Sensors, Sentry Owls and smart dust: since the summer of 2002, Sentry Owls have been helping guard US units operating in overseas locations close to Afghanistan.

Sensors, Sentry Owls and smart dust: since the summer of 2002, Sentry Owls have been helping guard US units operating in overseas locations close to Afghanistan. Readers wondering if the Pentagon's latest recruits fly only at night and are rewarded with newly-killed mice can relax--these particular owls are products of Lockheed Martin's famous Skunk Works, and a solution to part of the age-old military problem--short-range surveillance. (Electronic Warfare)

For some high-level commanders, the problem of battlefield surveillance is a task to be handed to a Northrop Grumman E-8 Joint Stars aircraft, a Lockheed Martin U-2 spy plane or even a reconnaissance satellite. Further down the command chain, it's a task for a tactical reconnaissance aircraft or a drone (if such expensive assets are available). But for the frontline commander, the question boils down to asking "What's going on in my area?" and "What can I find out about it using the resources I have?"

In the past, the traditional solution was to send out patrols, often at night--a task that infantrymen loathed. Today, there are technological aids able to examine the local area, giving commanders a good idea of what enemy forces are amassed against them, and what those forces are doing.

The five basic techniques currently in use are:

* short-range ground surveillance radars

* hand-held or tripod-mounted image-intensifiers

* hand-held or tripod-mounted thermal imagers

* integrated sensor packages combining several type of sensor

* remote sensors using acoustic, magnetic or infrared sensing.

There is also a sixth--the use of elint (electronic intelligence) receivers to monitor enemy communications, but this is a specialised subject best left for another article. It is also a technique that is unlikely to provide the immediate answer the commander wants.

This article will look at a few examples of hardware from each of these categories, then survey some of the more promising technologies likely to be used in future surveillance systems, including techniques that are still in the laboratory, or even little more than concepts.

Electromagnetic Eye

Short-range battlefield surveillance radars typically operate in either the I-or J-band. Some are specifically designed to deal only with ground surveillance tasks, while others can be used to detect low-flying aircraft and helicopters, to control artillery and mortar fire or even for sea surveillance. For example, the Alcatel Sel Bor-A 550 can automatically track and classify personnel, wheeled and tracked vehicles and helicopters, as well as naval targets such as inflatable crafts, fishing boats/trawlers, fast patrol craft and even large ships.

These radars are typically mounted on a tripod or similar transportable stand, or even on a dedicated vehicle. Some systems of East European origin are quite large. Russia's Snar-10 (Stanitsiya Nazemnoi Artilleriy Radiolokatsionnaya 10)--known to Nato as `Big Fred'--is carried by a specialised version of the MT-LB tracked chassis, a combination that weighs 12.6 tonnes. Originally thought to be an artillery-location radar, it is now known that it is for battlefield surveillance.

One of the classic designs is the Thales Sensors Man-portable Surveillance and Target Acquisition Radar (Mstar), a 46 kg, 10 to 20 GHz set that has been sold to at least five export customers and was built under licence in Spain, as was the Indra Arine. The latest Mstar 1-10 version was set to transmit either one or ten Watts of RF power, allowing the user to trade a reduction in detection range for greater probability of intercept.

The need for covert operation has been recognised by many manufacturers. The Thales Squire man-portable J-band radar owes its name to the acronym Signaal Quiet Universal Intruder Recognition Equipment. (Signaal is now part of Thales.) This solid-state radar uses frequency-modulated continuous wave techniques to ensure a low probability of interception. The launch order was from the Netherlands, but Thales has reported orders from several customers. In the autumn of 2002, the Polish electronics manufacturer CNPEP Radwar was reported to be negotiating an agreement for the local manufacture of Squire to meet a Polish military requirement.

Future sets are likely to combine active phased array antennas and low probability of intercept (LPI) waveforms. As with larger radars, keeping antenna side lobes as low as possible will make the main beam harder to detect, and thus the overall radar more resistant to countermeasures. The American company Millennium Antenna Corporation has designed, assembled and shipped to an unidentified customer a low side lobe 16 by 59 element battlefield surveillance radar antenna able to operate at 8 to 18 GHz.

