GB2368382A

GB2368382A - Command systems

Info

Publication number: GB2368382A
Application number: GB0012292A
Authority: GB
Inventors: Remo Giovanni Andrea Marzolini
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-05-23
Filing date: 2000-05-23
Publication date: 2002-05-01
Anticipated expiration: 2020-05-23
Also published as: GB2368382B; GB0012292D0

Abstract

A command system that allows operation from a distance, comprising: a module 1 which has navigational co-ordinates of its location either programmed 5 into said module 1 or received by said module 1 and that are used as said module 1 address; and a remote command means 9 of transmitting navigational co-ordinates to said module 1 hen said remotely commanded transmitted navigational co-ordinates of location 10 are received by said module 1 it is compared 4 with said navigational co-ordinates of module location address 5, and if identical, or within a defined tolerance, causes said module 1 to respond. An illustration is given of a munitions (demolition) module where the navigational co-ordinates are programmed into said module upon deployment. A further embodiment is described where the navigational co-ordinates are obtained by a receiving system incorporated in a remote battlefield sensor. For the purpose of this specification the assumption is made that the navigational system used is the Global Positioning System (GPS).

Description

IMPROVEMENTS IN OR RELATING TO COMMAND SYSTEMS Field of the Invention My invention relates generally to those command systems that involve the command of remote apparatus, and in particular those remotely operated systems that are used to selectively control various functions such as demolition systems, minefields and battlefield sensors, etc. More specifically my invention relates to munitions where it may be necessary to select specific units of munitions using the navigational coordinates of the unit's location, and remotely command those units that contain explosives to detonate at that specific location, whilst ignoring other units that contain explosives in the near vicinity and which are part of the same system.

Background of the Invention A long standing problem that occurs with radio command controlled munition systems is that of implementing selective control, where only one or more of the devices under control are required to be operated or detonated. A munition for the purpose of my invention is defined as consisting of any device containing an explosive substance, such as demolition charges, mines, bombs, shells, etc. For selective command control to be successful it is necessary for a particular device to have its identity, and its location, known by the remote operator wishing to send radio commands to control that item. Prior art has attempted to solve this requirement by requiring the soldier emplacing the device either to programme it with, or to record, its identity, together with its location. This information is then passed to the remote operator along what could be a long communications chain and possibly resulting in a long time delay. In the heat of battle communication of this information can be difficult to achieve, particularly if the friendly forces placing the munition are under attack and retreating. My invention seeks to overcome these limitations.

Prior art in selective control command systems, such as the selective detonation of units of explosives, have used systems that have assigned a specific carrier frequency, suitably modulated, to each unit. This provides a frequency selective system, where transmission on a selected frequency enables a specific unit of (say) munition to be controlled, e. g. detonated. This system was wasteful of carrier frequency and vulnerable to jamming, as well as being limited in the number of units it could control. Subsequent schemes, such as some early missile break-up systems, used a single RF carrier (either AM or FM) with tone modulation. Transmission of a specific tone, or combination of tones, allowed a specific unit of munition to be controlled. Other systems used pulse width modulation (PWM) or pulse position modulation (PPM) to control or select the unit of munition. The most recent development has been the use of digital modulation (PCM/FM) where many of the disadvantages of selection, control and immunity to interference have been overcome. However all these methods of command control suffer from the major disadvantage that the identity or digital address (say) of a specific unit of munition, and its specific location, must be known and advised to the remote operator, prior to any command instruction being issued.

My invention solves this problem by taking advantage of the great accuracy offered by satellite navigation systems such as the Navstar Global Positioning System (GPS), Global'naya Navigasionnay Sputnikovaya Sistema (GLONASS) and the future European Union GALILEO system, where either the programming, or measurement, of navigational co-ordinates can be used as an address or identity, of the unit of munition to be controlled. When the unit is installed it would be programmed with, or would receive the navigational co-ordinates of its location. Transmission of a command, say, to detonate units of munition at a specific location defined by the navigational co-ordinates, will result in all the units at that location being detonated.

The greater the accuracy of the navigational co-ordinates, the more precise the control. This results in the remote operator only needing to know that units of munition of interest have been placed in a specific area. It reduces the time delay between installation of the munition units and possible operation, to a minimum. The recent development of low cost single chip GPS receiver integrated circuits, has made the introduction of a navigational facility in low cost munition systems such as demolition charges and mines economically feasible.

