Articles de revues : « Radar de surveillance secondaire »

1

Vidal, Luis E., Ulises Román Concha, Justo Solís, José Piedra, Carlos Chávez, Dominga M. Cano et Juan C. Woolcott. « Implementation of a Transportable Radar Mode S of Monopulse Secondary Surveillance (MSSR-S) for the Peruvian Civil Aviation Surveillance ». Telecom 4, n^o 4 (3 octobre 2023) : 693–708. http://dx.doi.org/10.3390/telecom4040031.

Texte intégral

Résumé :

This article describes the process of implementing a transportable radar MSSR-S for Peruvian civil aviation (ACP) to minimize the operational impact in emergencies that affects air traffic without causing structural damage and restore data from the radar in a short time. In recent years, ACP has shown constant falls in the radars, causing radar data to be lost for long periods of time and putting air safety at risk due to the lack of maintenance and overlapping radar coverage of more than three radars. The deployment of the transportable radar in Mode S of Monopulse Secondary Surveillance (MSSR-S) has allowed for work that involves the prolonged stoppage of the radar to be carried out and provided coverage to eight more radars during maintenance and modernization, covering the areas without coverage in the Peruvian air space (EAP). For the implementation, this was divided into three SPRINTs using the SCRUM methodology; the first sprint refers to the equipment and radar coverage study, the second the implementation and service test phase, and the third the operational analysis phase with the eight modernized radars. As a result of the implementation and integration with the other ACP radar systems, they were able to operate together, providing highly reliable radar data, performing a continuous analysis of radar performance through the PASS software, complying with the thresholds established by ICAO and EuroControl, and guaranteeing that the systems operate under perfect conditions and with full coverage at all time.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Reader, K. « Secondary Surveillance Radar ». Electronics & ; Communications Engineering Journal 2, n^o 2 (1990) : 43. http://dx.doi.org/10.1049/ecej:19900013.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

3

Topilin, A. A. « Secondary radar azimuth accuracy with increased surveillance speed ». Journal of «Almaz – Antey» Air and Space Defence Corporation, n^o 3 (30 septembre 2019) : 52–57. http://dx.doi.org/10.38013/2542-0542-2019-3-52-57.

Texte intégral

Résumé :

The study introduces the dependence of the secondary radar aircraft azimuth accuracy on the space surveillance speed and the signal-to-noise ratio for various algorithms of the primary processing of radar data under the influence of normal Gaussian and Rice processes. The results obtained are practically applicable when upgrading software which implements the processing of radar data in existing radars

Styles APA, Harvard, Vancouver, ISO, etc.

4

Svyd, I. V. « Comparative analysis of the quality of detection of air objects by secondary radar systems ». Radiotekhnika, n^o 213 (16 juin 2023) : 78–87. http://dx.doi.org/10.30837/rt.2023.2.213.09.

Texte intégral

Résumé :

The work is devoted to a comparative analysis of the quality of detection of air objects by secondary radar systems. The purpose of the work is a comparative analysis of the optimal and quasi-optimal structure for detecting air objects by secondary interrogation radar systems. A significant role in the information support of the airspace control and air traffic control system is played by secondary radar systems for airspace surveillance, which include secondary radars and identification problems on the basis of “friend or foe” identification. Note that in existing networks of radar surveillance systems, tracking of airborne objects is usually carried out using information from primary radar surveillance systems, and secondary radar surveillance systems are used as sources of additional radar information. In this regard, the problems of assessing the quality of detection of air objects by secondary radar systems, the specifics of the construction and operation of which differ significantly from the primary airspace surveillance radar systems, are relevant. Thus, increasing the probabilistic characteristics of the system of secondary radar systems when an aircraft transponder operates in the field of significant flows of intentional and intra-system interference is ensured by choosing detection thresholds depending on the values of the transponder readiness coefficient and the probability of suppression of individual response signal pulses. On the other hand, the use of detection thresholds on secondary radar systems that are optimal for the given operating conditions of the transponder makes it possible to reduce the requirements for the throughput of the aircraft transponder with a significant intensity of flows of intra-system and intentional correlated interference. Analysis of the characteristics of detection of air objects by secondary radar systems shows that: optimal thresholds for detecting air objects in secondary radar systems significantly depend on the readiness factor of the aircraft transponder and the probability of suppression of individual pulses of response signals in the response channel; the use of decoding response signals and subsequent accumulation when choosing the optimal threshold significantly reduces the detection quality indicators compared to optimal processing of a burst of response signals; the digital threshold for detecting air objects in a secondary radar system largely depends on the probability of signal suppression in the request channel and response channel.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Svyd, I. V., et S. V. Starokozhev. « Distributed processing of radar information in airspace surveillance systems ». Radiotekhnika, n^o 212 (28 mars 2023) : 155–65. http://dx.doi.org/10.30837/rt.2023.1.212.15.

Texte intégral

Résumé :

The work is dedicated to the analysis of the quality of combining assessments of the radar signals and airborne objects detections in the implementation of distributed processing of radar information of airspace surveillance systems. The main sources of radar information about the air situation in the airspace control system are primary surveillance radars, secondary radar systems and identification systems on the basis of "friend or foe". It should be noted that the analysis of the information security of single-position radars shows their vulnerability in a wide range of unintentional and intentional interference, as well as determining their location. This is due to the ease of detection of the emitting transmitter of the probing signal in single-position radars. It led to the main disadvantage of single-position radars – low noise immunity and low survivability. The transition to a network of radar systems can significantly reduce the impact of deliberately directed interference. It also allows the use of methods for distributed processing of radar information in airspace surveillance systems. Analysis of the effectiveness of information support algorithms based on distributed processing of radar information of airspace surveillance systems, taking into account the final result, makes it possible to detect airborne objects using a packet of binary-quantized signals, taking into account two algorithms for combining detection results: channel accumulation and combining results; association of channel solutions and accumulation. It shows following: – the quality of consumer information support based on the proposed structure is much higher compared to the used radar information processing structure; the quality of information support for consumers has the best performance when using the signal processing method based on the accumulation of signals with the subsequent combination of detection results; the availability factor of the aircraft transponder significantly affects the quality of information support, already at P0<0.9 the use of integer logic for combining detection information is undesirable.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Weeda, D. J. A., L. P. Ligthart, L. R. Nieuwkerk, L. R. Nieuwkerk et D. C. M. van der Klein. « Quantitative Estimation of Secondary Surveillance Radar Information ». Journal of Navigation 45, n^o 1 (janvier 1992) : 26–35. http://dx.doi.org/10.1017/s0373463300010444.

