Fusion of information in heterogeneous multi-modal sensor networks has been proven to enhance sensing capabilities of ground troops to detect and track small unmanned aerial vehicles flying at low altitude. Nevertheless, the area coverage of a static sensor network could be permanently or temporally impacted by geographic topologies or moving obstacles which could reduce the local sensing probabilities. An additional moving sensor platform can be used to temporarily enhance sensing capabilities. First theoretical analysis and experimental field trials are presented using a static sensor network consisting of acoustical antenna array, a stationary FMCW RADAR and a passive/active optical sensor unit. Additionally, a measurement vehicle was applied, equipped with passive/active optical sensing devices. While the sensor network was used to monitor a stationary area with a sensor dependent sensing coverage, the measurement vehicle was used to obtain additional information outside the sensing range of the network or behind obstacles. A fusion of these data sets can provide an increased situational awareness. Limitations and improvements of this approach are discussed.
Small unmanned aerial vehicles (UAVs) are becoming increasingly popular and affordable the last years for professional and private consumer market, with varied capacities and performances. Recent events showed that illicit or hostile uses constitute an emergent, quickly evolutionary threat. Recent developments in UAV technologies tend to bring autonomous, highly agile and capable unmanned aerial vehicles to the market. These UAVs can be used for spying operations as well as for transporting illicit or hazardous material (smuggling, flying improvised explosive devices).
The scenario of interest concerns the protection of sensitive zones against the potential threat constituted by small drones. In the recent past, field trials were carried out to investigate the detection and tracking of multiple UAV flying at low altitude. Here, we present results which were achieved using a heterogeneous sensor network consisting of acoustic antennas, small FMCW RADAR systems and optical sensors. While acoustics and RADAR was applied to monitor a wide azimuthal area (360°), optical sensors were used for sequentially identification.
The localization results have been compared to the ground truth data to estimate the efficiency of each detection system. Seven-microphone acoustic arrays allow single source localization. The mean azimuth and elevation estimation error has been measured equal to 1.5 and -2.5 degrees respectively. The FMCW radar allows tracking of multiple UAVs by estimating their range, azimuth and motion speed. Both technologies can be linked to the electro-optical system for final identification of the detected object.
Small unmanned aerial vehicles (UAV) flying at low altitude are becoming more and more a serious threat in civilian and military scenarios. In recent past, numerous incidents have been reported where small UAV were flying in security areas leading to serious danger to public safety or privacy. The detection and tracking of small UAV is a widely discussed topic. Especially, small UAV flying at low altitude in urban environment or near background structures and the detection of multiple UAV at the same time is challenging. Field trials were carried out to investigate the detection and tracking of multiple UAV flying at low altitude with state of the art detection technologies. Here, we present results which were achieved using a heterogeneous sensor network consisting of acoustic antennas, small frequency modulated continuous wave (FMCW) RADAR systems and optical sensors. While acoustics, RADAR and LiDAR were applied to monitor a wide azimuthal area (360◦) and to simultaneously track multiple UAV, optical sensors were used for sequential identification with a very narrow field of view.
We investigated signatures of small unmanned aerial vehicles (UAV) with different sensor technologies ranging from acoustical antennas, passive and active optical imaging devices to small-size FMCW RADAR systems. These sensor technologies have different advantages and drawbacks and can be applied in a complementary sensor network to benefit from their different strengths.
Recent world events have highlighted that the proliferation of UAVs is bringing with it a new and rapidly increasing threat for national defense and security agencies. Whilst many of the reported UAV incidents seem to indicate that there was no terrorist intent behind them, it is not unreasonable to assume that it may not be long before UAV platforms are regularly employed by terrorists or other criminal organizations. The flight characteristics of many of these mini- and micro-platforms present challenges for current systems which have been optimized over time to defend against the traditional air-breathing airborne platforms. A lot of programs to identify cost-effective measures for the detection, classification, tracking and neutralization have begun in the recent past. In this paper, lSL shows how the performance of a UAV detection and tracking concept based on acousto-optical technology can be powerfully increased through active imaging.
