Locate and Strike -- Aiming the Guns.

Over the centuries gunners have been asking two basic questions as they go into action -- 'Where exactly am I?' and 'Where is the target?' In the old black powder days bath questions were easily answered as the ranges involved were close enough for the two sides involved to see each other, therefore there were no great problems that the direct vision human eyeball could not cope with. But after 1914 those days were over.

With current artillery projectile and rocket ranges now reaching out to 50 km (and even further in prospect) the two basic questions continue to be asked, although meaningful answers now demand some complex solutions.

Today, three electronics-based systems form the main answers to the gunners' basic questions. One is the Global Positioning System (GPS) and another the electronic computer. These first two are common to many military systems but a relative novelty for the gunner is the third item, the ring laser gyro. Exactly how all these three can be combined to deliver accurate data for long range artillery fire of all types will be outlined below.

Where am I?

Land forces, including the artillery, have come to rely heavily on GPS for just about every aspect of land navigation. GPS satellites now encircle the globe in such numbers that it seems there is no place on Earth where they cannot be accessed by all and sundry to provide a geographical location fix accurate enough for most purposes. However, too much reliance on GPS brings in its train some potential hazards.

One is that the gunner relies on precise location data to provide accurate fire. While artillery can still dominate any battlefield, the battlefield has become a much more dangerous environment for the gunner, even if they are protected under armour on self-propelled systems. Artillery location radars, such as the US Army's AN/TPQ-36(V) Firefinder (now a Raytheon Electronic Systems responsibility), can immediately detect when a battery, or even an individual gun or mortar, opens fire. Computing and presenting a precise ground location for counter-battery activity takes only seconds following that initial detection. Artillery, even when towed, therefore has to resort to `shoot and scoot' tactics to survive. Hence it becomes paramount that the first rounds despatched are effectively on target. The times needed for the former fire correction procedures are no longer available. It therefore follows that that the gunner has to be provided with accurate gun location data to deliver accurate fire.

This self-location factor remains equally important even during low-key operations where the chances of retaliation against artillery missions are low, such as those recently undertaken in the Balkans. Rounds that miss the target are then more likely to create collateral damage and casualties of the wrong sort, so the need for overall artillery accuracy remains paramount.

While GPS normally provides location data good enough for casual users such as yacht owners, gunners need something more accurate. They therefore employ limited access GPS codes that can deliver very precise fixes, so precise that it would seem to preclude the need for any other artillery navigation or survey systems. But it would be dangerous to rely on GPS indefinitely. In time of war, access to GPS satellite data could become very difficult if not impossible. Frequencies could be jammed or important codes garbled by the opposition who would no doubt do their utmost to eliminate GPS satellites entirely during the opening stages of what could become Star Wars. The possibilities of such actions are high, so total reliance on GPS during future conflicts would be most foolhardy.

This is one reason why the ancient skills of military map reading continue to absorb so much training time, but translating map details into terrain features in the dark or during fast-moving mechanised night operations can create unlimited navigation problems, as any who have attempted such activities will already know. The need has therefore been often stated for autonomous, reliable and highly accurate land navigation systems that can be installed on a gun carriage.

Such systems do now exist and are entering artillery service in increasing numbers. Most of them continue to integrate GPS data to monitor and confirm the base system's accuracy, but the systems have to be able to operate without such external inputs should the need arise. These systems rely on what is known as the ring laser gyro, equipment once only found on aircraft navigation and missile control systems but now adapted for land use.

In over-simplified terms, the ring laser gyro relies on the accuracy of a number of laser beams impinging on sensors. While the laser beams provide a constant and stable reference, any deviation of the sensors caused by the platform to which the ring laser gyro is attached will create an analogue or digital response directly related to the speed and angle of movement. Also involved is an odometer integrated into a wheel hub to add distance information for correlations. All responses are then processed through computers that translate those movements into a visual presentation form of co-ordinates that can be interpreted and used by a gunner.