Texte intégral

Résumé :

Improved radar surveillance for air traffic control can be obtained by the integration of radar systems. Integration, however, might cause the delay of radar information, which would hamper the air traffic controllers in their work. To estimate the delay, a mathematical equation to assess the amount of radar information causing this delay has been deduced from the properties of the behaviour of air traffic. The mathematical equation has been tested using results obtained from operational secondary surveillance radar in the Netherlands.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Ciećko, Adam, Grzegorz Grunwald, Natalia Malinowska et Artur Goś. « ACCURACY ANALYSIS OF AIRCRAFT POSITION PARAMETERS PROVIDED BY GCA 2000 AIRPORT SURVEILLANCE RADAR ». Aviation and Security Issues 4, n^o 2 (30 décembre 2023) : 1–15. http://dx.doi.org/10.55676/asi.v4i2.63.

Texte intégral

Résumé :

The aim of this article was to investigate the accuracy of determining the position parameters of an aircraft by the GCA 2000 airport control radar located at Deblin Airport (EPDE). In order to analyse the accuracy of determining the position of an aircraft by the GCA 2000 radar, a research flight was carried out. The position of the aircraft was recorded by the GCA 2000 radar and the Thales Mobile Mapper Pro GPS receiver on board the aircraft. The resulting position parameters were compared with each other to investigate the accuracy of the radar’s coordinate determination. In addition, a number of analyses and comparisons were performed to determine the reasons for the interruptions in the radar detection of the aircraft. Based on the study, it can be concluded that the GCA 2000 radar located at Deblin airport meets the requirements set by the International Civil Aviation Organisation (ICAO) for radar performance. According to ICAO, the standard deviation of the distance error should be 70–130 metres and the azimuth error for primary radars should be 0.15–0.2°, and for secondary radars 0.2–0.3°. The standard deviation of the distance error during a research flight by the GCA 2000 radar is 81.1 metres and the standard deviation of the azimuth error is 0.19°.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Stevens, M. C. « New developments in secondary-surveillance radar ». Electronics and Power 31, n^o 6 (1985) : 463. http://dx.doi.org/10.1049/ep.1985.0286.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

9

Svyd, I. V., et M. G. Tkach. « Synthesis and analysis of the trace detector of air objects of an interrogating radar system ». Radiotekhnika, n^o 212 (28 mars 2023) : 175–85. http://dx.doi.org/10.30837/rt.2023.1.212.17.

Texte intégral

Résumé :

The paper considers the features of tracking air objects in existing information networks of radar systems for monitoring airspace. It is shown that the tracking is carried out according to the information of the primary radar surveillance systems, and the secondary radar surveillance systems are used as sources of additional radar information. But the transition to automatic dependent surveillance implies the mandatory use of only request radar surveillance systems. Therefore, the problems of formulating methods and algorithms for tracking air objects based on information from secondary radar surveillance systems are relevant. The specifics of the construction and operation of secondary radar surveillance systems differ significantly from primary radar surveillance systems. The work carried out the synthesis and analysis of the structure of the tracks detector of air objects by interrogating radar systems for monitoring the airspace, namely: a comparative analysis of the quality of identifying the tracks of air objects was carried out; the quality of information support to consumers of the airspace control system with the proposed structure was improved in comparison with the used information processing structure; it is shown that the quality of information support for consumers has more preferable indicators when using the signal processing method during acquisition with subsequent information merging; the influence of the readiness factor of aircraft transponders of interrogative radar systems on the quality of information support for consumers of the airspace control system was evaluated.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Nagaoka, Sakae, et Osamu Amai. « Estimation Accuracy of Close Approach Probability for Establishing a Radar Separation Minimum ». Journal of Navigation 44, n^o 1 (janvier 1991) : 110–21. http://dx.doi.org/10.1017/s0373463300009784.

Texte intégral

Résumé :

A Long-range Secondary Surveillance Radar (LSSR) has been developed and recently used as an Oceanic Route Surveillance Radar (ORSR) in Japan. The LSSR is an SSR (Secondary Surveillance Radar) only system for which the maximum coverage is 250 nautical miles (n.m.). This system utilizes monopulse azimuth estimation techniques for improving the accuracy of azimuth estimation.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Kim, Euiho, et Kevin Sivits. « Blended secondary surveillance radar solutions to improve air traffic surveillance ». Aerospace Science and Technology 45 (septembre 2015) : 203–8. http://dx.doi.org/10.1016/j.ast.2015.05.018.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

12

Farid, Raihan Muhammad, Andhika Fawazaki Darman et Mayang Enggar Kusumastuti. « FAILURE ANALYSIS OF CHANNEL 1 MONOPULSE SECONDARY SURVEILLANCE RADAR IRS 20 MPS ». Journal of Airport Engineering Technology (JAET) 3, n^o 2 (14 juin 2023) : 102–10. http://dx.doi.org/10.52989/jaet.v3i2.105.

Texte intégral

Résumé :

Radio Detection and Ranging (Radar) is an electromagnetic wave used to monitor the movement of a moving object. RADAR will get information about the height and distance of an object by utilizing electromagnetic waves. Radar is surveillance equipment to monitor the aircraft’s position in the environment around the radar up to a radius of ± 250 NM. This article aims to analyze the surveillance facility at Kualanamu Airport Monopulse Secondary Surveillance Radar (MSSR) INDRA. This paper uses an exploratory study method with descriptive qualitative research to investigate and trace the problem. The problem on the INDRA IRS 20 MPS Radar is offline due to PLN supply maintenance activities, causing the supply voltage on the radar to be unstable. The failure problem on MSSR is due to damage to the Sum Amplifier Unit (SAU) module, which causes the SUM output on the Radar to be abnormal. The result of channel 1 INDRA IRS Radar 20 MPS operation can operate normally again after replacing a new SAU module. The conclusion of the operation of channel 1 INDRA IRS Radar 20 MPS can operate normally again after the replacement of a new SAU module.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Minteuan, Gheorghe, Tudor Palade, Emanuel Puschita, Paul Dolea et Andra Pastrav. « Monopulse Secondary Surveillance Radar Coverage—Determinant Factors ». Sensors 21, n^o 12 (18 juin 2021) : 4198. http://dx.doi.org/10.3390/s21124198.

Texte intégral

Résumé :

This paper presents a comprehensive study on monopulse secondary surveillance radar (MSSR) coverage. The design and radiation pattern of an improved MSSR antenna is presented herein, highlighting the horizontal and vertical factors of the SUM beam. Moreover, the impact of other determinant factors, such as signal reflection and atmospheric refraction, on the radar coverage were assessed in this work. Real positioning measurement data and coverage simulations were used to support and exemplify theoretical findings.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Anggraini Purwaningtyas, Dian, Johan Wahyudi, Feti Fatonah, Muh Wildan, Irvan Hanafi et Iga Ayu Mas Oka. « Rancang Bangun Virtual Laboratorium Monopulse Secondary Surveillance Radar Berbasis Augmented Reality ». Langit Biru : Jurnal Ilmiah Aviasi 15, n^o 03 (26 octobre 2022) : 107–16. http://dx.doi.org/10.54147/langitbiru.v15i03.721.

Texte intégral

Résumé :

Monopulse Secondary Surveillance Radar (MSSR) merupakan peralatan penting dalam pemantauan lalu lintas penerbangan, kompleksnya peralatan radar serta ketersediaan peralatan radar untuk praktikum membuat siswa dan peserta diklat kurang maksimal dalam pembelajaran radar baik teori dan praktek. Perkembangan teknologi dan pemanfaatan untuk pendidikan yang semakin meningkat menadi peluang untuk dilakukan pemutakhiran pembelajaran. Tujuan dari penelitian ini adalah untuk membuat rancangan virtual laboratorium radar berbasis augmented reality dalam pembelajaran radar dengan augmented reality dengan membuat prototype MSSR, metode untuk pembuatan dengan menggunakan metode prototype dengan pendekataan framework dari Sistem Development Life Cycle, selanjutnya untuk pengujian dengan menggunakan blackbox testing, menguji fungsi dari prototype dan hasil yang didapatkan fungsi dari prototype sudah sesuai dengan dokumen kebutuhan yang dipersyaratkan dalam penyelenggaraan pendidikan radar.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Strelnytskyi, Oleksii O., Iryna V. Svyd, Ivan I. Obod, Oleksandr S. Maltsev et Ganna E. Zavolodko. « Optimization of Secondary Surveillance Radar Data Processing ». International Journal of Intelligent Systems and Applications 11, n^o 5 (8 mai 2019) : 1–8. http://dx.doi.org/10.5815/ijisa.2019.05.01.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

16

Schejbal, V., P. Bezousek, J. Pidanic et M. Chyba. « Secondary Surveillance Radar Antenna [Antenna Designer's Notebook] ». IEEE Antennas and Propagation Magazine 55, n^o 2 (avril 2013) : 164–70. http://dx.doi.org/10.1109/map.2013.6578015.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

17

Trim, Richard M. « Radar Transponders and Radar Target Enhancers ». Journal of Navigation 48, n^o 3 (septembre 1995) : 396–409. http://dx.doi.org/10.1017/s0373463300012893.

Texte intégral

Résumé :

Radar transponders and radar target enhancers have been in use in a variety of applications for many years. Perhaps the most widely-known applications of radar transponders are in Identification Friend or Foe (IFF) and its civilian counterpart, secondary surveillance radar for air traffic control, and as racons in marine navigation and, most recently, as Search And Rescue Transponders (SART) in the Global Marine Distress and Safety System (GMDSS).

Styles APA, Harvard, Vancouver, ISO, etc.

18

Suchkov, A. V. « Frequency-Separating Devices for Secondary Surveillance Radar Systems ». Journal of Communications Technology and Electronics 68, n^o 8 (août 2023) : 875–82. http://dx.doi.org/10.1134/s1064226923080120.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

Suchkov, A. V. « Frequency-Separating Devices for Secondary Surveillance Radar Systems ». Радиотехника и электроника 68, n^o 8 (1 août 2023) : 790–97. http://dx.doi.org/10.31857/s0033849423080120.

Texte intégral

Résumé :

A frequency-separating device (FSD) with low insertion losses has been developed that provides electrical strength at high input power and combines the functions of several typical elements of the feeder path of a secondary surveillance radar (SSR): a receive/transmit switch, a harmonic filter, and a receiving band-pass filter. The issues of synthesis, analysis, and optimization of filters for the receiving and transmitting channels of the FSD are considered. Two options for the implementation of an FSD with insertion loss in the channel bandwidths within 0.7 dB, a harmonic suppression level of more than 40 dB, channel isolation, and attenuation at a deviation of ±60 MHz from the center frequencies of the passbands of at least 50 dB are proposed, the devices operate at frequencies of the FSD and of the seventh range of SSR systems with input pulse power up to 12 kW. The main dimensions of the FSD design, the results of numerical simulation, and the data of experimental verification of the characteristics are given. A comparative analysis of theoretical and experimental results is given.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Irfandi, Akhmad Hafidz, et Muhammad Taufik. « PENGGUNAAN SECONDARY SURVEILLANCE RADAR UNTUK PENENTUAN POSISI PESAWAT UDARA ». Geoid 9, n^o 1 (1 août 2013) : 17. http://dx.doi.org/10.12962/j24423998.v9i1.735.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

21

Petrochilos, Nicolas, et Alle-Jan van der Veen. « Algebraic Algorithms to Separate Overlapping Secondary Surveillance Radar Replies ». IEEE Transactions on Signal Processing 55, n^o 7 (juillet 2007) : 3746–59. http://dx.doi.org/10.1109/tsp.2007.894248.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

22

Tkach, M. G. « Estimation of the relative throughput of aircraft transponders of secondary airspace surveillance radar systems ». Radiotekhnika, n^o 207 (24 décembre 2021) : 123–31. http://dx.doi.org/10.30837/rt.2021.4.207.13.

Texte intégral

Résumé :

Secondary radar systems for monitoring airspace play a significant role in the information support of airspace control systems and air traffic control. These systems provide radar surveillance of airborne objects equipped with aircraft transponders and provide two-way communication via data request and response channels between ground radar stations and airborne objects. The paper assesses the relative throughput of aircraft transponders of secondary radar systems for monitoring airspace under the influence of correlated and uncorrelated interference in the request channel. The assessment of the throughput of the aircraft transponder shows that the aircraft transponder does not reach the maximum load included in the existing identification system under the influence of deliberate correlated interference. This indicates a sub-optimal determination of the aircraft transponder load factor of the existing secondary radar system. Incorrect determination of the maximum load of the aircraft transponder leads to a decrease in the noise immunity of both the aircraft transponder and the entire secondary radar system. At the same time, it should be noted that the interested party has the possibility of unauthorized use of an aircraft transponder to obtain information or paralyze the latter when applying interference of the required intensity.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Choi, Jong-Hwan, Hee-Duck Chae, Jong-Kuk Park et Hyung-Gi Na. « Monopulse Secondary Surveillance Radar Antenna with Sum/Difference/SLS Channels ». Journal of Korean Institute of Electromagnetic Engineering and Science 22, n^o 7 (31 juillet 2011) : 720–28. http://dx.doi.org/10.5515/kjkiees.2011.22.7.720.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

24

Manolakis, D. E. « Aircraft geometric height computation using secondary surveillance radar range differences ». IEE Proceedings - Radar, Sonar and Navigation 141, n^o 2 (1994) : 119. http://dx.doi.org/10.1049/ip-rsn:19949881.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

25

Grzybkowski, Maciej J., Daniel Niewiadomski et Marcin Mora. « Impact of Structures on the Operation of Air Traffic Radiolocation and Radionavigation Surveillance Systems ». Journal of Telecommunictions and Information Technology 4, n^o 2021 (30 décembre 2021) : 32–41. http://dx.doi.org/10.26636/jtit.2021.155221.

