TECHNICAL FIELD

[0001] The invention relates to environmental monitoring, and in particular to modular sensor towers.

BACKGROUND

[0002] Multiple sensors and their associated components, including electrical and processing components, can be wired together into a structure referred to as a sensor tower.

[0003] A sensor tower can be deployed to provide a variety of sensor measurements. Typically, one or more sensor towers are positioned on a site to monitor the environment. The sensor towers may measure a wide range of parameters including temperature, noise level, wind speed and humidity. Although they may be portable, sensor towers may be stationary for a significant period of time while monitoring the environment.

[0004] To form the sensor tower, the components are typically wired together manually and connected to a wire bus to allow data and electrical transfer between components. Insertable connectors, pogo pins and/or optical interfaces may be used between sections of components to pass electrical data between sensors and processors within the tower.

SUMMARY

[0005] In accordance with the present disclosure, there is provided a modular sensor tower comprising a plurality of modules including: one or more sensor modules, each sensor module comprising one or more sensors; and a control module comprising a processor, wherein each module has a ground line, a power line and a data line, and wherein at least one of the modules is an intermediary module, wherein the ground line, the power line and the data line of each intermediary module span between two opposing complementary connection surfaces, such that, when one of the intermediary modules is connected between two other modules using the opposing complementary connection surfaces, the ground lines, the power lines and the data lines of the three connected modules are connected to allow signals to be passed between them.

[0006] The ground lines and the power lines of connected modules may be electrically connected.

[0007] The ground lines and the power lines of connected modules may be electrically connected using spring loaded connectors (e.g., pogo pins).

[0008] A control module may also be a sensor module.

[0009] The data lines of connected modules may be connected using optical emitters and receivers. E.g., an optical data connection may comprise an LED/photodiode connection. An optical data connection may comprise a pair of optical data connectors to facilitate two- way transmission of information.

[0010] At least one of the sensor modules may comprise at least one removable sensor submodule, the sensor submodule comprising an environmental sensor configured to measure a parameter of the environment.

[0011] An environmental sensor may comprise one or more of: a light sensor, an anemometer, a thermometer, a humidity sensor, a gas sensor, and a soil sensor.

[0012] A sensor submodule may be connected to the ground line, the power line and the data line of the sensor module using a physical connector configured to grip both the sensor submodule and the ground, power, and data lines.

[0013] The physical connector may comprise a rigid component with separate spaced apart electrical terminals for each of: the ground line; the power line; and the data line, wherein the rigid component is configured to form a physical connection holding the sensor submodule to the ground line; the power line; and the data line.

[0014] The ground line, power line and data line may each form a rigid planar surface, and wherein the electrical terminals are configured to impinge on the rigid planar surfaces.

[0015] Each module may comprise a charging line configured to receive power from a power source and deliver it to a battery.

[0016] The sensor tower may comprise a battery module comprising one or more batteries. [0017] Each sensor may comprise a sensor controller configured to send a time-slot allocation signal to the processor to allocate a time slot during which the sensor can communicate with the processor via the connected data lines.

[0018] The modular sensor tower may comprise multiple sensors, and wherein the multiple sensors are connected to the same data line on the control module.

[0019] The modular sensor tower may comprise multiple sensors and multiple data lines, wherein the multiple data lines allow for communication between different sensors and the processor with different communication protocols.

[0020] Each sensor may be configured to transmit data to the processor only when the sensed value has changed by an amount exceeding a predetermined threshold, and wherein the processor is configured to report the last received sensed value from the sensor.

[0021] At least one of the modules may comprise a transmitter.

[0022] At least one of the modules may comprise a power generator.

[0023] The power generator may comprise a solar panel. The power generator may comprise a wind turbine.

[0024] One of the modules may be a base module comprising one complementary surface configured to connect to a corresponding complementary surface of an intermediary module, the base module configured to support the sensor tower.

[0025] One of the modules may be a head module comprising one complementary surface configured to connect to a corresponding complementary surface of an intermediary module, the head module configured to form the top of the sensor tower.