The concept that is proposed in my invention is a general one that can be applied to any command controlled system that requires selective control, and where only one or more of the devices under control are required to be operated at any specific time.

For applications where similar problems occur, reference is made to my earlier invention described in British Patent Application 0008579. 5. This specification discloses a drifting mine whose fuze system is activated within a defined zone about a target by means of a navigation system. Summary of the Invention The scope of my invention is defined by the claims.

It is therefore an object of my invention to provide an improved command control system which in principle has no limits to the number of units that can be controlled.

A further important object of my invention is to provide a new and improved command control system where unit addressing is provided by navigational co-ordinate means.

A further important object of my invention is to provide a new and improved command control system where selective control is provided by navigational co-ordinate addressing means, within which a sub-addressing means is used to control further units at said navigational address.

Still another object of my invention is to provide a new and improved command control system that provides an improved addressing facility by utilising a combined command and navigational measurement receiving system.

Another object of my invention is to provide an improved command control system where the resolution or accuracy of selection of unit to be controlled, is determined by navigational co-ordinate measurement accuracy.

A further object of my invention is to provide a new and improved command control system where the zone of influence can be calculated by commanded units.

Another object of my invention is to provide a new and improved command control system where the zone of influence is determined by a transmitted format command.

A further object of my invention is to provide a new and improved command control system where the zone of influence can be programmed into commanded units.

The foregoing and other objects, features and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention that is illustrated in the several figures of the accompanying drawings. Brief Description of the Drawings Figure 1 is a block diagram of a basic command control scheme scenario and which is useful in illustrating of my invention Figure 2 is a block diagram of a commanded module showing navigational coordinates programming features and which is useful in illustrating of my invention.

Figure 3 is a block diagram of a commanded demolition unit showing navigational coordinates programming features as applied to a demolition charge system and which is useful in illustrating of my invention.

Figure 4 is a flow diagram of the steps involved in the operation of the selective control command system shown in figure 3 and which is useful in illustrating of my invention.

Figure 5 is a block diagram of a commanded module including a GPS navigational coordinate receiver and which is useful in illustrating of my invention.

Figure 6 is a block diagram of a commanded module including a GPS navigational coordinate receiver as applied to a battlefield sensor system and which is useful in illustrating of my invention Figure 7 is a flow diagram of the steps involved in the operation of the selective command control system shown in figure 6 and which is useful in illustrating of my invention.

Figure 8 is a block diagram of a commanded module with a combined GPS navigational co-ordinates and command receiving system and which is useful in illustrating of my invention.

Figure 9 is a typical transmitted command format structure for a navigational coordinates system and which is useful in illustrating of my invention Figure 10 is a typical transmitted command format structure for a navigational co ordinates command system with a unit sub-address command facility and which is useful in illustrating of my invention. Description of preferred embodiments In the following description of the preferred embodiment of my invention I give various illustrations which in addition to a general scheme includes application to a demolition system where the navigational co-ordinates are programmed into the demolition unit upon deployment. A further embodiment is described where the navigational co-ordinates are obtained by a receiver which is incorporated in the said unit, which in the example shown is in a remote battlefield sensor. Various modifications and applications of these schemes are described. For the purpose of my description the assumption is made that the navigational system used is the Global Positioning System (GPS).

Referring now to figure 1 of the drawing; this shows a block diagram of a basic command control scheme scenario of my invention. The scenario shown here consists of a module 1, which is shown as consisting of two sub-systems 2 and 4. The first said sub-system is the local command receiving system 2 and the second said sub-system is the module function under control 4. The box 6 represents the module installer, with a GPS Receiver 11 and a navigational co-ordinate programming device 13, placing or installing the module 1. Initially the installer 6 on determining where the module 1 should be placed, determines the navigational co-ordinates of the location of said module 1 by means of the GPS Receiver 11. The output 12 of the GPS receiver 11 is connected to the local programming unit 13. Connection 5 of the local programming unit 13 to the module 1, enables the local module 4 to be programmed with the navigational co-ordinates of its location. These navigational co-ordinates would represent the location or identity of module 1. Connection 5 is then disconnected and the module 1 is then switched on and left in a listening state awaiting a command 10 to perform its specific function. At some subsequent time the remote operator 9 decides to transmit a command 10 to the module 1. The structure or format of this command 10 would contain as part of the identity of the module 1 the navigational co-ordinates of its location which had been programmed 5 into the module 1. Upon receipt of the command 10 transmission by the local receiving system 2, the command format structure 3 would be extracted and the module function under control 4 would compare the received navigational co-ordinates 3 with the programmed navigational co-ordinates 5. If they were identical, the module 1 would be activated and respond to the command 10. In practice the system described would not rely on the navigational co-ordinates being compared as being identical, but as being within a defined tolerance.