Texte intégral

Résumé :

The article describes interference affecting the operation of radiolocation and radionavigation devices used in the air traffic surveillance systems, caused by the proximity of building structures. The impact of a hypothetical structure on the operation of primary and secondary air traffic surveillance radars and DVOR/DME beacons was simulated. The results of this simulation are presented in the form of airspace sectors in which false identification of aircraft may occur, and where it will not be possible to identify aircraft or use beacons due to the certain portion of airspace being in the shadow created by the structure. Analysis of the possibility of the PSR radar receiver being blocked by a strong signal reflected from a nearby building was performed as well.

Styles APA, Harvard, Vancouver, ISO, etc.

26

McGrane, K. « Analysis and design optimization of monopulse receivers for secondary surveillance radar ». IEEE Transactions on Aerospace and Electronic Systems 27, n^o 5 (1991) : 838–52. http://dx.doi.org/10.1109/7.97328.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

27

Hessar, Farzad, et Sumit Roy. « Spectrum sharing between a surveillance radar and secondary Wi-Fi networks ». IEEE Transactions on Aerospace and Electronic Systems 52, n^o 3 (juin 2016) : 1434–48. http://dx.doi.org/10.1109/taes.2016.150114.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

Karan, Haldun, Patrick J. Fitzpatrick, Christopher M. Hill, Yongzuo Li, Qingnong Xiao et Eunha Lim. « The Formation of Multiple Squall Lines and the Impacts of WSR-88D Radial Winds in a WRF Simulation ». Weather and Forecasting 25, n^o 1 (1 février 2010) : 242–62. http://dx.doi.org/10.1175/2009waf2222263.1.

Texte intégral

Résumé :

Abstract A detailed observational and Weather Research and Forecasting (WRF) model analysis utilizing Weather Surveillance Radar-1988 Doppler (WSR-88D), surface, and upper-air observations, as well as Geostationary Operational Environmental Satellite (GOES) images, shows a chain of events that leads to the formation of two prefrontal squall lines along the western Gulf coast on 29–30 April 2005. An approaching surface cold front (CF) generated an atmospheric bore that propagated along an inversion layer and excited high-frequency, low-level tropospheric gravity waves, initiating a squall line 60 km east of the cold front. This sequence of events manifested itself as low-level convergence ahead of the CF, which was detected by nearby WSR-88D radars. Two WRF model experiments were conducted in which one assimilated conventional observations (CTRL), and another included radar radial winds from nine WSR-88D locations (denoted as RADAR). Better representation of the low-level kinematics in RADAR yielded a distinct convergence line associated with the primary squall line. The RADAR experiment, as well as observations (such as an 0600 UTC Slidell, Louisiana, sounding), show that the secondary squall line formed ahead of the primary squall line due to high water vapor and warm temperature advection from the Gulf of Mexico that, when combined with a deep dry layer above the atmospheric boundary layer (ABL), destabilized the atmosphere. Concurrently, a lower-tropospheric trough, propagating faster than the surface front, enhanced lifting in the region and instigated the formation of new convection. RADAR forecasted the secondary convection not only in the right place but also at about the right time, while the CTRL experiment completely missed this secondary convection.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Pietkiewicz, Tadeusz. « Fusion of Identification Information from ESM Sensors and Radars Using Dezert–Smarandache Theory Rules ». Remote Sensing 15, n^o 16 (10 août 2023) : 3977. http://dx.doi.org/10.3390/rs15163977.

Texte intégral

Résumé :

This paper presents a method of fusion of identification (attribute) information provided by two types of sensors: combined primary and secondary (IFF) surveillance radars and ESMs (electronic support measures). In the first section, the basic taxonomy of attribute identification is adopted in accordance with the standards of STANAG 1241 ed. 5 and STANAG 1241 ed. 6 (draft). These standards provide the following basic values of the attribute identifications: FRIEND; HOSTILE; NEUTRAL; UNKNOWN; and additional values, namely ASSUMED FRIEND and SUSPECT. The basis of theoretical considerations is Dezert–Smarandache theory (DSmT) of inference. This paper presents and uses in practice six information-fusion rules proposed by DSmT, i.e., the proportional conflict redistribution rules (PCR1, PCR2, PCR3, PCR4, PCR5, and PCR6), for combining identification information from different ESM sensors and radars. This paper demonstrates the rules of determining attribute information by an ESM sensor equipped with the database of radar emitters. It is proposed that each signal vector sent by the ESM sensor contains an extension specifying a randomized identification declaration (hypothesis)—a basic belief assignment (BBA). This paper also presents a model for determining the basic belief assignment for a combined primary and secondary radar. Results of the PCR rules of sensor information combining for different scenarios of a radio electronic situation (deterministic and Monte Carlo) are presented in the final part of this paper. They confirm the legitimacy of the use of Dezert–Smarandache theory in information fusion for primary radars, secondary radars, and ESM sensors.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Mehta, Rutika, Rohit Jain, Lori Rhodes, Joseph Abraham et Kenneth David Miller. « Long-term cancer survivorship care : On the radar screen ? » Journal of Clinical Oncology 31, n^o 15_suppl (20 mai 2013) : e20567-e20567. http://dx.doi.org/10.1200/jco.2013.31.15_suppl.e20567.

Texte intégral

Résumé :

e20567 Background: Long-term cancer survivors require comprehensive care. The purpose of this study was to describe how survivorship care fits into oncologists’ clinical time, and characterize long-term cancer survivors’ problems and oncology follow-up care. Methods: We abstracted 18,882 medical records of unique cancer patient visits during 2010 at a major NCI-designated cancer center and then evaluated survivor care for one week in April, 2010 to characterize how oncologists spend their clinical time. Finally, we selected three subgroups from the survivor population (n≈100 each) of survivors at 1-5 years, 6-10 years, and >10 years after diagnosis. We collected demographic data, purpose of visit, cancer-specific information, late and long-term effects, and type of care delivered, including surveillance for recurrence, intervention, prevention, and coordination of care. Results: In the larger group of 18,882, only 14% of survivors were more than 10 years post-diagnosis. Approximately two-thirds of the survivors were women. Breast cancer survivors comprised 38%, and survivors of hematologic malignancies accounted for 21% of the population. During the one week studied, the majority of oncologists' patients (74%) were actively receiving treatment; only 5% of their patients were 5 or more years post-diagnosis. Second or secondary malignancies were noted in 8% of patients. Late and long-term effects were uncommon. Approximately 25% of survivors beyond five years were observed to have late effects due to cancer treatment, most common being fatigue, neurological endocrine, and cardiac. Of the 300 selected survivors, sixty-two percent received only surveillance care during their visit. Only 3% of these patients received an entire array of survivorship care that included surveillance, intervention, co-ordination and prevention. Conclusions: A small proportion of oncologists’ visits were with long-term cancer survivors (5-14%) of whom only 25% had late or long-term effects of cancer treatment so overall very few of office visits were with long-term survivors who had late and long-term complications. All visits involved surveillance for cancer recurrence but there was little focus on prevention, intervention, and coordination of care for cancer survivors.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Piracci, Emilio G., Gaspare Galati, Nicolas Petrochilos et Fabrizio Fiori. « 1090 MHz channel capacity improvement in the air traffic control context ». International Journal of Microwave and Wireless Technologies 1, n^o 3 (juin 2009) : 193–99. http://dx.doi.org/10.1017/s1759078709000191.

Texte intégral

Résumé :

The aim of this study is to increase the capacity of the 1090 MHz secondary surveillance radar (SSR) channel by novel transmission and decoding techniques. In particular, multilateration stations have omni-directional antennae; hence considering aircraft traffic and including the extension of surveillance to cooperating vehicles, the reception of superimposed signals is more and more probable. We propose mitigating this problem by combining frequency agility and source separation techniques; we analyze the pertaining channel capacity improvement, and then evaluate the detection and timing estimation for frequency-shifted and separated signals.

Styles APA, Harvard, Vancouver, ISO, etc.

32

AMAI, Osamu, et Sakae NAGAOKA. « Evaluating the Performance of the Secondary Surveillance Radar for the Height Monitoring System ». Journal of Japan Institute of Navigation 92 (1995) : 27–35. http://dx.doi.org/10.9749/jin.92.27.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

33

Coakley, Maria, Prithika Sritharan, Guillermo Villacampa, Claire Swift, Kathryn Dunne, Lucy Kilburn, Katie Goddard et al. « Abstract PD5-03 : PD5-03 Comparison of a personalized sequencing assay and digital PCR for circulating tumor DNA based Molecular Residual Disease detection in early-stage triple negative breast cancer in the cTRAK-TN trial ». Cancer Research 83, n^o 5_Supplement (1 mars 2023) : PD5–03—PD5–03. http://dx.doi.org/10.1158/1538-7445.sabcs22-pd5-03.

Texte intégral

Résumé :

Abstract Background: Detection of circulating tumour DNA (ctDNA) in patients (pts) who have completed treatment for early-stage breast cancer is associated with a high risk of future relapse. Identifying those at high risk of subsequent relapse may allow tailoring of further therapy to delay or prevent recurrence. Previous analysis of this cohort showed that tools capable of detecting ctDNA at lower concentrations are needed to increase sensitivity and lengthen the lead time between ctDNA detection and relapse. We compared ctDNA detection via a personalised sequencing assay to dPCR in patients from the cTRAK TN clinical trial. Methods: The cTRAK-TN trial recruited 161 pts into prospective ctDNA surveillance with dPCR, with ctDNA positive pts randomised to 1) CT staging plus pembrolizumab therapy for patients without relapse or 2) observation. Pts had serial post-treatment surveillance plasma samples collected every 3 months for up to 2 years. Whole exome sequencing (WES) was performed on tumor DNA from FFPE samples to design personalised Residual Disease and Recurrence (RaDaR®) multiplex PCR based NGS assays. Retrospectively, plasma DNA extracted from a minimum of 2mls banked plasma, was sequenced with personalised RaDaR assays, and ctDNA detection identified with a proprietary algorithm. dPCR assays tracked 1-2 mutations, as previously described. Primary endpoint was rate of positive ctDNA detection by 12 months from start of surveillance in both assays. Secondary endpoints were agreement in ctDNA detection between RaDaR and dPCR assays and lead-time between ctDNA detection and disease recurrence. Results: Overall, 147 pts and 241 tissue samples were subject to WES, and RaDaR assays were developed for 142 pts with sufficient plasma for testing. RaDaR assays tracked a median of 47 variants (range 33-56) per patient, and a total of 907 timepoints were analysed (median 6 timepoints per pt, range 1-11). With RaDaR, 39.4% (56/142) patients tested ctDNA positive during follow-up, with a median ctDNA detected level of 0.081% estimated variant allele fraction (eVAF). With dPCR, 35.2% (50/142) pts tested ctDNA positive. The ctDNA detection rate by 12 months from the start of ctDNA surveillance was 36.2% (95% CI; 27.6% – 43.7%) with RaDaR and 29.9% (95%CI; 21.6% – 37.3%) with dPCR. The overall test agreement between RaDaR and dPCR assays was 92.7% (95%CI; 90.7% – 94.4%). From a patient perspective, 58.7% pts were ctDNA negative for both assays, 32.9% ctDNA were positive for both assays and 8.6% presented discrepancies. ctDNA was detected by RaDaR but not by dPCR in 9 pts and it was detected by dPCR but not by RaDaR in 3 pts. Among ctDNA positive pts, 55.2% were first detected positive by RaDaR, 5.2% by dPCR, and 39.6% were detected at the same time-point (test of proportions, p< 0.001). The median lead time from ctDNA detection to relapse was 7.1 months (95% CI 5.9 – 15.9%) with RaDaR and 5.7 months (95% CI 3.2% – 7.4%) with dPCR. Conclusion: The RaDaR personalised multi-mutation sequencing assay detected MRD with a longer median lead time prior to relapse, and with higher sensitivity, than dPCR mutation tracking assays. These findings have implications for the choice of ctDNA assay in clinical trials designed to treat patients at the point of MRD detection. Citation Format: Maria Coakley, Prithika Sritharan, Guillermo Villacampa, Claire Swift, Kathryn Dunne, Lucy Kilburn, Katie Goddard, Patricia Rojas, Andy Joad, Warren Emmett, Charlene Knape, Karen Howarth, Peter S. Hall, Catherine Harper-Wynne, Tamas Hickish, Iain Macpherson, Alicia F. Okines, Andrew M. Wardley, Duncan Wheatley, Simon Waters, Rosalind Cutts, Isaac Garcia-Murillas, Judith Bliss, Nicholas Turner. PD5-03 Comparison of a personalized sequencing assay and digital PCR for circulating tumor DNA based Molecular Residual Disease detection in early-stage triple negative breast cancer in the cTRAK-TN trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD5-03.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Vetoshkin, A., A. Аrtikula et D. Britov. « OVERVIEW OF MODERN APPROACHES TO SOLVING THE PROBLEM OF EXTENDED RADAR TARGETS RECOGNITION ». Наукові праці Державного науково-дослідного інституту випробувань і сертифікації озброєння та військової техніки, n^o 5 (22 décembre 2020) : 14–19. http://dx.doi.org/10.37701/dndivsovt.5.2020.02.

