Remote Monitoring System

Abstract

A remote monitoring system for monitoring parameters of underground assets, such as cable systems, pipelines for conveying water, gas, oil, sewage, etc. Parameter detectors (e.g., sensors measuring temperature, voltage, current, humidity, etc.) are distributed along the asset to provide electrical signals representative of various monitored parameters of the asset. The asset is coupled to the parameter detectors via an underground hub disposed in an underground cable room or manhole to acquire the signals provided by the parameter detectors. The hub includes a controller for providing data derived from the acquired signals, which are transmitted by a transceiver or modem to a remote central location via low power wide area network communications. The signals from the transceiver are transmitted directly from underground.

Description

[0001] This invention was made with U.S. Government support under Project DE-SC0004280 funded by the U.S. Department of Energy. The U.S. Government has certain rights in this invention. Technical Field

[0002] The present invention generally relates to monitoring systems for monitoring parameters of underground assets (eg, underground cable systems, pipelines, water pipes, sewer pipes). Background Art

[0003] In the field of underground power cables, water lines, oil and gas pipelines, sewage pipes, etc., commonly referred to as underground assets, it is of great significance to monitor the operational and / or environmental conditions of these assets. Unexpected or abnormal behavior conditions may indicate the existence of future dangerous or fault conditions. Once these conditions are noticed in underground assets, it can allow maintenance or remedial measures to be accelerated; which can subsequently avoid underground assets being out of service or offline for longer periods of time.

[0004] Monitoring the behavior of such underground assets can predict problematic conditions that can be remedied before repair becomes difficult and time-consuming. However, such underground assets (such as power cables) may not be easily accessible, making it difficult to monitor their operating characteristics. In addition, regular inspections of the routes and life of the assets' underground assets by technicians are labor-intensive and may require service interruptions to conduct equipment inspections. Such inspections are typically limited to cable rooms, manholes, smaller below grade enclosures (called handholes), and curb boxes placed at intervals along the routes of the underground assets. Accessing underground assets in large cabinet enclosures (e.g., manholes) requires safety equipment and procedures, and often requires "pumping out" of residual standing water that has entered through manhole covers or through pipe and conduit penetration seals. It has been found that the actual time required to inspect underground assets is significantly less than the time required to safely enter the confined space. Therefore, inspections are rarely performed; and are typically performed after an operational failure to investigate the cause and identify the scope of the system for similar scenarios that expose the problem.

[0005] There is therefore a need for a system that can monitor the operating characteristics of underground assets and, without human intervention, send an indication of the asset's condition to a monitoring center, typically several miles away, for analysis. Advantageously, such an indication goes beyond a simple alarm based on the device having reached or exceeded a pre-established operating limit. It would be beneficial if such an indication included a deviation from expected behavior based on historical factors. Sensors for generating electrical signals that are representative of operating and / or environmental parameters of underground assets are known. However, such sensors must be located underground; and it is difficult to transmit the signals, or to transmit data representing the parameters measured by the sensors, directly from the underground location to the monitoring center. The installation of physical conduits (such as fiber optic cables) can provide a communication line from such sensors to the monitoring center, however, the installation of physical conduits (such as fiber optic cables) is prohibitively expensive, particularly for retrofitting existing systems, and additional power sources are typically required for such communication lines.

[0006] In addition, monitoring devices set up along the assets and especially in underground cable chambers through which the assets pass should be independent. Therefore, the monitoring devices should be provided with a relatively long-life power supply. Although the power for the monitoring devices can be obtained from the power cables in the cable chamber, such power cannot be sustained for a longer period of time when the assets are lightly loaded or powered off, such as the time required for inspection and / or maintenance. In addition, although power can be obtained from the power cables, it is not possible to obtain power from other underground assets (e.g., water pipes and gas pipelines). Power from nearby power utility sources may require earthwork excavation and street repairs, and is therefore not preferred and should be avoided as much as possible. Therefore, it is preferred to obtain power from the power supply of the monitoring device, and it is expected that such power supply is energy-efficient, especially for underground monitoring devices installed in remote locations. Therefore, if possible, it is beneficial to extend battery life to operate the monitoring device and the entire monitoring system with caution, such as operating the monitoring device in a "watchdog" mode where frequent data transmission is not required.

[0007] Furthermore, it is not uncommon for a remotely located underground monitoring device to experience interruptions in the power supplied to the device, and more likely, inadvertent interruptions in communications between the device and the monitoring center. When such an interruption occurs, the operating status of the monitoring device may not be accurately known until power or communications are restored. Therefore, it is advantageous for the remote monitoring device to automatically and independently restore its operation, and for the system to be able to recover all available data from the last successful transmission. Summary of the invention

[0008] Thus, the present invention relates to a remote monitoring system for monitoring parameters of underground assets, such as cable systems and pipelines for conveying water, gas, oil, sewage, etc. Parameter detectors (e.g., sensors) are installed at discrete locations distributed along the asset to provide electrical signals representing various monitoring parameters of the asset, including parameters that provide an assessment of the condition of a cable room or manhole containing a pipeline or pipeline system. Examples of sensors include sensors that measure temperature, voltage, current, humidity, gas content, oil and water contamination, etc. In one embodiment, an underground hub is coupled to the parameter detector to acquire the signal provided by the parameter detector. Preferably, the hub is arranged in an underground cable room, or in a manhole through which the asset passes, or in a curb box below the ground, or in a handhole with an access to the asset along the route of the asset. The hub includes a controller for providing data derived from the acquired signal, which is transmitted to a remote central location by a transceiver or modem.

[0009] In one embodiment, the transceiver is located in a hub or cable closet below ground level; data is wirelessly transmitted from the cable closet to a central location via low-power wide-area network (LP-WAN) communications, and the transmitted data is analyzed at the central location to characterize the asset. The central location determines the behavior and condition of the asset based on the data transmitted by the hub, and preferably based on the data transmitted by multiple hubs.

[0010] The transceiver may also receive communications from the central location to control the controller via low power wide area network communications. In one embodiment, the communications are instructions to control the number of signals obtained from the parameter detectors, the frequency of signals obtained from the parameter detectors, and the rate at which sensor data is transmitted from the hub to the central location. Other instructions related to the operation of the hub may sometimes be issued to the controller.

[0011] According to an embodiment, the hub processes and transmits a reduced amount of data derived from signals acquired by the parameter detectors. Preferably, the signals from the parameter detectors are sampled at a relatively low rate when it is determined that the asset is not behaving abnormally, and the signals from the parameter detectors are increased when more data is needed to properly determine the asset behavior. The data transmitted is a set of derived values ​​representing the sampled values. Thus, battery power is conserved while sufficient information is sent to the central location to obtain a satisfactory determination of the asset behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following detailed description will be better understood by way of examples with reference to the accompanying drawings, in which:

[0013] Figure 1 is a block diagram of an embodiment of a remote monitoring system of the present invention;

[0014] Figure 2 yes Figure 1 A block diagram of a portion of a hub shown in ;

[0015] Figure 3A It is used to illustrate Figure 1 A timing diagram of the operating modes of the hub shown in;

[0016] Figure 3B is a timing diagram for illustrating another mode of operation of the hub;

[0017] Figures 4A to 4C Describe a technique for reducing the amount of data transmitted from a hub to a central location;

[0018] Figure 5 is a flow chart representing system initialization;

[0019] Figure 6 is a flowchart representing the default operation of the system;

[0020] Figures 7A to 7B A block diagram of one embodiment of a remote monitoring system having several hubs;

[0021] Figure 7C is a flow chart representing the functions performed by the central server;

[0022] Figure 8 is a flow chart showing the operation of a hub in "watchdog" mode. DETAILED DESCRIPTION

[0023] With reference to the accompanying drawings, Figure 11 is a block diagram of an embodiment of a remote monitoring system according to the present invention. In which, a hub 104 disposed in an underground cable chamber 108 monitors parameters of an underground asset 102; processes and sends data derived from the monitored parameters to a central location 120, for example, a central server. Optionally, the hub can be installed in a curb box or hand hole below the ground. In this embodiment, the hub 104 includes a sampler 107, which is coupled to sensors 106a, 106b, ..., 106n for sampling signals generated by the sensors. The sensors are distributed outside the hub and are suitable for generating signals representing detected or sensed parameters of underground assets, such as temperature, pressure, voltage, current, etc. The sensor can be a simple lead connector or a more complex transducer. The asset can be a power cable, a pipeline for transporting oil, gas, water, or other pipelines, accessories or auxiliary equipment related to the asset. For convenience, the asset 102 is described herein as a power cable, sometimes referred to as an underground cable system or simply a cable. However, as used herein, reference to a cable system is intended to include the above-mentioned assets, such as, but not limited to, water pipes, oil and gas pipelines, sewage pipes, and equipment included in manholes, connection boxes, etc.

