Satellite Data Link Research Articles

Guest Editorial Special Issue on Vacuum Electronics

The Time has come once again to chronicle recent advances in the vibrant and dynamic field of vacuum electronics. This Special Issue, published by the IEEE Transactions on Electron Devices, follows successful past issues published every four or five years since 2001. Dr. David Abe and Dr. David Whaley headed the group of Guest Editors for this issue, relying heavily on the expertise and dedication of their fellow Guest Editors, Dr. Jinjun Feng, Dr. John Jelonnek, and Dr. Lalit Kumar. Together, manuscripts covering the wide range of topics found within the following pages were ushered through a rigorous peer-reviewed process to provide a snapshot of the state-of-the-art in vacuum electronics technology for 2018. In a testament to the vitality and widespread activity in the field, contributions to this issue were submitted nearly equally from Europe, Asia, and the Americas. The subject matter of these contributions spans such a wide swath of applications that it is difficult to imagine that our lives are not impacted in some way every day by the benefits that this technology area provides. Communications, radar, accelerator and fusion research, satellite data links, and electronic defense are but a few examples.

A new high-precision and low-power GNSS receiver for long-term installations in remote areas

Abstract. We have developed a new high-precision GNSS receiver specifically designed for long-term unattended deployments in remote areas. The receiver reports its status, and can be reprogrammed remotely, through an integrated satellite data link. It uses less power than commercially available alternatives while being equally, if not more, accurate. Data are saved locally on dual SD card slots for increased reliability. Deployments of a number of those receivers in several different locations on the Antarctic ice sheet have shown them to be robust and able to operate flawlessly at low temperatures down to −40 °C.

VHF 대양 네트워크를 위한 Ad-hoc 기반 다중접속기법

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

대양항로에서 장거리 공대지통신을 위한 VHF Relay Network

In oceanic flight routes, HF radio and satellite data links have been used for air-to-ground communication, but these systems have long propagation delay and low data throughput. In this paper, we propose a reliable system to overcome the weakness of current HF radio and satellite communication systems for oceanic aeronautical flight routes. The proposed scheme uses only one aeronautical VHF channel in multi-hop oceanic communication environments and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. The proposed system improves performance on delay and throughput as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

저속 주파수 도약 방식 위성 데이터링크에서 송수신 신호중첩 및 주파수 다이버시티 적용

본 논문에서는 주파수 도약방식에서는 적용이 어려운 송수신 중첩통신 방식을 DSM형 중계기를 사용하는 위성 데이터링크에 적용하고 항재밍 성능 개선을 위해 잔여 주파수 자원을 주파수 다이버시티에 활용하는 방안을 제안 한다. 시뮬레이션을 통해 제안한 방식에 대한 항재밍 성능과 탐지회피 성능을 분석하였다. 항재밍 성능 분석 결과, 주파수 다이버시티 적용으로 데이터 통신시 18.5dB의 처리이득을 얻을 수 있으며, 500MHz 도약 방식에서 통신단말형태의 재머에 대해 4.8Mbps의 데이터 전송이 가능함을 확인하였다. 또한, 주파수 중첩에 의해 주파수 자원을 최대 2배까지 재사용 가능하며, 데이터 속도를 추정 할 수 있는 D&M 검출기를 대상으로 중첩을 하지 않았을 때 보다 2.5dB LPI 성능이 개선됨을 확인하였다. In this paper, we propose a possibility of usage of carrier superpositioning scheme for a specific slow frequency hopping(SFH) transmission method for the satellite data link in which all of hopping carriers have to be synchronized to DSM transponder of our previous work and usage of frequency diversity in the saved frequency to overcome the SFH disadvantage against jammer. We have analyzed anti-jamming performance and LPI performance and confirmed that the proposed scheme can support data service with 18.5dB processing gain against the worst case partial band jamming and give 2.5dB gain in the LPI performance against D&M detector which can estimate the data rate of unknown signals.

Soundscapes under sea ice: Can we listen for open water?

Different geophysical conditions at the ocean surface generate distinctive sound spectra underwater, thereby allowing the physical environment to be monitored using passive acoustics. In the central Bering Sea, a passive aquatic listener (PAL) was deployed on the NOAA M5 mooring through the 2008 and 2009 winter seasons, allowing the ambient sound under sea ice to be recorded. Distinctive features of sea ice soundscapes include loud sound levels during periods of ice formation and very quiet high-frequency levels during periods of solid ice coverage. These soundscapes do have distinctive spectra features that distinguish them from other geophysical conditions, including wind-generated spectra, drizzle, and rainfall onto open water. This indicates that it is possible to listen for ice-free surface conditions. In turn, this will allow sub-surface ocean instrumentation on drifters, profilers, or moorings to detect open water and surface during relatively safe ice-free surface conditions (by listening), thus minimizing damage risk and allowing data transfer by satellite data links, an important advance for engineering oceanographic studies in ice covered seas. [Work sponsored by ONR Marine Mammals.]