Texte intégral

Résumé :

The development of the theory and technology of radio location indicates the need to solve problems of radar recognition of targets by spatial parameters. This is due to the need to provide in promising radar stations (complexes) with a software overview of the required resolution to obtain three-dimensional images in all spatial coordinates. The task of radar targets recognition, which is to assign the observed objects to the appropriate classes and types, is of considerable and growing interest. Different classes (types) of targets make up a certain alphabet, the choice of which determines not only the effectiveness of the use of recognition, but also the difficulties that arise in its implementation. Currently, there are a large number of radar recognition algorithms. They differ in the stages of decision-making, the degree and nature of accounting for statistics of signs, obstacles and signals. Due to the fact that the secondary emission pattern of extended targets is multi-lobed, statistical algorithms are preferred. The information used for radar recognition is contained in the set of received radar signals. However, most often for target recognition certain measured target features are used, which are compared in accordance with the recognition algorithms with known (reference) features. The choice of recognition features is usually made heuristically. This set of parameters does not always allow providing the required quality of recognition. The synthesized algorithms work unstable or require unreasonably large computational costs due to a significant increase in the dimensionality of the feature space. Analysis of known radar recognition algorithms of extended targets shows that they were developed under significant constraints. At present, the tasks of point targets radar surveillance are most fully solved. The tasks of processing signals reflected from bodies of complex shape, given the difficulties of their formulation and solution are not fully explored. It is promising to consider a set of radar surveillance tasks and the criteria used in them as a multicriteria task, the solution of which is associated with vector optimization of the location system as a whole.

Styles APA, Harvard, Vancouver, ISO, etc.

35

ten Have, J. M. « Precision Aircraft Height Estimation with Horizontal Axis Marine Radars : (The Dual Autonomous Monitoring System (DAMS)) ». Journal of Navigation 46, n^o 3 (septembre 1993) : 412–21. http://dx.doi.org/10.1017/s0373463300011863.

Texte intégral

Résumé :

Civil aviation authorities have a requirement for the application of devices which are capable of determining the geometric height of aircraft above flight level 290 with a high degree of precision. These devices, called height monitoring units (HMUS), should pave the way for a safe and expeditious introduction of reduced vertical separation of 1000 ft above flight level 290.In this paper the design philosophy as well as the prototype development of such a device, which is called the dual-synchronized autonomous monitoring system (DAMS), are outlined. This device operates fully independently of any airborne equipment such as secondary surveillance radar transponders.The configuration basically consists of two standard marine radars with both axes of revolution situated in a horizontal plane. With this configuration it is possible to determine the trajectory of an aircraft and, in particular, the geometrical height above ground level within typical radar slant range coverage of some 18 km. The basic application of this equipment will be in the field of height monitoring of aircraft targets in environments with reduced vertical separation standards of 1000 ft above flight level 290, but a wider application of this concept is foreseen for local precision tracking of aircraft targets.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Nagaoka, Sakae, Osamu Amai et Yasuo Watanabe. « Evaluating the Feasibility of a Radar Separation Minimum for a Long-Range SSR ». Journal of Navigation 42, n^o 3 (septembre 1989) : 403–16. http://dx.doi.org/10.1017/s0373463300014703.

Texte intégral

Résumé :

This paper deals with an analytical method for establishing a separation minimum for air traffic control using a monopulse SSR (Secondary Surveillance Radar), namely the Long Range SSR (LSSR), of which coverage is extended to 250 n.m. The azimuth estimation accuracy of the monopulse SSR was significantly improved compared with that of conventional SSR.As an index of a collision risk due to azimuth errors of the LSSR, the close approach probability (CAP) associated with the probability of overlap of aircraft in azimuth is used for evaluating the safety of the surveillance system. The CAPs for both the LSSR and the conventional SSR are estimated by modelling and comparing distributions of azimuth errors. The CAP for the LSSR is significantly smaller than that for the conventional one under 5 n.m. separation minimum.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Wyndham, B. A. « Secondary Surveillance Radar. M. C. Stevens. Artech House Inc., Norwood. 300 pp. Illustrated. £55.00. » Aeronautical Journal 92, n^o 919 (novembre 1988) : 375. http://dx.doi.org/10.1017/s000192400001647x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

38

Horielyshev, Stanislav, Pavlo Volkov, Igor Boikov, Dmitro Baulin, Hryhorii Ivanets, Aleksandr Nakonechnyi, Svyatoslav Manzhura, Valentyn Yuriev et Natalia Gleizer. « Study of the secondary characteristics of the bistatic scattering of a combined object in a covert radar surveillance system ». EUREKA : Physics and Engineering, n^o 4 (30 juillet 2022) : 137–51. http://dx.doi.org/10.21303/2461-4262.2022.002493.

Texte intégral

Résumé :

The emergence of new means of attack, reconnaissance and methods of sabotage imposes special requirements on the technical means of protecting important state facilities (ISF). Modern trends in the construction of ISF physical protection systems are the integration of engineering barriers, perimeter signaling and detection tools. Detection tools should provide covert receipt of information about the approach of the intruder in "distant" intrigues. To do this, it is possible to use technical means built on the principle of semi-active bistatic radar with an external illumination source. However, in order to identify intruders in the ISF protection zone, it is necessary to have a priori information about the radar visibility of the combined location objects. The combined object is typically a complex object having both metallic and dielectric elements. To this end, a technique has been developed for estimating the radar cross-section (RCS) of combined objects in the field of external illumination. The electromagnetic field (EMF) scattered by a combined object in the meter and decimeter wavelength ranges is calculated as a coherent sum of fields, taking into account their phase, scattered by its metal and dielectric elements. This made it possible to take into account the electromagnetic interaction of the elements of the combined object. The method of integral equations (IE) was used to find the current density and magnetic field strength. The scatter diagrams of the person-intruder, the person-intruder in personal armor protection (PAP) under different conditions of irradiation and reception and illumination frequencies are obtained and analyzed. This made it possible to evaluate the effect of metallic elements on the scatter diagram of the combined object. The obtained a priori information is of significant practical importance at the stage of optimizing signal processing algorithms and designing new means of covert detection

Styles APA, Harvard, Vancouver, ISO, etc.

39

Leonardi, Mauro, et Fabrizio Gerardi. « Aircraft Mode S Transponder Fingerprinting for Intrusion Detection ». Aerospace 7, n^o 3 (18 mars 2020) : 30. http://dx.doi.org/10.3390/aerospace7030030.

