Patent Publication Number: US-2010127853-A1

Title: Method and apparatus for locating and tracking objects in a mining environment

Description:
TECHNICAL FIELD 
     This invention relates to systems and methods for locating and tracking objects in general and more specifically to systems and methods for locating and tracking equipment and personnel in mining operations. 
     BACKGROUND 
     Modern mining operations are highly complex and involve the movement of a large number of machines and personnel within an environment that is constantly changing due to ongoing mining activity. Generally speaking, mine safety and productivity can be improved if the locations and movements of mining equipment and personnel can be accurately ascertained, and numerous systems have been developed in attempts to allow mining equipment and personnel to be located and tracked as they move throughout the mine. However, the potential benefits of such locating and tracking systems are tied the ability of such systems to accurately and reliably track the locations of mine personnel and equipment. Indeed, the failure of such locating and tracking systems to reliably and accurately report the locations of personnel and equipment can be detrimental to mine safety and productivity. 
     One type of position locating and tracking system that has been proposed for use in mines is an RFID tracking or gating system. Basically, an RFID tracking system uses a plurality of radio-frequency identification or RFID “tags” and “readers” to locate and track personnel and equipment within the mine. In one configuration, several RFID readers are installed at various locations throughout the mine so that they define a plurality of zones or areas between adjacent readers. When an object having a tag closes within range of a reader, the reader detects the tag. The system is able to determine the location of the tag, thus object, based on the particular tag and on the particular reader that detected the tag. By sensing the passage of a tag, the readers thus serve as gates to the various zones, allowing the system to locate and/or track the tag as it moves from reader to reader (i.e., zone to zone). 
     While RFID tracking systems of the type just described have been proposed for use in mining operations, they are not without their problems. For example, while such tracking systems can track the whereabouts of objects provided with RFID tags by determining whether they have passed through the various gates defined by the RFID readers, such systems cannot provide information about the locations of objects within the zones defined between adjacent gates. If the distance between the gates is substantial, there will be considerable uncertainty as to the exact whereabouts of the object within the zone. 
     Another problem of RFID locating and tracking systems is that they are prone to erroneous location reporting if the object (e.g., person or vehicle) provided with the RFID tag happens to change direction in the vicinity of the RFID reader or gate. For example, if the object being tracked is traveling in an easterly direction when passing the gate, the system may report the incorrect location of the object if the object happens to change direction (e.g., reverse course) while in the vicinity of the gate. That is, the system may report the position of the object in the zone east of the gate, when the true location of the object will be in the zone west of the gate. Depending on the architecture of the particular RFID system, the position error will not be detected until the object passes another reader. 
     Another type of locating and tracking system that has been proposed uses a plurality of “position enabled” radio transceivers to provide locating and tracking information of various objects (e.g., equipment and personnel) carrying the radios. The radios are provided with position locating systems that allow the radios to determine their positions based on radio signals from other radio transmitters. For example, many radio-based locating and tracking systems require the use of global positioning system (GPS) signals to obtain and/or derive the required position information. Another type of tracking system derives position information from radio signals produced by other radios in the system, typically by measuring the time required for radio signals to travel between radios. 
     While such radio-based locating and tracking systems address some of the shortcomings associated with RFID gating-type tracking systems, they are not without their problems. For example, the GPS signals utilized by such systems often cannot be reliably obtained in mining environments, i.e., due to the fact that many mining environments will not allow line-of-sight contact with the number of GPS satellites required for accurate position fixes. In addition, GPS signals are not available underground, making such systems unsuitable for use in underground mines. 
     Still another problem associated with radio-based systems, particularly so-called “time-of-flight” radio systems, is that they are prone to multi-path radio interference and signal attenuation problems, both of which are exacerbated in mining environments, e.g., due to the presence of large geologic features and heavy mining equipment. In many cases, multi-path interference and signal attenuation problems degrade the performance of the system to the point where it becomes unusable. Still worse, even if the system appears to be functioning well, certain types of multi-path interference may not be detected and can result in false position fixes. That is, the positions of mining equipment and/or personnel will be erroneously reported. Moreover, the problems resulting from multi-path interference and signal attenuation problems are even worse in underground mining environments, again making such systems ill-suited for use in underground mines. 
     Still yet other problems with radio-based position tracking systems stem from latencies or time delays in determining and reporting the positions of objects within the mine. Such latencies may result from several sources, including signal modulation techniques, packet-based data transmission protocols, and data processing delays. In addition, other factors, such as multi-path interference, signal attenuation, and signal drop-outs, can also increase system latencies. If the latencies become large, they can result in substantial position reporting errors. In many cases, several seconds, or even tens of seconds, may elapse before the system is able to determine the position of a given object. In such instances, the position fix will not be the current position of the object, but rather the position of the object at some time in the past. In extreme cases, the latencies associated with such systems can result in position errors exceeding several tens or perhaps even hundreds of meters, particularly if the object being located is a moving vehicle. Furthermore, the latency problem tends to become worse as additional radios are added to the system, thereby reducing the likelihood that such systems can be successfully deployed in typical mining operations wherein it is desired to track many tens, and typically hundreds, of objects in the mine. 
     In addition to the issues described above, underground mining operations create additional difficulties in locating and tracking mining equipment and personnel. For example, and as already mentioned, GPS signals are not generally available underground, thereby disqualifying systems that require access to the GPS satellite system in order to provide accurate position fixes. Moreover, most time-of-flight radio systems are not well-suited for use in underground tunnels and drifts due to the signal attenuation and multi-path interference issues created by the tunnels and surrounding geology. 
     Consequently, the solution to the problem of accurately and reliably locating the positions of personnel and equipment in a mining environment is by no means trivial. The various systems and solutions proposed to date all involve numerous drawbacks and disadvantages that make them less then desirable for use in mining environments. 
     SUMMARY OF THE INVENTION 
     One embodiment of a method for locating and tracking objects in a mine may include: Selecting an operational area in the mine within which the locations of a plurality of objects are to be determined and tracked over time; providing a radio transceiver system to each of the plurality objects operating in the operational area; providing to each of the objects operating in the operational area a display system that is operatively associated with the radio transceiver system; operating the radio transceiver systems to form an ad-hoc, peer-to-peer network; determining the time-of-flight of radio signals exchanged between various ones of the radio transceiver systems; analyzing the time-of-flight of such exchanged radio signals to determine the relative positions of the various objects within the operational area; and displaying the relative positions of at least some of the various objects within the operational area on the display system. 
     A tracking system according to one embodiment of the invention may include a plurality of objects located within an operational area of a mine within which the locations of the plurality of objects are to be determined and tracked over time. A radio transceiver system operatively associated with individual ones of the plurality of objects includes: rf transceiver means for transmitting and receiving radio signals and processor means operatively associated with the rf transceiver means for determining a time-of-flight required for radio signals to be exchanged between various ones of the plurality of radio transceiver systems and for determining locations of various ones of the plurality of radio transceiver systems based on the time-of-flight of exchanged radio signals. A display system operatively associated with at least some of the plurality of radio transceiver systems is responsive to signals from the radio transceiver systems and displays the relative positions of at least some of the various objects within the mine. 
     Another disclosed method includes: Selecting an operational area in a mine within which the locations of a plurality of objects are to be determined and tracked over time; providing to each of the objects operating in the operational area a radio transceiver system; providing to each of the objects operating in the operational area a display system that is operatively associated with the radio transceiver system; operating at least one of the radio transceiver systems in a radar mode to determine a relative position of an object within the operational area; and displaying the relative position of the object within the operational area on at least one of the display systems provided to each of the objects. 