Once accurate location co-ordinates have been entered into a ring laser gyro system, culled from any available means, from manual artillery survey, GPS or whatever, any subsequent movements will generate precise details of the degree of platform movement away from the data input point. This will include movement across country or roads, up or down slopes and so on. It follows that the aiming direction and elevation angle of an artillery barrel or rocket launcher can be similarly monitored for data processing. Combining barrel pointing data with platform data (i.e. the towed gun or self-propelled carriage) can then provide the gunner with all the location and aiming data he is likely to require. This capability to combine land navigation with gun barrel aiming is a prominent feature of the equipment now in the supply pipeline for future artillery systems.

The ring laser gyro can therefore offer much and its attributes are now in the process of being adopted by the artillery divisions of several armed forces. Some are already in service, but as yet the scale is limited and most current systems are being offered more as retrofit options rather than being built into an artillery system from the outset, unless the example of the US Army's troubled XM2001/XM2002 Crusader programme is exempted. Thanks to the wonders of miniaturised electronics, ring laser gyros are relatively small and light at about ten kilograms, their technological wonders confined within visually unexciting black boxes. The barrel pointing display units present data to the gun layer from the same location on the gun carriage where the panoramic sight once used to be, for once a ring laser gyro system is installed the old laying methods and accessories become redundant (although they are often held as reserves in the case of unforeseen troubles). The navigation display unit is usually located close to the driver involved, either in the tractor cab or in the self-propelled platform driving compartment.

There is one further advantage for these updated gun laying (or gun pointing as an alternative term) systems in that they can be directly interfaced with fire control systems. Once a fire control computer has calculated the correct direction and angle at which a barrel has to be placed for any particular fire mission, they can be presented to the layer on the gun to make the necessary adjustments. However, even this interface can be eliminated by the fire control system directly controlling the barrel pointing mechanisms. On most existing artillery pieces, including self-propelled carriages, adjustments for azimuth and elevation still have to be carried out separately using manual or hydraulic drives. On the latest generation of turrets with electrical drives (such as the BAE Systems, RO Defence AS90) the two actions can be carried out simultaneously and at great speed, the gun layer still performing an important function by monitoring the process.

To continue this digital control process still further, the enhanced fire control systems can be readily interfaced with the huge number of digitised command control and communication ([C.sup.3]) systems now proliferating within many armed forces.

Examples of ring laser gyro-based systems are limited at present, but one can be quoted. It is a British system known as Linaps (Laser Inertial Automatic Pointing System) due to be retrofitted to the Royal Artillery's 105 mm L118 light guns within the next few years. Marketed as a BAE Systems Avionics product, the Linaps, in common with other similar systems, considerably reduces the time taken to get a gun into action once it arrives at a firing position, while allowing aiming changes to be carried out on the gun more rapidly and accurately. One great time saver is there is no need to carry out the involved artillery survey procedures that once had to be completed before firing could commence (although once again it would be unwise to neglect the associated skills).

The background to the Linaps is interesting as it had part of its origins in South Africa, where it has been applied to both towed and self-propelled artillery systems. It was developed jointly by the Kentron division of Denel and what was then GEC-Marconi (now part of BAE Systems Avionics). They based their system around the Marconi FIN 3110 Ring Laser Gyroscope, combining it with a rugged control and display unit originally devised for the Kentron Arachnida weapon management system. This joint project was originally designed as an add-on option for the 24 Denel/LIW 155 mm G6 self-propelled guns sold to Oman. It is now offered as an option for the Denel/LIW 155 mm G5 Mk 3 towed gun and has been trialled with the 127 mm Valkiri artillery rocket system.

One land navigation system without a gun pointing function is used on the Giat Industries Caesar 155 mm wheeled self-propelled gun. Mounted on the gun itself is a Sagem Sigma 30 onboard reference package/position data system that enables the gun to come into action without prior survey. If required, this could be combined with a gun laying system. The Caesar navigation system also has an embedded GPS capability. The 227 mm Multiple Launch Rocket System (MLRS), one of the most widely deployed of all artillery rocket systems, has a similar reference package/position data system.

A further example of land navigation and gun laying systems is the Israel Aircraft Industries, Tamam Division, Advanced Modular Azimuth Position System (Amaps). Designed as an artillery modernisation package, the Amaps forms the basis of the Vehicle Gun Laying and Positioning System (VGLPS) which can be utilised either on board a self-propelled artillery platform or deployed in a forward observation position (see below). VGLPS is completely autonomous and can be employed for many artillery roles as it incorporates a laser rangefinder.

