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精选优质文档-倾情为你奉上 河 北 建 筑 工 程 学 院本科毕业设计（论文）外文资料翻译 院别： 电气工程学院 专业： 电气工程及其自动化 班级： 电控102 姓名： 白宇 学号： 外文出处： CNKI （用外文写） 附 件：1、外文原文；2、外文资料翻译译文。指导教师评语：签字： 年 月 日1、外文原文Automatic meter reading systemThe present invention relates to automatic meter reading. More particularly, the present invention relates to an automated system for remotely monitoring a plurality of utility meters on command from a host server via an RF outbound broadcast. BACKGROUND OF THE INVENTION Historically, meters measuring electrical energy, water flow, gas usage, and the like have used measurement devices, which mechanically monitor the subscriber's usage and display a reading of the usage at the meter itself. Consequently, the reading of these meters has required that human meter readers physically go to the site of the meter and manually document the readings. Clearly, this approach relies very heavily on human intervention and, thus, is very costly, time-consuming, and prone to human error. As the number of meters in a typical utility's service region has increased, in some cases into the millions, human meter reading has become prohibitive in terms of time and money. In response, various sensing devices have been developed to automatically read utility meters and store the meter data electronically. These sensing devices, usually optical, magnetic, or photoelectric in nature, are coupled to the meter to record the meter data. Additionally, the meters have been equipped with radio frequency (RF) transceivers and control devices which enable the meters to transmit meter data over an RF link when requested to do so. Hand-held devices have been developed which include RF transceivers designed to interface with the meters' RF transceivers. These hand-held devices enable the human meter reader to simply walk by the meter's location, transmit a reading request over an RF link from the hand-held device to the meter's receiving device, wait for a response from the meter's sensing and transmitting device, and then record, manually or electronically, the meter data. Similarly, meter reading devices have been developed for drive-by reading systems. Utility vans are equipped with RF transceivers similar to those described in the hand-held example above. The human meter reader drives by the subscriber's location, with an automated reading system in the utility van. Again, the meters are commanded to report the meter data, which is received in the van via an RF link, where the data is recorded electronically. While this methodology improves upon the previous approaches, it still requires a significant amount of human intervention and time. Recently, there has been a concerted effort to accomplish meter reading by installing fixed communication networks that would allow data to flow from the meter all the way to the host system without human intervention. These fixed communications networks can operate using wire line or radio technology. FIG. 1 shows a conventional fixed communication network for automated meter reading (AMR) technology. As shown in FIG. 1, a fixed communication network having wire line technology in which utility meters 10 are connected to a wide area network (WAN) consisting of a suitable communications medium, including ordinary telephone lines, or the power lines that feed the meters themselves. One disadvantage of this approach has been that when a number of meters transmit meter data nearly simultaneously, the inherent latency on the wide area network results in packet collisions, lost data, garbled data, and general degradation of integrity across the system. To compensate for the collisions and interference between data packages destined for the central computer, due to the latency inherent in the WAN, various management schemes have been employed to ensure reliable delivery of the meter data. However, while this approach may be suitable for small systems, it does not serve the needs of a utility which monitors thousands or even millions of meters. In an attempt to better manage the traffic in the WAN, approaches have been developed wherein meter control devices similar to those described above have been programmed to transmit meter data in response to commands received from the central computer via the WAN. By limiting the number of meter reading commands transmitted at a given time, the central computer controls the volume of data transmitted simultaneously. However, the additional WAN traffic further aggravated the degradation of data integrity due to various WAN latency effects. Thus, while these approaches may serve to eliminate the need for human meter readers, reliance on the WAN has proven these approaches to be unsatisfactory for servicing the number of meters in the typical service region. Consequently, radio technology has tended to be the medium of choice due to its higher data rates and independence of the distribution network. The latest evolution of automated meter reading systems have made use of outbound RF communications from a fixed source (usually the utility's central station), directly to RF receivers mounted on the meters. The meters are also equipped with control devices which initiate the transfer of meter data when commanded to do so by the fixed source. The meters respond via a WAN as in the previous wire-based example. One disadvantage of these approaches is that there is still far too much interference on the WAN when all of the meters respond at about the same time. Thus, while these approaches reduce some of the WAN traffic (by eliminating outbound commands over the WAN), they are still unable to accommodate the large number of meters being polled. It is worthy of note that the wire-based systems typically use a single frequency channel and allow the impedance and transfer characteristics of the transformers in the substation to prevent injection equipment in one station from interfering with receivers in another station. This built-in isolation in the network makes time division multiplexing less critical than for radio based metering systems. Typical fixed network radio systems also utilize a single channel to read all meters but the systems do not have a natural blocking point similar to the substation transformer utilized by distribution line carrier (DLC) networks. Also, the latency inherent in the WAN has contributed significantly to the problems associated with time division multiplexing a single frequency communications systems. As a result, the systems require sophisticated management schemes to time division multiplex the channel for optimal utilization. Therefore, a need exists to provide a system whereby a utility company can reliably and rapidly read on the order of one million meters in the absence of any significant human intervention. Further, a need exists to provide such a system which accommodates changes to the network as well as changes in operating conditions without significant degradation of performance. SUMMARY OF THE INVENTION The present invention fulfills these needs by providing an automated meter reading system having a host server interfaced to a plurality of nodes, each node communicating with a number of utility meters. In a preferred embodiment, the system has a selection means for selecting a group of noninterfering nodes; and an outbound RF broadcast channel from the host server for communicating with the selected group to initiate the reading of meters that communicate with those nodes and the uploading of meter data provided by those meters to those nodes. This outbound RF broadcast channel can be an existing channel currently being used for demand side management. In a preferred embodiment, the system also has a two-way communication link over a wide area network between the host server and each of the nodes. In a more preferred embodiment, the host server receives meter data read from at least one million meters in no more than about five minutes. In yet another preferred embodiment, the system also has a number of gateways, each communicating with a plurality of nodes, grouped to form sets of noninterfering gateways. In this embodiment, the system also has a selection means for selecting one of the sets of noninterfering gateways, and a second outbound RF broadcast channel from the host server for communicating with the selected set to initiate uploading of meter data from the selected set to the host server. This second outbound RF broadcast channel can be an existing channel currently being used for demand side management. The present invention further fulfills these needs by providing a method for using an outbound RF channel to automatically read meters. In a preferred embodiment, the method comprises the steps of: defining a number of groups of noninterfering nodes: selecting a first group; broadcasting a read command to each node in the first group; selecting a second group; and broadcasting a read command to each node in the second group. In another embodiment, the method further comprises the steps of: reading meter data, in response to the read command, from each meter communicating with the node receiving the read command; recording the meter data in a data storage means associated with that node; broadcasting an upload message to each node in the first group; uploading the meter data recorded in the data storage means associated with the nodes of the first group to the host server; broadcasting an upload message to each node in the second group; and uploading the meter data recorded in the data storage means associated with nodes of the second group to the host server. In yet another embodiment, at least some of the nodes communicate through one of a number of gateways to the host server. In this embodiment, the method further comprises the steps of: selecting a first set of noninterfering gateways; broadcasting an upload message to each gateway in the first set; uploading the meter data recorded in the data storage means associated with the nodes that communicate with the first set of noninterfering gateways to the host server; selecting a second set of noninterfering gateways; broadcasting an upload message to each gateway in the second set; uploading the meter data recorded in the data storage means associated with nodes that communicate with the second set of noninterfering gateways to the host server. The present invention further fulfills the aforementioned needs by providing an automated meter reading system wherein the host server maintains a topology database in which each meter is assigned to at least one node, each node is assigned to at least one gateway. The nodes are preferably grouped together to define groups of noninterfering nodes and the gateways are preferably grouped together to define sets of noninterfering gateways. In another preferred embodiment, each of the plurality of nodes is adapted to receive RF broadcasts and the host server sequentially broadcasts a communication over an RF channel to each group of noninterfering nodes to initiate meter reading. In yet another preferred embodiment, each of the plurality of gateways is adapted to receive RF broadcasts and the host server sequentially broadcasts an upload message over a second RF channel to each set of noninterfering gateways, the gateways uploading the meter data to the host server via a wide area network in response to the upload message. The present invention further fulfills these needs by providing a method of automatically reading a plurality of meters in an AMR system comprising the steps of: selecting one of the nodes designated to communicate with each gateway; grouping the selected nodes to form groups of noninterfering nodes; forming sets of gateways such that each gateway within one set has an individual gateway designator; maintaining a topology database that uniquely identifies for each meter the set, gateway and node designators associated with said meter; and reading the meters based on the set, gateway and node designators. In another preferred embodiment, the method further comprises the step of initiating meter reading by sequentially broadcasting a read message over an RF channel to each group of noninterfering nodes. In yet another preferred embodiment, the method further comprises the step of initiating the uploading of meter data by sequentially broadcasting an upload message over the RF channel to each group of noninterfering nodes. The present invention will be better understood, and its numerous objects and advantages will become apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings, in which: FIG. 1 shows a conventional fixed communication network for automated meter reading technology; FIG. 2 shows a block diagram of an automated meter reading system according to the present invention; FIG. 3 shows a block diagram of an automated meter reading system in which an optional gateway is included according to the present invention; FIG. 4 shows a network of nodes and gateways exemplifying a group of noninterfering nodes; FIG. 5 shows communications traffic within one set of gateway service regions in an automated meter reading system; FIG. 6 shows the process by which a host server commands groups of noninterfering nodes to read meters and by which nodes read and store meter data gateways in accordance with a preferred embodiment of the present invention; FIG. 7 shows the process by which a host server commands nodes and gateways to upload meter data simultaneously in accordance with a preferred embodiment of the present invention; FIG. 8 shows the process by which a host server commands nodes and gateways to upload meter data by using groups of noninterfering gateways in accordance with a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 2 shows a diagram of a preferred embodiment of an automated meter reading system which uses broadcast technology to read utility meters in accordance with the present invention. The system includes a host server, a wide area network (WAN), a plurality of optional gateway interface (OGI) nodes, and a plurality of utility meters 。 The host server might be any widely available personal computer or mini-computer. The host server is basically a communications protocol converter which manages the access to a variety of different RF media by keeping routing algorithms and end item databases that include address information. The WAN might by any public or private network and based on any communications technology. The WAN preferably has a data rate of at least about 28.8 Kbps. The host server interfaces with the WAN preferably via two way links of at least about 56 Kbps using Internet Protocol (IP), for example. A plurality of OGI nodes are interfaced with the WAN via two way communication links. In a preferred embodiment, communication links use IP, for example, over serial links of at least about 9.6 Kbps. In a preferred embodiment, each OGI node interfaces with a plurality of meters. The outbound communications protocol between the OGI nodes and the meters will vary depending on the type of meter. For electric meters, the outbound communications protocol preferably uses a data rate at about 1 Kbps. For water and gas meters, the outbound communications protocol preferably uses a data rate at about 128 bps, single packet wakeup only. The inbound communications protocol from the meters to the OGI node preferably uses a data rate at about 93.75 Kbps with collision avoidance, single packet response only. In the embodiment shown in FIG. 2, the host server communicates directly with the OGI nodes via a one way outbound RF broadcast channel. The outbound RF channel may be frequency modulated (FM) subsidiary channel authorization (SCA) with a data rate of about 1.2 Kbps. However, it should be understood that other channel definitions may be employed and the invention is not intended to be limited to those examples described herein. FIG. 3 shows an alternate embodiment of the present invention in which a plurality of gateways is introduced to reduce the number of WAN connections to nodes. In this example, each gateway services a group of gateway interface (GI) nodes. Thus, for a group of GI nodes being serviced by a gateway, the system now requires only one WAN connection for the group (that being the WAN connection to the gateway ), rather than one WAN connection for each GI node in the group. A plurality of gateways are interfaced with the WAN via a two-way communication link . In a preferred embodiment, communications link uses IP over serial links of at least about 28.8 Kbps. A plurality of GI node are interfaced with each gateway via a two-way RF link . In a preferred embodiment, RF link might use, for example, a robust ACK/NAK protocol over a 900 MHz RF channel of at least about 9.6 Kbps. Each GI node interfaces with a plurality of meters . For electric meters, the outbound communications protocol preferably uses a data rate at about 1 Kbps. For water and gas meters, the outbound communications protocol preferably uses a data rate at about 128 bps, single packet wakeup only. The inbound communications protocol from the meters to the GI node preferably uses a data rate at about 93.75 Kbps with collision avoidance, single packet response only. Where OGI nodes are used instead of GI nodes and gateways , the host server preferably transmits upload commands directly to the OGI node over the outbound RF broadcast channel . It should be understood that this embodiment improves the transparency of the host server OGI node path since the host server now communicates directly with the node, but at the same time causes uncertainty as to which WAN links will be used when the OGI nodes upload the meter data, since the number of necessary WAN connection is increased. It is important to note that the more information the host server has regarding the network architecture, the better able it will be to adapt to architecture or protocol changes. In the embodiment shown in FIG. 3, the host server communicates directly with the GI nodes via a one way outbound RF broadcast channel . Similarly, the host server preferably communicates directly with the gateways via a one-way outbound RF broadcast channel . In a preferred embodiment, outbound RF broadcast channels , may include FM SCA with data rates of about 1.2 Kbps. However, it should be understood that other channel definitions may be employed and the invention is not intended to be limited to those examples described herein. The utility can use any existing low-latency broadcast technology such as DLC, VHF, 800 MHz utility trunked radio, 900 MHz utility MAS radio, a private paging system, SCA over audio channels of commercial VHF or UHF television stations, etc. In a preferred embodiment, the data rate should be at least about 50 bps. The host server preferably controls both the FM SCA broadcast path and the outbound host server-gateway-WAN link. Broadcasts reduce channel interference arising from having the meter/node and node/gateway links sharing RF channels because the host server-gateway-node (outbound) path through the WAN should rarely be used for meter reading. Furthermore, the node-gateway-host server (inbound) path is used under a strict authorization scheme controlled by the host server. Thus, c