     Another embodiment of a tracking system may include a plurality of objects located within an operational area in a mine within which the locations of the plurality of mine objects are to be determined and tracked over time. A radio transceiver system operatively associated with individual ones of the plurality of mine objects includes: rf transceiver means for transmitting and receiving radio signals and processor means operatively associated with the rf transceiver means for operating said rf transceiver means in a radar mode to determine locations of objects in the operational area by means of radar, and for causing a plurality of said radio transceiver systems to form an ad-hoc, peer-to-peer network. A display system operatively associated with at least some of the plurality of radio transceiver systems is responsive to signals from the radio transceiver system and displays the relative positions of objects located within the operational area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative and presently preferred exemplary embodiments of the invention are shown in the drawings in which: 
         FIG. 1  is a schematic overhead topographic view of an open pit mine showing defined operational areas within which objects may be located and tracked by the system of the present invention; 
         FIG. 2  is an enlarged schematic overhead view of a portion of an operational area illustrated in  FIG. 1  showing an example arrangement of objects being tracked; 
         FIG. 3  is a schematic block diagram of one embodiment of a radio system that may be utilized in conjunction with the present invention; 
         FIG. 4  is a flow chart of a method for locating and tracking objects according to one embodiment of the invention; 
         FIG. 5  is a depiction of a situational display that may be provided on a display device associated with the locating and tracking system; 
         FIG. 6  is a time domain depiction of an ultra-wideband electromagnetic pulse produced by the radio transmitter portion of the radio system; 
         FIG. 7  is a frequency domain depiction of the ultra-wideband electromagnetic pulse illustrated in  FIG. 6 ; 
         FIG. 8  is a time domain depiction of an ultra-wideband symbol; 
         FIG. 9  is a frequency domain depiction of the ultra-wideband symbol illustrated in  FIG. 8 ; 
         FIG. 10  is a depiction of an operations center and network administrator system that may be utilized in one embodiment of the present invention; 
         FIG. 11  is a timing diagram illustrating relative timing of sent and received signals from two different radios “A” and “B;” 
         FIG. 12  is a pictorial representation of a triangulation technique that may be used to locate a position of a radio in two dimensions based on time-of-flight measurements from three other radio systems; 
         FIG. 13  is a schematic representation of another embodiment of a position and location system as it could be used in an underground mine; and 
         FIG. 14  is a depiction of a global situational display that may be provided on a display system located at a central operations center. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of a locating and tracking system are shown and described herein as they may be used to locate and track the positions of various objects (e.g., mining equipment and personnel) in various types of mines, including surface mines and underground mines. The locating and tracking system of the present invention solves many of the problems associated with prior art systems and may be used to advantage in a wide variety of mining environments and applications to enhance mine safety and productivity. In addition, various embodiments of the locating and tracking system may be configured so that the system also forms a communications infrastructure capable of transferring large amounts of data at substantial data rates. The ability to provide not only locating and tracking functions, but also ancillary data transfer functions via the communications infrastructure, provides additional utility and the opportunity for further enhanced mine safety and productivity, as described herein. 
     Referring now primarily to  FIGS. 1 and 2 , one embodiment of a locating and tracking system  10  is shown and described herein as it may be used to locate and track the positions of various objects  12 , such as mining equipment and personnel, operating within an open pit mine  14 . Briefly described, the tracking system  10  may comprise a plurality of radio transceiver systems  16  that are provided to (or associated with) the various objects  12  that are to be located and tracked. See  FIG. 2 . For example, if the objects  12  to be tracked comprise mining equipment, each piece of mining equipment is provided with a radio transceiver system  16 . Similarly, mining personnel (not illustrated in  FIG. 2 ) may also be provided with portable or hand-held radio systems  16  to allow their positions to be identified and tracked as well, i.e., regardless of whether such personnel remain with the mining equipment being tracked. 
     Turning now to  FIG. 3 , in one embodiment, each radio system  16  may comprise a radio-frequency (rf) transceiver  18  as well as a processor system  20 . The rf transceiver  18  may in turn comprise a transmitter section  22  and a receiver section  24 , both of which are configured to transmit and receive radio signals  26  in the manner that will be described in more detail herein. 
     The processor system  20  is operatively associated with the rf transceiver  18  and may be used to control the function and operation of the rf transceiver  18  to transmit and receive radio signals  26 . In addition, the processor system  20  may be programmed or configured to perform other functions as well. For example, in one embodiment, the processor system  20  is programmed or configured to determine a time required for radio signals  26  to be exchanged between the “host” radio  16  and various other radios  16 . Processor system  20  then determines the location of the “host” radio  16  based on the time-of-flight of the various exchanged radio signals  26 . Thus, each radio system  16  is capable of determining its particular position based on the time-of-flight of radio signals  26  received from other radios  16 . 
     In one embodiment, the radio signals  26  transmitted by the various radio systems  16  comprise ultra-wideband (UWB) radio frequency pulses  88  ( FIG. 6 ) having high intrinsic bandwidths and broad spectral energy distributions. The ultra-wideband (UWB) frequency pulses  88  provide robust wireless operation at extended ranges even in applications operating in high multi-path, non-line-of-sight environments. The ultra-wideband frequency pulses  88  may also be modulated in a way so as to provide the radio system  16  with low latency and high data rate transmission capabilities. 
     With reference back now to  FIG. 3 , each radio system  16  may also be provided with a display system  28 . The display system  28  may be used to display the relative positions of nearby objects  12  (e.g., mining equipment and personnel), thereby allowing mining equipment operators and personnel observing the display  28  to see at a glance the positions of nearby equipment and personnel (e.g., objects  12 ). The display system  28  may also be used to present other information that may be useful or beneficial to the various equipment operators and personnel viewing the display  28 , as will be described in further detail herein. 
     The system  10  may be operated in accordance with a method  30 , illustrated in  FIG. 4 , to locate and track objects  12  in a mining environment  14 . A first step  32  in method  30  may involve selecting or defining an operational area  34  in the mine  14  ( FIG. 1 ) within which the locations of the various objects  12  are to be determined and tracked over time. The next steps  36  and  38  in method  30  involve providing at least one radio transceiver system  16  (and associated display system  28 ) to each of the objects  12  that is to be tracked. See  FIG. 2 . After each desired object  12  has been provided with a radio transceiver system  16  and display system  28 , the various radios  16  may then be operated (e.g., at step  40 ) so that they form or create an ad-hoc, peer-to-peer network  42  (illustrated schematically in  FIG. 2 ). 
     The ad-hoc, peer-to-peer network  42  formed by the various radio systems  16  allows the various radio systems  16  to perform a variety of functions and operations, many of which are described herein and others of which will become apparent to persons having ordinary skill in the art after having become familiar with the teachings provided herein. For example, and as will be described in greater detail below, the ad-hoc, peer-to-peer network  42  provides a convenient means for implementing one or more time-of-flight position location algorithms to allow the locations of various ones of the radio systems  16  to be determined with a great deal of accuracy (e.g., in the centimeter range), and without requiring access to the Global Positioning System. The network  42  also provides a wireless communications infrastructure that allows other types of data to be transmitted to the various other radio systems  16  and/or to a central operations center  44 . See  FIGS. 1 and 10 . 
     Continuing now with the description of the method  30  illustrated in  FIG. 4 , step  46  involves operating some or all of the various radio systems  16  to determine the time required for radio signals  26  (e.g., illustrated in  FIG. 2 ) to be exchanged between various ones of the radio systems  16  in network  42 . The time-of-flight of such radio signals  26  is then analyzed at step  48  to determine the relative positions of the various radio systems  16 , thus objects  12 , within the operational area  34 . Step  50  involves displaying on display system  28  the relative positions of at least some of the objects  12  within the operational area  34 . 
     An example of relative position data that may be provided on display system  28  is illustrated in  FIG. 5 . Briefly, situational display  52  shows the locations of nearby objects  12  (in this example, the objects  12  illustrated in  FIG. 2 ). In one embodiment, the particular object  12  carrying radio system  16  may be displayed at the center of the situational display  52  as a “self” or “own equipment” icon  54 . In this example, the “self” or “own equipment” icon  54  corresponds to the haul truck  55  illustrated in  FIG. 2 . Accordingly, an operator (not shown) viewing the situational display  52  associated with his particular vehicle or person will see his vehicle or person (as the case may be) displayed at the center of the situational display  52  as the “self” or “own equipment” icon  54 . The particular object located at the center of the situational display  52  may be referred to herein in the alternate as the “center” object  12  to distinguish it from “surrounding” objects  12 . 