[0026] At least two of the modules may each comprise a power source. The power source may be a battery (or another electrical energy storage device). The power source may be a power generator.

[0027] At least two of the modules may each comprise a controller, such as a sensor controller.

[0028] Providing at least two of the modules with a power source and/or controllers may allow the modular sensor tower to be separated between the two modules (e.g., to allow modules to be added or removed) to form two sections each section comprising one or more modules. This may allow each of the separated sections to operate independently without interruption.

[0029] A head module may be one of the at least two modules comprising a power source and/or controller. A base module may be one of the at least two modules comprising a power source and/or controller.

[0030] When connected to each other (e.g., either directly or indirectly via other modules), the power sources in the at least two modules may be connected to each other via connected power lines. When connected to each other (e.g., either directly or indirectly via other modules), the controllers in the at least two modules may be connected to each other via connected data lines.

[0031] The complementary connection surfaces may be shaped to prevent lateral movement of connected modules. This helps ensure that the lines of the connected modules are lined to maintain a physical or data connection. The complementary surfaces may comprise a locking mechanism to lock connected modules together.

[0032] The sensor tower may comprise an electrical component connected to the ground line, the power line and the data line, wherein the electrical component is controlled via data transmitted through the data line. The electrical component may comprise a removable electrical submodule configured for removable connection to the ground, power and data line.

[0033] According to a further aspect, there is provided a sensor tower comprising: one or more sensor submodules, each sensor submodule comprising one or more sensors; and a control module comprising a processor, wherein the sensor tower has a ground line, a power line and a data line, and wherein each sensor comprises a sensor controller configured send a time-slot allocation signal to the processor to allocate a time slot during which each sensor can communicate with the processor via the connected data lines.

[0034] According to a further aspect, there is a method of communicating within a sensor tower, the sensor tower comprising a plurality of sensors connected to a common data line, the method comprising: each sensor communicating with a controller to allocate a periodic time slot associated with that sensor; and each sensor transmitting sensor data during the associated allocated periodic time slot.

[0035] The controller may comprise a processor and memory. The memory may store computer program code. The processor may comprise, for example, a graphics processing unit, a central processing unit, a microprocessor, an application-specific integrated circuit or ASIC or a multicore processor. The memory may comprise, for example, flash memory, a hard-drive, volatile memory.

[0036] Directional words (e.g., top, bottom, upright) in the present disclosure are used with respect to the sensor tower in an operating position.

[0037] The sensor tower may be stationary while monitoring the environment. The sensor tower may be configured to operate independently of a user. The sensor tower may be configured to be controlled via commands received wirelessly. The sensor tower may have a height greater than 1 meter. The sensor tower may have a height less than 5 meters.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Various objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.

Figure 1 is a schematic diagram of a sensor tower.

Figure 2 is a schematic perspective view of an intermediate module and a sensor submodule of the sensor tower.

Figure 3 is a side view of multiple connected modules of the sensor tower.

Figure 4 is a top view of a sensor submodule connected to the lines of the sensor tower.

Figure 5 is a top view of a sensor submodule disconnected from the lines of the sensor tower.

Figure 6 is a perspective view of a sensor tower. DETAILED DESCRIPTION

Introduction

[0039] The present technology relates to sensor towers and associated methods for forming sensor towers. In a typical wired sensor tower, the process of wiring the components together can be difficult and time-consuming. There is also a high risk of human error during wiring, resulting in malfunctions that may be difficult to troubleshoot. When a section of tower needs to be replaced, added or removed, the wiring must be completely redone by cutting and resplicing wires, which can be incredibly time consuming. If additional sensor components are needed, it requires additional contacts which can cause compatibility issues between tower components.

[0040] The present technology addresses the above issues by providing a modular and flexible sensor tower that doesn’t rely on wiring between the various components and is quick and easy to build and modify by hand, without tools. At any time, components can easily be added, removed and replaced without requiring rewiring and without causing compatibility issues between components.

