GB2186351A - Combat simulation - Google Patents

Abstract

A combat simulation training and assessment system comprising a plurality of static beacons B which, in use, are distributed on a battlefield for a plurality of combat mobile units M to interact therewith, whereby the positions of the mobile units M can be automatically determined at various times during a simulated combat, dedicated means for transmitting beacon determined positions of mobile units M to a command data processing unit C. Combatant estimates of positions of hostile mobile units M and artillery aim estimates are also transmitted to the command data processing unit C, being programmed to compare the estimate data with automatically- determined positions of relevant mobile units M and to indicate the comparisons to the relevant combatants. <IMAGE>

Description

SPECIFICATION Combat simulation This invention relates to a combat simulation training and assessment system fortroops to gain battlefield experience under conditions as realistic as possible but with a cost lower than that which is inherent when live ammunition has to be used.

With the advent of modern electronic data processing apparatus and control systems it has become an accepted tenet that simulation is an advantageous wayoftraining in a variety oftechnological environ ments. The most widely know type oftraining simulation is probablythat used by airlines for training pilots to handle large modern aircraft. The bulk of the training can be carried outin complete safety on the ground with a considerable reduction in cost compared to real flying training. The principle of simulatortraining is being extended to other fields, e.g. a recent development is a simulatorfor automobile drivers.

However, simulators such as those for aircraft or automobilesareinherentlyfortraining one (the pilot ordriver) or at most a small number (one aircraft crew) in relative isolation. Military training of land troops involves considerable numbers oftrainees and cannot be performed in an isolated environment. Rather it requires movement oftroops in large numbers over extensive areas ofterrain.

The modern army is already equipped with a variety of electronic aids in the communications, navigation and weapons fields. Mobile radio enables quick, secure and reliable communication between troops on the battlefield and a remote headquarters. Various position fixing systems are available, including DME and radar based systems. Likewise a variety of computers are availablefor data logging and processing operations.

According to the present invention there is provided a combat simulation training and assessment system comprising a plurality of static beaconswhich, in use, are distributed on a battlefield for a plurality of combat mobile unitsto interacttherewith,wherebuthe positions ofthe mobile units can be automatically determined at various times during a simulated combat, dedicated means for transmitting beacon determined positions of mobile units to a command data processing unitto which combatant estimates of positions of hostile mobile units and artillery aim estimates are also transmitted to the command data processing unit being programmed to compare the estimate data with automatical ly-determined positions of relevant mobile units and to indicate the comparisons to the relevant combatants.

The term "mobile unit" defines a radio equipment mounted on a vehicle or carried by an individual combatant.

The term "beacon" defines a radio equipment suitablefor mounting at a high elevation point on the battletielci.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which Fig. 1 illustrates schematically the deployment of fixed beacons, mobile units and command data processing unit in a battlefield simulation, and Fig. 2 is a simplified diagram showing schematically components of a beacon system for position determination.

It is envisaged a 'battle' to be assessed takes place between two opposing forces referred to as force A andforce B.

Force A comprises tanks, foot patrols and a mixture of other units with varying vulnerability.

Force B comprises a similar but not necessarily an identical group and incorporates a forward observer.

The forward observer is capable of communicating by voice radio with the rest of his own force and it is assumed the opposing force cannot listen to those voice exchanges.

The system design shall enablethefollowing: (a) The forward observer in force B to gain experience in assessing the position of force A units relative to some previously identified grid and to guide his own guns to 'kill' those units in the most effective way using verbal instruction transmitted by radio.

(b) The guns of force B to gain experience in interpreting the above instructions and use them to adjustthe guns so asto achieve maximum 'kill'.

(c) The units offorce Ato gain experience in avoiding the oncoming shell fire in the most effective way while at the same time estimating the gun locationsfrom which they originate and thus seek to silence or suppress them as appropriate.

(d) The units of force Bto gain experience in making it as difficutas possible forforce Ato estimatetheir position.

(e) It shall be possible to incorporate simulation of minefields,thusdetectingwhethera unithastrig- gered a simulation mine, evaluate the extent of damage done and signal accordingly.

