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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 964701 (2015) https://doi.org/10.1117/12.2217596
This PDF file contains the front matter associated with SPIE Proceedings Volume 9647, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 964703 (2015) https://doi.org/10.1117/12.2202967
We present the recent development of high performance compact THz sources based on intracavity nonlinear
frequency mixing in mid-infrared quantum cascade lasers. Significant performance improvements of our THz
sources with respect to the continuous wave THz power output, monolithic THz tuning, and widely frequency are
achieved by systematic optimization of the device's active region, waveguide design, and chip bonding strategy.
Room temperature continuous wave THz power of more than 10 μW at 3.4 THz is demonstrated at room
temperature. Monolithic THz tuning of a chip-based THz source from 2.6 to 4.2 THz with power up to 0.1 mW is
achieved. Surface emission from the substrate via a diffraction grating with THz power up to 0.5 mW is also
obtained. The developing characteristics show the potential for these THz sources as local oscillators for many
astronomical and medical applications.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 964705 (2015) https://doi.org/10.1117/12.2186169
Advancements in image sensors and signal processing have led to the successful development of lightweight hyperspectral
imaging systems that are critical to the deployment of Photometry and Remote Sensing (PaRS) capabilities in unmanned
aerial vehicles (UAVs). In general, hyperspectral data cubes include a few dozens of spectral bands that are extremely
useful for remote sensing applications that range from detection of land vegetation to monitoring of atmospheric products
derived from the processing of lower level radiance images. Because these data cubes are captured in the challenging
environment of UAVs, where resources are limited, source encoding by means of compression is a fundamental mechanism
that considerably improves the overall system performance and reliability. In this paper, we focus on the hyperspectral
images captured by a state-of-the-art commercial hyperspectral camera by showing the results of applying ultraspectral
data compression to the obtained data set. Specifically the compression scheme that we introduce integrates two stages;
(1) preprocessing and (2) compression itself. The outcomes of this procedure are linear prediction coefficients and an error
signal that, when encoded, results in a compressed version of the original image. Second, preprocessing and compression
algorithms are optimized and have their time complexity analyzed to guarantee their successful deployment using low
power ARM based embedded processors in the context of UAVs. Lastly, we compare the proposed architecture against
other well known schemes and show how the compression scheme presented in this paper outperforms all of them by
providing substantial improvement and delivering both lower compression rates and lower distortion.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 964707 (2015) https://doi.org/10.1117/12.2194849
This paper presents possibilities of using the composite fence in the security systems. The fence made entirely of
dielectric materials is neutral for electromagnetic waves. Thus, the fence does not introduce disturbances in propagation
of electromagnetic waves. The use of composite fences reduces reflections of electromagnetic waves which cause
negative effects on fence sensors, microwave barriers and radars. Additionally, the sensing part of the fence sensors can
be integrated in the composite fence structure. Thus, the detecting elements mounted on the fence are invisible for
potential intruder. This paper presents the composite fence with integrated fiber for fiber optic sensors. By arranging the
fiber into fence grid it is possible not only discreet installation of the sensors, but also better transfer movements of the
fence to sensitive optical fiber. By using the fiber as a sensing element the whole fence remain dielectric. Thereby
obtaining a fence entirely transparent to electromagnetic waves which is also monitored for forcing attempts. Another
way to use the dielectric properties of the composite fence is possibility of use electromagnetic sensors. Installation of
the electromagnetic sensor directly on the fence allows to create a monitored zone in the close surroundings on both
sides of the fence. The use of two types of sensors based on different physical phenomena provides an improvement in
the detection properties of the entire security system by reducing the number of false alarms and increasing level of
safety by increasing the probability of detection an attempt to force the fence.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 964708 (2015) https://doi.org/10.1117/12.2201066
There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to
avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to “see” close
up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid
system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at
dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles
such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of
Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can
cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and
simultaneously generate an alarm signal if the obstacle enters within the SAA system’s adjustable “Protection Border”.