Hot Eye

Any pattern of night sight can be pressed into service as a surveillance aid. The British Army plans to use the thermal imager of whatever system it selects as its next light anti-tank missile as a frontline surveillance system, says MBDA, who has teamed with Rafael to offer that latter company's Spike family of missiles. The thermal imager in the Israeli weapon's firing post will have a standby mode so that it does not need to be powered up all the time, and does not require gas bottles for sensor cooling. Detection and recognition are possible at ranges of more than three km, says MBDA.

Elop developed the Artim-LR thermal imaging camera and night sight as an extended-range version of its Artim system. The six kg unit consumes less than 35 W of electrical power and can be used either as a dedicated observation and target-acquisition sensor or as a night sight for anti-aircraft or antitank weapons or for laser designators. It operates in the 8 to 10.5-gm band and uses an integral closed-cycle cooler. Two fields of view are provided--wide (7.3 x 4.5[degrees]) and narrow (2.1 x 1.3[degrees]).

The Flir Systems MilCam Recon operates in the three to five-[micro]m band, and weighs 2.49 kg (including battery). Specifically designed for the surveillance, reconnaissance and target-acquisition roles, it allows the detection of vehicle targets at ranges of more than 6000 metres, and target-recognition out to 3000 metres. As its designation suggests, the eight to nine-gm band MilCam Recon-Qwip uses the latest Quantum Well Infrared Photodetector technology.

Steady Eye

Video is a significant source of imagery for intelligence gathering, battlefield surveillance and targeting. Whether generated by television cameras or night vision systems it can provide the most current information in the field under the full control of the battlefield commander.

However, the field of view of a camera or imager is limited, so the operator must scan the area of terrain that needs to be monitored. This constant motion without geographical context can be disorienting, but the Views video imagery exploitation workstation developed by the National Technology Alliance (NTA) offers a solution. This cots-based system stabilises video input in real time, and merges successive frames of video into a single mosaic image of the area being surveyed. The Views aligns and integrates the contents of contiguous video frames into a unified view that extends far beyond the field of view of the camera. A monitor displays the images, scrolling to show a window of the mosaic containing the newest information.

Mixed Feelings

The L-3 Communications Rembass (Remote Battlefield Acoustic and Seismic System) is a hand-emplaced unattended ground sensor system that also uses magnetic sensors for target detection and classification. The Improved Rembass (I-Rembass) is now giving way to the upgraded Rembass-II, which is half the weight and volume of the earlier system.

Individual sensors can be placed by hand, dropped from aircraft or even delivered by 155 mm artillery shells. Once deployed they remain passive until nearby activity is detected. The alerted sensors detect and classify the target, then transmit that information back to a base station before returning to the passive stage to await a fresh target. If VHF radio line-of-sight is not available, repeaters can be used to receive and retransmit the signal. The sensors are battery-powered and have an operational life of a few weeks

In its latest form, the Rembass II system can detect personnel at a range of 75 metres, wheeled vehicles at 500 and tracked vehicles at 750 metres. Because the Rembass sensors cannot differentiate between friendly or enemy movement, the system needs to be deployed ahead of friendly forces, so that all activations will be due to enemy activity.

The Rembass was used by US forces during Operation Joint Guard in Bosnia-Herzegovina. Lacking the manpower needed to monitor all the areas of tactical significance, the American task force deployed the Rembass around the areas of major concern, in many cases planting sensors in heavily mined areas. These sensors created a virtual `tripwire' that detected nighttime activities such as personnel movements along trails or routes.

More recently, the I-Rembass was used to protect world leaders attending the annual G-8 Conference held in Alberta, Canada, between 26 and 27 June, 2002. The 1st Regiment Royal Canadian Horse Artillery successfully deployed and operated the system around a defensive perimeter to provide security for those attending the conference.

The Thales Defence Communications Classic 2000 (RGS 2740) ground sensor system is the result of a similar evolutionary process, being based on the earlier Racal (now Thales) Classic (Covert Local Area Sensor System for Intruder Classification). A Classic 2000 system is made up of an RA 4310 monitor unit and a network of TA 4312 (seismic/infrared) and TA 4314 (magnetic/infrared) sensors. The TA 4312 can be equipped with a geophone, a piezo cable, short-, medium- or long-range infrared detectors, trip wires and pressure pads. A Classic 2000 system can detect and classify targets and provide an indication of direction, using its different sensors and signal-processing algorithms to minimise false alerts. The distance between sensors and the monitor unit can be extended by the RTA 4311 relay unit.