The system is to be designed to incorporate an element of protection against cheating.

A means is to be incorporated whereby officers separate from the participating units can monitor the progress ofthe battle and so influence the experience- gaining-process as wetl as evaluating how different personnel respond tb different situations.

The system isto incorporate comprehensive automatic data logging facilities so the battle can be studied afterwards, thus giving maximumopportuni- ties for the various participants to learn from their mistakes.

The system comprises the foílowing: - (a) A precision position determination system by means of which the simulator knowsthe actual position of as many ofthe participants as is deemed necessary.

(b) A communication system by which the forward observer communicates to his own force his visual impression ofthe position of his targets.

(c) Sensors which determine the alignment in azimuth and elevation of the gun barrels.

(d) A computer which calculates the landing posi tion ofthe various 'shells' based on information from (c) above plus data on the type of shell manually input plus relevant meteorological data input manually or automatic plus knowledge ofthe land contours and elevation.

(e) A computerwhich compares the estimated 'shell' landing position with the known actual position ofthe various participants and which computes 'kills' and 'immobilisation'.

(f) A data communication system which informs the participants and the umpire about where 'shells' landed and the effect.

(g) Acomponentwhich provideseitherforcewith selected and umpire controlled data on part ofthe shell trajectories to give participants an opportunity to estimate the position ofthe opposition.

(h) A store in which all developments are dumped forsubsequent post-battle analysis and play back.

Central to the entire assessment system is the position determination system. It isthis part of the assessment system which enables both hit/missto be calculated and which enables data logging and subsequent analysis to be performed and which enables the minefield effects to be simulated.

Such position determination systems may be designed according to four basictechniques:- (i) theta-theta systems In these, position is determined by measuring the angle to or from several reference points with known location. This technique is employed in marine DF systems for coastal navigation and inaircraft naviga- tion using VORNOR. (VOR is an internationally agreed radio navigation system provided bearing atVHFthe name derived from VHF Omnidirectional Ranging).

(ii) rho-rho systems In these, position is determined by measuring the distanceto or from several reference points with known location. The technique is used in some survey systems and increasingly in aviation using DME/DME.

(DME is an internationally agreed radio navigation system, the name derived from Distance Measuring Equipment, operating at UHF).

(iii) rho-theta systems This is the basis of most radar systems which determine the range and azimuth angle between radar and target.

(iv) range difference systems Here a mobile determines the difference between its range to two fixed points and so determine a hyperbola as in LORAN-Cforcoastal navigation and in Omegaforworldwide navigation. Aderivative is TRANSIT the U.S. navigation system where distance difference is worked out over a period of time from Doppler measurments.

Thus a wide choice oftechniques is availableto suit the operating environmentandto meetthe relevant specification.

Forthe battlefield application a rho-rho type solution is particularly suitable on account ofthe severe multipath likelyto exist and because it does not require any azimuthal directivity, baseline or alignment. Simple antenna types will therefore suffice both atthe mobile and atthefixed beacon position.

The most common rho-rho system is the DME system which operates at 1 GHz, provides range up to 200 nautical miles and an accuracy of +0.2 to 0.5 nautical miles. Such systems have been in use around the world for many years and each DME beacon can provide continuous range information for several hundred mobiles simultaneously. Itisthussimllarto a busy battlefield environment with many array units operating simultaneously. Such a DME system would have reduced rangeatground level due in part to elevational polar diagram and in part to obstructions since it would be line ofsightonly.

The system would also need to be adapted to provide enhanced range accuracy. This can be achieved by sharper ieading edges to the system pulses and by satisfying the greater bandwidth requirmentsthrough a higher carrierfrequency.

C-band and X-band should enable this to be achieved.

An alternative to sharper pulses is to use a type of spread spectrum, which is also capable of providing higher resolution through its wider bandwidth.

In airborne DME systems the aircraft initiates the operation by sending a pulse pair to a ground station which responds with a different pulse pair. The aircraft calculates range by measuring the two-way delay when it receives the reply. In Secondary Surveillance Systems (SSR) a ground station initiates the operation and the aircraft replies, the ground station performing the calculation. Forthe battlefield application it is preferable for the beacon to initiate the operation and dothecalculation.Thusthe mobiles have minimal equipment of precision type, locating the main part of the precision gear at the fixed positions.

In a very busy battlefield one may then envisage several hundred mobile units M (Fig. 1) of minimal complexity, tens of fixed beacons B with some greater complexity and one ortwo command stations C calculating positions of each mobile unit. Mobile identity could be by PRF coding or by time position in a TDMX sequence or by pulse interval in a pulse pair coding or by code in a spread spectrum type of approach.

Since there will be both a high number of mobiles and extensive azimuthal multipath itis envisaged that a TDM structure may be useful. The one second basic period is divided into 500 groups, each having 4 slots at 500 us. Each mobile is assigned a unique address and is allocated the corresponding group oftime slots.

During this group it is interrogated by 4 beacons, one per time slot. Thus at any one time only one mobile is spoken to.

The command station has atwo way radio linkfor data exchange with every beacon. In view of the size of the battlefield this may have to be H.F. It is assumed standard military communication equipment may be usedwith an adaptorto enable data to be exchanged.

The control station does not communicate with the mobile units.

The beacon communicates with mobile units using a two-way microwave system, possibly at L-band.

This is used both for navigation and communication.

The particular mobiles which a particular beacon communicates which is determined by the control station, on a trial and error basis. Thus the control station, may say to beacon "F"-'Try interrogating mobile "N" - you succeed give me his range from yourself on a regular basis, when you lose contact let me know'.

A microprocessor based store (Fig. 2) in the beacon contains a list of - the unique address of all mobiles which it is to interrogate and the time slot which is to be used - any data which is to be sent to that mobile in its next slot. Examples of such data are: "you have been hit" or "you had a near miss bearing 170" at range 200 metres".

- the last measured rangetothatmobile - the quality ofthe signal from the mobile including any acknowledgement of messages received (I know I have been immobilised).

Periodicallythe beacon is advised to add to its list new mobiles to be interrogated. When the beacon communicates to the control station it will give range to all mobiles it has interrogated along with the quality ofthe radio link. Thuswhen a tankmoves such that a hill obstructs the radio path between beacon and mobile, the signal quality will deteriorate until it is no longer useful. The control station deletes that mobile from the list held by the beacon and transfers the mobiletothelistofa nearby beacon.

Assume maximum rangefor any beacon to mobile to by 5km. The go and return propagation delay is 5000 x 2 x 3.3 (feet = nS) x 10-3 I1S = us. Since500 usis available per beacon-mobile pair there should be some room for repeats and averaging. Average range is probably much less. If positional accuracy must be say 5 metres the pulse duration must be ofthe order of 10-20 nS.

For most cases mobile position is determined using 2 beacons, having 4 slots enable ambiguity to be resolved and enables one ortwo slots to be used to search for new beacon-mobile pairs when one link quality decays.

Forthe HF data links beacon to control we need to send every second for each mobile on its list -- unique address 1 in 500 say 9 bits - range 1 m in 5000 m 13 bits quality and acknowledgements 3 bits - error checking correction say 5 bits 30 bits If 100 mobiles are on the listthen the data rate is 30 x 100 = 3K bitsisec.

When a battlefield has been chosen an advance party will examine its layout and locate a quantity of beacons B at fixed positions throughoutthe field. The quantity required andtheir location will be such asto achieve good position fixing throughoutthe battle- field, i.e. each mobile unit must have a high probability of line of sight to at least two orthree beacons with good angle of intersection ofthe electronic loci.

Attention must also be paid to potential ambiguity and whether this requires a further beacon or whether ambiguity may be resolved from past track record.

The distances mobiie4o-beacon must also be within the range capabilityforwhich the system is designed.

Afterthe beacons are located their position must either be surveyed in (if minimum equipment cost is required) or a method of self-survey can be supplied though this will involve some extra cost.

The battle area also needs a headquarters forthe command data processor and message switching system. This may be inside a vehicle at some strategic fixed site.

The battle sequence is then as follows: Force A with their own electronics enterthe area initiating the position determination system and the electronic HQworks outthe position of each mobile entirely automatically and stores these positions at regular time intervals-- possibly on magnetictape forsubsequentanalysis.

Theforward observerofforce B notesthe position of the arriving units through his binoculars and communicates his estimate of their position by voice to his own guns. The electronic HQ also records this commentary-thus a comparison may subsequently be made between his perceived estimated position and the position as estimated by the electronics. (This comparison will haveto be a controlling factor in the required accuracyofthe position determination system).

Force B nowaimforthe position given bythe forward observer. Transducers on the guns measure azimuthal and elevational angles at the moment blanks are fired. These angles are automatically radioed along with gun positions to the HO computer which calculates where the simulated shells would land. Assuming a 'hit', this is radioed (automatically) to the 'damaged' target. Assuming a miss, a display at the forward position indicates the landing position of the 'shell'. The observer accordingly radios by voice correction instructions according to how the shell position compared with his perceived position of the targets.

Sincethe electronics is cooperative it will be possible to monitor cheating by the tank crew. For instance by continuously measuring the VSWR ofthe antenna, the system will 'know' if the crew unscrews the antenna in order to deceive the system. It will also be possible to test the data link continuously by sending messages like 'you have not been killed yet' and comparing the messages so transmitted to the mobile with those received back acknowledging them.

Thus cheating will show up during post battle analysis, as well as during the battle itself.

The same position determination system can be used for minefield simulation. The mine dispenser has a similar interrogator which emits a pulse pair each time a 'mine' or its equivalent 'sandbag' is dispensed.

The fixed beacons determine the position of the vehicle atthattime and a computer stores the position of each such simulated mine. This is always compared with the known position of all 'enemy' vehicles and the relevant ones are 'blown up' by simulation if position of 'enemy' vehicle corresponds with the mine position stored in the computer memory. The 'blow up' information is transmitted via the same data link-- and of course no explosives need be involved.

Claims (8)

1. A combat simulation training and assessment system comprising a plurality of static beacons which, in use, are distributed on a battlefield for a plurality of combat mobile units to interacttherewith,whereby the positions of the mobile units can be automatically determined at varioustimes during a simulated combat, dedicated meansfortransmitting beacon determined positions of mobile units to a command data processing unit to which combatant estimates of positions of hostile mobile units and artillery aim estimates are also transmitted to the command data processing unit being programmed to compare the estimate data with automatical ly-determined positions of relevant mobile unitsandto indicatethe comparisons to the relevant combatants.

2. A system according to claim 1 wherein each static beacon includes interrogation means interactive with response means in each mobile unit, and distance calculating means.

3. A system according to claim 2 wherein each static beacon includes a data storage means arranged to store a unique address for each mobile unitto be interrogated by the beacon, data to be transmitted to a mobile unitforwhich the beacon holds an address, the last calculated distance to each mobile unitforwhich the beacon holdsan address, data and/orsignals received from each mobile unit, and time slot data for controlling interrogation of and communication with each mobile unitforwhich the beacon has an address.

4. A system according to claim3 wherein each mobile unit has allocated to it predetermined time slots for interrogation and communications purposes.

5. Asystem according to any preceding claim including at each beacon means for measuringthe VSWR oftheantenna of each mobile unit being interrogated.

6. A system according to any preceding claim including a mine simulator dispensing mobile unit arrangedtoemita unique signal each time a simulated mine is dispensed whereby a beacon can determine the distance to the position of each dispensed simulated mine.

7. A system according to claim 3 in which each beacon includes test means for comparing data and/or signalstransmittedto mobiles with acknowledgementdata and/or signals received from respective mobiles and indicating when a beacon/mobile link becomes inoperative.

8. A combat assessment system substantially as described with referenceto the accompanying drawings.