[0024] The cable room 108 is accessible through a cover 109; it may also be a typical manhole known to those skilled in the art of electrical installation technology. The cables may be power cables suitable for high or medium voltage transmission or low voltage secondary circuits. The hub 104 is typically installed in the manhole through which the cable 102 passes. However, the hub may also be installed in a curb box below ground level, or in a handhole containing leads for attaching below ground assets. The asset may be the manhole itself or other equipment within the manhole. Those skilled in the art recognize that the cable room is structurally larger than the manhole and may contain multiple assets, including transformers, switches, etc.; manholes and handholes are smaller and simpler than cable rooms. The hub 104 is used to obtain a representation of the operating parameters of the asset. The hub is preferably located in a cable room or manhole, or may be buried directly below ground level.

[0025] The sampler 107 may be a conventional A / D converter and sampler for generating digital sample values ​​of signals from the sensors 106a, ..., 106n. The controller 110 located in the hub 104 is adapted to receive sensor samples from the sampler 107. Preferably, the sampler is disposed inside the hub 104, but optionally, the sampler may also be disposed outside the hub.

[0026] The hub also includes a wireless transceiver 114 or modem for communicating with a central server 120. As described below, the central server is remote from the hub 104 and analyzes data transmitted from the hub, and preferably, analyzes data transmitted from multiple hubs. As discussed below, the data is derived from the sampler, and the data represents the parameters monitored by the sensor. In one embodiment, the central server includes a data processor adapted to provide an indication of the local operating conditions of the cable 102 based on the data transmitted from the hub.

[0027] Data from the hub 104 can be integrated with data received from other hubs 104' installed in cable rooms 108' at other locations to characterize the entire cable system and enable asset managers to identify anomalies and schedule system maintenance as needed, rather than relying on fixed periodic inspections and audits. For example, the central server is suitable for determining whether the measured parameters and the cable system are operating within a normal or expected range. The central server is also suitable for determining whether the current operating conditions of the cable are consistent with past operations based on historical values. The central server senses that if there are changes in the operating conditions of the cable system, represented by the sensor signals from one hub compared to the sensor signals from another hub, to determine whether these changes are beyond the normal operating range of the cable system, and if so, an alarm is generated.

[0028] Data representing the sampled sensor signals are transmitted as data packets to a central server via a wireless transceiver 114. The transceiver operates according to a cellular low-power wide area network, such as LTE-M and NB-IoT communication technologies installed and operated by AT&T, Verizon, etc. and other cellular service providers known to those skilled in the art. In one embodiment, the hub transceiver can access several service providers of different networks and seamlessly prefer networks based on signal strength and quality. Therefore, the transceiver can transmit data directly from underground to the cellular network 122 via the Internet, cellular communication, etc., and then to the server. In one embodiment, the hub includes a transceiver 114 and a custom antenna to transmit data via low-power wide area network communication. In another embodiment, the transceiver set in the hub 104 is connected to an antenna located in a cable room but outside the hub 104. In another embodiment, the antenna is located below the ground, outside the cable room, manhole or handhole, and is connected to the transceiver by a cable. In another embodiment, the antenna and transceiver are located outside the hub 104 but are set below the ground. It is conceivable that the cellular network could be omitted and data could be transmitted directly from the hub to a central server.

[0029] The hub is powered by a suitable power source, such as a battery 105. Optionally, the necessary power may be harvested from the power cable 102 or associated shielding system by a harvesting device 111, such as an inductive coil, Rogowski coil, or other known device, or may be routed to the cable room from a locally available utility power source. In a preferred embodiment, the battery 105 exhibits a relatively long life, such as approximately two years or more, and the life may be extended by power harvesting to supplement the power required to support hub activities or battery recharging. As discussed below, the samplers and transceivers are operated discontinuously at controlled, preferably brief intervals, to improve battery life and conserve power. In addition, as described below, not all digitized samples are transmitted to the central server, thereby reducing the amount of data transmitted and reducing the power drawn from the battery.

[0030] exist Figure 1 In the illustrated embodiment, terminals 124 and 126 communicate with the monitoring system via the central server 120. As a management terminal, terminal 124 is used as a human-machine interface to manage remote monitoring equipment and upload hub instructions for controlling the hub to the central server for subsequent download or transmission to the hub. Although terminal 126 can also be used for management, system management operations are preferably limited to being performed by personnel with appropriate authority and security clearance. For the purposes of this discussion, it is assumed that terminal 124 is operated by such personnel and serves as an interface with such personnel. Communications between terminals 124, 126 and central server 120 can be wireless communications or hard-wired communications, such as based on cellular or Internet networks.

[0031] As described below, the central server 120 is adapted to send operating instructions to the hub 104 via cellular network low power wide area network communication. Instructions that can be uploaded from the terminal 124 to the central server are received by the transceiver 114 to control the controller. In one embodiment, the terminal 124 can be provided with a computer function that is adapted to analyze the instructions and data provided by the central server 120 and generate instructions to be sent to the hub; the terminal 126 can be adapted to access the instructions and data from the central server, but does not have the ability to generate instructions. For example, and as discussed below, the instructions uploaded to the central server establish a sampling interval for sampling the sensor signal (sample size), a sampling frequency (the frequency at which the sensor signal is acquired), and a transmission frequency (the frequency at which data representing the sensor signal is transmitted to the central server). Typically, in periodic sampling or "watchdog" mode, instructions issued by a technician at the terminal 124 via the central server to the hub require less frequent sampling and transmission of data to save battery power. However, based on the parameters sensed by the different hubs in the cable system, as determined by the central server, the central server can send instructions to increase or decrease the sampling interval, sampling frequency, and transmission frequency in order to adjust the monitoring parameters to obtain additional data at the expense of battery life. In one embodiment, as described below, the controller 110 can also operate autonomously to change the sampling interval, sampling frequency, transmission interval, and / or transmission frequency based on local sensed conditions derived from the sensors.

[0032] The hub 104 includes a storage device, such as a memory referred to as memory 112. The memory is suitable for storing data representing the sampled sensor signals. Advantageously, once power to the hub is interrupted or communication between the hub and the central server is lost, the data stored in the memory 112 can be transmitted to the central server 120 when power or communication is restored. Thus, when power or communication is restored, data that has been acquired but not sent when power or communication was interrupted and that may be needed to determine the operating condition of the cable system is transmitted.

[0033] The memory 112, or preferably, another memory (not shown) is suitable for storing instructions for initializing the controller 110, such as when the hub 104 is put into operation. The memory may also store instructions for operating the controller in a recovery mode when power or communication is restored. The functions performed by these instructions are described below. The memory or another memory is suitable for storing instructions received from a central server via the transceiver 114 for determining the operating mode of the controller. These instructions can establish a "watchdog" mode for sampling data less frequently and transmitting data to the central server, or a fast mode for sampling data more frequently and transmitting data. As described below, the instructions establish one or more of a sampling interval, a sampling frequency, a transmission interval, and a transmission frequency to control data collection and subsequent transmission to the central server.

[0034] In operation, sensor signals from sensors 106a, ..., 106n are sampled by sampler 107. The sampler samples the sensor signals during periodic sampling intervals at a predetermined sampling frequency, which is established by instructions sent from central server 120 to hub 104. In addition, the system operator can provide instructions to controller 110 via the central server to determine local operating conditions of the cable system based on the signals provided by the sensors, and to establish sampling intervals and sampling frequencies based on the determined operating conditions. Controller 110 also controls transceiver 114 to transmit the sampled sensor signals to the central server at a predetermined transmission frequency within the transmission interval. Controlling the transceiver based on a preferred or optimized transmission interval has advantages and economics, such as being set by a network service provider (e.g., a cellular service provider), being a function of the amount of data accommodated by the service provider, and being determined by the amount of traffic on the network.

[0035] In one embodiment, the controller 110 uses the sampled sensor signals to determine the specific operating conditions of the cable system and establishes a transmission interval and / or frequency for transmitting the sampled sensor signals accordingly. As described below, consecutive transmission intervals are separated by a sleep interval or sleep mode; the controller wakes up, transmits samples during an active operating mode, and then returns to the sleep mode. Optionally, the sleep interval can be adjusted in response to instructions received from a central server.

[0036] Figure 2A block diagram of a portion of the electronics included in the hub 104 is shown. Signals from the sensors 106a, ..., 106n are sampled by a front end that includes a sampler 207 operating at a determined sampling rate, an analog-to-digital (A / D) converter, and an amplifier (not shown separately) that produces digital samples. These samples are acquired during a predetermined sampling interval, preferably periodically analyzed and packetized at an adjustable sampling frequency, and stored in a memory 212. The packetized digital samples are read from the memory and transmitted as data packets by a transmitter 214 to the central server 120 at scheduled, spaced-apart transmission intervals. The transmitter 214 is included in the transceiver 114. Preferably, the digital samples are data-reduced prior to packetization, as described below.