A good measure for the probability to detect a sniper telescopic sight is the effective bi-directional laser retro-reflection cross section. This angular (bi-directional) property of an optical device can be measured and can be used for a fist estimation of its probability to be detected by an active imaging. In the present paper, the authors give examples for resolved and non-resolved sensing of a telescopic sight under mono-static and bi-static conditions. As a result of these measurements, the resolved sensing under mono-static conditions shows the highest signal response in a wide angular range.
KEYWORDS: Acoustics, Sensors, Weapons, Rockets, Missiles, Sensor networks, Digital signal processing, Signal detection, Signal processing, Global Positioning System
This paper briefly describes the set-up of the sensors and the instrumentation deployed by the French-German Research Institute of Saint-Louis (ISL) during the last NATO/ACG3/SG2 HFI Threat Data Collection (trial conducted during the summer 2014 in the Czech Republic). Measurements of acoustic signals generated by small-caliber weapons, ammunition, and rockets were carried out for the development of Hostile Fire Indicator (HFI) systems. For ground bases, imaging systems were associated with acoustic sensors in order to provide complementary information and better permanent surveillance / sniper detection. Our basic approach is to combine several technologies developed at ISL: acoustic detection, fusion of distributed sensor data, active imaging and 3D audio restitution of the threat.
KEYWORDS: Acoustics, Sensors, Sensor networks, 3D displays, Imaging systems, Data fusion, Algorithm development, Data communications, Stereoscopy, Short wave infrared radiation
Snipers have emerged as a major threat to troops in recent conflicts. To reduce this menace, the objective of the French-
German Research Institute of Saint Louis (ISL) research project “IMOTEP” is to improve the detection of snipers on the
battlefield. Our basic approach is to combine several sources of information for a fast and appropriate reaction when an
unusual signal (e.g. a flash or a shot) is detected. The project includes several technologies developed at ISL: acoustical
detection, fusion of distributed sensor network data, active imaging and 3D audio communication. The protection of
camps, convoys or dismounted soldiers rests on a distributed acoustical sensor network that detects and localizes sniper
attacks. An early estimation of the threat position is transmitted through a network to an active imaging system in order
to confirm and refine this position by 3D imaging. The refined position is then sent to the control center which generates
an alert message that displays the threat position using two formats: a tactical map and a 3D audio signal. In addition, the
camp is protected by an ad-hoc sensor network used for intruder detection.
KEYWORDS: Acoustics, Weapons, Sensors, Interference (communication), Rockets, Signal detection, Signal processing, Data modeling, 3D modeling, Digital signal processing
This paper briefly describes the set-up of the sensors and the instrumentation deployed by the French-German Research
Institute of Saint-Louis (ISL) during the last NATO/ACG3/SG2 HFI Threat Data Collection (Trial PROTEUS which
has been conducted during the summer 2012 in Slovenia). The main purpose of this trial was the measurements of
weapon and ammunition signatures for threat warning and hostile fire indicator (HFI) system development. The used
weapons vary from small caliber rifles to anti-tank rockets in ground-to-ground shooting configurations. For the ISL
team, the objectives consisted in measuring the acoustic signals for detection and localization of weapon firing events.
Experimental results of sound localization obtained by using ground based sensors are presented and analyzed under
various conditions.
KEYWORDS: Acoustics, Data fusion, Error analysis, Digital signal processing, Algorithm development, Global Positioning System, Network architectures, 3D modeling, Prototyping, Detection and tracking algorithms
The presence of snipers in modern conflicts leads to high insecurity for the soldiers. In order to improve the soldier's
protection against this threat, the French German Research Institute of Saint-Louis (ISL) has been conducting studies in
the domain of acoustic localization of shots. Mobile antennas mounted on the soldier's helmet were initially used for
real-time detection, classification and localization of sniper shots. It showed good performances in land scenarios, but
also in urban scenarios if the array was in the shot corridor, meaning that the microphones first detect the direct wave and
then the reflections of the Mach and muzzle waves (15% distance estimation error compared to the actual shooter array
distance). Fusing data sent by multiple sensor nodes distributed on the field showed some of the limitations of the
technologies that have been implemented in ISL's demonstrators. Among others, the determination of the arrays'
orientation was not accurate enough, thereby degrading the performance of data fusion.