In this specification this defined tolerance is termed the zone of influence (ZOI). The zone of influence is defined as a navigational co-ordinate zone computed about the location of the module 1 within which the module 1 can be activated. The inherent advantage of the system can be seen in that the remote operator 9 does not require any details of the unit apart from the information the a unit 1 has been installed at the location specified. In practice even this need not be known as the remote operator 9 could issue a command 10 to specific navigational co-ordinates on the assumption that a unit was located there.

Figure 2 illustrates a block schematic of a single module 1 for a multi-module scheme.

In this scheme the module 1 is programmed with the external navigational co-ordinates 5. Here the external programming input stores the navigational co-ordinates 5 in the stored location co-ordinates memory 29. These are supplied to the processor 31, via connection 30, where the initial calculation made would be to determine the zone of influence by means of a pre-programmed algorithm contained in a store within the processor 31. Assume that the remote operator 9 transmitted 10 a command, containing the module 1 location navigational co-ordinates, to activate the module 1.

This command would be received on the command antenna 20 and connected, via 21, to the command receiver 22. Here it would be demodulated and applied, via connection 23, to the command format decoder 26, which would extract the commanded navigational co-ordinates 27. Note that the receivers in all modules would respond to this remote operator command, but the specific module 1 will only respond if its stored navigational co-ordinates are within the zone of influence. The received commanded navigational co-ordinates 27, are stored in the commanded navigational co-ordinate store 28. This action, via connection 36, activates the processor 31 to compare the stored co-ordinates in memory 29 with the co-ordinates stored in memory 28. If the navigational co-ordinate values compare within the limits defined by the zone of influence, the processor 31 issues an activation command 32, to the command activation function 33. This in turn issues, on connection 34, an instruction to perform whatever action 35 the module is intended to perform; examples of which are given below. The battery supply 25 provides power 24 to all sub-systems in the module 1. It is switched on by the installer 6 upon initial installation. If the processor 31 determines that the received commanded navigational co-ordinates 27 are outside the zone of influence then the processor 31 clears the commanded navigational co-ordinates store 28 to await receipt of the next command.

The determination of the zone of influence can take several forms. It could be performed by an algorithm which is pre-programmed into the processor, or by a switch setting on the case of the module, or it could be part of the transmitted command format. This latter approach is discussed further below in the scheme of figure 10.

Several algorithms can be programmed into the Processor 31. The simplest algorithm is that which causes activation 32 to occur when the location navigational co-ordinates programmed in 29 are identical to those commanded navigational co-ordinates in 28, or differ to within a defined tolerance. In practice this approach would tend to be restrictive. Other algorithms would allow a zone to be computed about the location navigational co-ordinates programmed in 29. Another approach is to store within the module 1, the zone of influence co-ordinates about the location navigational coordinates programmed in 29 thus reducing the computational load on the processor 31. The processor 31 algorithm can also be used to determine the shape of the zone of influence, depending on the nature of the location of the module 1. This can, say, be circular or rectangular, or some irregular shape. For the example described below, a circular shape is assumed for the zone of influence. Several factors affect the size of the zone of influence, most of which are dependent upon the location and the type of structure to be influenced. A further application of my invention is that a number of modules could be simultaneously deployed, each programmed for a different application and for a different zone of influence.

A further feature affecting the zone of influence may be introduced into my invention. The size of the zone of influence could be controlled by the remote operator 9 with an additional command in the transmitted format, as is illustrated below in figure 10. This would allow the operator to control just one module 1, or by widening the zone of influence to embrace all modules 1 it was desired to control. In either example, only one set of navigational co-ordinates would need to be transmitted.

The accuracy of the measurement of the module 1 position navigational co-ordinates directly determines the strategy that is used in the choice of the zone of influence. If the GPS system is used, say, this means that the basic system available to all users, i. e. unaided positioning corrupted by selective availability, can be used. This provides an accuracy of positional measurement of some 100 metres. This error may well embrace a number of modules on a particular structure. The future removal of selective availability, or the implementation of GPS Block II F and GALILEO satellites, offer an accuracy of navigational measurement of better than 10 metres and possibly better than 1 metre. Differential GPS currently offers an accuracy of better than I metre, but such a system is unlikely to be generally used in a war zone; particularly in the remoter regions of the world. Future navigational satellite developments may well result in a navigational measurement accuracy of the order of centimetres. This error would probably be smaller than the size of the module, thus allowing specification of the navigational co-ordinates of the module to be made as a direct address to that module. The accuracy of the navigational measurement thus directly influences the choice of the zone of influence.

Figure 3 shows a specific application of the general scheme shown in figure 2. The scheme is applied to demolition units. Here a number of demolition units 42 would (say) be installed on a large bridge; the navigational co-ordinates of various key parts of the bridge, would be known to the remote operator 9. The demolition unit 42 on installation, as well as being programmed with the demolition 42 navigational coordinates and being switched on, would be mechanically armed 38. Assume that the remote operator 9 transmitted 10 a command, containing a demolition unit 42 location navigational co-ordinates which defined its location on a specific part of the bridge, to detonate the demolition unit 42. The operation of the unit is as for figure 2, up to the output 37 of the command activation 33. This output 37 now constitutes a fire, or detonate, command. This is applied to the detonation chain 39, which in turn, detonates 40 the explosive 41. If all the demolition units 42 on the bridge were to be simultaneously detonated, the zone of influence would have been made large enough to embrace all the demolition units 42, either on initial pre-programming or by means of the transmitted format. The detonation chain 39 would normally consists of a detonator and a booster charge. The detonator is a small, sensitive explosive which in this application would be electrically fired. This in turn ignites the booster charge, which acts as a medium of transferring a plane wave of detonating energy from the detonator to the insensitive main charge 41. The booster charge is necessary because the energy output from the detonator is insufficient to cause the main charge 41 to explode on its own. Note that the commanded receivers in all modules would respond to this remote operator command, but the specific module 42 will only respond if its stored navigational co-ordinates are within the zone of influence. If the commanded navigational co-ordinates 27 are outside the zone of influence the module 42 will not respond. The processor 31 will then erase the contents of the commanded navigation store 28 in each demolition unit 42 outside the zone of influence, allowing them to await the next command.

Referring now to figure 4 where is illustrated a flow diagram, generally designated 50, showing a sequence of steps employed by the selective control command system, shown in figure 3 of the present invention, to achieve its intended objective. Namely that being to detonate an explosive from a remote distance by means of commanding the demolition unit 42 by specifying the navigational co-ordinates of its location. As represented by block 51 of the flow chart, a target is determined to which demolition units 42 are to be installed and advised to field troops, the installers, and the remote operator 63. Troops in the field then commence to install demolition units 52. Using their portable programming unit 6, the navigational co-ordinates are determined 53 of the position of the installed demolition unit 42. These navigational co-ordinates are then programmed 54 into the demolition unit 42. The demolition unit 42 internal supplies, say a battery, are then activated 55. The demolition unit 42 is then armed by the installer 56. After the demolition unit 42 has performed its start-up sequence, it calculates the zone of influence 57 about the navigational co-ordinates previously programmed 54 into the demolition unit 42. The demolition unit 42 is then dormant until the remote operator issues a command 63, in the form of the navigational coordinates of that demolition unit 42 position, to detonate. This transmitted command 63 need only contain the approximate position of the demolition unit 42, provided it is within the zone of influence. The transmitted command 63 is then received by the demolition unit command receiver 22 and decoded 26 and the navigational coordinates extracted 58 The received navigational co-ordinates 58 are compared 59 with the programmed navigational co-ordinates 54. If the two sets of navigational coordinates are identical, or the received command 58 is within the zone of influence, then an OK within zone 60 clearance is given and the detonation chain is activated 61.

The demolition unit main charge is then detonated 62. For clarity, not shown in figure 4 are the additional steps that occur, namely the clearance of the commanded navigational co-ordinate store 28, if the commanded navigational co-ordinates are outside the zone of influence.

Figure 5 shows a block diagram of a module 70 for a scheme with a command receiver 22 and a GPS navigational co-ordinates receiver 73. Here the signal from the GPS satellite is received by the GPS antenna 71, and connected via 72 to the GPS receiver 73. The output 74 of the GPS receiver 73 are the navigational co-ordinates of the module 70 position. These navigational co-ordinates 74 are stored in the stored location co-ordinates memory 29. These navigational co-ordinates are supplied, via 30, to the processor 31 where the initial calculation would be made to determine the zone of influence by means of a pre-programmed algorithm. Assume that the remote operator 9 transmitted a command 10, containing the module 70 location navigational co-ordinates, to activate the module 70. This command would be received on the command antenna 20 and connected, via 21, to the command receiver 22. Here it would be demodulated and applied, via connection 23, to the command format decoder 26, which would extract the commanded navigational co-ordinates 27. The commanded navigational co-ordinates 27, are stored in the commanded navigational co-ordinate store 28. This action, via connection 36, activates the processor 31 to compare the stored co-ordinates in memory 29 with the co-ordinates stored in memory 28. If the co-ordinate values compare within the limits defined by the zone of influence, the processor 31 issues an activation command 32, to the command activation function 33. This in turn issues, via connection 34, an instruction to perform whatever action 35 the module is intended to perform, an example of which is given in figure 6. Note that the commanded receivers in all modules would respond to this remote operator command, but the specific module 70 will only respond if its stored navigational co-ordinates are within the zone of influence. If the commanded navigational co-ordinates 27 are outside the zone of influence the module 70 will not respond. The processor 31 will then erase the contents of the commanded navigation store 28 allowing it to await the next command. The battery supply 25 provides power 24 to all sub systems in the module 70. The battery supply 25 is switched on by the installer 6 upon initial installation. If the module 70 is mobile, the navigational coordinates 74 would be continuously changing, and the stored location co-ordinates memory 29, together with the zone of influence, would be continuously updated.

The advantages of the scheme shown in figure 5, where a separate GPS antenna 71 and receiver 73 are used, are of rapid installation. The installer 6 does not have to spend time programming the module 70 with its position navigational po-ordinates.

The scheme also has advantages when used in air deployed applications, as illustrated below in figure 6. It also has the advantage of being able to be used on mobile applications such as ships and missile break-up systems.

Figure 6 shows a specific application of the general scheme shown in figure 5 to battlefield sensor systems. In addition to a GPS antenna 71 and a command antenna 20, this unit 80 also contains a sensor transmitter antenna 86 and a sensor transmitter 84. Assume the scheme is applied to battlefield sensor units 80 deployed by an aircraft or remotely piloted vehicle (RPV). In this application sensors would be used to monitor troop and vehicle movements, or the deployment of specific types of weapons.

A number of sensor units 80 would (say) be deployed by an aircraft over a wide area; resulting in the navigational co-ordinates not being known of where the sensor units 80 landed. Not shown in figure 5 is the mechanism which would activate the sensor upon deployment, by switching on the battery unit 25 to provide power 24 to the sensor unit 80 internal sub-systems. Upon landing the sensor unit 80 would determine its location as has been described in figure 5. Assume that the remote operator 9 transmitted a command, containing the specific sensor unit 80 location navigational co-ordinates, defining its location in an area where enemy troop movements were suspected.

Following receipt of the command transmission the operation of the unit is as figure 5, up to the command activation 33. The output 81 of which turns the sensor system 82 on. If, say, the sensor system detects enemy troop movements, an output would appear on connection 83 activating and providing details to the sensor transmitter 84. The output of the sensor transmitter 84 is connected to the sensor antenna 86, and would transmit the information gathered by the local sensor unit 80.

Referring now to figure 7 where is illustrated a flow diagram, generally designated 100, showing a sequence of steps employed by the selective control command system shown in figure 6 of the present invention to achieve its intended objective. Namely that being to control a battlefield sensor system from a remote distance by means of commanding the sensor unit 80 by specifying its navigational co-ordinates of its location. As represented by block 101 of the flow chart, a surveillance area is determined to which battlefield sensor units 80 are to be deployed by aircraft drop. The area to be put under surveillance 101 is advised to the remote operator 113. Upon deployment the sensor unit 80 internal battery supplies are activated 103. After the sensor unit 80 has carried out its start-up sequence, the navigational co-ordinates of the sensor 80 location are determined 104. These navigational co-ordinates are then stored 105 in the battlefield sensor unit 80. The battlefield sensor 80 then calculates the zone of influence 106 about the navigational co-ordinates stored 105 in the sensor unit 80. The sensor unit 80 is then dormant until the remote operator 113 issues a command in the form of the navigational co-ordinates of the local sensor unit 80 location, to become active. This transmitted command 113 need only contain the approximate location of the local sensor unit 80, as long as it is within the zone of influence. The transmitted command 113 is then received by the local unit 80 command receiver 22 and decoded 26 and the navigational co-ordinates extracted 108.

The received navigational co-ordinates 108 are compared 109 with the internally stored programmed navigational co-ordinates 105. If the two sets of navigational coordinates are identical, or the received command 108 is within the zone of influence, then an OK within zone 80 clearance is given and the sensor 80 activated 111. The battlefield sensor unit 80 then transmits 112 any data, say, gathered on enemy troop movements. For clarity, not shown in figure 7 are the additional steps that occur, namely the clearance of the commanded navigational co-ordinate store 28, if the commanded navigational co-ordinates are outside the zone of influence.

The use of two receivers, GPS and command, in the schemes shown in figures 5 and 6 offer cost disadvantages in those systems where the modules 70 and 80 are intended to be disposable. Figure 8 shows a modification of the scheme illustrated in figure 5 which overcomes this cost disadvantage. The module 120 has the GPS receiver and command receiver combined in a single unit 123, together with a combined GPS and command antenna 121. The output of the antenna is connected to the receiver input via connection 122. The GPS output of the receiver 123 appears on the connection 125 and is applied to the stored location navigational co-ordinates function 29. The command output of the receiver 123 is connected to the command format decoder 26 via connection 124. Two approaches can be used to implement a common receiver 123 and antenna 121. Firstly, the command signal could be integrated into the GPS signal structure where after performing the navigation measurement the receiver 123 would extract the command 124. The second approach would be for the receiver 123 to initially receive the GPS signal and determine the navigational co-ordinates of the module 120. The receiver 123 would then change its structure to receive the command signal 124 which may be on a different carrier frequency. This approach could readily be implemented with a software controlled receiver.

Figure 9 shows a format structure 130 for the command transmission shown in the schemes of figures 5 and 6. It is assumed that the command transmission is a burst system with the transmission occurring left to right. The initial transmitted part of the burst is a preamble structure 131. The function of the preamble 131 is to allow the command receiver 22 to extract the bit rate clock from the burst timing to facilitate decoding. The next words transmitted in the format are the sync structure 132. The function of the sync structure 132 is to create a time marker from which all subsequent words are decoded. The next two words transmitted in the command burst 130 are the longitude 133 and latitude 134 navigational co-ordinates of the module 80 general position. The receipt of these activate the specific module 80 to respond to the function word 135 transmitted next. The final part of the command burst 130 transmitted is the postamble 136. The function of the postamble 136 is to allow the command receiver decoder to perform all its required functions before the command transmission 130 is terminated. The format structure described in figures 9 and 10 are basic ones used to clarify the operation of my invention. If the navigational coordinates also used height as a further diskriminator, then this would be included in the format structure 130 as an additional word.

One problem referred to earlier is if there are a number of modules within the zone of influence for a particular navigational co-ordinate transmission. In this case all units would respond. Figure 10 shows a further format structure 140 for the command transmission shown in the schemes of figures 5 and 6. The format structure and operation are as for figure 9 with the exception of the additional sub-address 141 and zone of influence control 142, contained after the navigational co-ordinates 133 and 134, and before the function 135. The additional sub-address 141 allows each unit within the zone of influence to be addressed separately. This approach is useful if the modules within the zone of influence, for a particular navigational co-ordinate transmission, each have a different function. An additional capability is provided by the zone of influence (ZOI) control word 142. This could be used to control the size of the zone of influence. For military application the provision of this additional facility would have to be introduced with care as any enemy interception of the system could have severe effects.

The basic formats shown in figures 9 and 10 have been described to illustrate my invention. In practice their structure would be more complex, particularly for military applications, with the incorporation of encryption, error coding and date-time code structures. These would be introduced to enhance the security of the system, and to minimise the effects of deliberate interference and such deception techniques as repeat jamming and spoofing.

In the examples given in this specification the navigational co-ordinates used are assumed to be latitude and longitude. However navigational systems such as GPS also allow the height or altitude to be determined. For some operational applications, it may be advantageous to use the height parameter as a further command discriminator.

Although an exemplary embodiment is described above, it will be obvious to those skilled in the art that many alterations and modifications may be made without departing from the invention. Accordingly, it is intended that all such alterations and modifications be included within the spirit and scope of the invention defined in the appended claims.

Claims

I claim : 1. A command system that allows operation from a distance, comprising - a module which contains means for the provision and storage of navigational co-ordinates of said module location and in which said navigational co ordinates are used as said module address; - a remote command means of transmitting navigational co-ordinates to said module; - when said remotely commanded transmitted navigational co-ordinates of location are received by said module a comparison is made with said stored navigational co-ordinates of said module location address and if identical or within a defined tolerance causes said module to be activated.
2. A command system that allows operation from a distance as set forth in claim 1 in which said means for the provision of navigational co-ordinates of said module location are provided by external programming of said navigational co ordinates into said module.
3. A command system that allows operation from a distance as set forth in claim 1 in which said means for the provision of navigational co-ordinates of said module location are provided by an internal navigational receiving system.
4. A command system that allows operation from a distance, comprising: - a module, including - means for programming said module with navigational co-ordinates of said module location; - means for storing navigational co-ordinates of said module location in said module; - processor means for determining a zone of influence from navigational co-ordinates of said module location; - means for receiving commanded signal; - means for decoding said received commanded signal structure and extracting commanded navigational signals; - means for storing said extracted commanded navigational signals; - said processor means for determining if said commanded received signal navigational co-ordinates fall within said zone of influence;

- means for activating module function if said commanded received signal navigational co-ordinates fall within said zone of influence ; and - a programming device remote from said module which includes - a means for receiving a navigational signal ; - a means for determining the navigational co-ordinates of said programming device location from said received navigational signal ; - a means for storing said received navigational co-ordinates ; - an output means for programming said module with said received navigational co-ordinates.
5. A command system module that allows operation from a distance, comprising : - a means for receiving a navigational signal ; - a means for determining the navigational co-ordinates of said module location from said received navigational signal ; - means for programming said module with navigational co-ordinates of said module location ; - means for storing navigational co-ordinates of said module location in said module ; - processor means for determining a zone of influence navigational co-ordinates of from said module location ; - means for receiving commanded signal - means for decoding said received commanded signal structure and extracting commanded navigational signals ; - means for storing said extracted commanded navigational signals ; - said processor means for determining if commanded received navigational coordinates fall within said zone of influence ; - means for activating module function if said commanded received navigational co-ordinates fall within said zone of influence.
6. A command system that allows operation from a distance, comprising : - a means for receiving a navigational signal ; - a means for determining the navigational co-ordinates of commanded system location from said navigational signal; - means for storing navigational co-ordinates of said commanded system location in said commanded system; - processor means for determining a zone of influence from navigational coordinates of said commanded system location; - a means for receiving commanded signal; - means for decoding said received commanded signal structure and extracting commanded navigational signals; - means for storing said extracted commanded navigational signals; - said processor means for determining if said commanded received navigational co-ordinates fall within said zone of influence; - means for activating commanded system function if said commanded received navigational co-ordinates fall within said zone of influence.
7. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said received navigational signals are from the Global Positioning System.
8. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said commanded received navigational co-ordinates store is cleared if said processor means determines if said commanded received navigational co-ordinates fall outside said zone of influence.
9. A command system that allows operation from a distance as set forth in claims 4,5 or 6 in which said zone of influence is determined by a pre-programmed algorithm contained within said processor means.
10. A command system that allows operation from a distance as set forth in claims 4,5 or 6 in which said zone of influence is defined by an additional command contained in said received command signal structure.
11. A command system that allows operation from a distance as set forth in claims 4,5 or 6 in which said zone of influence is defined either by programming of said commanded system or module or by switch setting on said commanded system or module.
12. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said commanded signal structure contains a sub-address structure for selecting a module if more than one module are located within said zone of influence.
13. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said commanded signal structure contains a sub-address structure for selecting types of modules if more than one type of said module is located within said zone of influence.
14. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said module is a demolition unit.
15. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said module is a battlefield sensor and in which said module additionally incorporates a data transmitter and antenna for transmission of said sensor data.
16. A command system that allows operation from a distance as set forth in claims 1,5 or 6 in which said means for receiving commanded signal and said means for receiving a navigational signal are provided by a common antenna in said module.
17. A command system that allows operation from a distance as set forth in claims 1,5 or 6 in which said means for receiving commanded signal and said means for receiving a navigational signal are provided by a common receiving system in said module.
18. A command system that allows operation from a distance as set forth in claims 1,4, 5 or 6 in which said navigational co-ordinates comprise latitude, longitude and height.
19. A command system that allows operation from a distance substantially as described herein with reference to figures 1 to 10 of the accompanying drawings.