SPIE Security + Defence最新文献

Evaluation of Error Correcting Code performances of a free space optical communication system between LEO satellite and Ground Station 低轨卫星与地面站自由空间光通信系统纠错码性能评价

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2195185

M. Chochol, A. Rissons, J. Lacan, N. Védrenne, G. Artaud

{"title":"Evaluation of Error Correcting Code performances of a free space optical communication system between LEO satellite and Ground Station","authors":"M. Chochol, A. Rissons, J. Lacan, N. Védrenne, G. Artaud","doi":"10.1117/12.2195185","DOIUrl":"https://doi.org/10.1117/12.2195185","url":null,"abstract":"The use of optical communication to transfer data between LEO satellite and optical ground station is being studied. It creates the opportunities to highly increase a transmitted data rate across a free space. The optical propagation channel has specificities that imply the potential use of error correcting code (ECC) and interleaving at physical and higher layer. The study aims to assess the performance of a combination of ECC and interleaving in presence of various channel scenarios and receiver architectures. As a result of these studies, a functional physical layer simulator is provided. The simulator emulates a signal generation and applies time series representing the propagation channel with an effect of receiver front-ends. It also features various detection methods and computes mutual information (MI) in order to approximate ECC performances. A number of receiver architectures and channel scenarios were studied. The channel scenarios combine a direct coupling of the received signal into the photo-detector (PD) and among other assume the use of pre-amplified receiver implying the signal coupling into a standard single mode fiber (SSMF) prior to the detection. Time series were generated and represent the power received at PD input depending on the chosen scenarios (without adaptive optics (AO), with tip-tilt correction, with no dynamical coupling losses or with higher order AO correction). Two modulations of OOK and DBPSK along with various detection methods were examined. The tuning of ECC parameters was studied through the computation of mutual information. Additionally two cases of physical and higher layer interleaving were implemented providing an excellent diversity to the channel seen by the codeword of ECC.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131805844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Preliminary results of Terabit-per-second long-range free-space optical transmission Experiment THRUST 太比特/秒远程自由空间光传输实验初步结果

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2193902

D. Giggenbach, J. Poliak, R. Mata-Calvo, C. Fuchs, N. Perlot, R. Freund, T. Richter

{"title":"Preliminary results of Terabit-per-second long-range free-space optical transmission Experiment THRUST","authors":"D. Giggenbach, J. Poliak, R. Mata-Calvo, C. Fuchs, N. Perlot, R. Freund, T. Richter","doi":"10.1117/12.2193902","DOIUrl":"https://doi.org/10.1117/12.2193902","url":null,"abstract":"Future Very High Throughput Satellite Systems (VHTS) will perform at several Tbit/s throughput and thus face the challenge of limited feeder-link spectrum. Whereas with conventional RF feeder links several tens of ground gateway stations would be required, the total capacity can alternatively be linked through a single optical ground station using Dense Wavelength Division Multiplexing (DWDM) techniques as known from terrestrial fiber communications. While intermittent link blockage by clouds can be compensated by ground station diversity, the optical uplink signal is directly affected by scintillation and beam wander induced by the atmospheric index-of-refraction turbulence. The transmission system must be capable to mitigate these distortions by according high-speed tracking and fading compensation techniques. We report on the design of a near-ground long-range (10km) atmospheric transmission test-bed which is, with its relatively low elevation of 1.8 degrees, exemplary for a worst case GEO uplink scenario. The transmitting side of the test-bed consists of a single telescope with a a fine pointing assembly in order to track the atmospheric angle-ofarrival and precisely aim towards the beacon of the receiver. On the other side of the test-bed, the receiver telescope is also capable of fine pointing by tracking the transmitted signal. The GEO uplink scenario is modelled by a precise scaling of the beam divergence and the receiver’s field of view as well as by the beacon offset to model the point-ahead angle. In order to make the experimental test-bed correspond to an actual feeder link scenario, the link budget as well as the turbulence profile of the experimental scenario are modelled and compared to the GEO uplink. Several DWDM channels are multiplexed to reach the total link capacity of above one Tbit/s.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131847076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

HgCdTe APDs for free space optical communications 用于自由空间光通信的HgCdTe apd

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2197171

J. Rothman, G. Lasfargues, J. Abergel

引用次数: 12

Ground stations for aeronautical and space laser communications at German Aerospace Center 德国航空航天中心的航空和空间激光通信地面站

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2194093

F. Moll, A. Shrestha, C. Fuchs

{"title":"Ground stations for aeronautical and space laser communications at German Aerospace Center","authors":"F. Moll, A. Shrestha, C. Fuchs","doi":"10.1117/12.2194093","DOIUrl":"https://doi.org/10.1117/12.2194093","url":null,"abstract":"Free-space laser communications are subject of current research and development in many research and industrial bodies. Long distance air-ground and space-ground can be implemented in future communication networks as feeder, backbone and backhaul links for various air- and space-based scenarios. The Institute of Communications and Navigation of the German Aerospace Center (DLR) operates two ground stations to investigate the communication channel and system: the Optical Ground Station Oberpfaffenhofen and the Transportable Optical Ground Station. The first one is a fixed installation and operated as experimental station with focus on channel measurements and tests of new developments. Various measurement devices, communication receivers and optical setups may easily be installed for different objectives. The facility is described with its dome installation, telescope setup and infrastructure. Past and current deployment in several projects is described and selected measurement achievements presented. The second ground station is developed for semi-operational use and demonstration purposes. Based on experience with the experimental ground station, this one is developed with higher level of integration and system robustness. The focus application is the space-ground and air-ground downlink of payload data from Earth observation missions. Therefore, it is also designed to be easily transportable for worldwide deployment. The system is explained and main components are discussed. The characteristics of both ground stations are presented and discussed. Further advancements in the equipment and capability are also presented.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121832368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21

LCT for EDRS: LEO to GEO optical communications at 1,8 Gbps between Alphasat and Sentinel 1a 用于EDRS的LCT: Alphasat和Sentinel 1a之间以1.8 Gbps的速度进行LEO到GEO光通信

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2196273

H. Zech, F. Heine, D. Tröndle, S. Seel, M. Motzigemba, R. Meyer, S. Philipp-May

{"title":"LCT for EDRS: LEO to GEO optical communications at 1,8 Gbps between Alphasat and Sentinel 1a","authors":"H. Zech, F. Heine, D. Tröndle, S. Seel, M. Motzigemba, R. Meyer, S. Philipp-May","doi":"10.1117/12.2196273","DOIUrl":"https://doi.org/10.1117/12.2196273","url":null,"abstract":"The European Data Relay System (EDRS) relies on optical communication links between Low Earth Orbit (LEO) and geostationary (GEO) spacecrafts. Data transmission at 1,8 Gbps between the S/Cs will be applied for link distances up to 45000 km. EDRS is foreseen to go into operation in 2015. As a precursor to the EDRS GEO Laser Communication Terminals (LCT), a LCT is embarked on the Alphasat GEO S/C, which was launched in July 2013. Sentinel 1A is a LEO earth observation satellite as part of ESAs Copernicus program. Sentinel 1A also has a LCT on board. In November 2014, the first optical communication link between a LEO and a GEO Laser Communication Terminal at gigabit data rates has been performed successfully [1]. Data generated by the Sentinel 1A instrument were optically transferred to Alphasat. From Alphasat, the data were transmitted via Kaband to a ground station. In the ground station, the original data were recovered successfully. So the whole chain from LEO to ground was verified. Since then, many optical communication links between the Alphasat LCT and the Sentinel 1A LCT were performed. During these tests, the acquisition and tracking performance was investigated. The first communication links showed a very robust link acquisition capability and tracking errors in the sub-μrad range. The communication link budget was verified and compared to the predictions, showing excellent overall system behavior with sufficient margin to support future GEO GEO link applications.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"198 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125973159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 42

A high sensitivity detector for underwater communication systems 一种用于水下通信系统的高灵敏度探测器

SPIE Security + Defence Pub Date : 2015-10-29 DOI: 10.1117/12.2194996

J. S. Cheong, A. Auckloo, J. S. Ng, A. Krysa, J. David

引用次数: 2

Low pressure cesium and potassium Diode Pumped Alkali Lasers: pros and cons 低压铯钾二极管抽运碱激光器:利与弊

SPIE Security + Defence Pub Date : 2015-10-27 DOI: 10.1117/12.2194318

B. Zhdanov, M. Rotondaro, M. Shaffer, R. Knize

{"title":"Low pressure cesium and potassium Diode Pumped Alkali Lasers: pros and cons","authors":"B. Zhdanov, M. Rotondaro, M. Shaffer, R. Knize","doi":"10.1117/12.2194318","DOIUrl":"https://doi.org/10.1117/12.2194318","url":null,"abstract":"This paper based on the talk presented at the Security plus Defence 2015 Conference held at Toulouse, France in September 2015. In this paper we present the results of our experiments on a comparative study of Cesium and Potassium based DPALs aimed to determine which of these two lasers has better potential for scaling to high powers. For both lasers we have chosen a so called “low pressure DPAL approach”, which uses buffer gas pressure of about 1 Atm for spin-orbit mixing of the exited states of alkali atoms to provide population inversion in the gain medium. The goal of this study was to determine power limiting effects, which affect performance of these DPALs, and find out how these limiting effects can be mitigated. The experiments were performed using both static and flowing gain medium. In our experiments, we studied the performance of both lasers in CW and pulsed modes with different pulse duration and observed output power degradation in time from the initial value to the level corresponding to the CW mode of operation. As a result of this study, we revealed some essential positive and negative features of both DPALs, which should be taken into account for power scaling experiments.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129714718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Helicopter engine exhaust rotor downwash effects on laser beams 直升机发动机排气旋翼下冲对激光束的影响

SPIE Security + Defence Pub Date : 2015-10-27 DOI: 10.1117/12.2194815

M. Henriksson, L. Sjöqvist, D. Seiffer

{"title":"Helicopter engine exhaust rotor downwash effects on laser beams","authors":"M. Henriksson, L. Sjöqvist, D. Seiffer","doi":"10.1117/12.2194815","DOIUrl":"https://doi.org/10.1117/12.2194815","url":null,"abstract":"The hot exhaust gases from engines on helicopters are pushed down by the rotor in a turbulent flow. When the optical path of a laser beam or optical sensor passes through this region severe aberrations of the optical field may result. These perturbations will lead to beam wander and beam distortions that can limit the performance of optical countermeasure systems. To quantify these effects the Italian Air Force Flight Test Centre hosted a trial for the “Airborne platform effects on lasers and warning sensors” (ALWS) EDA-project. Laser beams were propagated from the airport control tower to a target screen in a slant path with the helicopter hovering over this path. Collimated laser beams at 1.55-, 2- and 4.6-μm wavelength were imaged with high speed cameras. Large increases in beam wander and beam divergence were found, with beam wander up to 200 μrad root-mean-square and increases in beam divergence up to 1 mrad. To allow scaling to other laser beam parameters and geometries formulas for propagation in atmospheric turbulence were used even though the turbulence may not follow Kolmogorov statistics. By assuming that the plume is short compared to the total propagation distance the integrated structure parameter through the plume could be calculated. Values in the range 10-10 to 10-8 m1/3 were found when the laser beams passed through the exhaust gases below the helicopter tail. The integrated structure parameter values calculated from beam wander were consistently lower than those calculated from long term spot size, indicating that the method is not perfect but provides information about order of magnitudes. The measured results show that the engine exhaust for worst case beam directions will dominate over atmospheric turbulence even for kilometer path lengths from a helicopter at low altitude. How severe the effect is on system performance will depend on beam and target parameters.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"9650 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129703061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

IRCM spectral signature measurements instrumentation featuring enhanced radiometric accuracy IRCM光谱特征测量仪器具有增强的辐射测量精度

SPIE Security + Defence Pub Date : 2015-10-27 DOI: 10.1117/12.2195644

S. Lantagne, F. Prel, Louis M. Moreau, Claude Roy, C. Willers

{"title":"IRCM spectral signature measurements instrumentation featuring enhanced radiometric accuracy","authors":"S. Lantagne, F. Prel, Louis M. Moreau, Claude Roy, C. Willers","doi":"10.1117/12.2195644","DOIUrl":"https://doi.org/10.1117/12.2195644","url":null,"abstract":"Hyperspectral Infrared (IR) signature measurements are performed in military applications including aircraft- and –naval vessel stealth characterization, detection/lock-on ranges, and flares efficiency characterization. Numerous military applications require high precision measurement of infrared signature characterization. For instance, Infrared Countermeasure (IRCM) systems and Infrared Counter-Countermeasure (IRCCM) system are continuously evolving. Infrared flares defeated IR guided seekers, IR flares became defeated by intelligent IR guided seekers and Jammers defeated the intelligent IR guided seekers [7]. A precise knowledge of the target infrared signature phenomenology is crucial for the development and improvement of countermeasure and counter-countermeasure systems and so precise quantification of the infrared energy emitted from the targets requires accurate spectral signature measurements. Errors in infrared characterization measurements can lead to weakness in the safety of the countermeasure system and errors in the determination of detection/lock-on range of an aircraft. The infrared signatures are analyzed, modeled, and simulated to provide a good understanding of the signature phenomenology to improve the IRCM and IRCCM technologies efficiency [7,8,9]. There is a growing need for infrared spectral signature measurement technology in order to further improve and validate infrared-based models and simulations. The addition of imagery to Spectroradiometers is improving the measurement capability of complex targets and scenes because all elements in the scene can now be measured simultaneously. However, the limited dynamic range of the Focal Plane Array (FPA) sensors used in these instruments confines the ranges of measurable radiance intensities. This ultimately affects the radiometric accuracy of these complex signatures. We will describe and demonstrate how the ABB hyperspectral imaging spectroradiometer features enhanced the radiometric accuracy of spectral signature measurements of infrared military targets.","PeriodicalId":348143,"journal":{"name":"SPIE Security + Defence","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124177844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Different pulse pattern generation by frequency detuning in pulse modulated actively mode-locked ytterbium doped fiber laser 脉冲调制主动锁模掺镱光纤激光器中频率失谐产生的不同脉冲模式

SPIE Security + Defence Pub Date : 2015-10-27 DOI: 10.1117/12.2194824

He Chen, Sheng-Ping Chen, L. Si, Bin Zhang, Zong-fu Jiang

引用次数: 1