[0041] Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention.

First Embodiment

[0042] Figure 1 illustrates a first embodiment of a sensor tower 10 comprising a plurality of modules, including a head module 12 forming the top of the sensor tower, a base module 20 that supports the sensor tower, and an intermediate module 30 positioned between the head module and the base module.

[0043] The sensor tower includes various components, including a transceiver 14 configured to wirelessly receive and transmit data on a network, a battery 16 for storing electrical energy, and a processor 18 configured to receive, transmit and process data from the other components. The sensor tower may include a power generator, such as a solar panel 22, for generating power that is transmitted to the battery. In some embodiments, the head unit and the base unit both comprise batteries (e.g., a primary and a back-up) so that when the tower is split to add or remove a module, all the modules can continue to operate as they are all connected to at least one of the batteries.

[0044] The sensor tower includes multiple sensors, which are instrumentation devices for detecting and measuring physical properties. In the illustrated embodiment of Figure 1 , there is a wind sensor 36, a temperature sensor 38 and a soil sensor 40. The sensors may be located in the one or more intermediate modules.

[0045] The base module and head module may house components of the sensor tower that typically remain unchanged, such as the processor, battery, energy generation module, and transceiver. The intermediate module may comprise components that are more often changed, such as the sensors.

[0046] Each of the modules, including the head module, intermediate module, and base module, include multiple lines for transmitting power and data to and from the module. The lines 50 may include a power line 52 for transmitting electricity between the module and the power source (e.g., the battery), a ground line 54 grounded into the earth to provide a discharge point for excess electricity, a charging line 56 for transmitting data between the power generator and the battery, and a data line 58 for transmitting data between the module and the processor. The lines may individually or collectively form a rigid planar surface along the backplane of the module.

[0047] Referring to Figure 2, the lines 50 span each intermediary module from top to bottom and each have a connection surface 50a at either end of the module.

[0048] Referring to Figure 3, adjacent modules are positioned such that complementary connection surfaces of the modules are adjacent each other to allow for connection of lines between the modules. In this embodiment, the power, ground and charging lines are electrically connected, for example using a spring-loaded pin 60, often referred to as a pogo pin. The data lines are connected to allow data signals to pass between the lines, for example using optical emitters and receivers 62. Alternatively, the data lines may be connected using direct electrical connectors. Optical data connections may be less sensitive to noise which can arise due to imperfect connections between direct electrical connections.

[0049] As shown in figure 3, the lines in all three modules span between complementary connection surfaces. This means that all three modules could act as intermediary modules, so the order of the three modules could be changed. In addition, additional modules could be added to the tower, either between connected modules or above the top module or below the base module. One or more of the modules in the tower could be removed, and the remaining modules connected together using the connection lines.

[0050] As shown in figures 2 and 4, at least one of the modules may be configured to receive one or more removable sensor submodules 70 which comprise one or more sensors. The removable sensor submodule is configured to be removably connectable to one or more of the lines in the module, such as the data line, ground line, and power line. There may be one or more lines in the modules that the sensor submodule does not need to be connected to, such the charging line, which just connects other tower components together. One embodiment of a removable sensor submodule is shown in Figure 4, wherein the removable sensor submodule comprises a physical connector 72 that grips the lines 50 of the intermediate module 30. Figure 5 illustrates the physical connector 72 disconnected from the lines 50 of the module 30. In this case, the lines are rigidly positioned with respect to each other on a single block. It will be appreciated that other embodiments may have different arrangements of the lines.

[0051] The physical connector may comprise a rigid component 74, for example a plastic component, with separate spaced apart electrical terminals 76 for one or more of the lines. In this embodiment, the physical connector is shown as having an electrical terminal for connection to each of the lines 52, 54, 56, 58. However it is to be understood that it is may not be necessary to have an electrical terminal for each line. The rigid component may be configured to form a physical connection holding the sensor submodule to the lines. The electrical terminals may be configured to impinge on the rigid planar surfaces of each of the lines, for example with spring pins. The electrical terminals may be DIN style devices.