[0037] The timing signals that determine the sampling interval, sampling frequency, and transmission frequency are generated by the timing signal scheduler 215, which includes a clock controlled by the controller 210. In particular, the controller 210 includes a CPU that controls the timing signal generator 215, the sampler 207, and the transmitter 214. Figure 1 ) is received by the receiver 216, wherein the receiver 216 is included in the transceiver 114. As described below, in combination Figure 3A The transmission interval includes: a leading portion containing information for establishing communication with the central server (e.g., handshake or authentication), a data portion containing packetized samples, and a tail portion containing instructions from the central server for establishing the ongoing operation mode of the controller 210, such as the sampling interval, sampling frequency, transmission interval, and transmission frequency of the timing signal scheduler. The tail portion may also include "logout" information for terminating the communication session.

[0038] As previously described, the monitoring system has two primary modes of operation. A "watchdog" or slow mode is invoked when the cable system is behaving normally, that is, within the normal or historically expected operating range of the asset, and there are no reported anomalies or defects based on the experience of the system operator or previously reported data (i.e., data samples that have been transmitted). In "watchdog" mode, the sampling frequency may be slow because the amount of data acquired and reported to the central server is minimal and the amount of data does not change significantly between sample acquisitions. "Watchdog" mode is also invoked when the hub initially begins operation, such as at startup, where there is no previous data to determine "normal" or expected operating behavior. In one embodiment, a technician at terminal 124 can indicate a medium sampling and transmission frequency to acquire data for which a reference operating behavior can be determined. The initial frequency can be adjusted as needed or desired by the technician.

[0039] The duration of operation of the hub 104 in the "watchdog" mode is typically measured in weeks and months. When the operating conditions of the cable system change, as determined automatically by the controller or central server, or by a technician at the terminal 124, a faster mode or high-speed mode is called to evaluate the situation that requires a more comprehensive inspection. The high-speed mode can be activated to obtain signals that may have been lost during the long sleep interval of the sampler. For example, transient signals may exist during the sleep interval and can be observed and sampled in the high-speed mode. Examples of transient signals include unexpected pressure transients in fluid circulation systems, which may be due to unexpected valve closures. Other examples include gaps in the containment chamber and temperature increases due to equipment failures or fires. In high-speed mode, the sampling and transmission frequencies are higher. In high-speed mode, the continuous operation time is typically measured in hours or days relative to weeks or months. These operating modes are further described below.

[0040] In operation, the controller 210 controls the timing signal scheduler 215 to execute the sampling interval, sampling frequency, transmission interval and transmission frequency to acquire and transmit digital samples based on instructions stored in the CPU memory or instructions received from the central server. Figure 3A An example of this is described in, for example, a slow mode or a "watchdog" mode.

[0041] exist Figure 3B In the high-speed mode shown, the controller controls the timing signal scheduler to execute a longer sampling interval to obtain more samples. Figure 3A The same sampling and transmission frequencies as in the low-speed mode Figure 3BWhen operating in a high-speed mode, more data is acquired between transmission intervals, thereby, the time required to transmit data (i.e., the transmission interval) will be longer. Typically, instructions received from the central server 120 are used to determine the operating mode of the controller. These instructions can be provided by an asset manager or technician based on preferred or specific monitoring objectives. For example, the temperature of a cable room via a cable route depends on the number of circuits and the individual cable loads. Due to changes in power demand, seasonal demand, and the earth's ambient temperature, the temperature of the cable room is expected to change every day. High temperatures cause cable overloads, however, the temperature in the cable room is expected to change slowly. Therefore, it is reasonable to initially set a sampling interval of 1 minute, a sampling frequency of 1 sample / hour, and a transmission frequency of once / day. Environmental pollution or atmospheric conditions in the cable room are expected to develop slowly. Therefore, a sampling interval of 5 seconds, a sampling frequency of once every 30 minutes, and a transmission frequency of once a day are reasonable. For general cathodic protection measurements, a sampling interval of 30 seconds, a sampling frequency of once per hour, and a transmission frequency of once a day are reasonable. For a specific cathodic protection test scheduled every hour, a continuous sampling mode may include a 30-minute sampling interval that is performed once an hour and transmitted once an hour. In this "high speed" mode, the controller is instructed to return to "watchdog" mode after 4 hours, conditions permitting. The asset manager may elect to have the controller operate in an adaptive monitoring mode, wherein one or more of the sampling interval, sampling frequency, transmission interval, and transmission frequency are automatically varied based on signals from the sensors.

[0042] Figure 3A is a timing diagram that helps explain the sampling of sensor signals and the transmission of the sampled signals to a central server. For simplicity, Figure 3A The sampling and data transmission of signals generated by sensor 106a, referred to as sensor A, sensor 106b, referred to as sensor B, and sensor 106c, referred to as sensor C, are shown. Figure 3A (I) Figure 3A (II) and Figure 3A(III) The sensor signals from sensors A, B and C are sampled during the sampling interval shown. The sampler 107 may include separate sampling circuits, each of which may operate substantially simultaneously to sample the signals generated by sensors A, B and C. Alternatively, the sampler 107 may include a single sampling circuit that may continuously sample the signals generated by sensors A, B and C at a high sampling rate. As shown, during a first time period, the sampled signals generated by sensors A, B and C are referred to as sets A1, B1 and C1, respectively. During a second time period, the sampled signals generated by sensors A, B and C are referred to as sets A2, B2 and C2. During consecutive time periods, the sampled signals generated by sensors A, B and C are referred to as sets A3, B3 and C3, sets A4, B4 and C4, and so on. The time intervals between consecutive sets generated during these time periods, i.e., the time intervals between sets A1 and A2, between sets B1 and B2, and between sets C1 and C2, are referred to as sleep intervals. Successive sampling intervals are separated by consecutive sleep intervals. During the sleep interval, the sampler 107 does not sample the sensor signal.

[0043] The controller 110 is adapted to sub-package the sets A1, B1, C1; A2, B2, C2; A3, B3, C3; A4, B4, C4, etc. (e.g. Figure 3A (IV)), and Figure 3A (V) assembles the data packets into a common data packet 304 within the transmission interval shown in FIG. In the example shown, the controller 110 assembles a data packet 302a, 302b, and 302c, each of which contains 100 samples from each sensor 106a, 106b, and 106c per hour, or 12 data packets of 100 samples from all of these sensors every 4 hours. In this example, all data packets are transmitted at a frequency of one transmission interval every 4 hours. Figure 3A As shown in (V), a data packet containing the set [A1, B1, C1], [A2, B2, C2], [A3, B3, C3], [A4, B4, C4] is transmitted within a transmission interval of every 4 hours. If the sampling frequency is once an hour and the transmission frequency is a transmission interval of every 12 hours, then 36 independent data packets, each containing 100 samples (or 3600 samples), will be packaged and transmitted every 12 hours. If the transmission frequency is a transmission interval of once a day (or once every 24 hours), 72 data packets will be assembled into a data packet of 7200 samples transmitted once a day.

[0044] Thus, samples acquired from each set (ie, assembled data packet) of A, B, and C are transmitted during each of the illustrated transmission intervals 304, and in the illustrated example, the transmission frequency is once every 4 hours ( Figure 3A(V)). The transmission interval is usually longer than the sampling interval, but for clarity, Figure 3A and Figure 3B The sampling interval for sampling and accumulating sensor signals shown in is similar to the transmission interval.

[0045] Consecutive transmission intervals are separated by sleep intervals, during which no data packets are transmitted. Since data transmission requires as much battery power as possible, the period of waking up the hub (particularly the transceiver) operation is shorter than the sleep period to conserve battery power and extend the life of the battery 105. In this example, the transmission frequency (the frequency at which the transceiver is woken up) is adjustable and controlled by the controller. The transmission interval is mainly determined by the amount of information to be transmitted. The more information to be transmitted, the longer the transmission interval. Therefore, the sleep period will also vary accordingly. Figure 3A As shown in (V), the transmission frequency can be controlled according to instructions sent to the controller CPU or onboard instructions. Figure 3A In the embodiment shown in , the transmission frequency is once every 4 hours. That is, the sampled sensor signals gathered within a transmission interval 304 are transmitted once every 4 hours. In one embodiment, the duration of the transmission interval is adjustable, or in another embodiment, the amount of data gathered within the transmission interval is adjustable.