     In the particular operational scenario illustrated in  FIG. 5 , the center object  12  comprises the haul truck  55  (e.g., illustrated in  FIG. 2 ) and is represented by icon  54  located at the center of the situational display  52  in the manner just described. If the “center” object is moving, the direction of motion of the center object (i.e., represented by icon  54 ) may be indicated by an arrow icon  56  located adjacent icon  54 . In one embodiment, the direction of motion (and velocity) of each object  12  may be determined by analyzing the change in position data over time of each such object  12 . “Surrounding” objects  12  located nearby center object  12  (e.g., haul truck  55 ) may be represented with different icons depending on whether they are moving or stationary. For example, in the particular operational scenario illustrated in  FIG. 5 , stationary objects are represented by ring icons  58 , whereas objects in motion are represented by solid circle icons  60 . Alternatively, icons having other shapes and configurations may be used to designate moving and stationary objects  12 . The moving objects  12 , i.e., those represented by solid circle icons  60 , also may be provided with pointers or line segments  62  that indicate the direction of movement of the respective moving objects  12 . 
     The various icons presented on situational display  52  may be displayed in certain colors or with other identifying indicia depending on whether they are located within certain predetermined distances from the “center” object  12  (i.e., haul truck  55 , represented by icon  54 ). For example, surrounding objects  12  that are located nearby center object  12  may be displayed in a color red, thereby indicating to the operator that such objects are close and may pose collision or other hazards. Surrounding objects  12  located at greater distances (e.g., where they would not pose an immediate collision or other hazard) may be displayed in a color green. That is, objects  12  that are displayed in a green color indicate to the vehicle operator that they are located a safe distance away. Surrounding objects  12  located at intermediate distances (i.e., between a “red” or “close” distance and a “green” or “safe” distance), from the center object  12  may be displayed in a color yellow. 
     The situational display  52  may be also include other features and icons to convey additional information to the user or vehicle operator, as the case may be. For example, in the particular operational scenario illustrated in  FIG. 5 , the situational display  52  is divided into a plurality of regions (e.g., octants  64 ), each of which may be defined by broken lines  66 . In one embodiment, broken lines  66  may also be shown on situational display  52 , although this need not be the case. Moreover, each octant  64  may be provided with an “alert bar” or icon  68  that may be caused to appear on the situational display  52  when one or more objects  12  in the octant  64  is located within the predetermined distances just described. 
     The alert bars  68  may be displayed in the same color as that of the objects  12  that are located within the corresponding predetermined distance. For example, the alert icon  68  may be displayed in a color yellow if one or more objects  12  in the corresponding octant  64  are located in the “yellow” distance range from the center object  12  (i.e., represented by “self” icon  54 ). The alert bar  68  may be displayed in a color red if one or more of the objects  12  in the corresponding octant  64  are located in the “red” distance range from the center object  12 . 
     Situational display  52  may also be provided with other icons or information that may be helpful to a person observing the situational display  52 . For example, in the embodiment shown and described herein, situational display  52  may be provided with a compass rose icon  70 . A heading “bug” or indicator  72  may be displayed adjacent compass rose  70  to indicate the current heading of the center object  12 , in this scenario, haul truck  55  (i.e., represented by “own equipment” icon  54  in  FIG. 5 ). In one embodiment, the heading of each object  12  may be determined by analyzing the change in position data over time of each such object  12 . 
     In addition to showing the situational display  52 , the display system  28  of radio system  16  may also be operated in other modes to provide additional information to the user or vehicle operator. For example, display system  28  may be used to display video, graphic, or text information that may be of interest to the user or vehicle operator, as will be described in further detail below. 
     The situational display  52  just described may be displayed on the display systems  28  associated with each of the radio systems  16 , thereby allowing mine personnel, such as equipment operators, to immediately ascertain, at a glance, the operational situation in the immediately surrounding area. In addition, the position data from the various individual displays  28  may also be collected, integrated, and displayed on a display system  19  located at the central operations center  44 , as best seen in  FIG. 10 . 
     A significant advantage of the present invention is that it provides a means for locating and tracking personnel and equipment in a mining environment and for providing that information (e.g., via the display system  28 ) to each person or equipment operator. Accordingly, each such person or operator can readily ascertain the operational situation in the surrounding area. Moreover, the location and tracking information can also be provided to a central operations center  44  ( FIG. 10 ) to allow mine managers and others to monitor the current operational situation in the mine. 
     Still yet other advantages are associated with the situational display  52  ( FIG. 5 ). For example, besides showing the locations of objects in the immediately surrounding area, the situational display  52  may also indicate whether those objects are moving or stationary. Moreover, the direction in which the moving objects  12  are traveling may also presented on the situational display  52 , thereby allowing operators to identify and avoid objects  12  that may pose collision risks. 
     Additional utility is provided by the alert bar icons, which may be activated or illuminated in those regions (e.g., octants  64 ) that contain objects  12  within certain predetermined distances from the “center” object  12 . Yellow and red alert bar icons  68  may be utilized to provide a warning to the operator as the distance closes between the center object  12  and the surrounding objects  12 . In addition, the system  10  may provide an aural (i.e., sound) warning to ensure that an operator is aware of such nearby objects. Additional safety against collisions may be provided by connecting the system  10  to the control system of the associated vehicle. The system  10  could then be configured to automatically stop the vehicle, i.e., without driver input, if the system  10  determines that a collision is imminent. 
     Other substantial advantages are associated with the ultra-wideband radio frequency pulses  88  and modulation techniques that are utilized by the radio systems  16 . For example, the ultra-wideband radio pulses  88  and modulation techniques provide substantially increased immunity to multi-path interference and signal attenuation due to non-line-of-sight positioning compared to conventional, narrow-band radio systems using conventional modulation techniques. As a result, the use of ultra-wideband radio frequency pulses  88  substantially reduces problems associated with multi-path interference and signal attenuation or signal dropout events, thereby substantially increasing the likelihood that the system  10  can be successfully deployed in nearly all types of mining environments, including open pit mines and underground mines. 
     The ultra-wideband radio pulses transmitted by the radio systems  16  also allow the transceiver  18  to be operated in a radar mode, which can provide additional advantages and benefits with respect to obstacle detection and avoidance. For example, when operated in the radar mode, the radio system  16  may be used to detect the presence of berms, high-walls, or other obstacles that may not be provided with a radio system, but that nevertheless could pose a collision or other hazard. The radar mode of operation could be used to considerable advantage in adverse weather conditions, such as fog, rain, or snow, where visibility is substantially reduced. 
     Still other advantages stemming from the ultra-wideband radio pulses  88  is that they provide a high bandwidth. The high bandwidth allows for extremely high data transfer rates, which can be used to significant advantage in reducing system latencies. 
     In addition, the high data transfer rates that are possible with the high bandwidths provided by the ultra-wideband radio pulses means that the radio systems  16  also may be used to form a communications infrastructure that is capable of transferring large amounts of data at substantial data rates. Significantly, the communications infrastructure is in addition to the position locating and tracking functions that may be provided by the system  10 . That is, the same system  10  that provides locating and tracking information for objects  12  in the mining area may also provide a communications infrastructure to allow other types of information to be transferred via the network  42  formed by the various radio systems  16 . For example, the communications infrastructure may be used to transfer sound and/or video data, thereby allowing mining personnel to see and hear information from any one of the various operators, such as, for example, to see a video depiction of a piece of equipment in operation. The communications infrastructure can also be used to transmit data relating to certain operating characteristics (i.e., “machine health”) of mining equipment provided with the radio systems  16 . The communications infrastructure also supports conventional voice communications. 
     Still yet other information can be transmitted by system  10  via the communications infrastructure formed by the ad-hoc, peer-to-peer network  42 . For example, updated maps of the mine could be transferred over the network  42  and caused to appear on the display system  28 , thereby allowing personnel to view the updated maps and be informed of changes or closures of certain areas of the mine. 
     The communications infrastructure may be of substantial benefit in the event miners become trapped underground. Besides the fact that rescue personnel will know exactly where such mining personnel are trapped (i.e., by virtue of the substantially continuous position fixes provided by the system  10 ), the trapped miners may also be able to communicate to the rescue personnel via the radio system  16  because of the ultra-wideband radio transmission system. That is, the ultra-wideband transmission system will be capable of successfully transmitting data in situations that would be impossible with conventional, narrow-band systems. 
     Having briefly described one embodiment of a locating and tracking system according to the present invention, as well as some of its more significant features and advantages, various exemplary embodiments and operational modes of the locating and tracking system will now be described in more detail. However, before proceeding with the description it should be noted that while the various exemplary embodiments and operational modes of the system  10  are shown and described herein as they could be utilized in certain open pit and underground mining environments, applications, and operational scenarios, the present invention may also be used in any of a wide variety of other types of mining environments, applications and operational scenarios, as would become apparent to persons having ordinary skill in the art after having become familiar with the teachings provided herein. Consequently, the present invention should not be regarded as limited to the particular environments, applications, and operational scenarios shown and described herein. 