Something that will undoubtedly improve a commander's life in terms of precise information on the current state of affairs on the battlefield is the mobile Tac CP command post recently introduced with the US Army's III corps. Carried by a Hummer, the system essentially hinges on View video processors produced by RGB Spectrum which are fed from a variety of sources and battlefield sensors described here or even from drones on the battlefield as well as from video conferencing systems. The View processors can thus display those inputs in multiple windows on two plasma screens and a 100-inch rear-projection screen. The multiple display facility, of course, allows one to simultaneously examine different images obtained from remote locations and to set up video conference sessions.

Dahleks

There are two major components to the Terrain Commander System offered by Textron Systems. The Field Deployable Equipment (FDE), and the Central Monitoring Facility (CMF) where a single operator in a secure location can easily monitor a large number of remote surveillance sites simultaneously.

The man-portable Optical Acoustic Satcom Integrated Sensor (Oasis) is the eyes and ears of the system. The Oasis consists of extended range acoustic sensors and signal processing, day/night electro-optics and satellite-based global communication hardware. All of its components fit into an oversized backpack and the unit can be assembled by one person and brought online fully operational within minutes.

The acoustic sensors detect and classify a variety of intruders, including ground vehicles, watercraft and rotary and fixed-wing aircraft. The sophistication of these sensors and the system's digital signal processing capabilities enable the Oasis to identify acoustic signatures and to differentiate between predetermined threats and unimportant activity at the surveillance site.

If a threat is detected, the electrooptical system automatically pans to the target bearing, captures a series of images, which are processed and compressed using proprietary technology, then transmitted via satellite to the CMF. Communications with the CMF can be via civil Comsat systems such as GlobalStar and Iridium, or via a 200 to 400 MHz low-probability of intercept datalink.

The Oasis unit also functions as the receiving and central processing unit for an integrated array of distributed sensors. These can be customised to meet the needs of specific surveillance operations, and can include seismic, magnetic, piezoelectric and passive infrared sensors. If necessary, the Oasis can be further customised by integrating a variety of special use sensors including meteorological, nuclear, chemical and biological detectors.

The Terrain Commander has been demonstrated to the US Army and US Air Force at Aberdeen Proving Ground, Lackland Air Force Base, Fort Belvoir and Fort Huachuca. It has been selected by the Australian Defence Materiel Organisation (DMO) to meet that nation's requirement for an Unattended Ground Sensor (UGS) system as part of the Project Ninox ground-based surveillance programme.

Many countries face the threat of irregular forces such as guerrillas or terrorists penetrating their borders. For them, the task of battlefield surveillance includes border surveillance. Typical examples are Israel, which is potentially vulnerable along most of its borders, and India, which faces the problem of insurgents crossing the Line of Control in the Kargil region.

India has tested an unidentified Israeli sensor system, apparently a network of detectors linked to a central monitoring point by cable links. According to local press reports the system gave poor results, generating many false alarms.

India's Electronics and Radar Development Establishment has recently developed a portable short range Battlefield Surveillance Radar (BFSR) to meet an Indian Army requirement triggered by the Kargil conflict. Development seems to have been swift and the new radar is expected to enter service in the winter of 2002/3.

A Mind of its Own

Some manufacturers offer small ground surveillance radars specifically designed for anti-intruder operations. Once example is IAI's EL/M-2128 Minder (Miniature Detection Radar). Weighing less than five kg, this small I/J-band radar can be installed along a fence, or on poles, in order to secure an area, sending an alarm to a central control station when an intrusion occurs. It can also be mounted in a light vehicle such as a Jeep and used whenever the vehicle is not moving. It covers a 120o sector in azimuth, detecting personnel at a range of 500 metres and vehicles at 1000 metres.

One trend gathering momentum is to combine several sensor types into a single integrated system. One example is General Dynamics Canada's All-Weather Multi-Spectral Surveillance System, which is an integrated ground-based sensor package combining a Kuband pulse-Doppler radar, a continuous-zoom day/night high-resolution TV camera, an eight to twelve-micron thermal imager with wide and narrow fields of view and an Erbium glass eye-safe laser rangefinder. This hardware is mounted on an azimuth/elevation platform offering remote control pan/tilt capability for 360-degree surveillance and precise control for laser range-finding at long range. The remotely located operator station is based on a VME computer and incorporates a high-resolution monochrome monitor and a video recorder.