[0046] If the data sample samples from three time periods (instead of the data sample samples from four time periods, as shown in the figure) are aggregated into one transmission interval, the transmission interval can be considered to be reduced. Similarly, if the data sample samples from two sensors are aggregated (instead of the data sample samples from three sensors, as shown in the figure), the transmission interval can be considered to be reduced. Conversely, if the data sample samples from five time periods are aggregated into one transmission interval, the transmission interval can be considered to be increased. If the data sample samples from four sensors are aggregated, the transmission interval can be considered to be increased. Figure 3A The numerical examples shown in are exemplary; more or fewer sensors may be used as well as more or fewer sample intervals to be gathered.

[0047] The sampling interval and sampling frequency can be adjusted according to instructions from the central server or the onboard controller. The sleep interval between consecutive time periods and / or sampling intervals can be adjusted as needed to obtain more or fewer samples and then transmit them to the central server.

[0048] exist Figure 3A In the embodiment shown in , 100 samples are taken during each sampling interval, and the sampling interval is approximately 50 seconds. The sampling frequency is to take these 100 samples once every hour. Therefore, for each sensor, 100 samples are taken every hour during the sampling interval. As described below, in combination Figure 3B, if the central server requires more data, or if the data sent to the central server indicates abnormal operation of the cable system, the sampling interval and / or sampling frequency can be increased.

[0049] Figure 3A (V) is an overview of the contents of a typical transmission interval 307. The leading portion 303 of the transmission interval includes the resource overhead required to establish a communication handshake between the hub 104 and the central server 120. The resource overhead may include an identification of the hub, which identifies the cable room and thereby the location and type of sensors along the cable system 102; authorization data, if necessary; and the time of day, etc. The tail portion 305 of the transmission interval 307 includes a request issued to the central server for instructions to be downloaded to the hub. The tail portion also includes information for terminating the communication session between the central server and the hub. As shown in the figure, the data packet 304 is arranged between the leading portion and the tail portion of the transmission interval.

[0050] As previously mentioned, at least one of the sampling interval, sampling frequency, transmission interval, and transmission frequency is adjustable to establish different operation modes of the hub. Figure 3A As shown, the sleep intervals inserted between the sampling intervals and the transmission intervals are periods when the controller and transmitter are not operating, and these sleep intervals are also adjustable. In the "watchdog" mode, the sampling interval and sampling frequency are reduced or the sleep interval is increased to limit the amount of data acquired and transmitted, thereby maintaining battery life. Figure 3A A sampling frequency of once per hour and a transmission frequency of once every 4 hours are shown. Figure 3B is a timing diagram of hub 104 in high-speed operation mode. In this high-speed mode example, Figure 3B (I) to Figure 3B (III) shows a sampling interval of almost one hour; assuming a sampling frequency of once per hour (e.g. Figure 3A However, now, in a sampling interval of one hour, 7200 samples of data packets 312a, 312b, and 312c of sets A, B, and C are obtained from each sensor 106a, 106b, and 106c, respectively. Figure 3A The sampling interval is increased to approximately 1 hour compared to the approximately one minute sampling interval in Figure 3B More samples (7200 × 3) are taken in the sampling interval of , and more data is packetized for transmission. If 4 hours of samples are aggregated for transmission, 7200 × 3 × 4 = 86,400 samples are transmitted every 4 hours. Thus, the transceiver effectively transmits continuously and does not sleep during the period between sampling intervals, thereby consuming more energy. Therefore, it is preferred to limit the duration of hub operation in high-speed mode to preserve battery life.

[0051] In one embodiment, instructions from the central server, such as may be provided by a technician at terminal 124, cause the controller to control at least one of a sampling interval, a sampling frequency, and a transmission frequency for data derived from one or two separate sensors. In another embodiment, the controller may be preset to sample a predetermined parameter; the predetermined parameter, for example, a parameter detected by sensor 106a, is detected more frequently than other detected parameters. For example, the controller may control sampler 107 to sample signals from sensor 106a more frequently than signals from other sensors. Thus, high-speed operation may be invoked at any particular time and only on one sensor (e.g., sensor 106a), such as when only one parameter needs to be monitored in high-speed mode.

[0052] As described below, in a preferred embodiment, the sample data is statistically reduced to a subset representing the acquired sample values. Figure 3B As shown in (VI), the size of the data packets [A1, B1, C1], [A2, B2, C2], etc. is reduced, as described below, thereby reducing the transmission interval 314'. Therefore, the transceiver sleeps during the period between the transmission intervals.

[0053] The CPU of the controller 210 includes a memory for storing instructions, including startup instructions for operating the CPU in a startup mode, such as establishing initial communication with a central server when power is first supplied to the hub. In one embodiment, the CPU operates in a recovery mode when power supplied to the hub is lost and then restored, or when communication between the hub and the central server is lost and then reestablished. When power is restored or communication is reestablished, the controller reads a preset recovery instruction from its memory and transmits the instruction to the central server status information of the hub, including the number of data packets stored in the memory 212 that may have been assembled from the sensor signal but have not yet been transmitted to the central server. Typically, the low power wide area network protocol tracks the successful transmission of data packets. Therefore, in this recovery mode, the hub transmits those stored data packets that have not been successfully transmitted to the central server; the central server transmits instructions to the hub to update the sampling interval and sampling frequency for sampling the sensor signal, thereby establishing a transmission frequency for transmitting data packets to the central server.

[0054] In a preferred embodiment, the memory 112 in the hub 104 stores data that is transmitted to the central server. As more data is transmitted, the data stored in the memory 112 is updated. However, as described above, in the event of a loss of communication, the data stored in the memory 112 may be updated, but may not accurately reflect the data that has been sent to and received by the central server before the loss. Therefore, at the beginning of a transmission interval, the data stored in the memory 112 is compared with the data that was last transmitted to and received by the central server. In the event of a difference between the two, at least some of the data stored in the memory 112 is retransmitted, thereby updating the central server to match the data stored in the memory 112.

[0055] As described below, to save energy and reduce battery drain, the size of each data packet can be reduced and not contain the original 100 (or 7200) sample values. However, for each set of samples A, B, C, statistically derived values ​​representing the sample values ​​are transmitted. It has been found that the operation of an asset or cable system can generally be satisfactorily monitored by at least 5 statistically derived values ​​representing a larger set. In order to more accurately analyze the acquired data, and optionally, depending on the parameter being monitored, more values, but less than the values ​​in the set, can be transmitted. This significantly reduces the amount of data transmitted from the hub, thereby facilitating energy conservation, extending the operating life of the battery, reducing data storage requirements, reducing transmission time, and simplifying analysis.

[0056] Instructions determining the high speed or low speed (i.e., "watchdog") operating mode of the controller are initially established by a system technician at, for example, terminal 124 and sent from a central server to hub 104. These instructions are based on the knowledge and experience of the system technician and the asset manager and may be changed based on the sensing behavior of the cable system. In practice, the sampling and transmission frequencies depend on how closely the asset manager wishes to monitor the asset. In one example of a low speed "watchdog" mode, 50 samples of a signal from a sensor (e.g., sensor 106a) are acquired once per hour and transmitted once per day. In a high speed mode, the signal from the sensor is sampled and transmitted substantially continuously (e.g., Figure 3B This high-speed operating pattern reveals subtle changes in system behavior, allowing for closer inspection of any anomalies. As operational experience increases, asset managers can establish default conditions for these basic operating patterns.

[0057] In response to the monitoring parameters represented by the monitored sensor signals, if the central server or a technician at the central server detects a situation that requires more frequent inspection (such as a deviation from the expected operating behavior of the cable system) or an expected fault condition, the instructions sent by the central server cause the controller 110 to increase the sampling and / or transmission frequency; when the operating behavior stabilizes or returns to its expected behavior, it returns to the original or default instructions.

[0058] In addition to executing instructions sent from the central server, the controller 110 can modify its operating mode under certain predetermined conditions without relying on the central server. For example, placing the most recent sample data in Figure 2 The sample data representing the most recently sampled sensor signal is stored in the memory 212 of the controller 210, and the controller 210 compares the sample data representing the most recently sampled sensor signal with the previously sampled data in the memory 212. As a result, if the sample data changes rapidly or significantly within a predetermined period, the behavior change of the cable system can be detected at the hub before the behavior change of the cable system is determined at the central server, because the data has not yet been transmitted to the central server. For example, if the sample values ​​of a particular sensor (such as sensor 106a) change significantly from one sample to the next, and if the rate of change of these values ​​exceeds a predetermined threshold, the controller increases at least one of its sampling interval, sampling frequency, transmission interval, and transmission frequency. The specific frequency of acquiring samples and / or the specific transmission frequency of data packets (i.e., the transmission frequency of data packets) can be selected as a function of the rate of change. Conversely, if the data stored in the memory 212 changes slowly over a preset time period, for example, if the rate of change is less than a specific threshold, the controller can reduce its sampling interval, sampling frequency, transmission interval, and transmission frequency. This change in operating mode can change gradually over time.