Some new solutions have been developed in the past year in order to obtain better performance for data fusion.
Asynchronous localization algorithms have been developed and post-processed on data measured in both free-field and
urban environments with acoustic modules on the line of sight of the shooter. These results are presented in the first part
of the paper. The impact of GPS position estimation error is also discussed in the article in order to evaluate the possible
use of those algorithms for real-time processing using mobile acoustic nodes. In the frame of ISL's transverse project
IMOTEP (IMprovement Of optical and acoustical TEchnologies for the Protection), some demonstrators are developed
that will allow real-time asynchronous localization of sniper shots. An embedded detection and classification algorithm
is implemented on wireless acoustic modules that send the relevant information to a central PC. Data fusion is then
processed and the estimated position of the shooter is sent back to the users. A SWIR active imaging system is used for
localization refinement. A built-in DSP is related to the detection/classification tasks for each acoustic module. A GPS
module is used for time difference of arrival and module's position estimation. Wireless communication is supported
using ZigBee technology. These acoustic modules are described in the article and first results of real-time asynchronous
sniper localization using those modules are discussed.
During recent military conflicts, as well as for security interventions, the urban zone has taken a preponderant place.
Studies have been initiated in national and in international programs to stimulate the technical innovations for these
specific scenarios. For example joint field experiments have been organized by the NATO group SET-142 to evaluate
the capability for the detection and localization of snipers, mortars or artillery guns using acoustic devices. Another
important operational need corresponds to the protection of military sites or buildings. In this context, unattended
acoustic and seismic sensors are envisaged to contribute to the survey of specific points by the detection of approaching
enemy soldiers.
This paper describes some measurements done in an anechoic chamber and in free field to characterize typical sounds
generated by the soldier activities (walking, crawling, weapon handling, radio communication, clothing noises...).
Footstep, speech and some specific impulsive sounds are detectable at various distances from the source. Such detection
algorithms may be easily merged with the existing weapon firing detection algorithms to provide a more generic
"battlefield acoustic" early warning system.
Results obtained in various conditions (grassy terrain, gravel path, road, forest) will be presented. A method to
extrapolate the distances of detection has been developed, based on an acoustic propagation model and applied to the
laboratory measurements.
The presence of snipers in modern conflicts leads to high insecurity for the soldiers. In order to improve the soldier's
protection against this threat, the French German Research Institute of Saint-Louis (ISL) initiated studies in the domain
of acoustic localization of shots. Mobile antennas mounted on the soldier's helmet were initially used for real-time
detection, classification and localization of sniper shots. It showed good performances in land scenarios, but also in
urban scenarios if the array was in the shot corridor, meaning that the microphones first detect the direct wave and then
the reflections of the Mach and muzzle waves. As soon as the acoustic arrays were not near to the shot corridor (only
reflections are detected) this solution lost its efficiency and erroneous estimated position were given.
In order to estimate the position of the shooter in every kind of urban scenario, ISL started studying time reversal
techniques. Knowing the position of every reflective object in the environment (buildings, walls, ...) it should be possible
to estimate the position of the shooter. First, a synthetic propagation algorithm has been developed and validated for real
scale applications. It has then been validated for small scale models, allowing us to test our time reversal based
algorithms in our laboratory. In this paper we discuss all the challenges that are induced by the application of sniper
detection using time reversal techniques. We will discuss all the hard points that can be encountered and try to find some
solutions in order to optimize the use of this technique.
The detection and localization of weapon firing on the battlefield is envisaged by means of acoustic waves. The main
objective of this work is to compare various sensing elements that can be integrated in acoustic arrays. Experimental
measurements of sound waves obtained by using some of these elements in Unattended Ground Sensors are presented
for snipers, mortars or artillery guns. The emphasis will be put on the characteristics of the sensing elements needed to
detect and classify the Mach wave generated by a supersonic projectile and the muzzle wave generated by the
combustion of the propulsion powder.