The alarm signal alerts the drone’s autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar
modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes
and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and
has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470A (2015) https://doi.org/10.1117/12.2194310
A great number of design concepts of surface acoustic wave (SAW)-based gyroscopes was proposed through the last decade mainly due to their unique robustness and ability to survive extremely high shocks. At the same time, these devices are small, cheap and easy to produce. Later publications offered a novel idea of constructing a fully passive and wireless gyroscope using SAW-based elements. Although this idea is very attractive, proposed design concepts rise a number of questions. This paper is dedicated to give a short overview of existing design concepts, focusing on details of its operation. Moreover, a new design concept utilizing a single delay line and a phase detector is proposed.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470E (2015) https://doi.org/10.1117/12.2196890
This paper describes a system concept for persistent (up to 365 days, 24/7), unmanned, local-area surveillance of air and maritime surface and sub-surface objects in the Canadian Arctic. The system concept is based on unmanned, remotely controlled and monitored Arctic Surveillance Systems that could be deployed at one or more maritime chokepoints, at locations in the Canadian Arctic Archipelago. The Artic Surveillance Systems would be operated over a satellite communication channel from a Southern Control Centre located in the south of Canada. Surveillance information for each detected platform and environmental reports for the local operating area would be compiled semi-automatically, from the integration of data transmitted from multiple above-water and underwater sensors and self-reporting systems, and be disseminated, in near real-time, to defence, security, and public safety clients. Potential sensors and self-reporting systems include radar, radar intercept receiver, underwater acoustic arrays, electro-optical/infrared camera system, Automatic Identification System (AIS), Automatic Dependent Surveillance - Broadcast (ADS-B), and a meteorological sensor system. The system concept is comprised of a surveillance concept – which includes environmental and geographic factors, platform types under potential surveillance, end-user information requirements, contributions of individual sensor types to surveillance, and the role of local-area surveillance within the broader context of Arctic Domain Awareness – and a system operating concept. The system operating concept describes the system capabilities and operating modes required to achieve the surveillance concept. Specific consideration is given to the interplay between the automation level, the quality and timeliness of the resulting information productions, the allocation of processing functions between the Control Centre and the Arctic Surveillance System, and transmitted data volumes. The system concept is being used in support of the specification of functional requirements for a concept demonstration system for Arctic surveillance, currently under development by Defence R&D Canada.
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Joël Busset, Florian Perrodin, Peter Wellig, Beat Ott, Kurt Heutschi, Torben Rühl, Thomas Nussbaumer
Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470F (2015) https://doi.org/10.1117/12.2194309
Recent events of drones flying over city centers, official buildings and nuclear installations stressed the growing threat of
uncontrolled drone proliferation and the lack of real countermeasure. Indeed, detecting and tracking them can be difficult
with traditional techniques. A system to acoustically detect and track small moving objects, such as drones or ground
robots, using acoustic cameras is presented. The described sensor, is completely passive, and composed of a 120-element
microphone array and a video camera. The acoustic imaging algorithm determines in real-time the sound power level
coming from all directions, using the phase of the sound signals. A tracking algorithm is then able to follow the sound
sources. Additionally, a beamforming algorithm selectively extracts the sound coming from each tracked sound source.
This extracted sound signal can be used to identify sound signatures and determine the type of object.
The described techniques can detect and track any object that produces noise (engines, propellers, tires, etc). It is
a good complementary approach to more traditional techniques such as (i) optical and infrared cameras, for which the
object may only represent few pixels and may be hidden by the blooming of a bright background, and (ii) radar or other
echo-localization techniques, suffering from the weakness of the echo signal coming back to the sensor. The distance of
detection depends on the type (frequency range) and volume of the noise emitted by the object, and on the background
noise of the environment. Detection range and resilience to background noise were tested in both, laboratory environments
and outdoor conditions. It was determined that drones can be tracked up to 160 to 250 meters, depending on their type.
Speech extraction was also experimentally investigated: the speech signal of a person being 80 to 100 meters away can be
captured with acceptable speech intelligibility.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470H (2015) https://doi.org/10.1117/12.2193902
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.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470I (2015) https://doi.org/10.1117/12.2194093
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.
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H. Zech, F. Heine, D. Tröndle, S. Seel, M. Motzigemba, R. Meyer, S. Philipp-May
Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470J (2015) https://doi.org/10.1117/12.2196273
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.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470K (2015) https://doi.org/10.1117/12.2195185
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.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470N (2015) https://doi.org/10.1117/12.2197171
HgCdTe avalanche photodiode single element detectors have been developed for a large scope of photon starved
applications. The present communication is dedicated to use of these detectors for free space optical communications. In
this perspective we present and discuss the sensitivity and bandwidth that has been measured directly on HgCdTe APDs
and on detector modules. In particular, we report on the performance of TEC cooled large area detectors with sensitive
diameters ranging from 30- 200 μm, characterised by detector gains of 2- 20 V/μW and noise equivalent input power of
0.1-1 nW for bandwidths ranging from 20 to 400 MHz. One of these detectors has been used during the lunar laser
communication demonstration (LLCD) and the results The perspectives for high data rate transmission is estimated from
the results of impulse response measurements on HgCdTe APDs. These results indicate that bandwidths close to 10 GHz
can be achieved in these devices. The associated sensitivity at an APD gain of 100 is estimated to be below 4 photons
rms (NEP<10 nW) for APDs operated at 300 K.
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Proceedings Volume Unmanned/Unattended Sensors and Sensor Networks XI; and Advanced Free-Space Optical Communication Techniques and Applications, 96470O (2015) https://doi.org/10.1117/12.2194996
We demonstrate an AlInP detector grown on lattice-matched GaAs substrate for underwater communication applications.
This detector has a narrow inherent spectral response of 22 nm with central wavelength at ~ 480 nm and is capable of
having avalanche gain of ~ 20 which gives peak responsivity of ~ 2 A/W. A much higher multiplication of ~167 was
shown in the previous work. The full-width-half-maximum (FWHM) and responsivity of this detector is fairly
insensitive to the angle of the incident light. These properties enable it to detect an optical signal at 480 nm even in the
presence of high background illumination.
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