[0052] The physical connector may be configured such that it can be connected to the lines by hand (e.g., by simply snapping it in place), without requiring the use of tools. The physical connector may also be configured to be disconnected from the lines by hand, without the use of tools.

[0053] In this embodiment, each of the lines are exposed substantially all along their length between the two opposing connection surfaces of the intermediate module 30. This means that a sensor submodule can be connected anywhere between the opposing connection surfaces. One advantage of this design is that the height of the sensor submodule can vary because it does not have to fit to a slot of a particular height. Multiple sensor submodules may be connected between the opposing connection surfaces. The number of sensor submodules that can be connected in one intermediate module would be limited by the distance between the two opposing connection surfaces and the height of the sensor submodules connected therebetween.

[0054] It will be appreciated that a variety of different sensors can be designed to use a standardized connector to allow them to be interchangeably connected to the same data and power lines. For example, in the intermediate module of figure 2, the sensor submodule 70 may be a temperature sensor. This sensor module may be replaced by a wind speed sensor which has the same connecting surfaces to connect to lines 50.

[0055] It will be appreciated that in a sensor tower, multiple sensors are configured to exchange data with the controller along a common data line 58. For example, in this case, the controller 16 may receive sensor data from the wind sensor 36, temperature sensor 38 and the soil sensor 40 from the same data line 58. To facilitate this, the sensors and controller negotiate a protocol to ensure that all the sensors are not sending data simultaneously.

[0056] In this embodiment, this is achieved by each sensor in the removable sensor submodule having a sensor controller configured to send a time-slot allocation signal to the processor to allocate a time slot during which the sensor can communicate with the processor via the connected data lines.

[0057] For example, the controller may broadcast an initiation signal along the data line to indicate a periodically available common communication window. Upon receiving this, a sensor may be configured to transmit an identification signal to the controller indicating that it is connected to the data line. To prevent multiple sensors transmitting identification signals at once, the sensors may use an algorithm which determines when they send the identification signal. E.g., it could be generated in a random common communication window until a confirmation of receipt or allocation signal is received. As there are relatively few sensors in the tower (e.g., 20 or fewer), it would not take long for the controller to receive identifications from all 20, even if there were windows where multiple identification signals were sent simultaneously (which may or may not be understood by the controller) or where none were sent. Each identification signal may comprise an identifier associated with the sensor and possibly information associated with the type of sensor.

[0058] In response to receiving the identification signal, the controller is configured to allocate a periodic communication window for that sensor, and to communicate that periodic communication window along the data line using an allocation signal. The allocation signal may be sent to the sensor during a time outside the common communication window as it is addressed to a particular sensor and so that it does not interfere with new incoming identification signals. The allocation signal may comprise information on the sensor identifier, a specific time window, and a repeating period. The allocation signal may be transmitted in one of the time windows of the allocated periodic communication window. In response to receiving the allocation signal, the sensor controller can then transmit sensor data to the controller during the periodic allocated time windows. It will be appreciated that the allocated periodic communication window for a sensor may include a sensor-controller portion, in which the sensor can transmit data to the controller, and a controller-sensor portion in which the controller can communicate specifically with that sensor.

[0059] It will be appreciated that this common data line is useful where there are a relatively small number of sensors, and where the amount of sensor data is limited (i.e. , where each sensor does not need to be transmitting data continuously). It will be appreciated that the duration or frequency of the periodic communication windows may vary from sensor to sensor depending on the quantity of data that needs to be transmitted. For example, a single value sensor (e.g., a temperature sensor) may be allocated a shorter communication window and/or less frequent communication windows than a sensor configured to report a spectrum (e.g., noise and colour) and/or spatial information (e.g., from an image sensor).

