Abstract

The lightweight Unmanned Aerial Vehicle (UAV) flight activities are constrained, particularly in the UAV range or activity span and perseverance, by the strategic correspondence link capabilities. This paper tends to the different overlap issue of trading off a set of mission prerequisites, the UAV execution parameters, and strategic credibility; thus compromising between the communication load characterized by a crucial, communication link transmitting power necessities, power accessibility onboard UAV as a weight-restricted parameter, and the UAV security.

Introduction

In current years, an outcome of decreased sizes and weights concentrated charges and amplified functionalities of various sensors and devices. The Unmanned Aerial Vehicles are attracting progressively general trendy varied variety of internal submissions (atmosphere monitoring, surveillance, photography, search-and-rescue, etc.) [1]. Through the marketplace develops and the diversity of applications increases, additional necessities are present-day being compulsory in spreading the flight variety and growing adaptability toward complex assignments of UAV structures [2].

UAV stands for Unmanned Aerial Vehicle, which is commonly considered to be a drone or an aircraft with no pilot on board. UAVs can be remote-controlled aircraft [3]. The unmanned aerial vehicle contains cameras, sensors, communication belonging as well as other payload devices [4]. It was created for military usage, and civilian usage to protect the border. UAVs are widely used in the military [5]. Unmanned aircraft system manufacturing was started by the United States department of defense (DOD) in 2005 [6]. Presently, leading UAV manufacturing countries are the USA, Israel, China, Iran, and Russia [7]. Rustom series of Indian UAVs are under development [8]. The Building of a UAV is easier, it is less expensive and it can be created at a reasonable price. UAVs are made of essential components.

Conclusion

In this paper, we reviewed UAV systems and communication design, and methods used to connect and send data to the ground station. Further, we discussed data processing via sensors and applications with security. We provide key definitions and concepts of UAV systems and details of the development of communication systems and GCS. We provide reviews and analyses of the security of UAVs and the types of attacks that are launched to disturb the communication of the UAV system. Finally, open research areas are given for further development of the UAV system and communication, which leads to better UAV technology for the industry.

Abstract

     The rollout of 5G wireless service has been much anticipated by consumers across the U.S. since it will bring faster data download speeds and expanded service; however, the impact to aviation and air travel are as a major issue and the potential impact to aviation has not been estimated or assessed. This paper fills that gap and provides the first analysis of the potential number of flights impacted by 5G at ten of the busiest airports in the U.S. Using detailed historical weather and flight data in 2019 at 10 large hub airports, we find that nearly 15,700 flight arrivals could be directly impacted annually, at the ten airports considered. The geographical and seasonal impact varies significantly with more flights affected by the potential for 5G interference at airports in Seattle and Dallas Fort-Worth and relatively few flights affected at airports in Phoenix and Las Vegas. A case study examining ten years of data at Chicago O’Hare International, a hub for two major airlines, suggests that over 2,400 flights every year could be impacted by 5G interference. Fortunately, there has been increasing cooperation between the cell phone industry and aviation stakeholders to ensure a safe rollout of 5G C-band; this paper provides a significant contribution by documenting the issues and context for aviation operations.

Introduction

     The rollout of 5G wireless service has been much anticipated by consumers across the U.S. as data download speeds will be increased and service expanded. 5G C-band enables data intensive technology for personal and business use, ranging from entertainment such as video games to critical communications for public services (Pham et al, 2020), and provides more consistent, faster speeds and increased capacity. The communications band or “C” band was originally designated for industrial applications and satellite communications and were repurposed for 5G wireless between 3.7 and 3.98 GHz. C-band is one component of the mid-band frequency between 3.3 and 4.2 GHz. The benefits of the new 5G C-band service have been contraindicated near airports by the aviation industry due to the potential for negative operational and safety impacts. Since the 5G C-band frequencies is very close to the Aeronautical Radionavigation Service (ARS) spectrum (as shown in Fig. 1), there is a potential for signal interference which could potentially disrupt the operation of the radio/radar altimeter equipment on many transport aircraft. This equipment is necessary to conduct certain low visibility procedures when weather conditions do not permit use of standard precision or non-precision procedures. The inability of aircraft to safely perform these procedures could generate flight disruptions throughout the system. This fact was underscored by the acknowledgement that over 100 pilot reports of potential 5G interference have been made in the first few weeks of 5G rollout (Levin and Shields, 2022). Additionally, the U.S. Transportation Secretary noted that these issues will not be fixed by the summer flying season (Reardon, 2022).

Conclusions

     As the U.S. and other countries introduce 5G C-band, the need to understand the potential disruption to air travel is apparent. This paper provides the first estimates of the number of flights that could be potentially impacted at ten of the busiest airports in the U.S. These flights conducting low visibility procedures could be delayed, diverted, or cancelled. The number of flights conducting these low visibility approaches varies across seasons and location. Some airports, such as Seattle-Tacoma International could experience a significant impact to flight operations while others such as Harry Reid International in Las Vegas could be minimally impacted. Dallas Fort-Worth International, which area serves as several major airline hubs and headquarters, experiences numerous low visibility flight operations with the greatest monthly variation. The systemic impact from disruptions out of these ten busy hub airports presents a significant risk to travelers and airline operations. These risks include delays and cancelations as well as their direct and indirect economic costs. Further, to highlight the significant potential impact we determined that Chicago O’Hare International had over 27,000 flights conduct low visibility operations in the decade from 2009 to 2019.

1- Introduction

2- Mega-Archive

3- Data mining tools

4- Use case scenarios

5- Comparison with other services

6- Conclusions and recommendations

References

Abstract

The world astronomical image archives offer huge opportunities to time-domain astronomy sciences and other hot topics such as space defense, and astronomical observatories should improve this wealth and make it more accessible in the big data era. In 2010 we introduced the Mega-Archive database and the Mega-Precovery server for data mining images serendipitously containing Solar system bodies, with focus on near Earth asteroids (NEAs). This paper presents the improvements and introduces some new related data mining tools developed during the last years. Currently, Mega-Archive indexed 15 million images available from six major collections and other instrument archives and surveys. This meta-data index collection is daily updated by a crawler which performs automated query of five major collections. Since 2016, these data mining tools are installed on the new dedicated EURONEAR server, and the database migrated to SQL which supports robust and fast queries. To constrain the area to search for moving or fixed objects in images taken by large mosaic cameras, we built the graphical tools FindCCD and FindCCD for Fixed Objects which overlay the targets across one of seven mosaic cameras, plotting the uncertainty ellipse for poorly observed NEAs. In 2017 we improved Mega-Precovery, which offers now two options for the ephemerides and three options for the input (objects defined by designation, orbit or observations). Additionally, we developed Mega-Archive for Fixed Objects (MASFO) and Mega-Archive Search for Double Stars (MASDS). We include a few use case scenarios and we compare our data mining tools with other few similar services. The huge potential of science imaging archives is still insufficiently exploited. Their use could be strongly enhanced by defining a standard format needed to index the image archives. We recommend to the IAU to define such a standard, asking the observatories to index their image archives in a homogeneous manner.

Introduction

The world astronomical image archives provide valuable means to improve the physical properties of Solar System bodies, and in particular of near Earth asteroids (NEAs) which typically remain observable only for short period of times. NEAs represent laboratories for studying the formation and evolution of the minor planets and their physical interactions with the Sun and major planets. Part of NEAs, potentially hazardous asteroids (PHAs) and virtual impactors (VIs) could pose some risk due to their possibility of impact, but they also represent an opportunity for more accessible space missions and eventually future mining industries. Upon discovery, the recovery and follow-up of NEAs are essential for providing the initial orbital solution and for searching of possible linkage with previously known objects. In most cases, smaller NEAs fade rapidly and become invisible even for largest telescopes which are expensive to access and usually lack time for urgent reaction. However, the existing image archives represent a free opportunity to improve the orbital knowledge based on serendipitous encounters of targets searched using dedicated data mining tools. Searching for fixed objects (like stars or galaxies) in image archives is straightforward, because only the position of the target is needed to compare with the known telescope pointing and instrument field. The largest astronomical observatories or their collaborating institutions provide simple web searching tools or more sophisticated services which allow searches of fixed objects only in their image archives.

In this paper a low profile circularly polarized annular ring slot antenna (CPARSA) with high gain is presented. An inverted U-shaped meandered slot is cut at the inner patch of annular ring to obtain the circularly polarized (CP) radiation. This annular slot loaded ground plane on a substrate thickness of 0.5 mm results in a very low profile (0.009λ0) antenna in term of free space wavelength at its center operating frequency. The largest side lengths of octagonal shaped antenna are 0.89λ0×0.89λ0 according to its center frequency. Measured impedance bandwidth of 23.54% from 5.4 GHz – 7.0 GHz (for |S11| ≤ −10 dB) and AR bandwidth (AR<3dB) of 5.15% from 5.67 GHz – 5.97 GHz are achieved by the antenna. Meanwhile, stable radiation pattern is observed throughout the entire bandwidth with peak gain of 7.6dBi at the center frequency of 5.8 GHz. A defected ground plane is employed in the design which results in reduction of surface waves leading towards higher gain of antenna. The proposed antenna operating at 5.8 GHz band is fabricated on low cost substrate with standard printed circuit board (PCB) process. The proposed design provides favorable characteristics for various lightweight applications including miniaturized drones and airborne applications. To validate the prototype, measured results are compared with simulation outcomes and good agreement is obtained.

Introduction

Circularly polarized (CP) and high gain antennas with their favorable characteristics such as low profile, less massy and planner structure that offer ease in integration with monolithic IC’s are demanded recently. CP antennas are also favorable in situations where polarization mismatch may degrade the performance of communication system [1], [2]. Advantages of circular polarization over linear polarization are generally because of high efficiency in mobility, alleviate in multi-path distortion and polarization mismatch losses [3]–[5]. Moreover, CP antennas have influence to overcome multipath fading and mitigate Farady rotation effects [6] that can help to reduce the loss. These characteristics make them favorable candidate for wireless power transfer applications. Circular polarization requires generation of two equal but orthogonal radiating modes. This can be achieved either by employing multiple feeds or a single feed. Several CPARSA designs producing circular polarization have been reported in literature [5]–[13]. A circularly polarized antenna based on fractal geometry architect was reported for UHF RFID applications. The measured gain of the antenna is 1.35 dBi [5]. Another design based on metallic ground reflector was presented in [6] for dedicated short range communication (DSRC) applications. Although the antenna retains peak gain at 4.95 dBic but its 6.926 mm dense profile limits the use of antenna for various lightweight applications.

The performance of the Hatch Cover Drive Assembly operated in space is quite important for aircrafts. However, it is hard to experimental studies in space. As an alternative, theoretical analysis and simulation are employed to predict their performances on the ground. Herein, a mathematical model of the drive assembly was first established and simulated in Matlab. The armature current and mechanical efficiency were analyzed with respect to the operating temperature and load torque. Furthermore, a test setup according to the model was built to verify the validity of the proposed mathematical model. As a result, the prediction results are consistent with the experimental results very well with a maximum error of 11.0% in the armature current and 11.6% in the mechanical efficiency. The mechanical efficiency achieves to be the maximum value in vacuum as the load torque of 3.5N·m. It has the best performance as working around the room temperature. The proposed model would be used to predict the performance of drive assembly working in space. Our findings would be helpful for the designing, manufacturing and selection of motors and reducers for spacecrafts usage in future.

Introduction

Motors and reducers are the key components of the drive assembly of spacecrafts, which drive the payloads and functional components for finishing the specified actions and motions in space [1], [2]. Up to now, many kinds of motors and reducers are developed to fulfill the various missions, among them, the brushless DC motor driven by DC converter is widely used in aerospace due to its simple structure, reliable operation and long service life [3], [4]. In addition, the DC motor can drive a large load combined with the harmonic reducer. This drive assembly shows many advantages of the large transmission ratio, small mass and volume, high transmission accuracy, and is quite suitable for application in spatial motion [5], [7]. However, the special environment in space would degenerate the performance of the drive assembly of DC motor and harmonic reducer, resulting in a lot of disasters. For instance, the coil resistance and magnetic destiny in the motor, and the grease viscosity in harmonic reducer, are changed heavily upon the alternating of high and low temperature. As a result, the coupling effect of these factors highly degenerates the output performance of the drive assembly. Many studies have focused on these problems, but limited to DC motor or reducer or environment simulation technology [8], [9] rather than the drive assembly. Some scholars have carried out in-depth research on parameters, rotational speed, calculation of back EMF coefficient, thermal analysis and circuit control of brushless DC motor [10], [22].

1 Introduction

2 Analysis of Fuzzy Entropy

3 Fuzzy Entropy Feature Extraction Of Radar Signals

4 Conclusion

5 Acknowledgments

6 References

With the rapid application of the new radar system, radar signal sorting based on conventional parameters has not achieved the desired results. Therefore, new features need to be extracted for signal sorting. In response to this problem, the paper proposes to use the entropy theory to extract the fuzzy entropy characteristics of the radar signal to determine the uncertainty of the radar source signal. Experiments with test signals show that the fuzzy entropy characteristics are less affected by noise over a wide range of SNR.

Introduction

At present, in order to solve the problem of radar signal sorting in the modern electronic countermeasure environment, the sorting method combined with the intra-pulse feature extraction of radar signals has become a research hotspot. By analyzing the intrapulse data of radar signals, this method studies the intentional modulation features and unintentional modulation features in the pulse, constructs a new radar signal sorting model based on short-term observation data, expands the parameter space, and reduces the overlapping probability of multi-parameter space. To achieve fast and accurate sorting identification signals. Devijver [1] defined generalized feature extraction as: extracting the most relevant information (or features) from the original data, and the proposed information should have the property of minimizing intra-class and enhanced inter-model variability. For the in-pulse feature extraction, the feature with the intra-class aggregation and inter-class separation is extracted from the intrapulse data, so that the features between the signals are clearly distinguished, so as to prepare for sorting and identifying the radar signal.

1- Introduction

2- Materials and methods

3- Results

4- Discussion

References

Abstract

The increasing spatial resolution of earth observation satellites is creating new opportunities to survey wildlife. Satellites could be particularly valuable for surveying polar bears (Ursus maritimus) because of their remote circumpolar distribution and status of concern in the face of Arctic warming. However, the white coloration of bears does not contrast well with sea ice or snow in panchromatic imagery. We took advantage of the close-range observation capabilities of a drone to determine the spectral signature of polar bears as they would appear in multispectral satellite imagery, capturing low-altitude (≤100 m) multispectral images of bears in natural landscapes in Churchill, Manitoba, Canada. The bears’ spectral curves were similar to those previously measured from pelts, with reflectance increasing with wavelength through the visible spectrum, although live bears had higher reflectance than pelts in the red-edge and near-infrared region. Bears had sufficiently consistent reflectance across the overhead surface of their body that ≥50% of pixels comprising each subject could be confidently matched to its core spectral signature, boding well for detection in coarser satellite imagery. Bears were clearly distinguishable from snow by their much lower reflectance in the blue and green region, but could potentially be confounded with large bright boulders. Currently available multispectral satellite imagery may still be too coarse (1.2 m/pixel) to reliably detect polar bears on sea ice, but resolution will likely continue to increase in future systems. Drones are a useful tool to resolve the spectral signature of wildlife species that could potentially be detected in satellite imagery.

Introduction

Satellite-based remote sensing technologies are rapidly advancing and increasingly being used to monitor and model the abundance and distribution of wildlife species (He et al., 2015). The tremendous value of earth observation satellites for environmental and ecological monitoring over vast swaths of the Earth’s surface has long been recognized (Kerr and Ostrovsky, 2003), but only recently has satellite imagery achieved sufficiently high spatial resolutions to enable direct detection of wild animals or their signs. One of the first such studies involved detection of colonies of emperor penguins (Aptenodytes forsteri) (BarberMeyer et al., 2007). Subsequently, an increasing number of papers have reported detection of a variety of wildlife species in several parts of the world using satellite imagery (LaRue et al., 2017), including other penguins species (Lynch et al., 2012), flamingos (Sasamal et al., 2008), masked boobies (Sula dactylatra) (Hughes et al., 2011), seals (LaRue et al., 2011; McMahon et al., 2014), large African mammals (Yang et al., 2014; Xue et al., 2017), polar bears (Ursus maritimus) (Stapleton et al., 2014a; LaRue et al., 2015), whales (Fretwell et al., 2014) and albatrosses (Fretwell et al., 2017). The polar bear is a species for which satellite-based monitoring could be particularly attractive for several reasons. Polar bears occupy large geographic areas at low densities in remote locations throughout the Arctic and, as a result, can be challenging and expensive to monitor using traditional techniques such as mark-recapture methods (Lunn et al., 2016; Regehr et al., 2018) or low-level aerial surveys (Stapleton et al., 2014b). Both approaches are expensive, labour-intensive, and dangerous—several researchers have been killed or injured studying polar bears in the Arctic (Stirling, 2011). Moreover, several conservation concerns related to polar bears necessitate an increase in monitoring frequency and geographic scope. Shifts in the distribution and timing of sea ice melt affect where and when bears can hunt and may affect population health (Laidre et al., 2018).

1 Introduction

2 Analysis of Traditional Sorting Model Structure

3 Signal Sorting and Identification Model Structure Using Intra-pulse Features

4 Conclusion

5 Acknowledgments

6 References

iming at the problem that there are some defects and shortcomings of traditional radar emitter signal sorting model structure, the structure of radar signal sorting model based on intra-pulse characteristic parameters is analyzed. Although the model is more complete than the early recognition model, there are still some shortcomings in the face of the increasingly complex electromagnetic environment and the emergence of complex radar signal sources. This article has studied this.

Introduction

The purpose of radar emitter signal sorting is to separate the randomly interleaved signal streams using the inter-pulse and intra-pulse parameters of the signal, and use these parameters to perform the following functions [1]: (1) identify the enemy in the operational environment; (2) determine its deployment location and direction; (3) provide early warning to friendly forces based on its threats; (4) provide reconnaissance personnel with information on enemy radar technical parameters, radar systems and tactical operational characteristics. With the rapid development of modern military industry and electronic technology, the wide application of various electronic information devices has made the electromagnetic environment of electronic warfare increasingly complex. The generated electromagnetic signals are densely interleaved and the working parameters are seriously overlapped, resulting in degradation of signal sorting and recognition performance.

1 Introduction

2 Research Background of Radar Emitter Signal Sorting

3 Research Significance of Radar Emitter Signal Sorting

4 Conclusion

5 Acknowledgments

References

As an important part of electronic intelligence (ELINT) and electronic support measure (ESM) system, radar signal sorting affects the performance of electronic reconnaissance equipments directly, and is a key technology to campaign decision-making. However, as the radar systems are becoming more and more complicated, as the countermeasure activities in modern electronic warfare are becoming more and more drastic, and as the development of low-probability of intercept (LPI), the regularities of signal sorting are heavily destroyed. This leads to the results of radar signal sorting based on common five parameters are not well. At present, the deinterleaving of advanced radar signals has become the primary bottleneck of signal processing in ELINT and ESM system, and confined farther improvement of the performance of electronic countermeasure equipment. So this paper analyzes and studies the background and significance of radar signal sorting in complex systems.

Introduction

As one of the key technologies for signal processing of electronic reconnaissance equipment, the research on the theory and technology realization of radiation source signal sorting has been highly valued by various countries. Relevant research literature indicates that domestic and foreign research scholars have carried out signal sorting technology for radiation source signals. A lot of research work has also achieved a lot of results. In foreign countries, a large number of papers on signal sorting have been published in many important international journals and conferences. Each paper has achieved certain innovations and improvements in technology, which has greatly promoted the development of signal sorting. In China, many research institutions and institutions of higher learning have strengthened the research on the identification and sorting of radar signals from complex systems, and explored a theoretical system that can effectively support the technical improvement of radar emitter signal identification and sorting.

1 Introduction

2 EMD Analysis

3 Normalized Energy Entropy Feature Extraction

4 Conclusion

5 Acknowledgments

6 References

Aiming at this problem that the analysis of instantaneous frequency for radar emitter signal(RES), based on empirical mode decomposition(EMD) the intra-pulse feature extraction method for RES is studied. Using empirical mode decomposition the normalized energy entropy (NeEn) feature is extracted. The experiment result displays that if the signal-to-noise ratio is greater than 12 dB, the feature shows only small fluctuations.

Introduction

The radar emitter signal is a typical non-stationary signal, and the relatively straightforward analysis of non-stationary signals requires the use of localized fundamental quantities and basis functions. The instantaneous frequency(IF) is a concept that has been proposed very early, and it is a basic quantity with locality. The IF is defined under the concept of derivative of the phase for the resolved signal, but this definition often produces some erroneous results in actual signal analysis. Aiming at this problem, the feature extraction method of intra-pulse for RES based on EMD is studied.