[0059] As previously mentioned, when the transceiver is awake and working, power consumption is reduced by reducing the amount of data transmitted in each transmission interval. Although different data compression techniques can be used, it is preferred to reduce the size of the data packet, that is, reduce the amount of data in each data packet. A method of reducing the amount of data transmitted to the central server is described according to a technique shown in FIG. 4, which shows that Figure 3A and 3B Assume that sets A, B, and C contain 100 samples of sensor signals generated by sensors 106a, 106b, and 106c, respectively; and these sample values ​​are in Figure 4A106a. The values ​​are shown in the order in which they occur or are sampled. For example, in set A, the first sample value of the signal from sensor 106a is 45, the second sample value of the signal from sensor 106a is 47, the third sample value is 37, and so on. Each value can be a voltage level, such as millivolts, or a value representing a unit of current, temperature, pressure, or other parameter detected by sensor 106a. Similarly, in set B, the first sample value of the signal from sensor 106b is 45, the second sample value of the signal from sensor 106b is 47, the third sample value is 22, and so on. Sample values ​​from sensor 106c obtained from set C are shown as follows: Figure 4A shown.

[0060] While various statistical tools can be used to achieve this, a more robust technique is applied by calculating five eigenvalues ​​based on an empirical distribution function derived from the data collected during the period, as now described. The controller 210 reorders the sample values ​​in each set A, B, C from lowest to highest. Figure 4B In the example shown in FIG. 1 , the lowest sample value in set A is 35, and the highest sample value in the set is 60. Similarly, the lowest and highest sample values ​​of sets B and C are shown in the figure.

[0061] Figure 4C The median or 50th percentile sample values ​​in each set are shown. The median sample value in set A is 44, the median sample value in set B is 44, and the median sample value in set C is 32. The sample values ​​at the first quartile, corresponding to the 25th percentile level in each set of reordered samples obtained in each sample interval, are 39 in set A, 37 in set B, and 31 in set C. The sample values ​​at the third quartile, corresponding to the 75th percentile level in each set of reordered samples obtained in each sample interval, are 47 in set A, 51 in B, and 39 in C. It has been found that these five sample values ​​(i.e., minimum, maximum, median, first quartile value, and third quartile value) provide sufficient data for the central server to properly characterize and monitor the cable system and identify changes in the operating behavior of the cable system. By reducing the 100 sample values ​​in a set to 5 values, the power consumption of the hub is significantly reduced, especially the power consumption caused by data transmission.

[0062] The five sample values ​​acquired during each sampling interval, namely the minimum sample value, the maximum sample value, the median sample value, and the sample values ​​obtained at the first quartile and the third quartile for each set, are transmitted as a data packet representing the digitized data of all samples acquired during the sampling interval. This data reduction technique can be used for both high-speed and low-speed (e.g., "watchdog" mode) operations.

[0063] As mentioned above, the packets of each set are assembled into one packet ( Figure 3A and Figure 3B ), and transmits these data packets during each transmission interval. This data is collected using data packets from other hubs and analyzed at the central server to represent characteristic behavior of the cable system. If the behavior does not vary by more than a predetermined threshold over a period of time, the central server determines that the cable system is operating normally and no fault or alarm conditions are detected or expected. Therefore, it is sufficient to acquire and transmit these data packets at a relatively low frequency (e.g., every 8 or 12 or 24 hours or less frequently), thereby reducing power consumption. However, if the central server (or a technician) determines that the sensor signal should be checked more frequently, such as when the data represented by the data packet varies by more than a threshold over a period of time, then the controller 210 is instructed to transmit more data packets, such as Figure 3B (V) and 3B (VI), such as by increasing the sampling interval, sampling frequency, transmission interval and / or transmission frequency. Thus, when operating in a higher speed mode, more data is collected and the central server is able to more closely (i.e., more frequently) check the operating characteristics of the cable system, however at the expense of greater power consumption.

[0064] Likewise, if the controller determines that data packets in the acquired set of five representative samples have historically changed by more than a predetermined threshold, or if the data in those data packets has historically changed at a rate of change greater than a predetermined amount, the controller causes more data to be acquired and transmits data packets more frequently.

[0065] The comparison of the statistically reduced sample data with the historical data can be used to adjust the sampling and transmission frequency of one (or more) hubs. The comparison can be performed at the hub, where data from different sensors within the hub can be used for comparison; or at a central server, which collects data from different hubs distributed along the travel route of the cable system. The controller 110 of the hub 104 can operate in an adaptive mode, as described below, or can respond to appropriate instructions from the central server to compare the sampled signal from one sensor (such as sensor 106a) with the sampled signal from another sensor (such as sensor 106c), thereby adjusting the sampling interval, sampling frequency, transmission interval and / or transmission frequency of the data sent from one of the sensors if there is a significant difference between the sampled sensor signals. Similarly, if the sampled sensor signal from sensor 106b changes rapidly, the controller can change the sampling interval, sampling frequency, transmission interval and / or transmission frequency of the data sent from, for example, sensor 106b.

[0066] Figure 5A flow chart is shown representing the initialization of the hub 104, such as when the hub is first installed or commissioned. When the hub 104 is powered on, i.e., when power is first applied to the controller 110 (indicated as step 502), operation proceeds to step 504 to read operating instructions from the appropriate file in the memory 112. If it is determined at query 506 that the file is empty, as expected at startup, operation proceeds to step 508, which acquires initial data by sampling the signals from the sensor 106. In step 510, this initial data is stored in the memory 112, as at step 510, and this initial data is transmitted to the central server 120 in step 512, the hub is authenticated and the hub identification data is stored, as shown at 514. At the end portion 305 of the initial transmission interval, the protocol for monitoring the signals generated by the sensor 106 is acquired or uploaded from the central server. As shown in step 518, sensor sample collection or sensor sample acquisition or periodic measurement of the monitored cable system parameter is initiated in accordance with the instructions sent from the central server.

[0067] Initial operating instructions for hub 104 are stored in memory 112. These instructions may be updated with instructions from the central server sent during the tail portion 305 of the transmission interval. As previously described, these instructions may be considered recovery or default instructions to control the operation of the hub during power or communication events.

[0068] In the event that the answer to query 506 is negative, i.e., the specified file in memory 112 is not empty, such as in the case of a power or communication loss and subsequent restoration, the process proceeds to step 520. Step 520 is performed to reconcile the data in memory 112 with the data that has been transmitted to the central server. As described above, when power or communication is restored after an interruption, the data that has been acquired at the hub may not have been successfully transmitted to the central server. For example, the interruption of communication may occur when the hub is in a sleep mode, or the interruption may be attributed to a low power wide area network. However, in the case where there is still power locally, parameter sensing and data packaging continue despite the interruption of communication. When communication is restored, the data stored in memory 112 will be reconciled with the data stored in the central server; data packets that were not previously sent to the central server will also be transmitted. Therefore, as shown in 514, step 520 is used to send the data that has been acquired last time to the central server. Thereafter, as described above, the hub continues to sample the sensor signal and send data packets representing the sampled sensor signal to the central server.

[0069] Reference now Figure 6, a flow chart representing the operation of the hub in an adaptive sampling and transmission mode is shown. In the adaptive mode of operation, the controller 110 adjusts the sampling interval, and one or more of the sampling frequency and the transmission frequency in response to certain changes in the cable system parameters monitored at the hub location. The flow chart begins by operating the system in a "watchdog" mode, starting with operating in step 600 with instructions received from the central server and configuring the hub for normal monitoring represented by step 602. In conjunction with Figure 3A and Figure 3B , the hub (more specifically, the controller) is periodically awakened from its sleep mode, as shown in step 604. Under the control of the controller, the sampler 107 combines Figure 3A The sensor signal is sampled at the sampling frequency described. Therefore, the sensor signal is sampled or measured in step 606. In the "watchdog" mode, for example, the signal generated by each sensor is sampled 100 times during the sampling interval. In step 608, the controller reduces the amount of data from 100 samples to 5 sample values, as described above in conjunction with Figure 4. In step 610, these sample values ​​are packetized and stored as data packets for transmission. As shown in the flow chart, the process loops through wake-up 604, sampling 606, data reduction 608 and sleep 612. As shown in steps 614 and 616, according to the instructions received in step 600, the data packets assembled and stored in step 610 are transmitted at a predetermined transmission frequency and a predetermined time.

[0070] If the hub has been configured by previous instructions from the central server to operate in an adaptive monitoring mode, the answer to query 620 is affirmative; the hub is operated to automatically modify the sampling interval, sampling frequency, and transmission frequency within preset ranges based on application requirements and monitoring device limitations. Monitoring in adaptive mode optimizes battery life without losing meaningful data. In this adaptive monitoring mode, in step 622, the most recently acquired data packet in step 608 is compared with the previous data packet that has been stored in step 624 to determine the difference between the two. As shown in step 626, the previous data packet to be compared with the most recently acquired data packet is selected based on a preset decision, which is: whether the previous data packet is one that has been acquired within the last hour, last day, last week, last month, or any other desired period of time. If there is no significant difference, the answer to query 628 is negative, and the process proceeds to step 630; in step 630, the current sampling frequency (i.e., the frequency at which the most recent sensor signal is sampled) is compared with the minimum expected sampling frequency (set by the system operator).

[0071] If the current sampling frequency is not the minimum sampling frequency, the answer to query 630 is negative, and the sampling frequency of the sampler 107 (or 207) is reduced in step 634. In this example, the sampling frequency is reduced by half. However, if the current sampling frequency is already the minimum sampling frequency, the answer to query 630 is affirmative, and query 632 asks whether the current sampling interval is the minimum desired sampling interval (set by the system operator). If the answer to query 632 is affirmative, the sampling interval is not changed at step 638, and the hub continues to operate using the current sampling frequency and sampling interval, which is the slowest desired monitoring parameter. However, if the answer to query 632 is negative, the sampling interval of the operation of the sampler 107 (or 207) is shortened in step 636. In this example, the sampling interval is shortened by half. In step 634 or step 636, when the sampling interval or sampling frequency is changed, the transmission frequency is similarly reduced in step 640. The sampling frequency is reduced, the sampling interval is shortened, and the transmission frequency is reduced to save energy.

[0072] However, if the answer to query 628 is affirmative, such as when there is a significant difference between the most recent data packet 608 and the previous data packet 624, query 650 asks whether the current sampling frequency is the maximum sampling frequency. If the answer to query 650 is negative, the sampling frequency is increased in step 654. In this example, the sampling frequency is increased by a factor of 2, but other frequencies may also be increased. If the answer to query 650 is positive, query 652 asks whether the current sampling interval is the maximum sampling interval. If the answer to query 652 is negative, the sampling interval is increased in step 656. In this example, the sampling interval is increased by a factor of 2. When the sampling interval is increased or the sampling frequency is increased in step 654 or step 656, the transmission frequency is similarly increased in step 660. If the answer to query 652 is positive, the sampling interval is not changed at step 658, and the hub continues to operate using the current maximum sampling frequency and maximum sampling interval.

[0073] Increasing the sampling frequency 654, increasing the sampling interval 656, and increasing the transmission frequency allows for more regular sampling of the monitored parameter, as desired where the sensor signal is subject to greater variability or the cable system exhibits unusual behavior. This increases the amount of data transmitted to the central server, thereby improving analysis at the expense of battery life. To conserve battery power, it is recommended to set constraints on the sampling interval and sampling frequency in the adaptive operating mode. By operating the hub in a high speed continuous sampling mode for a short period of time, subsequent additional analysis of the monitored parameter can be performed. Continuous monitoring and transmission of sensor signals can be achieved simply by setting the sampling interval to be substantially equal to the sampling frequency.

[0074] Any logical test may be used in query 628 to determine if there is a significant difference between the most recently acquired data packet and a previous data packet stored in memory 112. The stored previous data packets are a historical reference, and the historical reference may be continually updated by setting a fixed storage file size and deleting the oldest acquired data packet from the file to make room for the most recently acquired data packet. A significant difference test may be whether the difference exceeds a certain change value, such as greater than 10%, or a certain deviation value, such as 2 or 10 scale units. The choice of comparison test for determining a significant difference may depend on the parameter being sensed and the tolerance or sensitivity allowed in the condition assessment for the asset.

[0075] It should be understood that the hub is awakened from its sleep mode (step 604) to obtain samples of the sensor signals and periodically transmit the obtained sample values, such as Figure 3A (I) to Figure 3A (V) and Figure 3B (I) to Figure 3B (V). The sampler 107 enters the sleep mode after sampling the sensor signal during the sampling interval. After transmitting the data packet, the transceiver 114 enters the sleep mode. In the adaptive monitoring mode, as described above in conjunction with Figure 6 As described above, the duration of the corresponding sleep interval, sample interval and transmission interval is set. Other operation modes of the hub are established by instructions received from the central server.

[0076] The remote monitoring system of the present invention can be operated with several underground hubs. One embodiment of the system is Figures 7A to 7B The system consists of a central server 720 ( Fig. 7A )、Terminals 724 and 724'( Figure 7B )as well as Fig. 7A and Figure 7B The plurality of hubs 704, 704' and 704" shown in the figure are composed of, wherein the above-mentioned terminals can be management terminals, similar to Figure 1 Terminal 124. It should be understood that the number of hubs and terminals can be increased or decreased. Each of hubs 704, 704', and 704" is similar to hub 104. For simplicity, the following discussion only focuses on hub 704; however, it should be understood that this discussion also applies to hubs 704' and 704".

[0077] As with hub 104, hub 704 is suitable for being located in an underground cable room or manhole and is composed of A / D converters 707a, 707b, ... and 707n. These A / D converters are used to sample the signals from transducers 706a, 706b, ... and 706n and are similar to Figure 1The sampler 107. The hub 704 includes: similar to Figure 1 Controller 710 of controller 110; and similar Figure 1 Memory 712 of memory 112. Hub 704 also includes a memory similar to Figure 1 Transceiver 714 of transceiver 114. Transceiver 714 is coupled to antenna 715 disposed within the hub housing. Hub 704 operates in the same manner as hub 104; further description of the operation of hub 704 is omitted for the sake of brevity.

[0078] Hub 704' is similar to hub 704, but differs from hub 704 in that it is provided with an antenna 715' coupled to transceiver 714', located outside the hub housing and within an underground cable room or manhole where hub 704' is located.

[0079] Likewise, hub 704" is similar to hub 704, but differs from hub 704 in that it is provided with antenna 715"; antenna 715" is coupled to transceiver 714" and is located outside the hub housing and outside the underground cable room. Antenna 715" may be located underground or above ground.

[0080] Hubs 704, 704' and 704" are constructed in substantially the same manner as hub 104 and operate in the same manner as hub 104. Data is sent from the hub to a central server 720. The central server processes data representing conditions sensed by the hub at various locations on the cable system or asset to monitor asset conditions and thereby characterize asset behavior. The central server also translates or converts operating instructions received from terminal 724 and / or terminal 724' into a form, format and language (e.g., machine language) compatible with the hub. As an embodiment, the central server includes a controller 732 (whose functions are more specifically described in Figure 7C ), interface 734, memory 736, interface 742, archive 744, graphical interface 746, user interface 748, hub modem 752 and user modem 754.

[0081] The hub modem 752 is adapted to receive data transmitted by the hubs 704, 704' and 704", and to transmit instructions from the interface 742 to the hubs via low power wide area network communications. As described above, the hub uses these instructions to establish one or more of a sampling frequency, a sampling interval, and a transmission frequency to acquire and transmit sensor signal samples.

[0082] Controller 732 processes data representing monitoring parameters of the asset. When the asset is operating as expected, controller 732 sends instructions to the hub via interface 742 and hub modem 752 to continue operating in the respective "watchdog" mode. However, if it is determined that the asset is operating in a manner different from expected or normal behavior, the instructions from terminal 724 or 724', in the "language" used by the technician at the terminal, for example, are translated by translator 749 into a machine language compatible with the hub. The address of the specific hub to which the instructions are to be sent, such as the IP address of the hub, is appended to or as part of the instructions via index 751; the index 751 converts the identification of the hub (as provided by the technician at terminal 724 or 724') to the hub address (e.g., IP address). As described above, these instructions are sent to the addressed hub, adjusting the transmission frequency, sampling interval and / or sampling frequency of the hub. Thus, data is sent to the central server for analysis as frequently or less frequently as desired.

[0083] The user modem 754 is adapted to communicate with the terminals 724 and 724' via a network such as a cellular network. Information from the central server is sent to these terminals via the network, allowing a technician or asset manager at the terminal to observe the behavior of the asset being monitored. The terminals 724, 724' are equipped with information based on the data provided by the hub. The controller 732 provides the data received by the hub modem 752 and converted into a language compatible with the terminals 724, 724' to the archive 744 through the interface 734, and stores the data in the archive 744 together with the address or identification of the hub that transmitted the data. The archived data is associated with the corresponding hub by the driver 740 and is used by the graphical interface 746 to generate a graphical representation displayed as a main control panel at the terminal, which enables the asset manager to understand the behavior of the asset. The asset manager can indicate remedial or other actions based on the information sent to the terminals 724 and 724'.

[0084] Advantageously, the central server 720 includes two distinct communication paths: one path for communicating with the remote hub and receiving data representative of the asset parameters being monitored; and another path for communicating with management or system user terminals 724 and 724' to provide asset managers with information sufficient to characterize the operation of the asset. Figure 7BAs shown, each management terminal includes a network interface 726 and 726' for communicating with a central server 720, a user interface 728 and 728', and a display 730 and 730'. The display 730 and 730' displays information from the central server, and the asset manager can access the display and the information displayed on the display via the interface 728 and 728'. An example of the displayed information is a so-called "box line" display, through which the asset manager can observe the behavior of the asset.

[0085] Each management terminal may be a workstation, a computer terminal, a tablet computer, a smart phone, a personal digital assistant, etc. The network interfaces 726 and 726' may be connected to the central server 720 via a hardwire. Alternatively, the network interface is a wireless connection, such as a cellular connection.

[0086] Figure 7C is a flow chart showing the relevant operations of the controller 732 of the central server. The purpose of the central server is to provide a human / machine interface to send operating instructions to the local hub via the communication network 122 and receive information and data from the hub via the communication network. The controller is used to extract individual data packets from the data packets transmitted from the hub, convert the raw data in the received data packets into meaningful engineering values, and save the data to the assigned asset identifiable file, where it can then be retrieved, analyzed and marked for subsequent review by technicians at terminals 724 and 724'.

[0087] Reference Figure 7C , as shown in step 760, one (or more) technicians enter from, for example, terminal 724: hub information related to the physical and electronic addresses of each hub; asset identifiers for identifying assets as, for example, cables, pipes, etc.; parameters to be monitored (such as temperature, humidity, voltage, current, etc.); and equations and algorithms for converting raw data measured by sensors into useful engineering units. To ensure security and authorization, a password or other security method that limits authorized personnel's control access to the server is used to enter the technician's information. Similarly, the authorized personnel enter instructions for setting the operating mode, sampling interval, sampling frequency, and transmission frequency of the remote monitoring hub, automatically translating the instructions into machine instructions that are compatible with the hub in form, format, and language; and enter an address, which identifies the corresponding hub to which the instruction is sent in step 762, and sends the instruction to the hub in step 776.

[0088] At step 764, one (or more) data packets are received from the hub, and at step 766, the hub that sent the data packet is identified and added or tagged to the data packet. At step 768, the sample data within the received data packet is extracted and separated into component parts; the component parts include environmental information common to all assets within the manhole and environmental conditions related to the hub 704 itself, and another part representing the sensor signal monitored by the specific hub. The extracted environmental information (such as local temperature, battery life, time of last transmission from the hub, etc.) is placed in a file and stored at step 770; step 770 is common to all sensors attached to the hub. The tagged sample data is saved at step 774, which stores a file specific to the asset and parameter being measured. For example, sample data from the same sensor is stored in a file associated with the sensor. As shown in step 778, partitioning in this manner preserves the raw data for future analysis, regardless of scaling and calibration factors, which can be applied after converting the data to meaningful engineering units. The converted data of step 778 is time stamped and saved to an engineering data file or database at 780 for historical trending, analysis, and alarm notification. All system users can access this data through computers, tablets, smart phones, etc. using appropriate software. After the sample data is saved, in step 776, operating instructions are sent to the hub. These instructions can be modified based on the sample data that has been extracted. Before disconnecting from the hub, based on the schedule update received from the technician at step 762, the central server sends updated operating instructions 776.

[0089] In step 781, the converted data of step 778 is compared with the previously saved data saved in step 780 to generate alerts, alarms, etc. The comparison can be based on absolute values, percentage changes, and statistical shifts based on daily, weekly or monthly, or based on rate of change information that can be obtained from the updated database 780. The criteria used for comparison can be combined with Figure 6 As described, the comparison is assigned by the operating engineer or technician at the terminals 724 and 724' and can be uploaded by the modem 754. Query 786 asks whether the comparison requires that a message or notification be sent to the technician, for example, at the terminal 724. If the answer to the query 786 is affirmative, the message or notification is sent to the technician via the modem 754 in step 782. The message can be sent to the system operator via one or more paths 726.

[0090] Advantageously, a technician at, for example, terminal 724 can access data received from other hubs installed on assets at other locations. Thus, characteristic behavior of an asset and criteria for messages or alerts from a central server can be based on a comparison of sensor signals from one hub or set of sensors with sensors at other locations along the route, or based on a comparison of sensor signals from the same hub with sensor signals from devices monitored at different locations. It should be understood that access to data received from other hubs along the route of an asset, characteristic behavior of an asset and criteria for messages, alerts or alerts from a central server can be based on a comparison or analysis of data from different sensors.

[0091] As an example, cathodic protection (CP) pipeline soil potential and cathodic protection current measurements along the pipeline line can be sensor signals that represent characteristic behavior of the pipeline. Cathodic protection systems can often be better characterized by how the measured parameter value (potential or current) changes based on the location of several sensors rather than the parameter value associated with a single sensor. Another example includes monitoring the cable shield voltage and current of each of the three phases of the cable. Voltage and current sensors can be connected to the cable shield of each of the three cable phases in a junction box that is installed in a connection box in a manhole along the cable route. The cable shield connected to each of the three cable phases can monitor the voltage and current sensors individually and comparatively between all three phase sensors. The sensor signals can also be compared at a central server with sensors installed in a similar manner at other hub locations. This monitoring method is used to characterize the behavior of the cable (or monitored asset) in a manner that will identify abnormal operating conditions that need to be checked and facilitate strategic maintenance operations rather than scheduled maintenance operations.

[0092] In yet another embodiment, similar to the above combination Figure 6 The adaptive monitoring described may be incorporated into Figure 7C Here, the trigger points for increasing or decreasing the sampling interval, sampling frequency, and transmission frequency will be based on the comparison of parameters or sensor signals from different hubs. Therefore, small behavioral changes that indicate abnormal operation of some asset operation can be determined by comparing data from similar devices, and a more aggressive sampling mode can be started before failure.

[0093] Figure 8A flow chart representing the operation of the hub 104 is shown, and specifically the operation of the controller 110 in the hub, referred to herein as an event monitor. In this mode, the controller continuously monitors the sensor signal, but does not transmit sensor data unless an event that satisfies a preset condition or a set of conditions triggers the controller to execute a user-defined data record transmission protocol. The event monitor mode can be called by an instruction from a central server, such as determined by a technician at the management terminal 124. Additionally or alternatively, the event mode monitoring mode can be preprogrammed in the hub controller and called in response to specific conditions. In the event monitor mode described below, a number N of sensor signal samples are acquired and stored in a suitable register, where N is determined by a technician. When the number of stored samples exceeds a predetermined threshold, for example, when the number of stored samples exceeds N / 2, the register is cleared and the newly acquired sample is stored. Preferably, the register clears one sample at a time, and the oldest sample in the register is deleted, thereby leaving room for the next newly acquired sample. The samples stored in the register do not need to be processed to be transmitted to the central server until an "event" as described below occurs. Thus, the register goes through cycles, storing the most recent N samples until an "event" occurs.

[0094] Referring to the flow chart, the event monitor mode is established at step 800 by a technician who sets the value of N, and who also sets the criteria for an "event". At step 801, the counter is reset to count n = 0. At step 802, a sample is acquired; query 804 determines whether the count n has reached N, i.e., query 804 asks whether n = N. If the answer to this query is negative, n ≠ N, the acquired sample is stored, for example, in memory 112 (or memory 212), as shown in step 806. However, if the answer to query 804 is positive, n = N, the oldest sample stored in the register is deleted, as shown in step 808, to make room for the latest sample that has been acquired; the latest sample is stored, as shown in step 806. The process loops through this loop 802, 804, 806 and 808 until an "event" occurs.

[0095] If the acquired sample meets or exceeds the criteria established by the technician, then an "event" occurs. Examples of such criteria include, but are not limited to: whether the value of the acquired sample exceeds a predetermined threshold, whether the value of the acquired sample is less than a preset level, whether the value of the acquired sample is outside of predetermined limits, whether the acquired sample differs from the previous sample by more than a predetermined amount, whether the value of the acquired sample is different from the sample history, whether the acquired sample deviates from the historical sample value, whether the acquired sample changes at a rate greater than a predetermined rate, and the like. As shown in step 810, a comparison 812 is made between the acquired sample and the established criteria. If the acquired sample does not exceed the established criteria, the sample is stored (step 806), and the process continues to loop through loops 802, 804, 806, and 808. However, if the acquired sample exceeds the established criteria, the answer to query 814 is affirmative, indicating that an "event" has occurred, and query 816 queries whether the number of stored samples N is greater than 0 (N 0). If this is the first sample acquired, then at step 818 the answer to query 816 is negative and the count N of the counter is set to 1 (n=1). The process then returns to step 802 and the next sample is acquired.

[0096] However, if the sample obtained is not the first sample, that is, N 0, then the answer to query 816 is affirmative and the process proceeds to query 820 to determine whether the number of stored samples n is n=N / 2. If the answer to query 820 is negative, then in step 822, the count of stored samples n is incremented by 1 (n=n+1); the process returns to step 802 to obtain the next sample. However, if the answer to query 820 is affirmative (n=N / 2), the process proceeds to step 824 and the hub transmits all samples that have been stored in memory 112 (or memory 212) to the central server. Therefore, half of the file transmitted to the central server contains pre-trigger records and the other half contains post-release trigger records. As a result, the technician is able to identify preview and post-view conditions for guiding and tracking events. Other conditions can be preset to transmit pre-event sample data and post-event sample data.

[0097] Preferably, when the samples stored in the memory are transmitted to the central server, the memory 112 (or memory 212) is not cleared. In this way, by transmitting the stored samples when n=N / 2, half of the stored samples are those samples that have been previously acquired, i.e., the "oldest" of the stored samples, and half of the stored samples are newly acquired.

[0098] The count n of the number of stored samples is reset to n=0 in step 826; and the process returns to step 802 to obtain the next sample. Thus, if an event as described above occurs, the stored samples are transmitted.

[0099] In another embodiment of the event monitor, an alarm is triggered when an event occurs, for example, when the answer to query 814 is affirmative. For example, an alarm is triggered if a temperature monitored by one of the sensors exceeds a threshold, or if a water level in a cable chamber monitored by another of the sensors exceeds a predetermined level, or if a pressure monitored by another of the sensors exceeds a preset threshold. Other examples of alarm triggering events will be apparent to those skilled in the art.

[0100] While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications in form and detail may be made without departing from the spirit and scope of the invention. For example, and as noted above, the antennas connected to the transceivers in the hubs described herein may be located in the hub, external to the hub but in a cable closet in which the hub is located, or external to the hub but below ground level, such as Fig. 7A As another example, Fig. 7A As shown in the reference Figure 1 and Figure 2 The sampler described may include sample-hold and analog-digital circuits. As another example, although in Figure 1 and Fig. 7A Two management terminals are shown, but it should be understood that more or fewer management terminals may be provided. In addition, some of the management terminals may be limited in their ability to communicate instructions to the hub to establish or change the above-mentioned sampling and transmission frequencies. Such instructions can be transmitted to the selected hub as needed. In addition, it should be understood that the above-mentioned numerical examples of sampling intervals, sleep intervals, transmission intervals, sampling frequencies, and transmission frequencies are not intended to limit the present invention to only these numerical examples.

[0101] Therefore, it is intended that the following claims be interpreted as including the foregoing as well as various other variations and modifications.

Claims

1. A remote monitoring system for monitoring parameters of an underground cable system, comprising: a distributed parameter detector configured to provide an electrical signal representative of a respective monitored variable parameter of the underground cable system; as well as An underground hub, which is disposed underground and coupled to the parameter detector and is configured to collect the signal provided by the parameter detector, the underground hub comprising: a controller for providing data samples representing different values ​​of each monitored variable parameter, the data samples being derived from the collected signals; and a transceiver for transmitting the data samples from underground to a central location above ground via low power wide area network communications and for receiving instructions for controlling the controller from the central location via low power wide area network communications, wherein the controller is programmed to process the signal provided by the parameter detector by sampling the signal at a variable sampling frequency during sampling intervals having a controllable duration, and to transmit the samples to a central location at a controllably variable transmission frequency during transmission intervals having a controllable duration, and Wherein the sampling frequency, the duration of the sampling interval, the transmission interval and the transmission frequency are established by instructions received from the central location or by the operating conditions of the underground cable system, and the operating conditions of the underground cable system are determined by the signal provided by the parameter detector.

2. The remote monitoring system according to claim 1, wherein: Successive transmission intervals are separated by sleep intervals such that the controller is awakened to transmit the samples during an active operating mode and then returns to a sleep mode.

3. The remote monitoring system according to claim 1, wherein: The controller includes a processor programmed to determine specific operating conditions of the underground cable system based on the signal provided by the parameter detector and to establish at least one of the sampling interval, the sampling frequency, the transmission frequency and the transmission interval according to the determined operating conditions.

4. The remote monitoring system according to claim 1, wherein: The controller is operable in a first operating mode to transmit the samples at a first transmission frequency and in a second operating mode to transmit the samples at a second transmission frequency, the first transmission frequency being less than the second transmission frequency.

5. The remote monitoring system according to claim 1, wherein: The controller is operable in a first operating mode to sample the signal at a first sampling frequency and in a second operating mode to sample the signal at a second sampling frequency, the first sampling frequency being less than the second sampling frequency.

6. The remote monitoring system according to claim 4 or 5, wherein: The instructions received from the central location determine an operating mode of the controller.

7. The remote monitoring system according to claim 1, wherein: The controller is programmed to determine a set of statistically derived values ​​representing sample values ​​acquired within a sampling interval and to cause the determined set of values ​​to be transmitted to the central location during the transmission interval.

8. The remote monitoring system according to claim 7, wherein: The determined set of values ​​is a value representing a selected number of samples that is less than a number of samples acquired within a sampling interval.

9. The remote monitoring system according to claim 7, wherein: The controller is programmed to reorder the sample values ​​from lowest sample value to highest sample value; wherein the determined set of values ​​is a minimum sample value obtained during the sampling interval, a maximum sample value obtained during the sampling interval, a median sample value obtained during the sampling interval, and sample values ​​corresponding to the 25th percentile and the 75th percentile of the reordered sample values.

10. The remote monitoring system according to claim 4, wherein: The controller switches to the first operating mode if the data samples transmitted to the central location do not change over time by an amount greater than a predetermined threshold or the data samples transmitted to the central location change at a rate of change less than a predetermined threshold.

11. The remote monitoring system according to claim 4 or 5, wherein: The controller is operative to selectively adjust at least one of the sampling interval, sampling frequency, transmission interval, and transmission frequency in response to the instructions received from the central location.

12. The remote monitoring system according to claim 11, wherein: The central location includes a data processor that processes the samples transmitted from the underground hub to determine an operating condition of the underground cable system.

13. The remote monitoring system according to claim 1, wherein: The underground hub is installed in the manhole chamber.

14. The remote monitoring system according to claim 13, wherein: The underground hub includes an antenna within the manhole chamber for transmitting the data samples via low power wide area network communications and for receiving the instructions transmitted from the central location via low power wide area network communications.

15. The remote monitoring system according to claim 13, further comprising: An antenna separate from the underground hub is used to provide a communication line between the central location and the underground hub.

16. The remote monitoring system according to claim 1, wherein: The controller includes a memory for storing startup instructions to operate the controller in a recovery mode to establish communication with the central location in the event that power to the underground hub is interrupted and subsequently restored, or in the event that communication between the underground hub and the central location is interrupted and subsequently reestablished.

17. The remote monitoring system according to claim 16, wherein: The controller responds to instructions transmitted from the central location, when the underground hub restores power or when communication between the underground hub and the central location is reestablished, to sample the signal provided by the parameter detector at a sampling interval and a sampling frequency determined by the instructions, and to transmit the samples at a transmission interval and transmission frequency determined by the instructions.

18. The remote monitoring system according to claim 1, wherein: The underground hub includes a memory for storing data samples provided by the controller; wherein the central location includes a data processor for storing and processing the data samples transmitted from the underground hub; wherein the operation of the controller compares the data samples stored in the memory of the underground hub with the data samples transmitted to the central location, and when there is a difference between the two, transmits the data that has not been previously transmitted to the central location.

19. The remote monitoring system of claim 1, wherein the underground cable system is a power transmission cable.

20. The remote monitoring system according to claim 1, wherein: The underground cable system is an oil pipeline.

21. The remote monitoring system according to claim 1, wherein: The underground cable system is a gas pipeline.

22. The remote monitoring system according to claim 1, further comprising: A battery is provided for providing power to the underground hub.

23. The remote monitoring system according to claim 1, further comprising: A collection device is used to obtain power from the underground cable system and supply the derived power to the underground hub.

24. The remote monitoring system according to claim 1, wherein: The hub includes a memory for storing data derived from the collected signals and for transmitting at least some of the stored data to the central location when the collected signals meet or exceed a predetermined criterion.

25. The remote monitoring system according to claim 24, wherein: When the collected signal does not meet or exceed the predetermined standard, the memory replaces old stored data with new data.

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