Where is the Target?

Today's gunners rarely see their targets. If they can it is usually a sign that something has gone seriously wrong. Indirect fire almost always has to rely on an observer remote from the gun position to detect and categorise targets, and for observation of the fall of shot to judge the effectiveness of the fire mission. It is technically possible to carry out fire missions `off the map' but these are few and far between, apart from set-piece barrages or nuisance fire. At most other times the battery fire will be directed by a forward observer close to the forward edge of battle and communicating to the gun position by radio.

The classic image of the artillery forward observer is of an individual or team concealed in a trench or behind cover and observing a wide area through binoculars. That image still holds true but these days the binoculars are only one item employed. In addition, in many cases the forward observer is now mobile, carrying out the observation duties from a vehicle or even a helicopter. Mechanised warfare dictates that the artillery has to keep up with the leading armoured formations. While the guns may be deployed some way behind the forward combat contact line they still need observers to find targets and direct fire.

Within mechanised formations special forward observation vehicles have evolved. The vehicles differ little in appearance from other armoured support vehicles, such as armoured personnel carriers, and are almost always specialised variants. This makes logistics a bit easier, but the main reason is that the observers specialised functions must not be apparent to an enemy as that would invite unwanted attentions.

For instance, the British Army's Royal Artillery fields 52 examples of a special version of the Alvis Vehicles (formerly GKN) Warrior infantry combat vehicle known as the Observation Post Warrior. This is visually identical to the basic Warrior combat vehicle (apart from extra radio aerials invisible from even a few metres away) but the usual 30 mm Rarden cannon barrel is a dummy. There is no main armament as the interior of the turret is occupied by specialised observation equipment, map tables, extra radios and other special-to-role equipment. The Observation Post Warrior can then merge easily with other Warriors without attracting special notice. Similarly disposed vehicles are deployed by many other armed forces, the M113 probably being the most numerous example.

On artillery observation vehicles the observer can mount his array of observation devices (widely known as the `Christmas Tree') on the vehicle hull or turret roof but they can also be dismounted for ground use. Within many infantry formations the latter will be the usual method of working. The various observation devices are usually mounted on a small tripod for they could be heavy to hold steady for prolonged periods and the stability imparted by the tripod assists accurate observation and instrument alignment.

The devices involved in the forward observation process can be many and various. One basic necessity is a method of aligning the forward observer's systems with those of the gun position. The most commonly used method of doing this is by a north-seeking module. This is not a technical term for a magnetic compass, for north-seeking modules rely on electronics to provide a north indication accurate to within one milliradian, far better than could be accomplished by the most refined magnetic compass that could always be deflected by nearby metal objects such as vehicles. This north indication is used to align all the other instruments used to observe targets.

The exact position of the observer also has to be known. There are numerous methods of doing this, from plain map reading to GPS, if it is accessible. At all times recourse could be made to local survey using some of the instruments involved in observation.

There are many levels of target acquisition systems, from the unadorned eyeball up to computer-based systems on which all the observer has to do is aim the instruments and press a button. To illustrate this point a description of the Azimuth Technologies Atlas light target acquisition system will serve. This is a portable system weighing 12 kg complete, primarily intended for operation by ground-based observers but capable of being used from a vehicle. It is in service with the Israel Defence Forces.

The system is tripod-mounted with an electronic north-seeking device. The tripod carries a platform for vision or other devices. These could include binoculars, a night vision device, a thermal imager or even a video camera. Adjusting the vision table to point at the required target results in the system providing all the azimuth and elevation information necessary, relative to the observer's position. Moving targets can be tracked automatically under computer control. A laser rangefinder is also part of the overall package.

All the relevant target data is displayed on a small screen close to a keyboard, with the keyboard being used to control the system and enter messages or data corrections; all operations are menu-prompted. The Azimuth Technologies system has its own modem-style communications package, so pressing a button on the keyboard will transmit a short burst of digital data in preset message form to the battery command centre. It is also possible to use the modem to transmit voice messages, while GPS is another option, either embedded in the system or as an add-on, hand-held unit.

A further example of a less involved observation instrument can be given with the Light, a modular-add-on device also from Azimuth Technologies. In this case the Light module is secured to a hand-held set of laser rangefinder binoculars. Operating the laser rangefinder against a target produces the usual range data and also results in the Light module presenting the user with electronically computed azimuth angle and target co-ordinates. The Light is based around GPS technology and provides an example of how simple and easy-to-use some of the modern target acquisition systems can be. The laser rangefinder binoculars could be of several types, one of the most widespread now being the Swiss Leica Vektor family of models.

Remote

One of the main drawbacks regarding the use of forward observers to obtain target data, apart from their general vulnerability, is that their operations are limited by what they can see and that they can rarely operate further forward than the forward edge of the battlefield. This may severely limit exactly what long-range artillery can achieve unless unique measures such as special forces personnel become involved. Small teams may be able to operate deep behind an enemy's rear line and under certain circumstances following a withdrawal, left-behind teams may be concealed within good vantage points to act as rear area observers once the enemy front formations have passed. But these are extreme measures, expensive in personnel and resources.

One way to observe what is happening in the enemy's rear areas is to introduce remotely-piloted aerial platforms equipped with real time sensors such as stabilised video cameras or thermal imagers that can transmit pictures to a command station close to a high-level command centre. This is too wide-ranging a subject to examine in detail here other than what the future may hold.

For many artillery commanders the remotely-piloted vehicle is too far removed from their control. While they welcome the data aerial platforms can provide they rarely have direct control of when and where the platform may be operating. There will always be instances when some form of rapid response is required or target confirmation that may be necessary. By the time an aerial platform is despatched that fleeting moment may be long past. Battery commanders want something more immediate under their direct control.

It has been proposed that gunners already have under their direct control a means of delivering observation devices to considerable ranges. This involves the projectiles they fire. In-service projectiles can already carry complex and delicate loads ranging from illumination flare bodies to electronic devices such as communication jammers. It takes very little to extend the loads to miniature video cameras to be ejected from the projectile body high over an area selected for surveillance, under the control of a time fuze. The camera could then descend to the ground suspended under a parachute or perhaps some form of para-glider wing body. Electronic techniques are already available to stabilise the camera to provide a clear and sharp image and it may even be possible to steer the lens in any required direction to automatically track a selected object. This technique could be extended to night vision devices or thermal imagers for operations in poor or limited visibility.

Although no such gun-delivered area surveillance system has yet been officially adopted, several nations are known to be developing them. One associated and generally similar system is known to have been marketed already, although it is somewhat removed from the gun projectile system outlined. It is a development from the State Research and Production Enterprise Splav at Tula in Russia.

Splav developed one of the 300 mm rockets used in the Smerch (Whirlwind) long range artillery rocket system to carry what is described as an unmanned air vehicle. Known as the R-90, it is carried inside a Smerch rocket nose cone to be launched while the rocket is still in flight. A parachute is deployed when the R-90 wing and tail surfaces unfold and a pulse jet engine starts to provide thrust. Using GPS data to navigate along or around a pre-set flight pattern, the R-90 is then able to remain over a target area for about 30 minutes at a height of up to 9000 metres. During its flight the R-90 uses a stabilised nose-mounted camera to transmit images and geographical coordinates of the scene below to a control station up to 70 km away. The R-90 weighs a mere 45 kg. Its exact status is still not certain but it has been offered for export sales.

One further artillery-orientated target surveillance system is known to have been under consideration in France in the recent past. Part of the investigations were carried out by Giat and several national research centres, concentrated around mounting a side-looking video camera in the wall of a 155 mm artillery projectile. The intention was that the spin of the projectile would enable the camera to create a continuous image strip of sky and ground to be transmitted to a ground station, using the projectile body as the transmitter antenna. Computers in the ground station would then unscramble and format the images to produce and record only the strip of ground images for later detailed examination. Again, exactly what has happened to this intriguing programme is uncertain, although its mention provides but one example of the direction that future artillery observation systems might soon follow.

Answering the gunners' two eternal questions does indeed result in some complex solutions.

In short

* "For artillery gun crews, speed of action and immediate accuracy are a sine qua non"

* "This requires GPS (and its shortcomings), laser gyros and north-seeking systems"

* "Drones are do not always prove a panacea"

* "Some nations, such as France and Russia, are known to be working on smart alternative solutions."