Texte intégral

Résumé :

Nowadays, aircraft safety is based on different systems and four of them share the same data-link protocol: Secondary Surveillance Radar, Automatic Dependent Surveillance System, Traffic Collision Avoidance System, and Traffic Information System use the Mode S protocol to send and receive information. This protocol does not provide any kind of authentication, making some of these applications vulnerable to cyberattacks. In this paper, an intrusion detection mechanism based on transmitter Radio Frequency (RF) fingerprinting is proposed to distinguish between legitimate messages and fake ones. The proposed transmitter signature is described and an intrusion detection algorithm is developed and evaluated in case of different intrusion configurations, also with the use of real recorded data. The results show that it is possible to detect the presence of fake messages with a high probability of detection and very low probability of false alarm.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Mauidzoh, Uyuunul. « ANALISIS PERAWATAN MODUL RPC 2000 PADA SECONDARY SURVEILLANCE RADAR (RADAR SSR) DENGAN MENGGUNAKAN METODE RELIABILITY CENTERED MAINTENANCE (RCM) DI PERUM LPPNPI AIRNAV INDONESIADISTRIK YOGYAKARTA ». Conference SENATIK STT Adisutjipto Yogyakarta 2 (18 novembre 2016) : 189. http://dx.doi.org/10.28989/senatik.v2i0.73.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

41

Cho, In-Cheol, Choung-Hyun Lee, Jae-Yup Shin, Hyun-Wook Moon et Sung-Hwan Sohn. « A Study on the Suppression of Secondary Reflected Signals during Naval Gun Fire Using Naval Surveillance Radar ». Journal of Korean Institute of Electromagnetic Engineering and Science 34, n^o 2 (février 2023) : 138–44. http://dx.doi.org/10.5515/kjkiees.2023.34.2.138.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

42

VOINEA, Vasilică, Dan STEFANOIU, Cătălin PETRESCU et Nicolai CHRISTOV. « EVALUATION OF GARBLED REPLIES FOR AIRCRAFTS INTERROGATED BY SSR SYSTEM ». Annals of the Academy of Romanian Scientists Series on Science and Technology of Information 15, n^o 1-2 (2022) : 56–70. http://dx.doi.org/10.56082/annalsarsciinfo.2022.1-2.56.

Texte intégral

Résumé :

In aviation, an undesirable phenomenon that can occur with increased airport traffic is garbling. The main problem is that if two aircraft are within a short critical distance to each other, the replay messages (response signals) can overlap. To better understand the garbling phenomenon by aviation students and engineers and to prevent the occurrence of this undesirable phenomenon that can lead to tragic events, we have modelled and simulated this phenomenon using an algorithm that statistically estimates the number of garbled replies (erroneous replay messages/ response signals) for several aircraft interrogated by a secondary surveillance radar.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Neemat, Sharef, et Michael Inggs. « Design and implementation of a digital real-time target emulator for secondary surveillance radar / identification friend or foe ». IEEE Aerospace and Electronic Systems Magazine 27, n^o 6 (juin 2012) : 17–24. http://dx.doi.org/10.1109/maes.2012.6328549.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

44

Kumjian, Matthew R., et Kelly A. Lombardo. « Insights into the Evolving Microphysical and Kinematic Structure of Northeastern U.S. Winter Storms from Dual-Polarization Doppler Radar ». Monthly Weather Review 145, n^o 3 (mars 2017) : 1033–61. http://dx.doi.org/10.1175/mwr-d-15-0451.1.

Texte intégral

Résumé :

The recent Weather Surveillance Radar-1988 Doppler (WSR-88D) network upgrade to dual-polarization capabilities allows for bulk characterization of microphysical processes in northeastern U.S. winter storms for the first time. In this study, the quasi-vertical profile (QVP) technique (wherein data from a given elevation angle scan are azimuthally averaged and the range coordinate is converted to height) is extended and applied to polarimetric WSR-88D observations of six Northeast winter storms to survey their evolving, bulk vertical microphysical and kinematic structures. These analyses are supplemented using hourly analyses from the Rapid Refresh (RAP) model. Regions of ascent inferred from QVPs were consistently associated with notable polarimetric signatures, implying planar crystal growth when near −15°C, and riming and secondary ice production at higher temperatures. The heaviest snowfall occurred most often when ascent and enhanced propagation differential phase shift ([Formula: see text]) occurred near −15°C. When available, limited surface observations confirmed heavy snowfall rates and revealed large snow-to-liquid ratios at these times. Other cases revealed sudden, large melting-layer excursions associated with precipitation-type transitions near the surface. RAP analyses failed to capture such complex evolution, demonstrating the added value of dual-polarization radar observations in these scenarios and the potential use of radar data for assessing model performance in real time. These insights are a preliminary step toward better understanding the complex processes in northeastern U.S. winter storms.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Karan, Haldun, et Kevin Knupp. « Radar and Profiler Analysis of Colliding Boundaries : A Case Study ». Monthly Weather Review 137, n^o 7 (juillet 2009) : 2203–22. http://dx.doi.org/10.1175/2008mwr2763.1.

Texte intégral

Résumé :

The kinematics of a head-on collision between two gust fronts, followed by a secondary collision between a third gust front and a bore generated by the initial collision, are described using analyses of Weather Surveillance Radar-1988 Doppler (WSR-88D) and Mobile Integrated Profiling System (MIPS) data. Each gust front involved in the initial collision exhibited a nearly north–south orientation and an east–west movement. The eastward-moving boundary was 2°C colder and moved 7 m s−1 faster than the westward-moving boundary. Two-dimensional wind retrievals reveal contrasting flows within each gravity current. One exhibited a typical gravity current flow structure, while the other assumed the form of a gravity wave/current hybrid with multiple vortices atop the outflow. One of the after-collision boundaries exhibited multiple radar finelines resembling a solitary wave shortly after the collision. About 1 h after the initial collision, a vigorous gust front intersected the eastward-moving bore several minutes before both circulations were sampled by the MIPS. The MIPS measurements indicate that the gust front displaced the bore upward into a neutral residual layer. The bore apparently propagated upward even farther to the next stable layer between 2 and 3 km AGL. MIPS measurements show that the elevated turbulent bore consisted of an initial vigorous wave, with updraft/downdraft magnitudes of 3 and −6 m s−1, respectively, followed by several (elevated) waves of decreasing amplitude.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Morrison, Ian, Steven Businger, Frank Marks, Peter Dodge et Joost A. Businger. « An Observational Case for the Prevalence of Roll Vortices in the Hurricane Boundary Layer* ». Journal of the Atmospheric Sciences 62, n^o 8 (1 août 2005) : 2662–73. http://dx.doi.org/10.1175/jas3508.1.