     Referring back now to  FIGS. 1 and 2 , one embodiment of a locating and tracking system  10  according to the present invention is shown and described herein as it could be used to locate and track the positions of various objects  12  within one or more defined operational areas  34 ,  34 ′, and  34 ″ of an open pit mine  14 . An operational area  34 ,  34 ″,  34 ″ of a mine  14  defines that region within which objects  12 , such as mining equipment and personnel, are to be located and tracked by the system  10 . The operational areas  34 ,  34 ′,  34 ″ encompass certain limited or defined portions of the mine  14  and need not include other areas of the mine, such as inactive or closed areas, administrative offices  74  and the like, wherein it is not desired to locate and track objects. 
     The provision of one or more defined operational areas  34 ,  34 ′,  34 ″ may be used to advantage in configuring and operating the locating and tracking system  10 . For example, each defined operational area  34 ,  34 ′,  34 ″ may be used to impose a limit (i.e., due to the defined size of the operational areas  34 ,  34 ′,  34 ″) on the number of radios  16  that are located within a defined operational area at any given time, thereby reducing the possibility that an excessive number of radios  16  will lead to network congestion, increased latencies, or other problems. Stated simply, the use of the defined operational areas (e.g.,  34 ,  34 ′, and  34 ″) allows radio systems  16  located within a first operational area (e.g., operational area  34 ) to ignore transmissions from radio systems  16  located in other operational areas (e.g., operational areas  34 ′ and  34 ″). Likewise, radio systems  16  located in such other operational areas (e.g.,  34 ′ and  34 ″) may ignore transmissions from radio systems  16  located in the first operational area (e.g.,  34 ). 
     However, and as will be described in greater detail below, the position and location information derived from radio systems  16  located in the various defined operational areas  34 ,  34 ′ and  34 ″ are nevertheless available to the system  10  and may be collected, integrated, or further processed by the system  10  to allow such information to be displayed or otherwise made available to operations managers or personnel located at the central operations center  44  ( FIG. 10 ). In addition, other functions, such as the communication of supplemental data, may be exchanged among the various radio systems  16  regardless of the operational area  34 ,  34 ′,  34 ″ within which they are located. 
     The operational area(s)  34 ,  34 ′,  34 ″ may comprise any of a wide range of sizes, shapes, and configurations depending on the particular mining operation and other factors that would become apparent to persons having ordinary skill in the art after having become familiar with the teachings provided herein. For example, while the various operational areas  34 ,  34 ′, and  34 ″ illustrated in  FIG. 1  have generally irregular shapes, their illustration in  FIG. 1  is notional only, and does not necessarily correspond to the sizes, shapes, and configurations of the operational areas might actually exist in a particular mine  14 . In many cases, it may be desirable to define the operational areas  34 ,  34 ′, and  34 ″ so that they have regular, geometric shapes (e.g., square, rectangular, circular, etc.), as it will be generally easier to define the boundaries of the operational areas. Also, while the various operational areas  34 ,  34 ′, and  34 ″ are illustrated in  FIG. 1  as separate, non-contiguous areas, they may be arranged or configured so that one or more of the operational areas  34 ,  34 ′,  34 ″ are contiguous, as illustrated in  FIG. 10 . The sizes and shapes of the operational areas  34 ,  34 ′, and  34 ″ may also change over time as the mining environment changes due to continuing operations. That is, the sizes and shapes of the operational areas  34 ,  34 ′,  34 ″ need not be fixed over time. 
     In any event, and regardless of the number, size, shape, and configuration of the various defined operational areas  34 ,  34 ′ and  34 ,″ tracking system  10  may comprise a plurality of radio systems  16  that are provided to, or associated with, the various objects  12  that are to be located and tracked in the defined operational areas (e.g.,  34 ,  34 ′,  34 ″). For example, and referring now primarily to  FIG. 2 , if the object  12  to be tracked comprises a piece of mining equipment, such as a haul truck  55 , a shovel  76 , or a service vehicle  78 , each such piece of mining equipment should be provided with a radio system  16 . Stationary objects, such as a building  80 , may also be provided with a radio system  16 , although the locations of such stationary objects could be programmed into the system  10  instead. So providing each piece of mining equipment with at least one radio system  16  will allow the system  10  to locate and track the mining equipment as it moves within the operational area  34 . The system  10  will also be able to locate and track the piece of mining equipment as it moves between and among various other operational areas  34 ,  34 ′ and  34 ″ in the manner that will be described in further detail below. 
     Mining personnel that are expected to travel on foot within the defined operational area(s)  34 ,  34 ′,  34 ″ may also be provided with portable or “hand-held” versions of the radio systems  16  that are sized to be readily carried by such personnel. While not specifically shown herein, a portable or hand-held version of the radio system  16  could be similar in size and shape to a cellular telephone or personal digital assistant. The display system  28  of such a portable or hand-held version could comprise an integral portion of the radio system  16 , also in a manner akin to a cellular telephone or personal digital assistant. 
     Referring now primarily to  FIG. 3 , and regardless of its particular physical package or configuration, each radio system  16  may comprise a radio-frequency (rf) transceiver  18  and a processor system  20  suitable for transmitting, receiving, and processing radio signals  24  in the manner described herein. In addition, radio system  16  may be provided with any of a wide range of ancillary systems and devices (not shown), such as battery systems, user interface systems (e.g., keypads or touch screens), wired or wireless ethernet ports, etc., that may be required or desired in any given application. However, because such ancillary systems are well known in the art and could be readily provided by persons having ordinary skill in the art after having become familiar with the teachings provided herein, the particular ancillary systems and devices that may be utilized in the radio system  16  will not be described in further detail herein. 
     The radio transceiver  18  may comprise a transmitter section  22  and a receiver section  24 , both of which are operatively associated with an antenna system  82 . Radio transceiver  18  may also comprise a field programmable gate array (FPGA)  84  that may be programmed or configured to control the function and operation of the transmitter and receiver sections  22  and  24  of transceiver  18 . Alternatively, other types of devices, such as general purpose programmable processors or application-specific integrated circuits (ASICs) could be used to control the function and operation of the transmitter and receiver sections  22  and  24  of transceiver  18 . 
     The radio transceiver  18  (i.e., comprising transmitter and receiver sections  22  and  24 ) may comprise any of a wide range of radio transceiver systems that are now known in the art or that may be developed in the future that would be suitable for the intended application. While not required, it is generally preferred that the radio transceiver  18  comprise an ultra-wideband transceiver  18 , as opposed to a narrow band transceiver. As described herein, the use of ultra-wideband radio frequency transmission provides the system  10  with significant advantages compared to narrow band transceiver systems. By way of example, in one embodiment, the radio transceiver  18 , i.e., comprising the transmitter and receiver sections  22  and  24 , comprises an “Aspen” radio chip set available from General Atomics Corporation of San Diego, Calif., as model no. 2000-006. 
     Briefly described, and with reference primarily to  FIGS. 6 and 7 , the Aspen radio chipset comprises an ultra-wideband radio transceiver  18  that transmits and receives ultra-wideband (UWB) radio signals  26 . More specifically, the transmitter section  22  of transceiver system  18  produces a series of ultra-wideband electromagnetic pulses  88 , as best seen in  FIG. 6 . While the electromagnetic pulses  88  appear to be narrow when depicted in the time domain, as illustrated in FIG.  6 , each ultra-wideband (UWB) pulse  88  has a high intrinsic bandwidth and broad spectral energy distribution, as illustrated in  FIG. 7 , which depicts one of the UWB pulses  88  in the frequency domain. Stated simply, each UWB pulse  88  comprises a wide range of frequencies. In one embodiment, each electromagnetic pulse  88  may have a duration in the range of about 100 picoseconds (ps) to about 5 nanoseconds (ns) and comprises a fractional bandwidth that is at least about 20% of the center frequency of the UWB pulse  88 . 
