Aircraft Satellite Research Articles

LEO satellites selection-based computation offloading algorithm in aircraft–satellite multi-access edge computing networks

The emergence of sixth-generation (6G) mobile networks and non-terrestrial networks (NTNs) has led to increased interest in low Earth orbit (LEO) satellite-based communication networks for their potential to provide global coverage and ubiquitous connectivity. In this paper, we investigate the LEO satellites selection-based computation offloading problem in the aircraft–satellite multi-access edge computing (ASMEC) network, where LEO satellites and edge computing processors are integrated to provide ubiquitous and low-latency communication and computation services for aircraft during flights. In contrast to most existing works, which directly assume a fixed number of satellites or orbits in satellite-based MEC networks, we investigate the problem of how many satellites and which satellites to select in the ASMEC network. Our objective is to minimize the average total time delay of tasks during aircraft–satellite computation offloading. To achieve this, we formulate a nonlinear integer programming (NLIP) problem and propose the LEO satellites selection-based computation offloading (LSSBCO) algorithm to solve it, which includes the shortest aircraft–satellite distance based access satellite selection (ASS-SD) algorithm and the nearest k(t) neighboring satellites selection (NSS-k(t)) algorithm. We evaluate the performance of the LSSBCO algorithm in terms of the average total time delay, the maximum throughput, the average aircraft–satellite distance, the average connection duration, and the number of satellite handovers. Numerical results show that the proposed algorithm outperforms the benchmark algorithms with a lower average total time delay.

Compensation for Laser Beam Wavefront Aberration Distortions Induced by Aero-Optical Effects along Aircraft–Satellite Paths Based on Backscatter Signals

Compensation for Laser Beam Wavefront Aberration Distortions Induced by Aero-Optical Effects along Aircraft–Satellite Paths Based on Backscatter Signals

Flexible and extendable advance satellite tracking system

Aircraft tracking via satellite uses four dimensional aircraft position information to enhance flight safety by recording, scrutinizing and visualizing the information generated by an Airborne Tracking Unit (ATU) fitted onboard of aircraft flying from one point to another. It is an important device for aircraft operator to ensure its operational safety. Starfish Tracker SF3100-1 aircraft tracking unit can be used in aircraft satellite tracking applications. Research collaboration between Worldgate Technologies (WGT), Universiti Pertahanan Nasional Malaysia (UPNM) and Universiti Putra Malaysia (UPM) has developed the ATU originally from land base to airborne vehicles tracking, hence it provides multitudes of civil and military applications. The ATU is a unique device that enables multi-tasking application such as Air Combat Manoeuvring Instrumentation (ACMI), Network Centric Warfare and Flight Data Monitoring systems. In this paper, system characteristics and its applications are presented with the potential applications for Flight Data Monitoring system.

The course correction implementation of the inertial navigation system based on the information from the aircraft satellite navigation system before take-off

The use of the correction course option before aircraft take-off after inertial navigation system (INS) inaccurate alignment based on the platform attitude-and-heading reference system in azimuth is considered in the paper. A course correction is performed based on the track angle defined by the information received from the satellite navigation system (SNS). The course correction includes a calculated track error definition during ground taxiing along straight sections before take-off with its input in the onboard digital computational system like amendment for using in the current flight. The track error calculation is performed by the statistical evaluation of the track angle comparison defined by the SNS information with the current course measured by INS for a given number of measurements on the realizable time interval. The course correction testing results and recommendation application are given in the paper. The course correction based on the information from SNS can be used for improving accuracy characteristics for determining an aircraft path after making accelerated INS preparation concerning inaccurate initial azimuth alignment.

Neutron single event effects testing and evaluation method for avionics

The atmospheric neutron radiation reliability parameters,such as hard failure,hard error and soft error for avionics neutron single event effect( NSEE) were defined. A set of testing and evaluation method to demonstrate the avionics NSEE-resistance capability was presented and verified by a case study on some aircraft satellite navigation receiver NSEE testing and evaluation. The testing and evaluation method included test stress determination method on ending condition and starting condition,MNSEEprediction method,test procedures,testing and evaluation method,etc. This case study verifies that the NSEE testing and evaluation method for avionics is practical,operational and effective in the engineering application. The NSEE sensitivity features of DSP,SRAM and FPGA in aircraft satellite navigation receiver may provide pinpointed technical support for NSEE mitigation and protection for the related NSEE failure. The theoretical and application foundation is paved for atmospheric neutron single event effects testing and evaluation for avionics in China. In the meantime,it provides important and valuable reference for the atmospheric NSEE testing and evaluation for other electronic and information products in China.