The American company Remote-Reality is currently working with security system specialists McQ Associates to develop an advanced battlefield surveillance system for the US Army and Marine Corps. Known as the Ovets (OmniSense Visually Enhanced Tracking System), it will combine 360-degree visual, infrared, audio, seismic and magnetic sensors. RemoteReality is developing specially designed optics that will integrate with a thermal infrared imager, providing a full 360-degree field of view and allowing the automated location, tracking and enhancement of contacts that radiate heat.

Conducted under the American Department of Defence's Small Business Innovation Research (Sbir) programme, the' Ovets is intended to demonstrate a sensor's ability to detect, locate, track and classify targets, the integration of target data with a communications network and presentation of the information and 360-degree imagery on a map-based Situational Awareness Display at a command post. Four prototypes are due to be field-tested by the end of 2002.

Integrated sensors can be vehicle-mounted to create a mobile all-weather surveillance tool, a concept that is attracting a number of manufacturers. For example, the Modular Armoured Reconnaissance and Surveillance Vehicle (Mars-V), produced by the Turkish company Aselsan, teams a ground surveillance radar second-generation thermal imager and a daylight television system. These are fitted on an elevating mechanism carried by a 4 x 4 armoured vehicle.

Volatile Minds

One snag with fighting terrorism is that the terrorist recognises no fixed front line; he or she may bring war to your doorstep. That's the problem which American forces positioned at locations around the periphery of Afghanistan have faced for over a year. Just over the hill from their temporary air base may be a terrorist armed with an Igla or Stinger missile and determined to down an American aircraft. If there isn't one today, perhaps there will be one tomorrow, and if you catch one, how soon will it be before another takes his place?

The classic solution is to patrol the surrounding area as intensively as is necessary to keep it threat-free, but that approach needs infantrymen, vehicles or even helicopters. However, as the US Department of Defense has learned, temporary operating locations on the other side of the world from your homeland are at the end of a very long logistic `tail'. Every extra soldier or technician you deploy there puts additional strain on the logistics chain.

The solution devised by Lockheed Martin's famous Skunk Works in Palmdale, California, was a ten-pound drone that can be catapulted into flight with elastic cords; flying at altitudes of 300 to 500 feet and sending back real-time overhead video images. It entered operational service this summer.

Each deployed system consists of a ground control station--a computer, displays, a recorder and communications equipment; six aircraft, a remote imagery viewing terminal and interchangeable payloads of colour cameras and thermal imagers for day and night time imagery. The system uses cots equipment wherever possible. The airframe is manufactured from damage-resistant moulded material and is designed for limited field repair. Powered by rechargeable batteries, it has an endurance of one hour. It does not need a runway, but can operate from a 100-metre by 100-metre clearing. The Sentry Owl can be pre-programmed for autonomous missions and reprogrammed in flight or remotely controlled by two operators via a laptop computer. It can therefore be diverted to quickly monitor an area of concern.

Lockheed Martin named the system the Sentry Owl Force, but the programme's official designation is the Force Protection Airborne Surveillance System. It was later dubbed Desert Hawk by Lt General T Michael Moseley, Commander, 9th Air Force and US Central Command Air Forces,

The US Marines are in the process of developing a similar drone known as the Dragon Eye; the two services are looking to collaborate on the payload sensors, autopilot and the software--elements that account for half the cost of the system.

In 2001, Systems Planning & Analysis in America began a study of a mortar-launched, lighter-than-air recoverable sensor system known as the Moltar. Intended to provide US military ground forces with greater battlefield situational awareness, the system would be fired from a standard 60 mm mortar and have a cruise and loiter capability of at least two hours before returning to the launch site for retrieval.

Tomorrow's Mini

Coughing can result from having a cold. In the future it could be a result of having accidentally breathed in an enemy surveillance sensor!

Under a project known as Smart Dust, a team at the University of California at Berkeley hopes to create micro-miniature devices no bigger than one-millimetre cubes, yet equipped with sensors, a computer, an optical communication system and a power supply. Each of these `motes' would be able to communicate with other motes and with conventional computers.

The project is being funded by the US Defense Advanced Research Projects Agency (Darpa), and potential applications include the creation of sensor networks for battlefield surveillance, treaty monitoring, transportation monitoring or even Scud hunting. On tomorrow's battlefield, it may be `Microscopic Brother' who is watching you, rather than the `Big Brother' predicted by George Orwell.