[0060] The sensor controller may be configured to convert input signals from the sensor to a common communication protocol to be output to a single data line. [0061] Alternatively or in addition, sensors may transmit data using different communication protocols along the same data line. For example, once the communication windows are established, the controller may be configured to interpret signals from a first sensor (e.g., temperature sensor) within the first sensor allocated periodic communication window in accordance with a first protocol, and to interpret signals from a second sensor (e.g., image sensor) within the second sensor allocated periodic communication window in accordance with a different second protocol.

[0062] In other embodiments, the lines may include multiple data lines for transmitting multiple types of communication protocols.

[0063] The sensor controller may be configured to transmit data via the data line to the processor only when the sensed value from the sensor has changed by an amount exceeding a predetermined threshold. This prevents the unnecessary transmission of data. For example, if a temperature sensor continually monitors the outside air temperature, the temperature data may only be transmitted to the processor if the temperature has changed by 0.5°C or more. When the processor receives new data from a sensor, the data may be transmitted immediately to another source via the transceiver. Alternatively, data may be transmitted to another source based on predetermined criteria, such as time intervals.

[0064] When a new removable sensor submodule is connected to the lines, the processor may auto-discover the submodule and add one or more additional time slots that are allocated to the new sensors for transmitting data from the newly added sensors on the data line. The reverse happens when a sensor submodule is removed from the lines, i.e., the processor auto-discovers the removal of the submodule and removes the time slots that were allocated to the sensor(s) of the removed submodule.

[0065] The removable sensor submodule allows for the easy addition and removal of any number of sensors in the sensor tower without affecting the connectedness of modules and submodules in the sensor tower. It also allows a sensor submodule to remain connected to the lines but be powered off without interfering with the transfer of data or power along the lines. For example, the electricity supply between the power line and the sensor submodule could be turned off in the submodule using the submodule controller, without disconnecting the submodule from the power line. The electricity and data running through the lines that the submodule is connected to would not be affected. The processor would auto-discover that the submodule is no longer active, and in the same way it does when a submodule is removed, it would remove the time slot allocated to that sensor submodule. If the submodule is powered back on, the processor would auto-discover this (like it does when a submodule is added) and allocate a time slot to the submodule again.

Second Embodiment

[0066] Figure 6 illustrates another embodiment of a sensor tower 610 wherein there are multiple intermediate modules 630a-c.

[0067] In this embodiment, the sensor tower comprises three sensor modules 630a-c, each sensor module comprising one or more sensors. The sensor tower also comprises a base 620 with multiple extendible feet 624 to provide lateral support and keep the sensor tower upright. The sensor tower also comprises a head unit 612 with solar panels to provide electrical power and a transmitter to send information to a remote computer wirelessly.

[0068] As with the embodiment of figure 1 , the sensor tower comprises a control module comprising a processor, in this case housed in the base.

[0069] The physical structure of the tower is provided by each intermediate module having two opposing complementary connection surfaces. In an operating configuration, these are the top and bottom surfaces of each of the intermediate modules. In this case, they have a complementary shape so that any top complementary connection surface can connect to any bottom complementary connection surface. Each module may have a supporting structure so as to bear the weight of any modules connected above it. In this embodiment, each module comprises walls (surfaces aligned with the connection axis) or pillars which are robust enough to support the weight of modules connected above. The two opposing complementary connection surfaces may be substantially parallel.

[0070] In the case of a tower, a connection axis is substantially vertical. The lines are aligned with the connection axis. The lines have a uniform cross-section along their length. This means that a submodule with rigidly positioned connectors can be connected to the lines anywhere along their length within the module. The complementary connection surfaces lie transverse to the connection axis. In this embodiment, the supporting walls are aligned with the connection axis. [0071] To connect the modules such that power and data signals may be transmitted between modules, each module has a ground line, a power line and a data line. The potential difference between the power line and the ground line can be used to power the various electrical components of the sensor tower. The data line is used to allow the sensors to communicate with the controller. The sensor tower may also comprise a transceiver for communicating with remote devices.