Comparison between satellite spectrometric and aircraft measurements of the gaseous composition of the troposphere over Siberia during the forest fires of 2012

The vertical profiles of the O3, CO, CO2 and CH4 concentrations measured onboard the Optik Tu-134 aircraft laboratory and retrieved from data obtained with an IASI Fourier transform spectrometer operating aboard a MetOp satellite (European Space Agency) have been compared. This comparison shows that absolute differences between aircraft satellite ozone concentrations may vary from 55 to 15 ppb at the land surface and within the lower boundary layer and from 30 to −15 ppb at a height of 7000 m. Their relative differences range within 60 to 30% at a height of 500 m and 30 to −35% at a height of 7000 m. Absolute differences between aircraft and satellite carbon-monoxide concentrations may vary from 80 to 2300 ppb, while their relative differences range within −140 to 98%. For methane, the mean difference is maximal within the atmospheric boundary layer (90 ppb). According to the data on all profiles, the maximum and minimum differences reach 220 and 8 ppb, respectively, within the atmospheric boundary layer. Minimum differences range from zero at the land surface to −100 ppb in the upper troposphere. For carbon dioxide, the mean difference between the results of aircraft and satellite measurements ranges from −2 to −9 ppm. In the free troposphere, at a height of more than 3000 m, this difference is almost constant and amounts to −6 ppm. Over all flights, the maximum and minimum differences between aircraft and satellite CO2 concentrations range from 14 to −4 ppm and from −7 to −16 ppm, respectively, within the atmospheric boundary layer. In this case, the maximum and minimum relative deviations over all flights amount to 3.4 and −4.2%, respectively, within the atmospheric boundary layer. These differences are significantly larger than those found earlier for the background conditions. It is necessary to improve the vertical gas distribution models used in the algorithms of satellite-data processing.

The Search for MH370

At 17:22 UTC on 7th March 2014 Malaysian Airlines flight MH370 carrying 239 passengers and crew from Kuala Lumpur to Beijing lost contact with Air Traffic Control and was subsequently reported missing. Over the following days an extensive air and sea search was made around the last reported location of the aircraft in the Gulf of Thailand without success. Subsequent analysis of signals transmitted by the aircraft's satellite communications terminal to Inmarsat's 3F1 Indian Ocean Region satellite indicated that the aircraft continued to fly for several hours after loss of contact, resulting in the search moving to the southern Indian Ocean. This paper presents an analysis of the satellite signals that resulted in the change of search area.

Ionospheric Threat Mitigation by Geometry Screening in Ground-Based Augmentation Systems

Large spatial variations in ionospheric delay of Global Navigation Satellite System signals observed during severe ionospheric storms pose potential threats to the integrity of the Ground-Based Augmentation System, which supports aircraft precision approaches and landing. Range-domain monitoring within the Ground-Based Augmentation System ground facility cannot completely eliminate all possible ionospheric threats, because ionospheric gradients are not observable to the ground monitor if they impact the satellite-to-ground lines of sight with the worst-possible geometry and velocity. This paper proposes an algorithm called position-domain geometry screening to remove potentially hazardous satellite geometries under worst-case ionospheric conditions. This is done by inflating one ormore integrity parameters broadcast by the ground facility. Hence, the integrity of the system can be guaranteedwithout anymodification of existing avionics. This paper develops an algorithm that allows the ground station to conservatively estimate the worst-case ionospheric errors for Ground-Based Augmentation System users. The results of this algorithm determine which potential aircraft satellite geometries are safe and which are unsafe, and inflation of the broadcast vig parameter is used to make all unsafe geometries unusable for the Ground-Based Augmentation System. Although the elimination of unsafe geometries reduces system availability, this paper shows that acceptable availability for category I precision approaches is attainable at Memphis International Airport and Newark Liberty International Airport while guaranteeing system integrity under anomalous ionospheric gradients.

«Nature's workshop» industry and urban expansion in Southern California, 1900–1950

Scholars and pundits have cast Los Angeles as a prototype for the twentieth century North American metropolis. Most accounts focus primarily, if not exclusively, on residential development and rely on stock suburban theses for their interpretation. Regional expansion has been presented as a new landscape order where precise location is a secondary concern, development proceeds without planning, and the result is a homogeneous sprawl. Studies of manufacturing and industrial location in southern California often share these conventions. An historical investigation reveals that industry and industrial location have been key determinants of urban form, and that industrial, commercial, and residential development have been co-ordinated, complementary, and highly planned. These coincident enterprises recast the region during the first half of the twentieth century. There were three interrelated but qualitatively distinct types of industrial zones in Los Angeles during this period: a mixed-use, home-market district adjacent to the central business district; an industry-only, mass-production, branch-plant zone in Vernon and the eastside; and a series of oil, film, and aircraft satellites on the urban periphery. This finding challenges the received wisdom regarding industrial geography, a progressive narrative of technological innovation and production regimes that chronicle ascension, transformation, and succession.

Application of Satellite Navigation Techniques to Marine and Air Navigation

Satellite Navigation Techniques based on the Navy Navigation Satellite System are currently being exploited for both military and commercial uses. This paper discusses equipment requirements and related performance characteristics for Marine and Aircraft Satellite Navigation user equipment. Performance limitations due to system errors and inaccurate user data inputs are analyzed and several techniques for improved system utilization are presented.