     The Aspen radio chipset comprising the radio transceiver system  18  may be configured or programmed to modulate the UWB pulses  88  in accordance with a modulation technique known as “Spectral Keying,” which is a registered trademark of General Atomics Corporation. The details of the Spectral Keying modulation technique are described in detail in U.S. Pat. No. 6,895,059, entitled “Method and Apparatus for Data Transfer Using a Time Division Multiple Frequency Scheme” which is specifically incorporated herein by reference for all that it discloses. 
     Briefly, and with reference now to  FIGS. 8 and 9 , the Spectral Keying modulation technique utilizes the frequency content of the pulses  88  to convey or transmit information. The information to be transmitted is encoded through the time-dependency of the various frequency components within the UWB pulse  88 . In effect, each UWB pulse  88  comprises a sequence of smaller pulses or subpulses  89 , each of which is centered on a different frequency, as best seen in  FIGS. 8 and 9 . The order of the frequencies of the subpulses  89  comprising each pulse  88  may be used to define a symbol  90 .  FIG. 8  depicts the symbol  90  in the time domain, whereas  FIG. 9  depicts the symbol  90  in the frequency domain. 
     The number of symbols  90  that can be defined for a given number of frequency bands (i.e., subpulses  89  centered on different frequencies) is the factorial of the number of frequency bands. For example, three frequency bands will allow 3! (i.e., 6) symbols  90  to be used to transmit information. Five frequency bands will allow 5! (i.e., 120) symbols  90  to be used to transmit data, whereas the use of 6 frequency bands would allow 6! (i.e., 720) symbols  90  to be used. In the embodiment illustrated in  FIGS. 8 and 9 , subpulses  89  used to define the symbols  90  are centered on three different frequencies of about 3.48, 4.02, 4.56 gigahertz (GHz). However, in another embodiment, the subpulses  89  are centered on five different frequencies, e.g., at about 3.48, 4.02, 4.56, 6.12, and 6.96 GHz, which will allow 120 symbols to be used to transmit data. 
     The high data density resulting from the Spectral Keying modulation technique just described substantially increases the resistance of the system to multi-path interference. Increasing the data sent in each symbol reduces the number of symbols that must be sent. As a result, the time between symbols can be large, which reduces inter-symbol interference that would otherwise result from multi-path interference. 
     Referring back now primarily to  FIG. 3 , each radio system  16  may also be provided with a processor  20  and a memory system  86 . As mentioned above, processor  20  may be used to control the function and operation of the rf transceiver system  18  as well as to process data received from the transceiver system  18 . For example, in one embodiment, processor  20  processes radio signal data from the rf transceiver system  18  to determine the time-of-flight of radio signals  26  exchanged between various ones of the radios  16 . Processor  20  then uses the time-of-flight data to calculate or determine the positions of the various radios  16 . 
     Processor system  20  may also be used to process other data received by the rf transceiver  18 . For example, processor system  20  may be programmed to analyze position data associated with various objects  12  as such data change over time in order to determine the heading or direction of travel of the corresponding objects  12 . The change of position data over time may also be used to determine the headings of objects  12  as well as their velocities. Processor  20  may also use the position data of each object  12  to generate a network identifier tag  27  in the manner that will be described in greater detail below. Processor system  20  may also interface with the memory system  86  to store data. 
     Processor system  20  may comprise any of a wide range of general purpose programmable processors that are now known in the art or that may be developed in the future that would be suitable for the intended application. Consequently, processor system  20  should not be regarded as limited to any particular type of processor. Alternatively, other types of processors, such as application-specific integrated circuits, could also be used. Likewise, memory system  86  may comprise any of a wide range of memory systems that are now known in the art or that may be developed in the future that would be suitable for the intended application. By way of example, in one embodiment, memory system  86  may comprise a flash memory system of the type that is well-known in the art and readily commercially available. 
     In the embodiment illustrated in  FIG. 3 , radio system  16  may also be provided with an auxiliary radio transceiver  92 . Auxiliary radio transceiver  92  may be operatively associated with processor system  20  and may be used to transmit auxiliary data and information not transmitted by the transceiver  18 . Auxiliary radio transceiver  92  may also be used as a back-up radio system. Depending on the nature of the auxiliary data that are to be transmitted and/or whether auxiliary radio transceiver  92  is to be used as a back-up system, the auxiliary radio transceiver  92  may comprise an ultra-wideband radio transmitter of the type already described for the radio transceiver  18 . Alternatively, the auxiliary radio transceiver  92  may comprise a narrowband transmitter of the type that is well-known in the art and readily commercially available. 
     Still referring primarily to  FIG. 3 , each radio system  16  may also be provided with additional systems and devices to provide increased functionality to the radio system  16 . For example, radio system  16  may be provided with a microphone/speaker system  94  to allow voice communications between the various radios  16  and to provide various aural (i.e., sound) warning signals to the operator. Radio system  16  may also be provided with a camera system  96  to allow still photographs and/or video to be captured by the radio system  16 . Such visual data may then be transmitted (e.g., via network  42 ) to other radio systems  16  and/or the central operations center  44 . The various additional systems and devices may be operatively associated with radio system  16  via conventional wired interfaces, infrared interfaces, or wireless interfaces. However, because such additional systems and devices, e.g., such as microphone/speaker system  94  and camera system  96 , as well as systems for operatively connecting them to radio  16  are well-known in the art and could be easily provided by persons having ordinary skill in the art after having become familiar with the teachings provided, the particular microphone/speaker system  94  and camera system  96  that may be utilized in one embodiment of the present invention will not be described in further detail herein. 
     Each radio system  16  may also be provided with a display system  28  to allow various information and data collected by the radio system  16  to be presented in visual form to the user. The particular type of display system  28  may vary depending on the intended application of the radio system  16 . For example, if the radio system  16  is to be carried by mine personnel, i.e., where the radio system  16  comprises a portable, hand-held unit, then display system  28  may comprise a small LCD display of the type commonly used in portable cellular telephones and personal digital assistants. The display system  28  in such an application may comprise an integral portion of the radio system  16 . In another configuration, i.e., where the radio system  16  is configured to be installed in a piece of mining equipment or a vehicle, display system  28  could comprise a larger LCD display. The display may also be “hardened” e.g., provided in a shock- and weather-resistant housing, to provide increased reliability and resistance to the mining environment. 
     In accordance with the foregoing considerations, then, display system  28  may comprise any of a wide range of display systems and devices that are now known in the art or that may be available in the future that would be suitable for the intended application. Consequently, the present invention should not be regarded as limited to use with any particular type of display system  28 . 
     In an application wherein the radio system  16  is to be installed in a piece of mining equipment, radio system  16  may also be provided with a vehicle interface system  98 . Vehicle interface system  98  will allow the radio system  16  to send commands (e.g., via the vehicle interface system  98 ) to the associated vehicle under certain conditions. For example, in one embodiment, the radio system  16  could issue commands that will be used by the vehicle interface system  98  to automatically stop the vehicle if continued movement of the vehicle could result in a collision or other unsafe condition. 
     Vehicle interface systems  98  of the type that may be utilized herein are well-known in the art and could be readily provided by persons having ordinary skill in the art after becoming familiar with the teachings provided herein and after considering the particular type of equipment or vehicle on which such an interface system  98  will be used. Consequently, the particular vehicle interface system  98  that may be used in one embodiment of the invention will not be described in further detail herein. 
     The system  10  may also be provided with other devices and systems to provide increased functionality and capability in certain situations. For example, in the embodiment shown and described herein, the system  10  may also comprise a central operations center  44  ( FIGS. 1 and 10 ), which may be situated at a remote location to allow operations managers to monitor and/or manage the mining operation as well as the deployment of mining equipment and personnel. 
     Referring now specifically to  FIG. 10 , the operations center  44  may be provided with a network administrator system  13  that communicates with the various ad-hoc, peer-to-peer networks  42 ,  42 ′,  42 ″ that are formed or created by the various radios  16  located in the various operational areas  34 ,  34 ′,  34 ″. The network administrator system  13  may communicate with the various networks  42 ,  42 ′, and  42 ″ via corresponding network access points  15  and communications links  17 . The operations center  44  may also be provided with one or more display systems  19  that are operatively associated with network administrator system  13 . An operations manager (not shown) may operate the network administrator  13  and display system  19  to cause any of a wide variety of information to be displayed. For example, the operations manager may command the system  10  to display a duplicate of the situational display  52  that is currently being displayed on any desired radio system  16  in any desired operational area  34 . 
