GB2312801A - Locating and reading tags by phase comparison - Google Patents

Abstract

This invention relates to an Infra-Structure and System which will poll and read data by low powered radio from Tagged Devices that is also able to locate their positions to a degree of accuracy within specified physical boundaries using a technique involving the phase comparison of a reference radio signal with that of the carrier signal received from the tag at each of four slave stations 3. The invention may be utilised to poll and collect data from Tag Devices < attached to objects or vehicles and/or controls, sensors, apparatus, personnel badges, and other appliances relating to facilities management and/or mechanical engineering and service functions as, for example, heating, ventilation, air conditioning and from alarms, communication, security and surveillance systems; and/or from the positional readings trace the Tag Device locations and/or track the changes with sufficient accuracy to enable computer aided drawing files and related databases to be updated.

Description

AN INFRA-STRUCTURE FOR READING COutu l-AG DEVICES AND DETERMINING THEIR LOCATIONS BY PHASE COMPARISONS UTILISING LOW LEVEL POWERED RADIO TRANSMISSIONS.

Field of this Invention.

1. This invention comprises the equipment, apparatus and devices, and an operating methodology, which form an Infra-Structure and System for providing a means of polling from time to time by low powered radio transmissions a plurality of fixed and/or movable coded Tag Devices of differing types which will, on command prompts, wake-up and transmit identifying and status data about the tag and other data as may be arranged. The invention also enables a measure of the present positioning of the Tag Devices to be calculated relative to a predetermined Cell Area, or a plurality of such Cell Areas, by comparing the phase shift of a known reference carrier signal with those of the carrier signal received from the Tag Devices. For example, such as Cell Areas that may be conveniently arranged within the curtilage of a building and/or site, or some part, or parts, of a building and/or site in a single occupation - be they at different levels or not, or simply of an area of land.

2. The Infra-Structure and System this invention provides may also be utilised to collect data by radio in the same manner and at the silme time, or separately if wished, by polling Tag Devices attached to objects or vehicles and/or controls1 sensors, apparatus, items, personnel badges, and other appliances relating to many facilities management and/or mechanical engineering and service functions such as, for example, heating, ventilation, air conditioning, fire alarms, communication systems, and security and surveillance systems; and/or from the databases of the outcome of a series of the positional readings trace the movements, and/or track positional changes, if any.

Background to the Invention.

3. A number and a variety of prior inventions in this field concerning Location, Tracking and Identification Systems within a localised area based on infra-red transmissions are known. U.S. Patent Numbers 4837568 and International Patent WO 93/18476 are examples. Also known - as was disclosed by our own previous patent application which was given reference GB 9502808.0 - is an invention for an Infra-Structure for Locating and/or identifying Coded Tag Devices by Low Level Radio transmissions making use of high speed counters and measurements taken from wave forms.

4. The level of accuracy of the locational readings of the methodology described in our earlier application is itself constrained by the economic implications of rectifying the drift in the readings that occurs in practice.

5. Those Systems utilising infra-red transmissions are constrained by the inability of the transmissions to penetrate through solids as, for example, screens and partitions; positional accuracy is limited to within a localised field area; and when partitioning is resited, or alterations to layouts are made, the system requires extensive physical modification or, on occasion, complete renewal.

6. Infra-red Systems also need extensive cabling networks to connect units in each and every space; and for additional accuracy a multiplicity of field devices and additional nodes to avoid or circumvent obstruction to signals - all of which would need to be modified and/or renewed whenever material changes are made to room layouts.

7. Moreover; other low voltage systems for controlling and monitoring the service and environmental facilities usually found in buildings which rely on cable networks equally require extensive and time consuming modification when anything other than minor alterations are made.

8. The primary object of this invention is to introduce a more cost effective technique over that disclosed before by utilising relative phase comparison of radio waves to provide the measurements required for locating the positions of the Tag Devices - whilst exploiting the advantages that can be gained over infra-red systems by the capacity of radio waves to pass through solid objects generally.

9. Thereby providing a Location, Identification and Tracking System by which significant operational improvements can be achieved compared to the other methodologies that are known; which is not constrained/restricted to the same extent or limited by the capacity of cable network systems; more readily accommodates changes or alterations without involving significant cost or prolonged delay; that also has the added ability to prioritise poll requests and/or responses at will; is sufficiently accurate to be utilised in conjunction with computer aided drafting systems and related databases; and is much more effective in terms of its economic application, performance, and viability.

Description of the Invention.

1. This invention comprises a system of equipment, apparatus and devices, and the operating techniques and methods that form an Infra-Structure which consists of a Master Unit with four Slave Units and a Computer Facility Host System - that are linked together by generic hardware - and arranged either as a single Cell, or a plurality of such Cells; that will on request, or command prompt, poll a plurality of uniquely encoded Tag Devices of differing types in series by low powered radio signals and receive back, process and store any relevant data output in response from the Tag Devices; (which may, of course, be attached to items or objects or sensors or apparatus or persons or vehi cles or animals or other appliances) for the purpose of determining, for example, their identities, status and/or locations and/or movement and/or other relevant monitoring and/or control information as may be arranged.

11. Based on the effective range of the low level powered radio devices of up to 10 mW operating within a band of up to 500 MHz, a Cell would be say some twenty five metres square in a typical office environment, or a like pre-determined area of various geometric shapes and/or at different levels as may be conveniently arranged within the curtilage of a building or site, or some part or parts of a building or site, or simply a land area of limited extent and normally each Cell will usually have a Master Unit and four Slave Units. However, adjoining Cells may share Master Units and/or Slave Units depending on the geometric configuration of the Cell Areas.

12. The operational methodology of the invention can be more fully understood when read in conjunction with the schematic layout of a single Cell - as illustrated on Figure 1 where: 1. represents the Host System; which comprises any computing facility capable of running the control software: 2. represents the Master Unit; which includes a low voltage power supply unit; a micro-processor controller unit incorporating an analogue to digital converter; a signal generator; a transceiver; four phase comparators; and suitable co-axial, power and communication ports: 3. represents the Slave Units RXa, RXb, RXc and RXd; each of which includes a receiver; a mixer; a filter, a power and two co-axial ports; a low voltage feed from the Master Unit and a power regulator unit: 4a. represents an example of a Tag Device; which includes a low powered transceiver; a coded EPROM or similiar device; a battery(s); and a battery management device: 4b. represents an example of a Solar Tag Device; as described for 4a, but with an added solar cell and charging circuit where the polling activities might be more frequent; (such as for a security badge and/or paging system): 4c. represents an example of an Interface Tag Device; as described for either 4a or 4b, but with an added interface capable of generic hardware communication with other devices; (such as will accept readings from heat sensors or radio fields for example): 5. represents co-axial links each of the same length to the Slave Units: 6. represents hard wire low voltage power links to the Slave Units: 7. represents hardwire communication links to and from the Host System and the Master Units:and 8. represents additional hard wire communication links to and from other Cells in the System, if any.

13. Referring to Figure 1; all types of Tag Devices 4(a, b and c) incorporate power management techniques arranged to prolong battery life by providing a series of pre-set periods of complete shut-down. Otherwise the Tag Device 4 transceiver normally resides in a sleep mode and is only woken to an operational mode in response to the receipt of a unique code transmitted by a radio carrier signal 9 from the transceiver in the Master Unit 2 acting on a command prompt from the micro-processor controller unit - which in turn had acted on command received via Communication Link 7 that was originated from the Host System 1.

14. Whenever any Tag Device 4 transceiver has been woken to an operational mode it is arranged for it to transmit an encoded radio carrier signal 9 of its own for pre-defined time interval carrying its unique identification code and status data about the tag, as for example its battery condition, as well as the other forms of data, if any, determined to be relevant: followed, after a brief pause, for a further pre-defined time interval by bursts of a pure carrier signal 10; and then to resume the pre-set periods of complete shut-down.

15. Once the unique identification code, status and other encoded data, if any, of the response carrier signal 11 originating from the Tag Device 4 transceiver received by the transceiver at the Master Unit 2 is confirmed for signal quality it is decoded and passed to the micro-processor controller unit and stored.

16. It is also arranged - as illustrated by Figure 2 - for the bursts of pure carrier signals 10 originating from a Tag Device 4 transceiver that is received by each Slave Unit 3 receiver to be mixed with the continuous reference signal 12 received via Co-axial Links 5 from the signal generator at the Master Unit 2 and filtered to give an output 10.7 MHz signal 13 with its phase referenced to the phase of the pure radio carrier signal 10 received by the Slave Unit 3 from the Tag Device 4.

17. The resultant two component phased output signals 13 are then fed back from the Slave Unit 3 via a second Co-axial Link 5 to phase comparator units at the Master Unit 2 which generate from from these signals voltage outputs which are then fed to the analogue to digital converter section of the micro-processing controller unit. The analogue to digital converter converts these two component signals into positive or negative values and the micro-processor controller unit then carries out geometric calculations to a programme where an input to the analogue to digital convertor of 1 m/v equals one eighth of a degree and stores the outcome together with the other data that has been obtained for each of the Tag Devices 4.

18. As the differences between the respective two components of relative phased output signals 13 from each of the Slave Units 3 are effectively a measure of the displacement offset of the Tag Device 4 from an imaginary centre line between any pair of Slave Units 3, the x,y location co-ordinates of the individual Tag Devices 4 can be deduced from the results of these geometric calculations relative to an imaginary coordinated grid overlaying the Cell area.

19. This because the geometric calculations assume that - given a Tag Device 4 is located precisely in the middle of the intervening space - and the measured phase difference between Slave Units RXa and RXb is lp2 - pal), and the corresponding phase difference between RXb and RXc is (p3 - p2} - then the location of that Tag Device 4 is given by the calculation (p2-pl) = (p3-p2) = 0.

20. And, when a Tag Device 4 is located other than at the middle of the space - as illustrated in Figure 2 - and assuming the location of Slave Unit RXa is the origin of a coordinated grid; the location of a Tag Device 4 is given by calculating its x,y positioning from:

x = Q + n3-p2 2 360 and y = D + 2 \ 360 where D is the length of the assumed space in metres1 2 is the mixer wavelength in metres and (p3-p2), (p2-p 11 are the measured phase differences.

21. Moreover, as the relative phased output signals can take on both positive and negative values depending on whether the Tag Device 4 signal leads or lags the reference signal, the x and y value(s) will alter accordingly to take account of locational differences relative to the said imaginary centre lines of the spaces.

22. When passed a request, or command prompt, from the Host System 1 via the generic communication link 7 the resultant x,y value that has been calculated from each individual Tag Device 4 that has been polled together with the outcome of other data readings can be sent from the microcontroller processing unit to the Host System 1 and stored.

23. With this method the invention will also allow extension and/or offsetting of the imaginary grid in order accommodate any curved or irregular building forms and/or non-rectangular Cell Area shapes; and provide a method of compensating for slight errors that are anticipated to occur at the edges of the Cell Areas.

24. Should changes in orientation of any object or item be anticipated which are considered necessary to measure and/or record then these can be identified by attaching to the object two Tag Devices spaced a suitable distance apart. Alternatively, an Interface type Tag Device can be utilised which incorporates readings either from a Hall Effect device or a Piezo device or from the phase comparison of the output signals from a suitably configured directional or omni-directional antennae.

25. Shouid any particular Tag Device 4 not be located in the Cell area being polled, the Tag Device 4 will be included in the poll of the next Cell in the series and, if necessary, subsequent Cells. Where it proves a Tag Device 4 cannot be located for any reason provision can be made for recording and/or reporting this.

26. Routines can be also included for confirming, detecting and/or determining any forms of corrupt, defective or suspect data at any stage so this can be recorded and/or reported upon; and arrangements incorporated to re-poll any specific Tag Device and/or groups or types of Tag Devices 4 on request, or by command, from the Host System 1.

27. Subsequently the confirmed data thus collected and stored by the Host System 1 can be reported upon and/or applied to a number of different purposes including tracing from the outcome of the x,y positional readings the locations, and/or movements, and/or positional changes, if any, of each of the individual Tag Devices 4 together with the objects, items, vehicles and/or the personnel to which they may be attached.

28. The Host System 1 would comprise any computer facility capable of executing the control software; and thus have the capacity to manage up to, say, 255 Cells. The Host System 1 could also be linked into a Network if desired and receive requests via this from other Host Systems of other installations.

Description of an embodiment of the invention 29. A practical embodiment of the invention is the utilisation of the identification, location, tracking and reporting capabilities within, for example, a building facilities management environment by polling the Tag Devices attached to various objects and/or items via the Infra-Structure of the invention.

30. For example; consider a building layout with a floor area of several thousand square metres in which a number of Cells have been arranged where the operating system utilises low powered radio signals with a frequency of up to 10 mW at, say, 433.92 MHz as the carrier and bursts of pure radio signals at, say, 423.92 MHz as the continuous reference signal to the Slave Units; and where tagged items, devices and sensors in the building have also been delineated as entities/objects (i.e. tables, chairs, desks, outlets, sensors, equipment, etc.,) in the computer aided drawing file of the layout.

31. The outcome of routinely polling the coded Tag Devices and reading, processing and storing the data as described before would allow for the Host System to identify, monitor, and track by comparison and/or log the relative movement, if any, of any objects to a theorectical accuracy of 9 mm. by radio. This, for example, enables the computer aided drawing file and any related and other database to be up-dated without it being essential to inspect the premises physically.

32. Other coded tagged sensors and control devices related to mechanical engineering and services infra-structure - as, for example, attached to controls and/or sensors and/or apparatus or appliances relating to functions such as heating, ventilation, air conditioning, fire alarms, communication, security and of survelliance systems - can also be routinely polied by radio so avoiding the need for either installing costly hardwired control systems initially or carrying out extensive rewiring exercises when material changes are made to layouts. Something of particular advantage when frequent changes and/or long runs are involved and time is at a premium.

33. A particular example being for an interface Tag Device to be attached to all hot water valves and tap outlets so that compliance with future EU regulations can be monitored and maintained with regard to the temperature control of the hot water supply.

34. Other applications, for example, would be automatic maintainance of inventories - whereabouts of nearest fire extinguishers - luggage monitoring - security access - and fire prevention.

35. Tracking virtually every movable object within a pre-determined area and its location(s) beyond and/or out of that area can also be achieved by taking the positional readings from the Tag Devices at suitable time intervals dependent on the parameters required.

36. With these facilities numerous applications of the ability of the invention to locate objects and people become possible - including a means and method of tracing and/or tracking and/or identifying and/or positional reading location data at time intervals sufficient to allow the tracking of and recording the movement of individual Tag Devices can be introduced - of which some examples given below are in no way exhaustive.

37. One such is where service vehicles, containers, pallets, carts, trucks, waggons, barrows and trolleys might be provided with Tag Devices, or Solar Tag Devices, so that they be located and identified and/or their usage tracked; as, for example, the tracking of the pattern of movements taken by supermarket trolleys.

38. Moreover; the facilities of the invention could be extended to include incorporating Solar Tag Devices into Personnel Badges which can then be tracked - which could also support a low cost pager and messaging system for staff.

39. Furthermore; the capacity of the system could be increased substantially by various types of Tag Devices each using different radio bands.

40. The information could also be utilised for automatic control and dynamic re-programming of facilities such as re-directing telephone calls to an extension nearest to the intended recipient, or configuring computers and workstations to current users personal requirements.

41. Also, physical access to buildings and facilities, and access to computers, can be controlled and the system configured, for example, to control the locking and unlocking of doors.

42. Special Tag and/or Badge Devices to accommodate each one of these functions could then be developed to suit every one of the requirements of individual situations - the data from which could be arranged to be read by radio via the infra-structure of equipment, apparatus and method of operation claimed by the invention described herein.

43. Then, given the provision of an appropriate Computer Facility Host System and suitable software, a plethora of useful applications of the invention become possible for which the System can be tailored to suit the particular use(s) to which it is to be applied.

Claims (40)

The Claims.

1. The invention of a System of equipment, apparatus and devices1 and an operating methodology which form an Infra-Structure comprising a Master Unit with four Slave Units arranged as a Cell connected to Host System - which are linked by generic hardware - that will on request, or command prompt, poll a plurality of uniquely encoded Tag Devices of differing types in series by low powered radio signals of up to 10 mW operating at up to 500 MHz and receive back, process and store any relevant data output in response from the Tag Devices; (which may, of course, be attached to items or objects or sensors or apparatus or persons or vehicles or animals or other appliances): that is also able to locate their positioning by using a technique involving the phase comparison of a referenced radio signal with that of a pure radio carrier signal received from the tag.

2. A System according to claim 1; whereby the Host System comprises any computing facility capable of executing the control software.

3. A system according to claim 1 and 2; whereby, based on the effective range of low powered radio devices of up to 10 mW operating at up to 500 MHz, the Cell would be some twenty five metres square or a like pre-determined area of various geometric shapes.

4. A system according to any of the claims 1 to 3; whereby the capacity and/or scope of the system is increased by utilising different radio bands and added transceivers in tandem.

5. A system according to the claims 1 to 4; whereby it is arranged that there are a plurality of such Cells - which (based on the effective range of the low powered radio devices) will each range in size up to, say, twenty-five metres square or a series of like pre-determined areas of various geometric shapes and/or at different levels as conveniently arranged within the curtilage of a building or site, or some part or parts of a building or site, and/or a land area of limited extent - where each Cell will have a Master Unit and four Slave Units.

6. A System according to claim 5; whereby adjoining Cells may share Master Units and/or Slave Units depending on the specific geometric configuration of the Cell Areas.

7. A system according to claims 5 and 6; whereby the Host System comprises any computer facility capable of executing the control software having the capacity to manage up to, say, 255 Cells per Host.

8. A System according to any of the claims 1 to 7; whereby the Host System of the invention is interlinked with a Network System and can receive requests via this from other Host Systems of other installations.

9. A System according to claims 1 to 8; whereby the Master Unit(s) includes a low voltage power supply unit with hardware links to each Slave Unit; a transceiver; four phase comparators; a micro-processor controller that incorporates an analogue to digital convertor capable of carrying out geometric calculations to a programme where an input to the analogue to digital convertor of 1 m/v equals one eighth of a degree; and a signal generator capable of sending continuous reference signals via co-axial links: and the Slave Units include a transceiver; a mixer; a filter; two co-axial ports and a low voltage power port; and a voltage regulator unit.

10. A system according to claims 1 to 9; whereby power is fed continuously via hardwire links from the low voltage power supply unit at the Master Station to the voltage regulator unit at each of the Slave Units; and the reference signal from the low powered signal generator is fed continuously to each mixer at the Slave Units; via co-axial links each of the same length.

11. A System according to claims 1 to 10; whereby the Tag Devices include a low powered transceiver; a coded EPROM or similiar device; a battery and a battery management device to prolong battery life which incorporates arrangements to provide a series of complete shut-downs for pre-set periods and otherwise for the transceiver to reside in a powered down sleep mode that is only woken to an operational mode in response to being polled by a uniquely encoded radio signal from the Master Unit transceiver acting on a request, or command prompt, from the micro-processor controller unit which was originated via a communication links from the Host System.

12. A system according to claims 1 to 11; whereby - whenever any Tag Device transceiver has been woken to an operational mode - it is arranged for it to transmit an encoded radio carrier signal of its own for pre-defined time interval carrying a unique identification code and status data about the tag, as for example its battery condition, as well as other forms of encoded data, if any, that is determined to be relevant followed, after a brief pause, by bursts of a pure carrier signal for a further pre-defined time interval; and then to resume the series of pre-set periods of complete shut-down.

13. A system according to claims 1 to 12; whereby a Solar Tag Device type includes an added Solar Cell and charging circuit.

14. A system according to claims 1 to 12 and/or 13; whereby an Interface Tag Device type includes an added interface with suitable ports capable of communication with other devices.

15. A system according to claims 1 to 12 and/or 13 and/or 14; whereby two Tag Device spaced apart are attached to any item or object in order to provide an arrangement for determining the relative orientation of an items or object.

16. A system according to any of the preceeding claims 1 to 15; whereby a Tag Device also incorporates an added device for determining its relative orientation by readings taken from, for example, either a Hall Effect device or a Piezo device or from the comparative measure of the phase differences between attennae output.

17. A system according to claims 1 to 16; whereby, once the unique identification code and status data as well as any other encoded data, if any, from the Tag Device transceiver that is received by the transceiver at the Master Unit and its signal quality confirmed, it is then passed to the Master Unit micro- processor controller unit for decoding and processing and, if found to be satisfactory for the intended purposes, stored.

18. A system according to claims 1 to 17; whereby it is also arranged for the further bursts of pure carrier signals originating from a Tag Device transceiver received by each Slave Unit receiver to be mixed with the continuous reference signal received from the signal generator at the Master Unit and filtered to give a 10.7 MHz signal output with its phases referenced to the phase of a radio carrier signal received from the Tag Device.

19. A system according to claims 1 to 18; whereby the resultant two component signal output from the mixers is arranged to feed back via second co-axial links to phase comparator units at the Master Unit which generate from these signals voltage outputs which then feed to the micro-processing controller that incorporates an analogue digital converter; and where the analogue to digital converter then converts these signal into positive and negative values and the micro-processor controller carries out geometric calculations to a programme where an input to the analogue digital convertor of 1m/V equals one eighth of a degree; and stores the outcome.

20. A system according to claims 1 to 19; whereby, it being so that the differences between the respective relative phased output signals from each of the Slave Units are effectively measures of the displacement offset of the Tag Device from an imaginary centre line between any pair of Slave Units, the x,y location co-ordinates of the individual Tag Devices relative to the Slave Units are determined by geometric calculations which assume that - where a given Tag Device is located at the precise middle of the intervening space and the measured phase difference between Slave Units in the x,x plane is tp2 - p 1), and the corresponding phase difference between Slave Units in the y,y plane is (p3 - p2) - the location of that Tag Device is given by the calculation (p2-pl) = (p3-p2) = 0.

21. A system according to claims 1 to 20; whereby the geometric calculations assume that - where a given Tag Device is located other than at the precise middle of the space and assuming one Slave Unit is located at the origin of a coordinated grid system then the location of that Tag Device is given by calculating its x,y location from:

x =LZ +k (p3-p2 2 360 and y= n +h 1 02-01\ 2 360 where D is the length of the assumed space in metres, 2 is the mixer wavelength in metres and tp3p2), (p2-p 1) are the measured phase differences.

22. A system according to claims 1 to 21; whereby, as the relative phased output signals takes on both positive and negative values depending on whether the Tag Device signal leads or lags the reference signal, the calculations of x and y values will alter accordingly to take account of locational differences relative to the said imaginary centre lines of the space(s).

23. A System according to claims 1 to 22; which also provides a method of compensating for slight errors that are anticipated to occur at the edges of the Cell Areas.

24. A System according to claims 1 to 25; which also allows for the extension and/or offsetting of the imaginary grid in order accommodate any curved or irregular building forms and/or non- rectangular CelI Area shapes.

25. A system according to claims 1 to 24; whereby the x,y coordinate outputs from the calculations and the identification coding, status and other data received from the Tag Devices via the Master Unit transceivers is aggregated and stored in the Master Unit micro-processor controller.

26. A system according to claims 1 to 25; whereby arrangements are incorporated for any corrupt, defective or suspect data at any stage to be confirmed, detected, and/or determined and then recorded and/or reported upon; and routines arranged to re-poll Tag Devices on request, or by command, from the Host System.

27. A system according to claims 1 to 26; whereby, when passed a request, or command prompt, from the Host System via the hardware communication link the resultant x,y value that is calculated from each individual Tag Device in the Cell Area that has been polled together with the outcome of other confirmed data readings can all be transferred from the micro-processor controller unit in the Master Unit to the Host System and stored.

28. A system according to claims 1 to 27; whereby, when passed a request, or command prompt, from the Host System via the hardware communication links the resultant x,y value that is calculated from every individual Tag Device in each and every Cell Area that has been polled together with the outcome of other confirmed data readings can ali be transferred in series from all the micro-processor controller units in the Master Units to the Host System and stored.

29. A system according to claims 1 to 28; whereby the data thus collected can be reported upon and/or applied to a number of different purposes including tracing the outcome of the x,y positional readings, andlor movements, and/or positional changes, if any of individual Tag Devices; together with the objects, items, vehicles and/or personnel to which tags may be attached.

30. A system according to any of the preceeding claims; which also provides a means and method of tracing and/or tracking and/or identifying and/or reading data at intervals from Interface Tag Devices relating to mechanical engineering and services infra-structure as, for example, attached to controls and/or sensors and/or apparatus relating to functions such as heating, ventilation, fire alarms, air conditioning, communication and survelliance systems.

31. A system according to any of the preceeding claims; which also provides for such other applications as, for example, the automatic maintenance of inventories - the whereabouts of nearest fire extinguishers - luggage monitoring - controlling security access - the monitoring of fire prevention related alarms - and communication systems.

32. A System according to any of the preceeding claims; which also provides a means and method of tracing and/or tracking and/or identifying and/or reading location data at sufficient accuracy outcome to the computer database(s).

33. A System according to any of the preceeding claims; which provides a means and method of tracing and/or tracking and/or identifying and/or reading location data at sufficient accuracy to apply the outcome to the updating of computer aided layout drawing files and their related databases.

34. A system according to any of the preceeding claims; which also provides a means and method of tracing and/or tracking and/or identifying and/or positional reading location data at time intervals sufficient to allow the tracking of and/or recording the movement(s) of the individual Tag Devices.

35. A system according to any of the preceeding claims; whereby Tag Devices are incorporated into Personnel Badges which can then be located and tracked.

36. A System according to any of the preceeding claims; whereby location information can be utilised for automatic control and dynamic programming of facilities such as re-directing telephone calls to an extension nearest to the intended recipient, or to configure computers or workstations to current users personal requirements.

37. A System according to any of the preceding claims; whereby a low cost pager and messaging system for staff can be supported.

38. A System according to any of the preceeding claims; whereby physical access to buildings and facilities, and/or access to computers and other equipment and/or items requiring security provisions, can be controlled: and where the system could also be configured, for example, to control the locking and unlocking of doors.

39. A System according to any of the preceeding claims; whereby service vehicles3 containers, pallets, carts, trucks, waggons, barrows and trolleys may be provided with Tag Devices so that they may be located and identified and/or their usage tracked; as, for example, the paths taken by supermarket trolleys.

40. An Infra-Structure and System substantially as here-in-before described by any and/or all of the preceeding claims for polling and reading data from Tag Devices by low powered radio which is also able to locate their relative positions to a degree of accuracy within specified physical boundaries using a technique involving the phase comparison of a referenced radio signal with that of the pure carrier signal received from the Tag Device transceiver.