The AMELIA Air Traffic and Radar Simulator and Its Use in the Assessment of Costs and Benefits of Future Air Traffic Scenarios

An air traffic and radar simulator, AMELIA, which has been developed at the University of Iceland, is described in this paper. The simulator has several application areas, as a training tool for air traffic controllers, as a test tool for radar data processing systems and as a tool for calculating costs/benefits associated with various types of airspace organization.Three case studies are then presented in this paper, in which the simulator is used to assess some of the costs or benefits associated with different future air traffic scenarios. The first case study addresses the operational benefit of locating radars in Greenland for air traffic control, thereby forming a continuous bridge of radar coverage across the North Atlantic. Scenarios associated with current traffic and separation standards, future traffic and current separation standards, and future traffic and RVSM (Reduced Vertical Separation Minimum) are compared with and without radar’s coverage in Greenland. Results indicate that substantial operational benefits can be expected, as aircraft can be given more economical flight profiles. The second case study is a comparison of communication option costs associated with ADS (Automatic Dependent Surveillance) implementation in the North Atlantic. Results here indicate that a combined VHF/satellite data link is much more economical than solely relying on satellite data link in areas with substantial VHF coverage. The third study is an ongoing one and addresses the benefits of the future CNS/ATM (Communications, Navigation, Surveillance/Air Traffic Management).

Assessment of the Costs and Benefits of Future Air Traffic Scenarios

Two case studies are presented in this paper, in which an air-traffic simulator is used to assess partial costs or benefits associated with different future air traffic scenarios. The first case study addresses the operational benefit of locating radars in Greenland for air traffic control, comparing scenarios with and without radars in Greenland associated with current traffic and separation standards, future traffic and current separation standards, and future traffic and RVSM (Reduced Vertical Separation Minimum). By locating radars in Greenland, a continuous bridge of radar coverage across the North Atlantic is formed. Results indicate that substantial operational benefits can be expected as aircraft can be given more economical flight profiles. The second case study is a comparison of communication option costs associated with ADS (Automatic Dependent Surveillance) implementation in the North Atlantic. Results here indicate that a combined VHF/satellite data link is much-more economical than a satellite data link in areas with substantial VHF coverage.

Development of experimental automatic dependent surveillance system and inflight performances

AbstractThe automatic dependent surveillance (ADS) system has been developed and tested through flight trials using INMARSAT satellites. ADS is a new surveillance system that uses a satellite datalink for aircraft in oceanic areas. Test results showed that the ADS transmission protocol is reliable and message losses are very few, the transmission delay for the R channel is about 3.4 s and that for the T channel is 15.6 s under fair link conditions. The latter should be reduced for additional improvement in surveillance capability in the future. It may increase due to degradation of link condition by aircraft attitude change.

Multisite Real-Time DGPS System Using Satellite Data Link: Operational Results

This paper describes a multiple-reference-station DGPS system using a geostationary satellite-based data link. The role of multiple reference stations in improving DGPS accuracy is discussed. Operational multiple-reference-station DGPS results are presented. They are compared with standard DGPS results on short and long baselines. The results demonstrate the system capability of maintaining 2.5 m (1-sigma) horizontal position accuracy (about the mean error) at long distances up to 1000 km from the reference stations.

静止衛星を用いた航空管制実験について

An ATC (Air Traffic Control) experiment using ETS-V (Engineering Test Satellite V) was conducted. In the experiment, the position of aircraft was measured by CIS (Cooperative Independent Surveillance) and ADS (Automatic Dependent Surveillance). Data communication and voice communication using NBFM and LPC between ground and air was conducted. The result shows that the positioning accuracy of CIS and ADS is enough to minimize present oceanic separation of aircraft. More than 95% of the controllers participated in the experiment evaluated the quality of voice communication using NBFM as bettr than that of present HF communication. Also 81% of them prefer LPC to HF. An error rate of received characters on aircraft through data communication is less than 2×10^<-4>, which shows that the satellite data link has the possibility of improving oceanic ATC capability.

On large deviations theory and asymptotically efficient Monte Carlo estimation

It is shown how large-deviations theory can be applied to construct an asymptotically efficient simulation distribution for Monte Carlo simulation using the importance sampling technique. A sufficient and necessary condition is given for the asymptotic efficiency of the candidate simulation distributions. This is done in the multidimensional setting that is required by many practical simulation problems. The result obtained is applied primarily in two areas. First, the generalization of previous work dealing with functionals of Markov chains is discussed. A second area of application is the simulation of nonlinear systems with Gaussian inputs. As an example of a system with Gaussian inputs, the simulation of a digital communication channel with nonlinear ISI (intersymbol interference) characteristic of satellite data links is considered. In the case of linear ISI, the asymptotically efficient exponentially twisted distribution turns out to agree with a method previously proposed by D. Lu and K. Yao (1988). The large-deviations point of view provides some useful insight on how to extent the Lu and Yao method to nonlinear channels.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance analysis of a satellite communications backchannel architecture

The definition of a backchannel architecture for open systems interconnection over satellite links has been the subject of the SENS-project 1 The new proposal is based on existent international standards and uses the options of the ISO-class 4 transport layer protocol in order to enclose in level 4 data link control functions for unidirectional satellite links following the rules of the IBM-checkpoint protocol. This paper provides performance values of the SENS architecture in comparison with those of common satellite communication systems. With means of elementary probability theoretical methods an approximate analysis of the IBM-checkpoint protocol is accomplished. The results show that for large amounts of data the new architecture proves to be best suited for cost efficient use of public satellite data links.

Aeronautical satellite data link concept, design, and flight test results

The MITRE Corporation has conducted a three-year study of aeronautical satellite communications that culminated in a set of flight tests over the North Atlantic during August of 1985. The flight tests required the cooperation of four organizations in addition to MITRE: The Communications Satellite Corporation (COMSAT), Rockwell International, Ball Aerospace and Avantek. A test aircraft, equipped with a specially designed satellite data link terminal and antenna configuration, was flown from Cedar Rapids, Iowa across the North Atlantic to Iceland, and north of Iceland to 75° latitude. The purpose of the flight tests was to measure the performance of a full duplex aeronautical satellite data link (ASDL) using the International Maritime Satellite Organization's (INMARSAT's) spacecraft and earth station at Southbury, Connecticut, and to demonstrate potential applications. The data link operates at 200 bits-per-second (bps), uses forward error correction (FEC) coding, and employs a terminal monitor that provides interfaces to on-board avionics, data recording equipment, and an industry-standard personal computer (PC). The PC serves as a user terminal as well as a real-time monitor of bit-error-rate (BER) performance. In addition to channel propagation and BER experiments, demonstrations of potential applications of an oceanic ASDL system were conducted. A standard commercial airline data link management unit (MU) was used to communicate data over the ASDL using standard protocols. The interface to the MU allowed access to data from two distinct navigation systems: an inertial navigation system (INS) and a Global Positioning System (GPS) receiver. Aircraft position data was transmitted from the aircraft to the earth station on an automatic basis to simulate automatic dependent surveillance (ADS) of oceanic air space. This paper is divided into three sections: 1) A discussion of background issues, such as the motivation for the reported research and development, and important operational ASDL system design topics; 2) a detailed description of the developed ASDL design; and 3) a description of the test program and a preliminary summary of the results.

A Simulation Model Of The Satellite Communications System I (Scsi)

AbstractThe Satellite Communications System i (scsi) consists of a half-duplex, single-channel, high-speed satellite data link, AN/UYK-20 computers, peripheral hardware, and related software to provide automatic two-way communication between the shore and a specified number of ships using a modified round robin network discipline. A simulation model was written in order to address initial software design and subsequent system performance issues without incurring the expenses of software redesign or fleet exercises. In the model, messages are generated at both shore and ships nodes according to an exponential distribution. Each message is assigned a source, destination(s), a length, a precedence, and a type from specified distributions, and is queued, processed, and routed to destination (s) via the network discipline. Provision is made for message logical unit errors, system control messages, and random access time slots. Output of the model includes the following: the mean total time to route messages fr...

Implications of a Selective Acknowledgment Scheme on Satellite Performance

Data link response time is becoming more of a concern today with the onset of satellite transmissions of computer data. The long propagation delay inherent to satellite communications may lead to a degradation in data link response time as compared to the same transmission over purely terrestrial links. Furthermore, data link errors need be considered in any such study of response time of satellite data links. A model has been developed to study data link response time under a selective acknowledgment retransmission protocol. The model not only calculates mean link response time, but also the second moment of the response time. This model is then applied to various interactive data transmission schemes over a half-duplex (HDX) satellite link with terrestrial tails, although modifications can easily be made to analyze pure terrestrial or satellite links. The model parameters include bit error rate (BER), terrestrial as well as satellite propagation delay, modem transit delay, MAXOUT (maximum number of unacknowledged data frames), frame size (bits), and message size (bits).