     Other information may be displayed on display system  19 , as would become apparent to persons having ordinary skill in the art after having become familiar with the teachings provided herein. For example, in another scenario, the operations manager could instruct a particular vehicle operator to turn-on or otherwise activate the camera system  96  associated with the radio  16 . The operations manager could then operate the network administrator system  13  to cause video data from the camera system  96  to appear on display system  19 . The operations manager could then observe any desired area, vehicle, or operation in real time. 
     The ability to transmit photos and/or video data in real time to the operations center  44  could also be of assistance in troubleshooting equipment problems or repairing disabled equipment. For example, an equipment expert or mechanic located at the operations center  44  could view the malfunctioning and/or disabled equipment and dispatch the necessary personnel and/or replacement parts to the particular location. In addition, radio systems  16  provided on vehicles could transmit to the operations center  44  certain information about the vehicle (e.g., “machine health” data), via the vehicle interface system  98 . Still other types information can be exchanged between the operations center  44  and any or all of the radio systems  16 . For example, updated mine maps or other information about current mine operations could be transmitted over the system  10 . Other information of benefit to personnel operating in the mine, such as scheduled blasting times and/or equipment servicing needs could also be transmitted on a real-time basis or as the need arises. 
     Referring back now to  FIG. 4 , the system  10  may be operated in accordance with a method  30  to locate and track objects  12  in a mining environment. A first step  32  of method  30  may involve selecting or defining an operational area  34  in the mine  14  within which the locations of the various objects  12  are to be determined and tracked over time. As discussed above, one or more operational areas (e.g.,  34 ,  34 ′,  34 ′) may be defined depending on any of a wide variety of considerations. For example, the operational areas (e.g.,  34 ,  34 ′,  34 ″) may be selected or defined so as to exclude certain areas in the mine wherein it is not desired to locate or track objects  12 . Such areas may include, for example, administrative offices and support buildings  74  ( FIG. 1 ). Certain other areas of the mine may be closed to operations or otherwise inactive, and it may be desirable in certain situations to exclude those areas from the operational area(s) as well. 
     The careful selection of the operational area(s) (e.g.,  34 ,  34 ′,  34 ″) may also be used to reduce the likelihood of creating excessive amounts of network congestion and/or system latencies. For example, in the example embodiments shown and described herein, the radio systems  16  within each operational area (e.g.,  34 ,  34 ′, and  34 ″) form respective ad-hoc peer-to-peer networks  42 ,  42 ′,  42 ″ ( FIG. 10 ). Accordingly, the “size” (i.e., the logical size, not necessarily the physical size) of each network  42 ,  42 ′,  42 ″ is related to the “size” of each operational area, i.e., as defined by the number of radio systems  16  that are present in the operational area  34  at any given time. See  FIGS. 1 and 10 . Consequently, each operational area  34  may be configured so as to divide the mine area  14  into smaller portions that, by virtue of the limited sizes of the various operational areas  34 ,  34 ′ and  34 ,″ will effectively limit the number of radio systems  16  that will comprise the ad-hoc, peer-to-peer network  42  within the operational area  34 . Consequently, the networks  42 ,  42 ′,  42 ″ that correspond to the operational areas  34 ,  34 ′ and  34 ″ will, in effect, be “subnetworks” that need only interface with the other “subnetworks” on a limited basis. In this manner, then, careful design of the operational areas  34 ,  34 ′,  34 ″ may be used as a network management tool to limit the sizes of the various networks  42 ,  42 ′,  42 ″ to ensure optimal performance within each network. 
     Besides being used as a network management tool, the operational areas  34 ,  34 ′, and  34 ″ may also be configured to follow certain physical boundaries or operational zones within the mine. For example, a given operational area  34  may be shaped or configured to correspond to the physical boundaries of a haul road (or drift, in the example of an underground mine), because the haul road (or drift) defines those areas within which other objects  12  will be located and tracked. The operational area  34  may also be configured to exclude, for example, high walls and other obstructions, wherein objects  12  are not expected to operate. In this manner, then, several operational areas  34 ,  34 ′,  34 ″ may be defined adjacent one another so that objects  12  moving from operational area to operational area will be tracked by the particular network (e.g.,  42 ,  42 ′,  42 ″) associated with each operational area. 
     With reference back now to  FIG. 4 , method  30  may next involve providing at least one radio system  16  and associated display system  28  to each of the objects  12  that is to be tracked. If the object  12  to be tracked comprises a vehicle, the radio system  16  and associated display  28  may be mounted within the cab of the vehicle to allow easy access by the vehicle operator. Unmanned vehicles (e.g., remotely controlled or autonomous vehicles) could likewise be provided with a radio system  16 , thereby allowing such vehicles to be tracked by system  10  as well. Regardless of whether the mine vehicles are manned or unmanned, the radio system  16  may be provided with a vehicle interface system  98  ( FIG. 3 ) to allow the radio system  16  to automatically operate the vehicle in certain circumstances. For example, in one embodiment, the radio system  16  may instruct the vehicle interface system  98  to stop the vehicle (e.g., by disengaging the transmission and/or applying the vehicle brake) if the system  10  determines that a collision is imminent. 
     Objects  12  other than vehicles can also be provided with a radio and display system  16 ,  28 . For example, one embodiment of the invention may utilize a portable, i.e., hand-held, radio system  16  that is battery powered and can be easily carried by persons moving around on foot within the operational area  34 . The display system  28  may be combined with the radio system in a manner akin to a cellular telephone or personal digital assistant. Consequently, persons on foot can be readily located and/or tracked by the system  10 , even though they are not with or operating a moving vehicle or other piece of mining equipment. Generally speaking, it will be desirable to provide such a hand-held radio/display system  16 ,  28  to all personnel to ensure that their locations will be known at all times and to nearby personnel and equipment. 
     After each object  12  has been provided with a radio system  16  and associated display system  28 , the various radios  16  may then be operated at step  40  so that they form or create an ad-hoc, peer-to-peer network, e.g.,  42 ,  42 ′,  42 ″. See  FIG. 10 . Each of the radios  16  may be programmed so that the resulting network  42  is logically limited to radio systems  16  operating in the defined operational area  34 . That is, the network  42  can be limited to only those radios  16  that happen to be located within the defined operational area  34  at any point in time. Radios  16  contained in other operational areas (e.g.,  34 ′,  34 ″) will comprise parts of their respective networks (e.g.,  42 ′,  42 ″), as best seen in  FIG. 10 . 
     In one embodiment, a given network  42  may distinguish between radios  16  within its own network (e.g., network  42 ) from those contained in other networks (e.g., networks  42 ′ and  42 ″) by analyzing an appropriate network identifier tag  27  broadcast by each radio  16 . See  FIG. 11 . Processor system  20  ( FIG. 3 ) may generator or produce the network identifier tag  27  by correlating the current position of the radio  16  with the defined operational areas, e.g.,  34 ,  34 ′, and  34 ,″ which may be stored in memory system  86 . For example, if a given radio  16  determines (based on its current position data) that it is located within operational area  34 , then that radio  16  can broadcast the appropriate network identifier tag  27  to inform the system  10  (and other radios  16 ) that the particular radio  16  is a part of network  42 . Other radios  16  located in other operational areas, e.g.,  34 ′,  34 ″, will broadcast other network identifier tags that associate such other radios  16  with the networks that correspond to the operational areas within which the radios  16  are currently located. 
     The broadcasting of network identifier tags  27  allows the various networks  42 ,  42 ′,  42 ″ to effectively limit their sizes to only those radios contained within their respective operational areas  34 ,  34 ′,  34 ″. That is, the various radios in a given network may be configured to ignore radios contained in other networks. Moreover, the system allows radios  16  to move from operational area to operational area (i.e., from network to network) without the need to reconfigure the system or otherwise inform the radio of its new position and associated network. That is, because the radio  16  knows its position, as well as the boundaries of the various operational areas, the radio  16  will automatically update its network identifier tag  27  without the need for additional user input. 
     Still referring primarily to  FIG. 11 , in one embodiment, the network identifier tag  27  may be one of the first pieces of information in the data set  29  broadcast by each radio  16 . Because the network identifier tag  27  is one of the first pieces of information sent (and received) by the various radio systems  16  within range of the broadcasting radio, the radio systems  16  within a given network (e.g., network  42 ) may readily determine which radio signals  26  originated from radios outside the network  42 . The radio systems  16  may then ignore signals from radios  16  confirmed to be outside the network  42 . 
     After the network(s) (e.g.,  42 ) have been formed by the radio systems  16 , the various radio systems  16  are operated, e.g., at step  46 , to determine the time-of-flight of radio signals  26  exchanged between the various radio systems  16  within a given network  42 . The time-of-flight of radio signals  26  exchanged between the various radio systems  16  may then be analyzed to determine the positions of the various radio systems  16 . 
     Referring now to  FIG. 12 , the position of a radio system  16  in two-dimensional space can be determined by determining the time required for radio signals  26  to travel between radio system  16  (the position of which is unknown) and three (3) other radios  16 ′,  16 ″,  16 ′″ the positions of which are known. Because radio signals  26  travel at the speed of light, the time required for radio signals  26  to travel between two radios  16  defines the distance between the radios. Thus, the position of a fourth radio  16  can be determined in two dimensional space by determining the time-of-flight, thus distances D 1 , D 2 , and D 3 , between radio  16  and radios  16 ′,  16 ″,  16 ′″, when the positions of those radios are known. Similarly, the position of a radio system  16  in three-dimensional space can be determined based on the time-of-flight of radio signals from four (4) other radios, the positions of which are known. 
     The present invention may utilize any of a wide range of time-of-flight algorithms that are now known in the art or that may be developed in the future to determine the time required for radio signals  26  to travel between two radio systems  16 . Generally speaking, the particular time-of-flight algorithm that is used should provide a high degree of positioning accuracy, such as, for example, within a few 10&#39;s of centimeters or less. In this regard it should be noted that the ultra-wideband (UWB) radio systems utilized in one embodiment provide higher accuracy than conventional, narrow-band systems when estimating the time-of-flight of a radio signal between a transmitter and receiver. The increased accuracy is due in large part to the large bandwidths associated with the UWB pulses  88 . See  FIG. 7 . More specifically, the high bandwidth results in narrow pulses with fast rise and fall times that yield high accuracy for time of arrival measurements. For example, the UWB transmission system of the exemplary embodiment shown and described herein, the incoming UWB pulse  88  (i.e., radio signal  26 ) is sampled at a frequency of about 500 megahertz (MHZ), which is about ten times the sampling frequency used in conventional time-of-flight radio systems. The high sampling frequency coupled with the fast rise and fall times allows highly-accurate time of arrival measurements to be made. Of course, the ability to accurately determine the time of arrival of the radio signal is directly correlated to the distance determination, thus positional accuracy of the system. 
     Referring now primarily to  FIG. 11 , one embodiment of a time-of-flight algorithm that may be implemented by the system  10  involves a so-called two way ranging technique to determine the time-of-flight of radio signals  26  between two radios. Briefly, the two way ranging technique involves the measurement of the round trip time  21  required for the radio signal to be received by a radio  16 , processed, and re-transmitted to the originating radio. The round trip time  21  therefore embodies or contains two time-of-flight times  23 , as well as the processing time  25  required to process the radio signal and re-transmit it to the originating radio. Processing time  25  includes the times required to receive and transmit the signal (i.e., in the antenna and rf-sections of the transceiver  18 ). The one-way time-of-flight time may be calculated by subtracting from the round trip time  21  the processing time  25  and dividing by two. 
     Other methods for computing the time-of-flight of radio signals are also known and could be used as well. For example, alternative methods may involve one way ranging or time difference of arrival of signals. However, because algorithms for determining the time-of-flight of radio signals are well-known in the art and could be readily provided by persons having ordinary skill in the art after having become familiar with the teachings provided herein, the particular time-of-flight algorithm that may be utilized in the present invention will not be described in further detail herein. 
     Because the various radios  16  determine their respective positions by reference to other radios (whose positions are known), a certain minimum number of radios  16  comprising a given network  42  will need to “know” their positions before other radios  16  in the network  42  can determine their positions. In one embodiment, each network  42  may be provided with a number of radios or “nodes” at known or surveyed-in positions. Other radios  16  in the network  42  can then determine their positions based on signals received from the surveyed-in radios. 
     As briefly described above, the ultra-wideband radio transceiver system  18  in one embodiment may be operated in a radar mode to detect obstacles and other objects that may not be provided with a separate radio system  16 , but may nevertheless pose hazards. For example, the radio system  16 , when operated in the radar mode, may be used to detect the presence of berms, high-walls, or other obstacles. Obstacles detected by the radio when operated in the radar mode could be displayed on display system  28 , either alone, or in conjunction with the other objects  12  provided on situational display  52 . 
     Processor system  20  may be programmed to operate the radio transceiver system  18  in the radar mode of operation on a periodic basis (i.e., automatically, without requiring user input). Alternatively, the radio system  16  could be provided with a control switch to allow the user to manually engage the radar mode of operation when desired. 
     The next step  50  in the method  30  involves displaying the relative positions of at least some of the objects  12  contained within the operational area  34  on a situational display  52 . See  FIG. 5 . In this particular example, the situational display  52  shows the various objects illustrated in the particular operational scenario illustrated in  FIG. 2 . As already briefly described above, the particular object  12  carrying radio system  16  and display system  28  may be displayed at the center of the situational display  52  and, in this example, corresponds to the haul truck  55  illustrated in  FIG. 2 . An operator viewing the situational display  52  associated with his particular vehicle or person will see his vehicle or person displayed at the center of the situational display  52  as icon  54 . The particular object located at the center of the situational display  52  may be referred to herein in the alternate as the “center” object  12  to distinguish it from “surrounding” objects  12 . 
     In the particular operational scenario illustrated in  FIG. 2  (which is represented in the situational display  52  illustrated in  FIG. 5 ), the center object  12  comprises the haul truck  55  and is represented by icon  54  located at the center of the situational display  52 . If the center object is moving, the direction of motion of the center object (i.e., represented by icon  54 ) may be indicated by an arrow icon  56  located adjacent icon  54 . As mentioned above, the processor system  20  ( FIG. 3 ) may be programmed to calculate or derive the direction of motion, heading, and velocity of one or more of the objects  12  by analyzing the change in position data over time for the corresponding object or objects  12 . 
     “Surrounding” objects  12  located nearby “center” object  12  (e.g., haul truck  55 ) may be represented with different icons depending on whether they are moving or stationary. For example, in the particular operational scenario illustrated in  FIG. 5 , stationary objects are represented by ring icons  58 , whereas objects in motion are represented by solid circle icons  60 . Alternatively, icons having other shapes and configurations may be used to designate moving and stationary objects  12 . The moving objects  12 , i.e., those represented by solid circle icons  60 , also may be provided with pointers or line segments  62  that indicate the direction of movement of the respective moving objects  12 . 
     The various icons presented on situational display  52  may be displayed in certain colors or with other identifying indicia depending on whether they are located within certain predetermined distances from the “center” object  12  (i.e., haul truck  55  ( FIG. 2 ), represented by icon  54  ( FIG. 5 )). For example, surrounding objects  12  that are located within 25 meters (about 82 feet), of center object  12  may be displayed in a color red. Surrounding objects  12  located at a distance greater than about 100 meters (about 328 feet) from the center object  12  may be displayed in a color green. Surrounding objects  12  located at intermediate distances, e.g., between about 25 meters and about 100 meters from the center object  12  may be displayed in a color yellow. Alternatively, other distances may be used, depending on a wide variety of factors. Consequently, the present invention should not be regarded as limited to the particular distances described herein. 
     The situational display  52  may be also include other features and icons to convey additional information to the user or vehicle operator, as the case may be. For example, in the particular operational scenario illustrated in  FIG. 5 , the situational display  52  is divided into a plurality of regions (e.g., octants  64 ), each of which may be defined by broken lines  66 . In one embodiment, broken lines  66  may also be shown on situational display  52 , although this need not be the case. Moreover, each octant  64  may be provided with an “alert bar” or icon  68  that may be caused to appear on the situational display  52  when one or more objects  12  in the octant  64  is located within the predetermined distances just described. 
     The alert bars  68  may be displayed in the same color as that of the objects that are located within the corresponding predetermined distance. For example, the alert icon  68  may be displayed in a color yellow if one or more objects  12  in the corresponding octant  64  are located in the “yellow” distance range (e.g., between about 25 meters and about 100 meters) from the center object  12  (i.e., represented by “self” icon  54 ). The alert bar  68  may be displayed in a color red if one or more of the objects  12  in the corresponding octant  64  are located in the “red” distance range (e.g., less than about 25 meters) from the center object  12  (i.e., represented by “self” icon  54 ). 
     Situational display  52  may also be provided with other icons or information that may be helpful to a person observing the situational display  52 . For example, in the embodiment shown and described herein, situational display  52  may be provided with a compass rose icon  70 . A heading “bug”  72  may be displayed adjacent compass rose  70  to indicate the current heading of the center object  12 , in this operational scenario, haul truck  55  (i.e., represented by “own equipment” icon  54  in  FIG. 5 ). 
     As already mentioned, in one embodiment, each radio  16  may be operated in a radar mode from time to time in order to determine whether any obstacles are present that might pose collision or other hazards. Any such obstacles could also be presented on the situational display  52 . Moreover, such obstacles may be displayed in any of the green, yellow, or red colors, depending on their distance from the center object  12 . 
     The situational display  52  just described may be displayed on the display systems  28  associated with each of the radio systems  16 , thereby allowing mine personnel, such as equipment operators, to immediately ascertain the operational situation in the immediately surrounding area. In addition, the position data from the various individual displays  28  may also be collected, integrated, and displayed on a display system  19  located at the central operations center  44 , as best seen in  FIG. 10 . 
     Besides presenting the operator with a display of the surrounding area (e.g., via situational display  52 ), the display system  28  may be used to display other information. For example, video data (e.g., from another radio  16  or from the central operations center  44 ) may be presented on the display  28 . Similarly, text or graphics data may also be provided on display system  28 . Such text or graphics data may comprise any of a wide variety of information that may be useful to the particular operator receiving the data. Such additional data may be communicated between an among the various radio systems  16  by the communications infrastructure created by the various networks  42 ,  42 ′,  42 ″ and the network administrator  13 , as best seen in  FIG. 10 . 
     The locating and tracking system according to the present invention may be used to advantage in other types of mining environments as well. For example, in another embodiment  110 , the locating and tracking system according to the present invention may be used in an underground mine  114 . Referring now to  FIG. 13 , a notional representation of an underground mine  114  may comprise a plurality of drifts or tunnels  145  within which various objects  112 , such as personnel and mining equipment (not shown), are to be located and tracked. As was the case for the first embodiment, each of the objects  112  may be provided with a radio system  116 . The radio systems  116  for underground use may be substantially identical to the radio systems  16  already described. Radio signals  126  transmitted by the various radio systems  116  comprise ultra-wideband frequency pulses (e.g., pulses  88  illustrated in  FIG. 6 ) modulated in accordance in accordance with the Spectral Keying modulation technique already described herein. 
     While the ultra-wideband radio signal transmission system provides for greatly enhanced signal propagation and detection characteristics in environments, such as drifts  145 , that create substantial multi-path interference, it may nevertheless be advantageous in certain underground mining environments and drift configurations to also provide the system  110  with one or more network tracking synchronizing nodes  147 . The network tracking synchronizing nodes  147  may serve as signal repeaters or relays to ensure the efficient and reliable propagation of the ultra-wideband radio signals  126  throughout the drifts or tunnels  145 . Generally speaking, it will be desirable to located the network synchronizing nodes  147  at areas, such as tunnel bends or intersections, that may be prone to signal attenuation due to a substantial change in direction of the drift  145 . 
     If provided, the network tracking synchronizing nodes  147  may be substantially identical to the radio systems  116 , except that they need not be provided with a corresponding display system (e.g.,  28 ), although they could be. In addition, the various network tracking synchronizing nodes  147  may be provided at fixed, “surveyed-in” locations within the drifts or tunnels  145  in the manner best seen in  FIG. 13 . Such surveyed-in network tracking synchronizing nodes  147  may then serve as “known position” radios required to provide position location information to radios  116  whose positions are not known. 
     The various radio systems  116  and network tracking synchronizing nodes  147  may be operated so that they form one or more ad-hoc, peer-to-peer networks  142 ,  142 ′ in the manner already described for the first embodiment  10 . The second embodiment  110  of the locating and tracking system may also involve the use of one or more defined operational areas  134 ,  134 ′ in a manner analogous to the defined operational areas  34 ,  34 ′ and  34 ″ described above for the first embodiment. When used in an underground mine  114 , the defined operational areas  134 ,  134 ′ may be generally co-extensive with the various drifts  145  comprising the mine  114 . 
     The system  110  may also be provided with a central operations center  144 . Position and other data from the radio systems  116  associated with the various objects  112  (e.g., mining equipment and personnel) moving within the tunnels  145 , may be collected, integrated, and displayed on a suitable display system  119  provided in the central operations center  144 . 
     The system  110  may be operated in accordance with a method that is similar to the method  30  described above for the first embodiment  10 . For example, a first step in the method may involve selecting or defining one or more operational areas  134 ,  134 ′ in the mine  114  within which the locations of the various objects  112  are to be determined and tracked over time. As mentioned above, the various operational areas  134 ,  134 ′ in an underground mine  114  may be defined to be generally coextensive with the various tunnels or drifts  145 , in that the tunnels or drifts  145  effectively physically define those areas in which mining personnel and equipment will be located. The next step in the process may involve providing at least one radio system  116  to each of the objects  112  that is to be tracked. The various radio systems  116  may then be operated to that they form or create an ad-hoc, peer-to-peer network  142 ,  142 ′. A separate network  142 ,  142 ′ may be associated with each defined operational area  134 ,  134 ′ in the manner already described for the first embodiment  10 . 
     The radio systems  116  may then be operated to determine the time required for the radio signals  126  to be exchanged between various ones of the radio systems  116  in the various networks  142 ,  142 ′. The time-of-flight of such radio signals  126  is then analyzed to determine the relative positions of the radio systems  116 , thus various objects  112  within the corresponding operational area (e.g.,  134 ,  134 ′). The relative positions of at least some of the objects  112  within the operational area  134 ,  134 ′ may then be displayed on a display system (not shown in  FIG. 13 ) associated with each radio system  116 . More specifically, the relative position data may be provided by means of a situational display similar to the situational display  52  illustrated in  FIG. 5  and described for the first embodiment  10 . 
     Referring now primarily to  FIG. 14 , and as mentioned above, the various data (such as position data) collected by the various radio systems  116  may be collected, integrated, and displayed on display system  119  provided in the central operations center  144 . The system  110  may be programmed or operated to allow a mine manager or other personnel to “call-up” or caused to be displayed on display system  119  any of a wide range of data and information. For example, the system  110  may be operated to cause the situational display (e.g., similar to situational display  53 ) associated with any one of the radio systems  116  to be displayed on the display system  119 , in the manner already described for the first embodiment  10 . In addition, the system  110  may be configured or programmed to allow operations managers in the central operations center  144  to view a global situational display  153  that shows the positions of all the equipment and personnel within the various drifts or tunnels  145  that comprise the underground mine  114 . 
     Various icons  154  may be used to represent the various objects  112  carrying or otherwise provided with radio systems  116 . For example, in the embodiment illustrated in  FIG. 14 , mining equipment may be depicted by circular icons  157 , whereas personnel on foot (i.e., carrying “hand-held” radio systems  116 ) may be depicted by square icons  159 . Various colors may also be used to further distinguish the icons and to allow the various objects  112  to be even more readily distinguished. In the embodiment illustrated in  FIG. 14 , the circular icons  157  representing mining equipment may be presented in a color blue. The square icons  159  (e.g., representing personnel on foot) may be presented in a color yellow. 
     If the system  110  is provided with one or more network tracking synchronizing nodes  147 , such nodes  147  may also be depicted by square icons  161  which may be displayed in a color red to distinguish them from the yellow square icons  159 . The global situational display may also be provided with a compass rose icon  170 , if desired. 
     Having herein set forth preferred embodiments of the present invention, it is anticipated that suitable modifications can be made thereto which will nonetheless remain within the scope of the invention. The invention shall therefore only be construed in accordance with the following claims: