Abstract:
A fueling environment is equipped with leak detection probes and liquid level probes. Each of the probes is associated with a wireless transceiver. The wireless transceivers send probe data to a site communicator wireless transceiver. To ensure that the site communicator receives the probe data, repeaters are used within the fueling environment. The repeaters receive the probe data, and some period of time after the sensor transceivers stop transmitting, the repeaters retransmit the probe data to the site communicator. The site communicator discards duplicative information and processes the probe data as needed.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to a leak detection system in a fueling environment, and, more particularly, is directed to a system that includes sensors that report wirelessly to a site controller or tank monitor in the fueling environment. 
     BACKGROUND OF THE INVENTION 
     Fueling environments are being subjected to increasingly rigorous statutes and regulations that prohibit fuel leaks and detail how leaks are to be detected within the fueling environment. One particular area in which leak detection is critical is in the storage tank in which the fuel is stored prior to sale. Such storage tanks, which are typically located beneath the ground, and thus, are commonly referred to as “underground storage tanks”, are typically equipped with a probe that measures the height of the fluid within the storage tank. Additionally, the probe may measure temperature, pressure, and other environmental factors that are used in determining the volume of fluid within the storage tank. These factors are then reported to a tank monitor or other site controller to determine if the tank is leaking and for inventory reconciliation. 
     In the past, the probe reported the factors and parameters through an electromagnetic signal sent over a wirebased system. While adequate for its intended purpose, such wirebased systems have at least two drawbacks. The first drawback to conventional systems is that the communication wires must be routed through an intrinsically safe conduit to reduce the risk of explosion. Such intrinsically safe conduit is expensive, raising the cost of compliance to the fueling environment operator. The second drawback to the conventional systems is that the communication wires must run from the underground storage tank to the tank monitor, which is usually located in the central office of the fueling environment. These communication wires are typically run underneath the concrete slab that forms the fueling environment&#39;s forecourt. If the communication wires are damaged or need to be replaced, the entire forecourt is disrupted as the concrete slab is broken, and the communication wires excavated. Thus, it is difficult to upgrade or repair existing systems without great expense and disruption to the ordinary course of business for the fueling environment. 
     The current leak detection statutes and regulations extend beyond just the underground storage tank and affect the entire piping system of the fueling environment. Thus, sumps associated with the piping system likewise have leak detection probes. These sumps may be positioned underneath the fuel dispensers, at low points in the piping system, or other locations as needed. The sump probes are usually liquid level sensors and generally lack some of the sophistication of the underground storage tank probe. However, this relative lack of sophistication does not lessen the complications associated with establishing the communication link to the tank monitor or other site controller. Specifically, the sump is considered to have the potential for fuel vapors therein, and thus, the environment must be intrinsically safe. The wiring for the sump probe is also usually run underneath the concrete slab of the forecourt. The intrinsically safe requirement and the need to run wires under the forecourt mean that such sump probes likewise increase expense for the fueling environment operator. 
     A few systems have proposed a wireless communication link between the tank probe and the tank monitor in an effort to alleviate costs associated with the conventional wire based systems. While seemingly simple in concept, such systems have run into implementation difficulties. Specifically, the large metallic bodies of cars that move around the fueling environment may create unpredictable capacitive and inductive elements in the signal path, thereby disrupting the signal path. In extreme cases, the cars may cause the signal to be canceled. Even when the impact of the cars does not cancel the signal, the concrete slab and other environmental factors help attenuate the signal from the probe such that the tank monitor&#39;s receiver does not receive an interpretable signal. While it is conceivably possible to boost the wireless signal from the probe sufficiently to overcome the variable attenuation of the forecourt, this is not always an optimal solution as more power is required to boost the signal in this manner. The wires and circuitry providing power to the sump may not be able to handle the increased load associated with the increased power supply. Even if the power level can be boosted to a level strong enough to reach the tank monitor, the signals with the increased power may exceed the emission limits permitted by the Federal Communication Commission (FCC). 
     Thus, an improved system is needed that allows sensors and probes within sumps to communicate wirelessly with the tank monitor or site controller of a fuel environment. 
     SUMMARY OF THE INVENTION 
     The present invention solves the problems of the prior art systems by introducing wireless repeaters to the fueling environment to work in conjunction with wireless transmitters associated with probes. Specifically, the sumps and underground storage tanks are provided with liquid level probes, leak detection probes, and/or other comparable sensors, which generically are called “sensors” herein, to detect various conditions in the fueling environment. Each sensor communicates with a wireless transceiver. A site communicator is likewise associated with a wireless transceiver adapted to communicate with the wireless transceivers of the sensors. Furthermore, one or more repeaters are associated with a repeater transceiver and are positioned within the fueling environment. The repeaters are adapted to receive signals from the sensor transceivers and retransmit the signals from the sensor transceivers to the site communicator transceiver. 
     In a preferred embodiment, the site communicator transceiver emits a relatively strong beacon signal periodically. The sensor transceivers receive this beacon signal and synchronize thereto. Once synchronized, each sensor transceiver receives sensor data from the sensor. The sensor transceivers then transmit the sensor data through an antenna. Ideally, the site communicator transceiver receives the transmitted sensor data and sends an acknowledgement signal. However, recognizing that circumstances may not be ideal, the repeater is also positioned such that it receives the transmitted sensor data. A predetermined amount of time after the repeater receives the transmitted sensor data, the repeater appends a repeater identification to the transmitted sensor data, and transmits the transmitted sensor data (along with the appended repeater identification) to the site communicator transceiver. 
     The site communicator now potentially has two copies of the same transmitted signal data: one from the sensor transceiver, and one from the repeater. The site communicator checks to see if it has received two copies of the signal data. If the site communicator has received two copies, then the copy from the repeater is discarded, and the copy from the sensor transceiver is used in a conventional fashion. If the site communicator does not have two copies, then the site communicator uses the copy from the repeater in place of the missing copy from the sensor transceiver. 
     Several variations on the present invention exist. In an alternate embodiment, the site communicator never sends an acknowledgment signal, and the repeater always sends the transmitted sensor data (along with the appended repeater identification) to the site communicator transceiver. In another alternate embodiment, the repeater delays a random amount of time to transmit the transmitted sensor data (along with the appended repeater identification) to the site communicator transceiver. The randomness of the time delay may help minimize the risk of interference from other signals from other repeaters. The sensor and the sensor transceiver may be powered by batteries, or may draw power from nearby components such as the fuel dispenser. Likewise, the repeater may have a battery power source or may draw power from a nearby component such as the fuel dispenser. The housing for the sensor transceiver should ideally be leak resistant, and may optionally be intrinsically safe. The protocol between the various components may also be varied. For example, in an alternate embodiment, if the site communicator transceiver sends out an acknowledgement signal before the repeater sends its copy of the transmitted sensor data, the repeater may not send the duplicate copy to the site communicator transceiver. 
     Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  illustrates a simplified view of a fueling environment; 
         FIG. 2  illustrates a sump associated with an underground storage tank and a transceiver of the present invention positioned within the sump; 
         FIG. 3  illustrates a sump associated with a fuel dispenser and a transceiver of the present invention positioned within the sump; 
         FIG. 4  illustrates a repeater of the present invention positioned on a fuel dispenser and a second repeater positioned on a canopy associated with the fueling environment; 
         FIG. 5A  illustrates a front view of a transceiver/repeater box connected to a battery power supply; 
         FIG. 5B  illustrates a back view of a transceiver/repeater box connected to an AC power supply; 
         FIG. 5C  illustrates a side view of a transceiver/repeater box connected to a hybrid solar based power supply; 
         FIG. 6  illustrates a flow chart showing an exemplary communication process of the present invention; 
         FIG. 7  illustrates a flow chart showing an alternate communication process of the present invention; 
         FIG. 8  illustrates a packet sent from the sensor transceiver; and 
         FIG. 9  illustrates a packet sent from the repeater transceiver. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
     The present invention associates wireless transceivers with probes in a fueling environment. To help ensure that the wireless signals being generated by the wireless transceivers reach a wireless transceiver associated with a fueling environment site communicator, the present invention positions repeaters at various locations within the fueling environment. The repeaters receive the signals from the probe transceivers and repeat the transmissions such that the site communicator transceiver receives at least one copy of the probe data. Before discussing the operational aspects of the present invention starting with  FIG. 6 , the system components and fueling environment are discussed, as illustrated in  FIGS. 1-5 . 
       FIG. 1  illustrates a fueling environment  10  which may include a central building  12 . This central building  12  may house a convenience store, a quick serve restaurant, a service garage, or the like, as is well understood. While such central buildings  12  are “central” in the sense that they are the focal point of the fueling environment  10 , such central buildings  12  need not be positioned in the “center” of the fueling environment  10 . The fueling environment  10  further has a number of fueling islands  14  upon which fuel dispensers  16  (also labeled “FD” in  FIG. 1 ) are positioned. The fuel dispensers  16  provide fuel to consumers through hoses and nozzles, as is well understood. The fuel provided to the consumers is typically stored in one or more underground storage tanks (UST)  18  (also labeled “UST  1 ” and “UST  2 ” in  FIG. 1 ). The USTs  18  contain fuel that is delivered to the fuel dispensers  16  through a piping network  20  using a submersible turbine pump (not shown). 
     A site communicator  22  (also labeled “SC” in  FIG. 1 ) may be positioned in the central building  12  and has a communication link  24  that communicates with a remote network  26 , such as the Internet, for example, as needed or desired. Until this point, the fueling environment  10  is essentially conventional. The present invention associates a site communicator wireless transceiver  28  with the site communicator  22 . The function of the site communicator wireless transceiver  28  is explained in greater detail below. While the site communicator wireless transceiver  28  is shown inside central building  12 , it should be appreciated that site communicator wireless transceiver  28  may be positioned externally on the central building  12 , or other location as desired. 
     The fuel dispensers  16  may be the ENCORE® or ECLIPSE® fuel dispensers sold by Gilbarco Inc. of Greensboro, N.C., or other suitable fuel dispenser as needed or desired. The USTs  18  are preferably double-walled underground storage tanks and may conform to the description of the underground storage tanks presented in U.S. patent application Ser. Nos. 10/209,962; 10/337,221; and 10/390,346, which are hereby incorporated by reference in their entireties. In  FIG. 1 , UST  1  may hold low octane fuel and UST  2  may hold high octane fuel, with an intermediate octane fuel being achieved by blending, as is well understood. The piping network  20  preferably uses double-walled piping, and may conform to the description of the piping networks presented in U.S. patent application Ser. Nos. 10/238,822; 10/430,890; and 10/03,156, which are hereby incorporated by reference in their entireties. 
     The site communicator  22  may be the G-SITE® or PASSPORT® point of sale systems sold by Gilbarco Inc. of Greensboro, N.C., or more preferably may be one of the various tank monitors, such as the TLS 350, sold by Veeder-Root Company of Simsbury, Conn., the assignee of the present invention. Both site controllers and tank monitors are collectively referred to as site communicators, because they provide the gateway for communication between elements of the fueling environments. Other comparable site communicators may also be used as needed or desired. The connection to the remote network  26  is not required for a device to be considered a site communicator. The communication link  24  may be a two-wire, T1, ISDN, phone line, or other communication link, although a wideband communication link is preferred. 
     A UST  18  is illustrated in  FIG. 2 . The UST  18  is preferably a double-walled UST with inner wall  30  and outer wall  32  forming an interstitial space  31  therebetween. The interstitial space  31  may contain leaks, as is well understood. The inner wall  30  delimits an interior chamber  34  in which fuel is stored. A tank probe  36  measures the level of fuel within the interior chamber  34 . In an exemplary embodiment, the tank probe  36  measures the level of the fuel through a float  38 . The tank probe  36  may be the MAG 1 LEAK DETECTION PROBE or similar device sold by Veeder-Root Company. Alternate probes may be used if needed or desired. These probes or sensors may detect leaks or other conditions within the fueling environment as needed or desired. Exemplary conditions include, but are not limited to: vapor pressure, temperature, the presence or absence of fluid, the presence or absence of hydrocarbons, the presence or absence of oxygen or other atmospheric component, environmental factors, and the like. 
     The head of tank probe  36  is positioned within a fill sump  40 . Fill sumps  40  are designed to allow the UST  18  to be refilled, and are thus positioned beneath a forecourt concrete slab  42 , and may have a manhole or similar access means positioned thereover. The manhole is removed, and the flexible pipes from the tanker are extended through the fill sump  40  into the interior chamber  34  when the UST  18  is being refilled. 
     In an alternate, non-illustrated embodiment, the tank probe  36  may be positioned within a sump designed to hold a submersible turbine pump (STP), such as the STP disclosed in U.S. Pat. No. 6,223,765, which is hereby incorporated by reference in its entirety. If the tank probe  36  were so positioned in the STP sump, the tank probe  36  would extend from the STP sump into the UST  18  in a fashion substantially similar to that illustrated for the fill sump  40 , making allowances for the position of the STP. 
     The tank probe  36  is associated with a tank wireless transceiver  44  according to the present invention. The tank probe  36  is connected to the tank wireless transceiver  44  via a conventional probe cable, such as an RS-485 cable. The tank wireless transceiver  44  receives standard probe signals relating to the tank probe  36 &#39;s measurements and formats the signals from tank probe  36  onto a carrier signal for transmission to the site communicator wireless transceiver  28 . It should be appreciated that the formatting of the signals may take place in a signal processor (not shown) that is associated with the tank wireless transceiver  44 . This signal processor may be integrally formed with tank wireless transceiver  44 , with tank probe  36 , or a separate device as needed. As used herein, “formatted for transmission by the transceiver,” and permutations thereof, include a signal processor associated with the transceiver formatting the data for the transmission, regardless of whether the signal processor is integrated into the transceiver. 
       FIG. 3  illustrates a fuel dispenser  16  associated with a fuel dispenser sump  46 . The piping network  20  extends through the fuel dispenser sump  46 , and a branch conduit (not labeled) extends up into the fuel dispenser  16 , as is well understood. A sump probe  48  is positioned within the fuel dispenser sump  46  to detect fluid within the fuel dispenser sump  46 . The sump probe  48  may be a MAG SUMP SENSOR sold by Veeder-Root Company, or other comparable probe. The sump probe  48  is connected to a sump wireless transceiver  50  via a conventional probe cable. The data from the sump probe  48  is formatted onto a carrier signal and broadcast. The sump wireless transceiver  50  is designed to communicate with the site communicator wireless transceiver  28 . Generically, tank wireless transceiver  44  and sump wireless transceiver  50  are referred to herein as sensor wireless transceivers. 
       FIG. 4  illustrates a fuel dispenser  16  covered by a canopy  52 . Canopy  52  covers a portion of the forecourt concrete slab  42  so that users may fuel their vehicles without being unnecessarily exposed to environmental conditions, such as rain, and to provide lighting to the user at night. A fuel dispenser repeater  54  is positioned on fuel dispenser  16 , preferably near the top portion of the fuel dispenser  16 . The fuel dispenser repeater  54  may be positioned in alternate locations on the fuel dispenser  16  such as within the face of the user interface, proximate the bottom of the fuel dispenser  16 , or other position as needed or desired. However, a higher position is preferred as this reduces the likelihood that line of sight to the site communicator wireless transceiver  28  is blocked by a car or similar transient obstruction. 
       FIG. 4  also illustrates an additional repeater, namely a canopy repeater  56 , which is positioned on the canopy  52 . While the canopy repeater  56  is shown positioned proximate to an edge of the canopy  52 , alternate placements on the canopy  52  are possible, and in fact, the canopy repeater  56  could be positioned on a support pole  58  if needed or desired. While the fuel dispenser repeater  54  and the canopy repeater  56  are shown, it is within the scope of the present invention to provide repeaters on other stationary elements within the fueling environment  10  as needed or desired. Preferably, any such alternate location is elevated and is communicatively coupled to the site communicator wireless transceiver  28  and at least one of the sensor transceivers  44 ,  50 . 
     It should be appreciated that while the present disclosure treats the sensor transceivers  44 ,  50  differently from the site communicator wireless transceiver  28  and the repeaters  54 ,  56 , all these elements are transceivers and contain electronic circuitry capable of sending and receiving electromagnetic signals. The transceivers of sensor transceivers  44 ,  50 , the site communicator wireless transceiver  28 , and the repeaters  54 ,  56  are generically referred to herein as transceivers  60 . In a preferred embodiment, the transceivers  60  may be made by AeroComm of 10981 Eicher Drive, Lenexa, Kans. 66219, and the electromagnetic signals are at 900 MHz, 868 MHz or 433 MHz using a frequency hopping spread spectrum (FHSS) modulation scheme. It should be appreciated that such frequencies are currently preferred, but that other frequencies could be used if needed or desired. 
     While it is possible that there are a number of potential arrangements for each transceiver  60 ,  FIGS. 5A-5C  illustrate an exemplary structure along with a variety of power options. Each transceiver  60  includes a box  62 , and, as better illustrated in  FIG. 5C , the box  62  has a lid  64 , which helps enclose the box  62 . Together the box  62  and the lid  64  make a liquid tight enclosure for the electronic components of the transceiver  60 . In a more preferred embodiment, the box  62  and the lid  64  make an intrinsically safe container such that the transceiver  60  may be positioned in a location that is exposed to fuel vapors. The lid  64  may be secured to the box  62  via screws  66  as shown in  FIGS. 5A and 5C . Box  62  may be secured to a vertical surface via mounting brackets  68  as shown in  FIGS. 5B and 5C , or other mounting mechanism as needed or desired. A conventional monopole antenna  70  extends from the box  62  and is enclosed in a nonconductive material such that the monopole antenna  70  does not create a spark risk or otherwise compromise the intrinsically safe nature of the transceiver  60 . Other antenna arrangements are also possible including but not limited to: a dipole antenna, a patch antenna, an F-antenna, or the like as needed or desired. 
     The box  62  has a first connector  72  that connects the electronics of the transceiver  60  to a power supply. The power supply can be one of several different power sources. In  FIG. 5A , the power source is a battery  74 . In  FIG. 5B , the power source is an AC power supply  76 . In  FIG. 5C , the power source is a battery  78  that is recharged via a solar cell  80 . As shown in  FIGS. 5A and 5B , the box  62  has a second connector  82  which connects to a conventional cable that is connected to either the probe (tank probe  36  or sump probe  48 ) or the site communicator  22 . An exemplary cable is an RS-485 cable, although other such cables are contemplated depending on the exact nature of the probe  36 ,  48 , the site communicator  22 , and/or the transceiver  60 . 
     In an exemplary embodiment, the tank wireless transceiver  44  operates on batteries  74 ; the sump wireless transceiver  50  operates on an AC power supply  76  from the fuel dispenser  16 ; and the repeaters  54 ,  56  operate on either an AC power supply  76  from the fuel dispenser  16  or a hybrid power supply with the solar cell  80  positioned on top of the canopy  52  so that it is well positioned to receive copious amounts of sunlight. The site communicator wireless transceiver  28  preferably transmits at 500 mW, while the sensor transceivers  44 ,  50  and the repeaters  54 ,  56  transmit at 100 mW. 
       FIG. 6  illustrates a flow chart of an exemplary embodiment of the transceivers and repeaters of the present invention in use where the repeaters  54 ,  56  retransmit received probe data with a delay in case the site communicator  22  did not receive the probe data directly from the sensor transceivers  44 ,  50 . 
     In particular, the site communicator wireless transceiver  28  broadcasts a beacon signal (block  100 ). This beacon signal may be broadcast several times per second. The client transceiver (sensor transceivers  44 ,  50 ) detects the beacon signal (block  102 ). The client transceiver synchronizes with the beacon signal (block  104 ). Periodically, the client transceiver will receive data from the probes  36 ,  48  associated with the client transceiver and will format the probe data for transmission. An exemplary format for transmission is explored below with reference to  FIG. 8 . After assembly into a suitable format, the client transceiver transmits the probe data (block  106 ). The repeaters  54 ,  56  then receive the transmitted probe data (block  108 ). 
     The repeaters  54 ,  56  delay a random amount of time (so as to avoid collisions), and then retransmit the probe data with the repeater ID added to the original message from the client transceiver (block  110 ). An exemplary format for this signal is described below with reference to  FIG. 9 . The site communicator wireless transceiver  28  receives the probe data from the repeaters  54 ,  56  and determines if the probe data was received from the client transceiver directly (block  112 ). Note that the actual determining may be performed by a processor within site communicator  22  or within the site communicator wireless transceiver  28 , as needed or desired. As used herein, “the site communicator determines” includes determining in either location. 
     If the site communicator wireless transceiver  28  received the probe data from the client transceiver directly (i.e., the answer to block  112  is yes), then the site communicator  22  discards the probe data from the repeaters  54 ,  56  (block  114 ) and the site communicator  22  uses the probe data (block  116 ) as desired. If however, the answer to block  112  is no, the site communicator  22  did not receive the probe data from the client transceiver, then the site communicator  22  uses the probe data (block  116 ) provided by the repeaters  54 ,  56 . 
     An alternate embodiment of the methodology of the present invention is presented in  FIG. 7  where the repeaters  54 ,  56  do not repeat transmission of the probe data unless the site communicator  22  did not receive the probe data from the sensor transceivers  44 ,  50 . 
     In particular, the site communicator wireless transceiver  28  broadcasts a beacon signal (block  200 ). This beacon signal may be broadcast several times per second. The client transceiver sensor (transceivers  44 ,  50 ) detects the beacon signal (block  202 ). The client transceiver synchronizes with the beacon signal (block  204 ). Periodically, the client transceiver will receive data from the probes  36 ,  48  associated with the client transceiver, and will assemble the probe data into a format appropriate for transmission. After assembly into a suitable format, the client transceiver transmits the probe data (block  206 ). The repeaters  54 ,  56  then receive the transmitted probe data (block  208 ). 
     The site communicator wireless transceiver  28  determines if the site communicator wireless transceiver  28  received the probe data from the client transceiver directly (block  210 ). Again, note that this determining may be done by the site communicator wireless transceiver  28  or the site communicator  22 , as needed or desired. If the answer to block  210  is yes, the site communicator wireless transceiver  28  did receive the probe data from the client transceiver, then the site communicator wireless transceiver  28  sends an acknowledgement (ACK) signal (block  212 ). 
     If the answer to block  210  is no, the site communicator wireless transceiver  28  did not receive the probe data from the client transceiver (or as part of the normal processing after sending the ACK signal), the repeaters  54 ,  56  determine if the repeaters  54 ,  56  received the ACK signal (block  214 ). If the answer is no, the repeaters  54 ,  56  have not received the ACK signal, then the repeaters  54 ,  56  add the repeater ID to the probe data and transmit the probe data (block  216 ). The site communicator transceiver  28  receives the probe data from the repeaters  54 ,  56  and transmits an ACK signal (block  218 ). Then, either as a result of the site communicator wireless transceiver  28  receiving the probe data from the client transceiver or the repeaters  54 ,  56 , the site communicator  22  uses the probe data as normal (block  220 ). 
     It should be appreciated that in both embodiments, the initial transmission of the probe data from the client transceiver may be repeated periodically for a set number of times. For example, the client transceiver may repeat its transmission every sixteen milliseconds for sixteen times in an exemplary embodiment. Other periods and numbers of retransmissions are also possible. Likewise, the repeaters  54 ,  56  may transmit the probe data periodically for a set number of times. In the exemplary embodiment, the repeaters  54 ,  56  may retransmit the probe data every sixteen milliseconds for up to sixteen times, or until an ACK signal is received as needed or desired. Again, the precise numbers may be varied as needed or desired. The numbers presented herein are for the purposes of example, and are not intended to be limiting. 
     Exemplary formats for the signals are presented in  FIGS. 8 and 9 , although any format may be used with the present invention.  FIG. 8  illustrates a packet  300  sent from a client transceiver (sensor transceiver  44  or  50 ). The packet  300  is approximately one hundred bytes long, and includes the packet header  302 , which includes the probe transceiver identification so that the site communicator  22  knows from which client transceiver the probe data originated, and the payload  304 , which includes the probe data.  FIG. 9  illustrates the packet  306  from the repeaters  54 ,  56 . The packet  306  is similar to the packet  300 , and includes a new header  308 , which has the repeater identification such that the site communicator  22  knows from which repeater  54 ,  56  the packet originated, as well as a modified payload  310  which includes the original probe transceiver identification and the original probe data. In this manner, the site communicator  22  can determine from where the probe data originated. 
     It should be appreciated that alternate packet structures can be used if needed or desired. The packets presented herein are by way of example and are not intended to be limiting. Further, the present invention is not limited to any particular type of probe or sensor, transceiver, or site communicator. 
     Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.