data, we examined the channel transition and channel tracking with the prediction method. Then we obtained the bit-error rate (BER) performance. The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case.

In this paper, the performance of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels is evaluated using measurement data. We consider the multi-user MIMO system using a block diagonalization (BD) scheme and an eigenbeam-space division multiplexing (E-SDM) technique. In an ideal case, the BD scheme eliminates inter-user interference, and the E-SDM technique suppresses inter-stream interference. In actual radio environments, however, channels change over time. This causes interference in the multi-user MIMO system even though the BD scheme and the E-SDM technique are used. To overcome this problem, the authors have developed a simple channel prediction scheme on the basis of a linear extrapolation and have demonstrated its effectiveness by computer simulations assuming the Jakes' model. To verify the performance of the channel prediction scheme in actual environments, we conducted a measurement campaign in indoor environments and measured a large amount of channel data. Using these data, we examined the channel transition and channel tracking with the prediction method. Then we obtained the bit-error rate (BER) performance. The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case.

In this paper, we derive the Cramer-Rao Bounds (CRBs) for the 2-dimensional (2D) target localization and velocity estimations for widely separated Multiple-Input Multiple-Output (MIMO) radar. The transmitters emit signals with different frequencies and the receivers receive these signals with amplitude fluctuations and with Doppler shifts due to the target motion. The received signal model is constructed using the Swerling target fluctuations to take into account the undesired effects of target amplitude and phase fluctuations. Moreover, the time delays and the Doppler frequencies are included in the signal model to get a more realistic model. Then, the Cramer-Rao Bounds are derived for the proposed signal model for the target position and velocity estimations. Contrary to known models of CRBs, we derived the CRBs jointly and using the Swerling target fluctuations.

In this paper, the performance of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels is evaluated using measurement data. We consider the multi-user MIMO system using a block diagonalization (BD) scheme and an eigenbeam-space division multiplexing (E-SDM) technique. In an ideal case, the BD scheme eliminates inter-user interference, and the E-SDM technique suppresses inter-stream interference. In actual radio environments, however, channels change over time. This causes interference in the multi-user MIMO system even though the BD scheme and the E-SDM technique are used. To overcome this problem, the authors have developed a simple channel prediction scheme on the basis of a linear extrapolation and have demonstrated its effectiveness by computer simulations assuming the Jakes' model. To verify the performance of the channel prediction scheme in actual environments, we conducted a measurement campaign in indoor environments and measured a large amount of channel data. Using these data, we examined the channel transition and channel tracking with the prediction method. Then we obtained the bit-error rate (BER) performance. The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case.

In this paper, we derive the Cramer-Rao Bounds (CRBs) for the 2-dimensional (2D) target localization and velocity estimations for widely separated Multiple-Input Multiple-Output (MIMO) radar. The transmitters emit signals with different frequencies and the receivers receive these signals with amplitude fluctuations and with Doppler shifts due to the target motion. The received signal model is constructed using the Swerling target fluctuations to take into account the undesired effects of target amplitude and phase fluctuations. Moreover, the time delays and the Doppler frequencies are included in the signal model to get a more realistic model. Then, the Cramer-Rao Bounds are derived for the proposed signal model for the target position and velocity estimations. Contrary to known models of CRBs, we derived the CRBs jointly and using the Swerling target fluctuations.

In this paper, we derive the Cramer-Rao Bounds (CRBs) for the 2-dimensional (2D) target localization and velocity estimations for widely separated Multiple-Input Multiple-Output (MIMO) radar. The transmitters emit signals with different frequencies and the receivers receive these signals with amplitude fluctuations and with Doppler shifts due to the target motion. The received signal model is constructed using the Swerling target fluctuations to take into account the undesired effects of target amplitude and phase fluctuations. Moreover, the time delays and the Doppler frequencies are included in the signal model to get a more realistic model. Then, the Cramer-Rao Bounds are derived for the proposed signal model for the target position and velocity estimations. Contrary to known models of CRBs, we derived the CRBs jointly and using the Swerling target fluctuations.

In this paper, the performance of a multi-user multiple-input multiple-output (MIMO) system in time-varying channels is evaluated using measurement data. We consider the multi-user MIMO system using a block diagonalization (BD) scheme and an eigenbeam-space division multiplexing (E-SDM) technique. In an ideal case, the BD scheme eliminates inter-user interference, and the E-SDM technique suppresses inter-stream interference. In actual radio environments, however, channels change over time. This causes interference in the multi-user MIMO system even though the BD scheme and the E-SDM technique are used. To overcome this problem, the authors have developed a simple channel prediction scheme on the basis of a linear extrapolation and have demonstrated its effectiveness by computer simulations assuming the Jakes' model. To verify the performance of the channel prediction scheme in actual environments, we conducted a measurement campaign in indoor environments and measured a large amount of channel data. Using these data, we examined the channel transition and channel tracking with the prediction method. Then we obtained the bit-error rate (BER) performance. The prediction technique was shown to track the channel and improve the BER performance almost to that in the ideal time invariant case.

In order to achieve focused SAR images it is necessary to have accurate knowledge of the radar antenna position during its motion over the synthetic aperture. This position information is used to ensure proper focusing of the SAR image by phase compensating the data collected over the entire SAR path. This process is known as motion compensation and requires precise measurement of the position of the phase center of the GPR antenna. The positioning measurement system utilized on this project used electronic repeaters that act as reference targets within the SAR field of view. The repeater-based measurement technique works as follows. Each repeater receives the radar signal, alters it by imposing a pseudo-Doppler modulation onto the signal, and then transmits this modulated signal back to the radar. The repeater signals are, thus, embedded in the normal radar data stream; no special radar modifications are required to receive the repeater signals. A different Doppler frequency is used for each individual repeater allowing each repeater to be uniquely identified. After Doppler processing, the responses from the repeaters stand out above the background clutter with high signal quality (i.e., high signal to clutter ratio) because the repeater signals have been Doppler shifted away from the zero-Doppler background clutter. Due to the high quality of the repeater signals, with post processing of the data, the range between each repeater and the SAR antenna is precisely determined. A tri-lateration algorithm is then used on three repeater ranges to accurately locate the SAR antenna's 3D position. Only the precise relative locations of the repeaters with respect to each other are needed in order to form a sharply focused SAR image; absolute geo-location of the repeaters also allows the focused SAR image to be accurately geo-referenced as well., SERDP Project No. CU-1173.

The development of high-quality digital mobile radio systems has become a major goal in the field of digital communications. The possibility of providing speech and data services free of wire constrictions in different environments is a very attractive proposition, supported by means of the personal communications network (PCN) concept. The aim of the present article is to analyze the behavior of different receiver structures for such systems in order to obtain some clues to be used in designing the next generation of mobile systems. These systems have to provide both low- and high-data-rate services (up to 1 Mb/s) and be efficient in environments where a high density of traffic is generated. Moreover, as the carrier frequencies will range between 1 and 4 GHz, and the vehicle speed can be as high as 400 km/hr (e.g., high-speed trains), large Doppler frequency values must be coped with. Under certain conditions, diversity techniques perform better than equalization techniques in typical mobile radio environments., Peer Reviewed

A particle sizing interferometer designed to measure particle sizes from 0.3 to 500 micrometers has been constructed for the Ballistics Research Laboratory. The device was constructed to measure droplet size distributions produced by high pressure pneumatic nozzles. This report describes the expected operational response of this instrument in high density liquid sprays. Additionally, discussion is provided of theoretical concepts which are required for data interpretation when the interferometer sample volume depends on droplet sizes.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.

Tato práce se zabývá vlivem vnitropulsní modulace na funkci neurčitosti. Funkce neurčitosti nám udává rozlišovací schopnost systému v dálce a Dopplerově kmitočtu. Práce se skládá z obecného popisu základů radiolokace, jednotlivých modulací a vlastního řešení v programu MATLAB s využitím řídkých matic. V textu jsou obsaženy grafy funkcí neurčitosti pro jednotlivé modulace, vytvořené v MATLABu, This thesis is dedicated to pulse modulation influence to the ambiguity function. The ambiguity function indicates the resolution of the system in range and Doppler frequency. The thesis contains the general introduction of radiolocation basis, individual modulations and the solution in MATLAB environment utilizing spare matrix principles. Graphs of ambiguity function for individual modulations created in MATLAB environment are included in the text.