Texte intégral

Résumé :

Abstract Doppler velocity data from Weather Surveillance Radar-1988 Doppler (WSR-88D) radars during four hurricane landfalls are analyzed to investigate the presence of organized vortices in the hurricane boundary layer (HBL). The wavelength, depth, magnitude, and track of velocity anomalies were compiled through analysis of Doppler velocity data. The analysis reveals alternating bands of enhanced and reduced azimuthal winds closely aligned with the mean wind direction. Resulting statistics provide compelling evidence for the presence of organized secondary circulations or boundary layer rolls across significant areas during four hurricane landfalls. The results confirm previous observations of the presence of rolls in the HBL. A potential limitation of the study presented here is the resolution of the WSR-88D data. In particular, analysis of higher-resolution data (e.g., from the Doppler on Wheels) is needed to confirm that data aliasing has not unduly impacted the statistics reported here. Momentum fluxes associated with the secondary circulations are estimated using the covariance between the horizontal and vertical components of the wind fluctuations in rolls, with resulting fluxes 2–3 times greater than estimated by parameterizations in numerical weather prediction models. The observational analysis presented here, showing a prevalence of roll vortices in the HBL, has significant implications for the vertical transport of energy in hurricanes, for the character of wind damage, and for improvements in numerical simulations of hurricanes.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Mahale, Vivek N., Jerald A. Brotzge et Howard B. Bluestein. « An Analysis of Vortices Embedded within a Quasi-Linear Convective System Using X-Band Polarimetric Radar ». Weather and Forecasting 27, n^o 6 (1 décembre 2012) : 1520–37. http://dx.doi.org/10.1175/waf-d-11-00135.1.

Texte intégral

Résumé :

Abstract On 2 April 2010, a developing quasi-linear convective system (QLCS) moved rapidly northeastward through central Oklahoma spawning at least three intense, mesoscale vortices. At least two of these vortices caused damage rated as category 0 to 1 on the enhanced Fujita scale (EF0–EF1) in and near the town of Rush Springs. Two radar networks—the National Weather Service Weather Surveillance Radar-1988 Doppler network (WSR-88D) and the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network—collected high spatial and temporal resolution data of the event. This study is an in-depth polarimetric analysis of mesovortices within a QLCS. In this case study, the storm development and evolution of the QLCS mesovortices are examined. Significant findings include the following: 1) The damage in Rush Springs was caused by a combination of the fast translation speed and the embedded circulations associated with QLCS vortices. The vortices’ relative winds nearly negated the storm motion to the left of the vortex, but doubled the ground-relative wind to the right of the vortex. 2) A significant differential reflectivity (ZDR) arc developed along the forward flank of the first vortex. The ZDR arc propagated northeastward along the QLCS with the development of each new vortex. 3) A minimum in the copolar correlation coefficient (ρhv) in the center of the strongest vortex was observed, indicating the likely existence of a polarimetric tornado debris signature (TDS). A secondary ρhv minimum also was found just to the right of the vortex center, possibly associated with lofted debris from straight-line winds.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Andrić, Jelena, Matthew R. Kumjian, Dušan S. Zrnić, Jerry M. Straka et Valery M. Melnikov. « Polarimetric Signatures above the Melting Layer in Winter Storms : An Observational and Modeling Study ». Journal of Applied Meteorology and Climatology 52, n^o 3 (mars 2013) : 682–700. http://dx.doi.org/10.1175/jamc-d-12-028.1.

Texte intégral

Résumé :

AbstractPolarimetric radar observations above the melting layer in winter storms reveal enhanced differential reflectivity ZDR and specific differential phase shift KDP, collocated with reduced copolar correlation coefficient ρhv; these signatures often appear as isolated “pockets.” High-resolution RHIs and vertical profiles of polarimetric variables were analyzed for a winter storm that occurred in Oklahoma on 27 January 2009, observed with the polarimetric Weather Surveillance Radar-1988 Doppler (WSR-88D) in Norman. The ZDR maximum and ρhv minimum are located within the temperature range between −10° and −15°C, whereas the KDP maximum is located just below the ZDR maximum. These signatures are coincident with reflectivity factor ZH that increases toward the ground. A simple kinematical, one-dimensional, two-moment bulk microphysical model is developed and coupled with electromagnetic scattering calculations to explain the nature of the observed polarimetric signature. The microphysics model includes nucleation, deposition, and aggregation and considers only ice-phase hydrometeors. Vertical profiles of the polarimetric radar variables (ZH, ZDR, KDP, and ρhv) were calculated using the output from the microphysical model. The base model run reproduces the general profile and magnitude of the observed ZH and ρhv and the correct shape (but not magnitude) of ZDR and KDP. Several sensitivity experiments were conducted to determine if the modeled signatures of all variables can match the observed ones. The model was incapable of matching both the observed magnitude and shape of all polarimetric variables, however. This implies that some processes not included in the model (such as secondary ice generation) are important in producing the signature.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Petrochilos, Nicolas, Gaspare Galati et Emilio Piracci. « Coherent sources separation based on sparsity : an application to SSR signals ». International Journal of Microwave and Wireless Technologies 1, n^o 3 (15 mai 2009) : 185–91. http://dx.doi.org/10.1017/s175907870900018x.

Texte intégral

Résumé :

Systems based on secondary surveillance radar (SSR) downlink signals, both with directional and with omni-directional antennae (such as in multilateration), are operational today and more and more installations are being planned. In this frame, high-density traffic leads to the reception of a mixture of several overlapping SSR replies. By nature, SSR sources are sparse,i.e.with amplitude equal to zero with significantly high probability. While in the literature several algorithms performing sources separation with anm-element antenna have been proposed, none has satisfactorily employed the full potential of sparsity for SSR signals. Most sparsity algorithms can separate only real-valued sources, although we present in this study two algorithms to separate the complex-valued SSR sources. Recorded signals in a live environment are used to demonstrate the effectiveness of the proposed techniques.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Svyd, I. V., V. V. Semenets, O. S. Maltsev, M. G. Tkach, S. V. Starokozhev, O. O. Datsenko et I. O. Shevtsov. « Comparative analysis of methods for determining the air objects’ coordinates using wide-area multilateration systems ». Radiotekhnika, n^o 209 (24 juin 2022) : 162–77. http://dx.doi.org/10.30837/rt.2022.2.209.16.

Texte intégral

Résumé :

The presented work considers the place and role of wide-area multi-position airspace surveillance in the information support of airspace control and air traffic control systems. Classification of methods for estimating the coordinates of air objects using various primary measurements of the parameters of received signals in multi-position observation is given. A quantitative assessment of the accuracy in determining the air objects’ coordinates by the considered methods is also given. The capabilities of wide-area multi-position surveillance systems increase significantly when using the principles of constructing a secondary surveillance radar as a non-synchronous network, and an aircraft responder as an open single-channel queuing system with servicing the first correctly received request signal. An unauthorized request from an aircraft responder makes it possible to switch from completely passive methods for detecting and determining the coordinates of an air object to active-passive ones, which provide an increase in the accuracy of solving a coordinate task by dozens of times while maintaining the energy secrecy of a wide-area multi-position observation system. It is shown that the use of active and passive methods for constructing wide-area multi-position observation systems makes it possible to implement goniometric, difference-range, goniometer-range, total-range and goniometer-total-range methods for determining the coordinates of an air object. This increases significantly the number of options for estimating the coordinates of an air object. As a result, it allows improving the quality of information support for users by choosing the optimal method for estimating the coordinates of the observed air objects using various primary measurements of the received signals parameters.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Radar de surveillance secondaire »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres