AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Innovation Patent Applicant: Technological Resources Pty. Limited Invention Title: A MINE OPERATION MONITORING SYSTEM The following statement is a full description of this invention, including the best method for performing it known to us: - 2 A MINE OPERATION MONITORING SYSTEM Field of the Invention 5 The present invention relates to a mine operation monitoring system for monitoring and/or controlling equipment at a plurality of mine operations. Background of the Invention 10 It is known to provide a mine operation such as a mine site with a monitoring station arranged to facilitate control and/or monitoring of mine equipment by mining personnel. 15 However, with such a monitoring station it is necessary for operators to travel to the mine operation, which can be expensive for mining operators and, moreover, the mine operations are often disposed at relatively remote 20 locations, which is undesirable for many operators. In addition, with the current arrangement wherein a monitoring station is provided at each mining operation, it is difficult for a mining company to holistically 2S manage several mining operations. Summary of the Invention It will be understood that in the present specification a 30 mine operation means any operation or facility associated with extracting, handling, processing and/or transporting bulk commodities in a resource extraction environment or part of such a process, for example mine sites, rail facilities, port facilities, and associated 35 infrastructure. In accordance with a first aspect of the present 444429820381 (GHMatters) P81117.AU.4 - 3 invention, there is provided a mine operation monitoring system comprising: a plurality of equipment interfaces, each equipment interface being located at a mine operation and being 5 associated with at least one item of equipment, and each equipment interface being arranged to monitor and control operation of the at least one associated item of equipment; and a local monitoring station disposed locally relative 10 to the mine operation and arranged to communicate with at least one of the plurality of equipment interfaces so as to monitor and control operation of the at least one item of equipment associated with the at least one equipment interface from the mine operation; is the system being arranged to communicate with a remote monitoring station remotely located relative to the mine operation at a remote monitoring facility such that the at least one item of equipment associated with the mine operation is monitorable and controllable from the 20 remote monitoring facility. In one embodiment, the local monitoring station is arranged to facilitate control of the at least one associated item of equipment, and the system is arranged 25 to receive control commands for controlling operation of the at least one item of equipment from the remote monitoring station. In one embodiment, the system comprises a control server 30 arranged to receive control commands for the at least one item of equipment from the remote monitoring station and/or the local monitoring station, and to generate control signals for controlling operation of the at least one item of equipment in response to the control commands. 35 In one embodiment, the control server is arranged to send operational data indicative of operation of at least one 44443764887_1 (GHMalers) P81117.AU.4 -4 item of equipment to the local monitoring station and/or to the remote monitoring station. Brief Description of the Drawings 5 The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic conceptual diagram 10 illustrating a plurality of mine operations and components of a mine operation monitoring system according to an embodiment of the present invention; Figure 2 is a block diagram illustrating a mine operation monitoring system according to an embodiment of 15 the present invention; Figure 3 is a diagrammatic representation showing components of the mine operation monitoring system disposed at a mine operation; Figure 4 is a diagrammatic representation showing 20 components of the present invention disposed at a central monitoring facility; Figure 5 is a diagrammatic representation of an example screen displayed to an operator at a monitoring station at a mine operation or at a central monitoring 25 facility Figure 6 is a conceptual diagram illustrating an example layout of components of the present invention disposed at the central monitoring facility; Figure 7 is a diagrammatic representation of an 30 example wide area network configuration which may be used in an embodiment of the present invention; Figure 8 is a software architecture diagram illustrating storage and handling of data in the mine operation monitoring system; and 35 Figure 9 is a conceptual diagram illustrating a mine operation including an audio messaging system of a mine operation monitoring system according to an embodiment of 44442982038_1 (GHMatters) P811 17.AU-4 -5 the present invention. Description of an Embodiment of the Invention 5 An example conceptual diagram 10 illustrating relationships between mine operations and a central monitoring facility 18 is shown in Figure 1. In this example, the mine operations comprise mine sites 12, a port facility 14 and a rail facility 16, although it will 10 be understood that the invention is applicable to any operation associated with extracting, handling, processing or transporting bulk commodities in a mining environment. In this example, the central monitoring facility 18 is 15 remotely located relative to the mine sites 12, the rail network 16 and the port facility 14. Typically, the central monitoring facility 18 is situated at a significant distance from the mine sites 12, the rail network 16 and the port facility 14 such that it is 20 impractical for daily commuting by operators via road or rail to the mine sites, the port facility and the rail network, for example a distance exceeding 250km. The conceptual diagram 10 shows a plurality of mine sites 25 12 which may be of open pit or underground type. The mine sites 12 typically produce a single bulk commodity, such as iron ore, coal or bauxite, and are serviced by the rail network 16 comprising rail lines 20 that transport the bulk commodities produced at the mine sites 12 to a port 30 facility 14, or other facility incorporating a stock yard 29 for storage and/or processing of the bulk commodities. Each mine site 12 has an associated locally disposed monitoring facility 22, the rail network 16 has an 35 associated locally disposed rail monitoring facility 24 and the port facility 14 has an associated locally disposed port monitoring facility 26. Each local 444429820381 (GHMatters) P81117.AU.4 - 6 monitoring facility 22, 24, 26 communicates with a regional communications network 25 that in turn communicates with the central monitoring facility 18 via a wide area network (WAN) 28. The central monitoring 5 facility 18 may be in communication with a metropolitan area network (MAN) 30 connected to the WAN 28. The monitoring facilities 22, 24, 26 incorporate operator monitoring stations from which operators may monitor, 10 activate, deactivate and control operation of plant and equipment at the mine sites 12, the rail network 16 and the port facility 14. The central monitoring facility 18 incorporates a remote monitoring station for each mine operation 12, 14, 16. 15 The system may also include a data warehousing facility 19 in networked communication with the mine operations 12, 14, 16 and the central monitoring facility 18. The data warehousing facility 19 may be arranged to receive at 20 least some operational data from the mine operations 12, 14, 16 and store the operational data in a data warehouse. The operational data stored in the data warehouse may be subsequently retrieved by the central monitoring facility 18. 25 In operation, each mine site 12 typically has daily, weekly, monthly and annual schedules for mining of ore and waste. Transportation of ore from each of the mine sites 12 to the port facility 14 is typically scheduled 30 according to the daily, weekly and monthly schedules of the various mine sites 12. A stock yard 29 receives ore from the rail network 16 at a train load out facility 32 which places the ore onto conveyors 34 that in turn route the ore to a designated stock pile 36. The placement of 35 ore onto the stockpiles 36 is scheduled so that the ore from the various mine sites 12 is blended to produce a uniform product prior to loading onto ships 38 at the port 444429820381 (GHMatters) P81117.AU.4 -7 facility 14. Alternately, the stock piles 36 may be blended into various qualities of ores, such as high grade ore and low grade ore or ore with specific characteristics. Alternately, ore may be blended at each 5 mine site 12 prior to railing so that each mine site 12 produces a specified average grade of ore that is then railed to the port facility 14. Under these conditions the ore is routed from the train load out facility 32 to a designated stock pile 36 without further blending. 10 In one embodiment, some operational data from each mine site 12, from the rail network 16 and from the port facility 14 is displayed centrally at the central monitoring facility 18. Preferably, the operational data is for central display at the central monitoring facility 18 is updated at a rate that is at least an order of magnitude slower than the rate at which data at the operator monitoring stations is updated. This reduces, and preferably minimises, the bandwidth requirements 20 between the central monitoring facility 18 and the mine sites 12, the rail network 16 and the port facility 14. Alternately, or in addition, some or all of the data for central display is sourced in association with the relevant monitoring stations so that bandwidth 25 requirements of the communications network between the central monitoring facility 18 and the mine sites 12, the rail network 16 and the port facility 14 is reduced, and preferably minimised. 30 Plant and equipment at each mine site 12, within the rail network 16, and at the port facility 14 (including the stock yard facility 29) can be monitored and controlled from the local monitoring stations at the local monitoring facilities 22, 24, 26 and from the remote monitoring 35 stations at the central monitoring facility 18. 44442982038_1 (GHMatters) P81117.AU.4 - 8 The remote monitoring stations at the central monitoring facility 18 may be used to transmit operating commands to plant and equipment located at the mine sites 12, within the rail network 16 and at the port facility 14 (including s the stock yard facility 29) via a communications network that includes the MAN 30, the WAN 28, and regional networks 25. Plant and equipment transmit operational data to the remote monitoring stations which in turn display the operational data on display screens for 10 operators of the remote monitoring stations. In a typical arrangement, plant and equipment servers located on site at the mine monitoring facility 22, the rail monitoring facility 24 (or other suitable location 15 within the rail network 16) and at the port monitoring facility 26 (or other suitable location) receive operating commands from the operator monitoring stations. The plant and equipment servers translate these operating commands into signals which may be implemented by the relevant item 20 of plant / equipment associated with the signal and operating command or which may be received by an equipment interface such as a PLC which then instructs the plant / equipment to implement the command. In addition, the plant / equipment transmit operating signals to the 25 relevant server which in turn transmits operational data to the monitoring stations for display on terminals of the monitoring stations. The operational data displayed on the terminals provides the operator(s) of the monitoring station(s) with information indicative of the operational 30 status of the relevant plant and equipment. Location of the plant and equipment servers and operator monitoring stations locally at the mine sites 12, the port facility 14 and the rail network 16 allows the plant and 35 equipment to be monitored, operated and controlled locally in the event of an interruption to communications between 44442982038_1 (GHMatters) P81117.AU.4 -9 the central monitoring facility 18 and any of the various mine, port and rail monitoring stations 46. Location of the plant and equipment servers locally at the s mine sites 12, the port facility 14 and the rail network 16 also ensures that network overheads are not too large during use. In circumstances wherein the central monitoring facility 10 18 communicates with the mine monitoring, rail monitoring and port monitoring facilities 22, 24, 26 over a corporate network that also carries e-mail, and other non-time critical data traffic, it is preferable that the operating commands transmitted from the remote monitoring stations is to plant and equipment servers and operational data received from the plant and equipment servers occur in real time or near real time such that an operator located at the central monitoring facility 18 perceives an average system response time between transmitting operating 20 commands and seeing operational data displayed in response is less than 2.0 seconds. Preferably the delay is less than 1.5 seconds and preferably less than 1.0 seconds. A particular embodiment of the mine operation monitoring 25 system 10 for the mine operations 12, 14, 16 shown in Figure 1 will now be described with reference to Figures 2, 3 and 4 of the drawings. Each mine operation 12, 14, 16 includes equipment 40 which 30 may be distributed around the mine operation, and each item of mine equipment 40 is electronically monitorable and controllable by an equipment interface device, in this example a mine equipment controller 42 which may be in the form of a programmable logic controller (PLC). 35 The equipment 40 at a mine site 12 may include crushers, screens, conveyor belts, stackers & reclaimers, train load 44442982038_1 (GHMatters) P81117.AU 4 - 10 out facilities, mobile equipment including trucks and excavators. The equipment at the rail network 16 may include locomotives, track based signalling systems, points, wayside equipment and wayside signals. The s equipment at the port facility (including the stock yard 29) may include rail car unloading facilities, conveyor belts, stackers & reclaimers and ship loaders. However, it will be understood that any monitorable and/or controllable equipment for use in a mine operation is 10 envisaged. The equipment controllers 42 are each connected to a local network 44, which may be of LAN type. Also connected to the local network 44 is a control server 48 which is 15 arranged to coordinate control of the items of equipment by the local monitoring station 46. The equipment controllers 42 through the control server 48 are arranged to receive control signals from and send signals to a local monitoring station 46 disposed at the mine operation 20 12, 14, 16. As shown more particularly in Figure 3, each local monitoring station 46 includes a plurality of terminals 50, each of which is arranged to display information 25 indicative of and facilitate monitoring and/or control of different items of equipment 40 associated with the mine operation 12, 14, 16. For example, the terminals 50 may be arranged to enable mine personnel to monitor and control items of mine equipment 40 grouped by equipment 30 type, equipment location, or in any other way. In the present example, the terminals 50 are of thin client type and, as such, a terminal server 52 and a plurality of thin client devices 54 are provided. This 35 arrangement allows multiple computing devices to be realised without the need to provide multiple full function personal computers. With this arrangement, most 444429820381 (GHMatters) P81117.AU.4 - 11 of the processing activity occurs at the terminal server 52 with the thin client devices 54 functioning to drive the respective displays on the terminals 50 and receive inputs from terminal operators. 5 However, it will be understood that other arrangements are possible. For example, instead of providing each terminal 50 with a respective thin client device 54, a single thin client device may be provided to drive the multiple 10 terminals 50. As a further alternative, multiple full function computing devices may be used, the important aspect being that for each local monitoring station 46 sufficient computing terminals are realised for use by one or more operators in order to monitor and control the 15 equipment 40 over the local network 44. In the present example, the terminals 50 communicate with the equipment 40 through the control server 48, with each terminal 50 being arranged to send communications to and receive communications from the control server 48 particular to 20 one or more different groups of equipment 40. Using the local monitoring stations 46, it is possible for operators located at a mine operation 12, 14, 16 to monitor and/or control mine equipment 40 associated with 25 the mine operation 12, 14, 16. Typically there are a number of operators at each mine site, each operator oversees and controls the operation of various items of plant and/or equipment. Typically, each operator has their own terminal 50, or set of terminals 50, from which 30 they monitor and control the various items of plant and equipment which they have responsibility for. These terminals 50, or set of terminals 50, are often located at different points around the mine and commonly are located in close proximity to the plant and/or equipment they 35 control. The local networks 44 at the respective mine operations 444429820381 (GHMatters) P81117.AU.4 - 12 12, 14, 16 are connected to a wide area network (WAN) 28, which may comprise the Internet, a dedicated wide area network (WAN), or any other suitable wide area communications network, and through the WAN 28 to the 5 central monitoring facility 18, in this example disposed remotely relative to all of the mine operations 12, 14, 16, for example at a metropolitan location. The central monitoring facility 18 comprises a network 62 10 which may be in the form of a local area network (LAN) in communication with the wide area network 28 and thereby with the respective local networks 44 at the mine operations 12, 14, 16. is The central monitoring facility 18 also comprises a plurality of remote monitoring stations 64, each of which in this example is associated with one of the mine operations 12, 14, 16. As shown in Figure 4, each remote monitoring station 64 is similar in configuration to a 20 local monitoring station 46 in that a plurality of terminals 66 are provided, each terminal 66 having an associated thin client device 68 and the thin client devices 68 communicating with a terminal server 70 through the network 62 in order to implement a plurality of 25 computing devices at each monitoring station 64. The remote monitoring stations 64 operate in a similar way to the local monitoring stations 46 in that a number of operators are able to use the terminals 66 associated with 30 a remote monitoring station 64 to monitor and/or control mine equipment, with each remote monitoring station 64 typically being associated with one mine operation 12, 14, 16 and thereby with equipment 40 associated with the mine operation 12, 14, 16. 35 By providing a local monitoring station 46 at each mine operation 12, 14, 16, and a plurality of remote monitoring 44442982038_1 (GHMatters) P81117 AU.4 - 13 stations 64 associated with the respective mine operations 12, 14, 16 and disposed at a single remote location, it is possible to monitor and control mine equipment 40 at all of the mine operations from the same remote location, or 5 to monitor and control the equipment 40 locally from the respective mine operations 12, 14, 16 if necessary, for example because communications between the mine operations 12, 14, 16 and the central monitoring facility 18 have broken down or deteriorated to the extent that monitoring 10 and/or control from the central monitoring facility is not feasible. By disposing all monitoring stations for the mine operations at the same location, significant cost savings 15 can be achieved, particularly if the central monitoring facility is disposed at a metropolitan location since the need for operators to travel to the mine operations, which are often at relatively remote locations, in order to carry out the monitoring and/or control operations is 20 reduced. An example screen 90 displayed to an operator at a terminal 50 disposed at a local monitoring station 22, 24, 26 or disposed at the central monitoring facility 18 is 25 shown in Figure 5. The screen 90 includes navigation controls 92 usable to display desired control and/or monitoring screens associated with one or more items of plant and /or 30 equipment. In the screen shown in Figure 5, a reclaimer is being monitored and controlled and a representation of the reclaimer 94 is shown on the screen. The representation 35 of the reclaimer 94 may be modified according to the operational status of the reclaimer. For example, the colour of the reclaimer may change depending on whether 444429820381 (GHMatters) P81117.AU.4 - 14 the reclaimer is currently operating or on stand-by. The representation of the reclaimer 94 may also show that the reclaimer is functioning by showing parts of the reclaimer moving. 5 The screen 90 also shows an operational data display area 96 including relevant operational data 97 indicative of the current status of the reclaimer such as the reclaim rate, speed of bucketwheel, maintenance information, and 10 so on. The screen 90 also shows a control display area 98 including control buttons 99 usable to modify operational parameters, such as speed of bucketwheel, to turn the 15 reclaimer on or off, and so on. In this example, the screen 90 displayed to an operator is implemented using a web browser arranged to communicate with control servers 48 associated with the mine 20 operations 12, 14, 16. As shown in Figure 2, in this example each mine operation 12, 14, 16 also has one or more associated VOIP devices 80, each of which is capable of communicating with a VOIP 25 device 82 disposed at the central monitoring facility, the VOIP devices 80, 82 being usable by personnel located at the mine operations 12, 14, 16 and at the central monitoring facility 18 to communicate with each other through the wide area network 28 as required. 30 The system 10 in this example also includes an A/V server 84 disposed at each mine operation 12, 14, 16, the A/V server 84 being associated with an A/V client 86 disposed at the central monitoring facility 16 and arranged to 35 communicate with the A/V servers 84 so as to receive audio/visual information from the mine operations 12, 14, 16, and in particular video information for displaying at 44442982038_1 (GHMatters) P81117.AU.4 - 15 the central monitoring facility 18, for example on a common display 88. For this purpose, the A/V server 84 may communicate with one or more still and/or video cameras disposed at selected locations at the mine 5 operation 12, 14, 16 for example so that the status of particular activities occurring at the mine operations 12, 14, 16 may be visually monitored from the central monitoring facility 18. 10 In one arrangement, the cameras are also controllable from the central monitoring facility 18 so that the direction and/or magnification of the cameras may be modified from the central monitoring facility 18. is The A/V servers 84 may use a multi-cast protocol to transmit video images to the central monitoring facility 18. Typically, each remote monitoring station 64 accommodates a number of operators each with a number of terminals. Each operator may view simultaneously several 20 video feeds of the plant and/or equipment they are controlling. A number of the operators at a remote monitoring station 64 may have a number of the same video feeds open on their terminals at the same time in order to effectively monitor and control the plant and/or equipment 25 they are responsible for. The video feeds also enable operators to be aware of upstream and downstream activities within the operations they are controlling. Use of a multi-cast protocol in the transmission of video images from the mine operations to the central monitoring 30 facility avoids unnecessary duplication of images and therefore unnecessary utilisation of bandwidth over the WAN 28. In order to improve the reliability of communications 35 between the central monitoring facility 18 and the mine operations 12, 14, 16, the system 10 may incorporate quality of service measures such as prioritizing 444429820381 (GHMatters) P81117 AU.4 - 16 communications through the WAN according to type. In the present example, communications related to monitoring and control activities, and VOIP communications 5 are given higher priority than CCTV data, email and file transfers. In an alternative arrangement, different types of communications are allocated different priority values 10 which are used by routers in the WAN to manage queues in the routers and thereby the speed of transfer of the communications through the routers. For example, the system may be arranged to allocate is different bandwidth percentages to different types of communications, such as to communications related to monitoring and control activities, VOIP communications, CCTV data, email, file transfers, and so on. 20 In one embodiment, priority values for each communication are allocated according to the IP addresses associated with the communication. For example, the IP addresses of all network enabled devices in the system 10 may be recorded in system network routers and the priority level 25 allocated by the routers according to the priority level recorded for the network addresses in the routers. In one example, all communications to or from a network enabled device outside the system 10, that is, having an IP address that does not appear in the routers, is allocated 30 the lowest priority level. In the present embodiment, in order to provide a degree of protection against system failure, multiple network connection arrangements 90 may be provided for connecting 35 the remote monitoring stations 64 with the wide area network 28 so that a backup network connection is available should one of the connections between the 44442982038_1 (GHMatters) P81117.AU.4 - 17 central monitoring facility 18 and the wide area network 28 fail. Similarly, a power backup arrangement is provided such 5 that should mains power 94 to the central monitoring facility 18 fail, the failure condition is detected by a suitable sensor 96 which actives a backup generator 98 to commence providing electrical power to the central monitoring facility 18. 10 For this reason, the central monitoring facility 18 according to the present embodiment may be located at, or in the vicinity of, an airport of the type which already comprises suitable backup communications and power 15 arrangements. The system 10 may also be arranged to monitor whether communications between the central monitoring facility 18 and the mine operations are reaching their destination, 20 for example by requiring a handshake to occur periodically between the central control facility 18 and the mine operations 12, 14, 16. In the present example, this is achieved by configuring the equipment controllers 42 to periodically send a heartbeat communication to an 25 associated remote monitoring station 64. on receipt of the heartbeat communication, the remote monitoring station is arranged to send a reply signal indicating that the heartbeat communication has been received. 30 If the reply signal is not received, an alarm signal may be generated to indicate to appropriate personnel that an outage may have occurred between the central monitoring facility 18 and one or more of the mine operations 12, 14, 16. 35 Referring to Figure 6, a conceptual layout of the central monitoring facility 16 is shown. In this example, two 44442982038_1 (GHMatters) P81117 AU.4 - 18 mine operations 12a, 12b, one port operation 14, and a rail network 16 are monitored and controlled from the central monitoring facility 18, with the port operation, rail network and each mine site having an associated 5 separate monitoring station 64a, 64b, 64c, 64d and associated respective terminals 66a, 66b, 66c, 66d. A display 88 is provided that is of a sufficiently large size such that information, such as data, images and/or 10 video shown on the display is easily viewable by all operators associated with the remote monitoring stations 64, and in this example the common display 88 is separated into a plurality of display areas 100, each of which is associated with a different aspect of the mine operations. 15 In this example, each of the mine sites 12 and the port facility 14 has a dedicated remote monitoring station 64a, 64b, 64c such that plant and equipment associated with the port facility 14 or with a particular mine site 12 may be 20 monitored and controlled from one monitoring station 64a, 64b, 64c. Similarly, the rail network 16 may be monitored from a single monitoring station 64d. A conceptual diagram of a wide area network 102 which may 25 be used with the present invention is shown in Figure 7. The diagram shows interconnected nodes, including mine operations 12, 14, 16, metropolitan offices 104 and the central monitoring facility 18. In order to improve reliability of the WAN 102, each node in the network is 30 connected to at least two other nodes, and in some cases to four other nodes using respective communications links 106 so that should one or more of the communications links fail, traffic may be re-routed through other nodes and other communications links which are still active. 35 The operational data indicative of the operational status of equipment at the mine operations may be derived 44442982038_1 (GHMatters) P81117.AU.4 - 19 directly from the equipment interfaces associated with the equipment, and/or at least some of the operational data may be stored in a common database or in a plurality of associated databases which may be disposed at the same or 5 different locations and extracted as required. An example of a data storage and distribution infrastructure 120 used in the present monitoring system is shown in Figure 8. 10 The infrastructure 120 includes a data source layer 122 having a plurality of databases 124, each of which is arranged to derive data from one or more sources from one or more mine operations, and an extraction/transformation 15 layer 126 arranged to act on the data in the databases to produce data of suitable type for storage in a common data warehouse 128 in a data warehouse layer 130. The data in the data warehouse 128 is organized into data cubes at a cubes layer 132 such that near real-time pre 20 aggregated and highly indexed data is produced. This allows for sub second response times to queries. The infrastructure 120 also includes a presentation layer 134 arranged to serve data in the data cubes to users on 25 request, and a user front end layer 136 which comprises the common display and the terminals 66. The presentation layer 134 may be implemented using web browsers or any other suitable interface arranged to communicate with the presentation layer 134. 30 Referring to Figure 9, there is shown a mine operation which includes an audio messaging system usable to transfer audible messages between personnel 140 at the mine operation and personnel at the central monitoring 35 facility 18. The audio messaging system includes an audio device, for example in the form of a handset 142, disposed at the central monitoring facility 18 and in this example 44442982038_1 (GHMatters) P81117.AU.4 - 20 arranged to interface with a remote monitoring station 64 at the central monitoring facility 18. Audio captured by the handset 142 is communicated through the wide area network 28 to the mine operation and at the mine operation s is converted to an analogue signal which may be used by a radio transmitter 146 to drive one or more radio antennas 148. In this example, several radio antennas 148 are provided, with each radio antenna connected directly to the radio transmitter 146. However, other arrangements io are possible. For example, the radio transmitter 146 may connect to one radio antenna 148, with the other radio antennas configured so as to repeat the received signal. The transmitted radio message is receivable by all radio equipped handsets carried by the mine personnel 140. is Similarly, audio received by a radio handset carried by a person at a mine operation is received by a radio antenna 148, is converted to suitable digital signal and communicated through the wide area network 28 to the central monitoring facility 18 and to the handset 142. 20 In this way, it is possible for an operator at the central monitoring facility 18 and one or more people at a mine operation to send audio messages to each other in a cost effective simple way. 25 In the present example, each remote monitoring station has an associated handset usable to communicate with personnel at a mine operation. However, it will be understood that other arrangements are envisaged. For example, the 30 central monitoring facility 18 may be provided with one or more common handsets configured to communicate with any mine operation. It will be understood that communications between network 35 enabled devices on the system may be communicated in a unicast or multicast way depending on communication type. For example, A/V communications and communications 44442982038_1 (GHMatters) P81117.AU.4 - 21 associated with the audio messaging system may be communicated in a multicast way such that any IP address associated with the system is able to receive the communication. Alternatively, communications such as from 5 an equipment interface to the central monitoring facility may be communicated in a unicast way. Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the 10 present invention. 44442982038_1 (GHMatters) P811 17.AU.4