Examples of preliminary prototypes are presented to illustrate our topic. We will concentrate on a wearable system
considered to improve the soldier's awareness of the surrounding threats: this realization consists of a network of three
helmets integrating an acoustic array for the detection and localization of snipers.
The detection and localization of artillery guns on the battlefield is envisaged by means of acoustic and seismic waves.
The main objective of this work is to examine the different frequency ranges usable for the detection of small arms,
mortars, and artillery guns on the same hardware platform. The main stages of this study have consisted of:
data acquisition of the acoustic signals of the different weapons used, signal processing and evaluation of the localization performance for various types of individual arrays, and modeling of the wave propagation in the atmosphere.
The study of the propagation effects on the signatures of these weapons is done by comparing the acoustic signals
measured during various days, at ground level and at the altitude of our aerostat (typically 200 m). Numerical modeling
has also been performed to reinforce the interpretation of the experimental results.
The detection and localization of small fire arms is envisaged by use of acoustic devices. This paper describes the
capability to detect and localize snipers in open field and in urban conditions. This work was performed by ISL and
DGA during various national and NATO trials.
During recent military conflicts, as well as for security interventions, the urban zone has taken a prominent place.
Experimental results measured in free-field conditions, compared with those measured in a village used for military
training, show that the streets and houses can generate many reflections of the original gunshot, requiring new signal
processing techniques to separate each contribution. For this purpose a specific numerical model has been developed.
A few examples of experimental and numerical results obtained for the validation of this methodology will be
presented.
KEYWORDS: Signal detection, Algorithm development, Environmental sensing, Polonium, Sniper detection, Acoustics, Firearms, Detection and tracking algorithms, Signal to noise ratio, Defense and security
The presence of snipers in modern conflicts leads to high insecurity for the soldiers. In order to improve the soldier's
protection against this threat, the French German Institute of Saint-Louis (ISL) and Rheinmetall Defence Electronics
GmbH (RDE) work together under the hospice of the German MOD to develop a helmet integrated acoustic array for
the detection and localization of snipers. This paper summarizes the results obtained during the collaboration between
RDE and the ISL concerning the detection and the localization of the Mach and muzzle waves generated by rifle shots.
It summarizes the technical choices that have been made and explains the algorithms that have been used in October
2006 in Lehnin (proving ground of the German MOD), where some measurements in an urban environment have been
made.
The estimation of the distance between the shooter and the arrays is made with one head equipment alone. In the first
tests that have been made with the algorithms developed in ISL, more than 2000 shots have been detected and localized
successfully in real-time in non-urban environment. No false alarms have been observed. This paper will present the
first results that have been obtained in urban environment.
This paper presents an application implying higher order statistics in source localization. Such techniques have been first introduced in the early 1990’s. Some interesting properties of higher order statistics are exploited in zone survey applications. A large global array constituted by a set of moving sub-arrays (soldiers wearing a Head Equipment (HE) equipped with one or more microphones, a GPS receiver and a magnetometer) allows the localization of the menaces near a survey zone. Studying a large global array, with second order statistics high resolution localization techniques, the local informations are not significant enough in order to have an influence on the estimation of the position of the acoustic sources (for instance, the orientation of the HE has no influence on the estimation of the position of the sources). We expect that the use of higher order statistics and their properties concerning especially the virtual equivalent network (VEN) will improve the significance of these local information and thus, allow to have a better estimation of the source position. A first study has been based on simulations, and then, some results with real data, collected in october 2003, are presented.
KEYWORDS: Sensors, Error analysis, Acoustics, Unattended ground sensors, Interference (communication), Data processing, Data acquisition, Signal processing, Magnetic sensors, Meteorology
This paper presents different ways to process acoustic data in order to localize targets.Beamforming and the MUSIC high resolution method have been tested for different propagation conditions during a NATO experimental campaign. This campaign,organized by DG /DCE/ETBS,has involved 6 countries in October 2002 in Bourges (France). Different localization methods were used to get the position of moving sources on a 4 kilometres circuit.The I.S.L. (French-German research institute of Saint Louis)has deployed a network of arrays nearby the circuit to test those localization techniques in different propagation conditions (day/night,early morning,...).Variance and mean error of the localization are compared for the different techniques used.
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