[0072] In this case, each of the three sensor modules is an intermediary module, wherein the ground line, the power line and the data line of each intermediary module span between two opposing complementary connection surfaces (top to bottom), such that, when one of the intermediary modules is connected between two other modules using the opposing complementary connection surfaces, the ground lines, the power lines and the data lines of the three connected modules are connected to allow signals to be passed between them.

[0073] In this embodiment, the ground lines and the power lines of connected modules are directly electrically connected. This may the most efficient way of transmitting power between the modules. The direct electrical connection is provided via spring loaded pins. It will be appreciated that when a new module is added, there will be movement as the connection surfaces are brought together. Using spring loaded pins facilitates some movement between the connecting lines without causing damage, and may also compensate for some inconsistencies between the connection surfaces.

[0074] In contrast to the lines used for transmitting power, the data line in this case is connected using optical emitters and receivers. That is, in this embodiment, each modular portion of the data line is not connected to adjacent portions by a direct electrical connection, but instead by transducing the electrical signal to an optical signal and then back to an electrical signal. Using an optical transducer in this case also allows there to be a good data connection even where the optical transducers are imperfectly aligned. Using optical transducers may provide for a more reliable transfer of data than an imperfect electrical connection which may introduce noise into sensitive data signals.

[0075] In this embodiment, intermediate module 630a comprises a battery backup and multiple removable sensor submodules, in this case, including a temperature sensor and a humidity sensor. This allows this intermediate module to be customised by replacing these sensor submodules without changing the whole sensor module. For example, the humidity sensor submodule may be replaced with a soil sensor submodule without changing the overall configuration of the sensor tower. In another scenario, if there is room in an intermediate module, a sensor submodule may be added. A sensor submodule may also be removed without affecting the configuration of the other components or affecting the transfer of data and power through the tower.

[0076] The addition, removal or replacement of a sensor submodule can be done by hand, without requiring tools or changes to be made to the wiring or other components of the tower.

[0077] In the configuration of figure 6, other sensor modules may be fixed. For example, the wind-speed or anemometer sensor module 630b may be configured to be a standard component in which the sensor components are permanently connected to the data and power lines. For this sensor, if the user wished to use the tower without the sound sensor, they could remove this module and connect the image (or camera) sensor module 630c directly to the flexible sensor module 630a. It will be appreciated that adding or removing a module changes the overall height of the tower. Having the connection axis substantially vertically means that the mass of the upper modules is supported by the complementary connection surfaces. It will be appreciated that the order of the intermediate sensor modules may be switched.

[0078] In this embodiment, the intermediate modules have a uniform cross-section. The cross-section is a regular polygon, in this case a hexagon. For some modules, each side of the polygon is occupied with an identical sensor. For example, sensor module 630c has identical image sensors and sensor module 630b has identical sound sensors. This allows spatial and/or directional information to be determined by the sensor module.

[0079] As noted above, the sensor tower in this embodiment comprises a renewable energy source, in the form of solar panels. In some embodiments, a battery is stored in the unit comprising the renewable energy source, and so can be charged directly with a permanently connected line. The sensor tower may alternatively or in addition be wired to an electrical source external to the sensor tower, for example to a power grid.

[0080] In this embodiment, the battery is located in the base unit because the weight of the battery at the base lowers the centre of mass of the sensor tower which makes it more stable. To allow the renewable energy source to charge the battery, each module comprises a charging line configured to receive power from a power source and deliver it to a battery. Like the data, power and ground lines, the charging line spans between the opposing complementary connection surfaces and is connected using a resilient direct electrical connection (e.g., spring loaded pins).

[0081] As with the embodiment of figure 1 , the sensor tower of figure 6 has multiple sensors communicating with a common controller along a common data line. To facilitate this communication, each sensor comprises a sensor controller configured to communicate with the controller to generate a time-slot allocation signal which allocates a time slot during which the sensor can communicate with the processor via the connected data lines.

[0082] To reduce the amount of communication between the sensors and the controller, each sensor is configured to transmit data to the processor only when the sensed value has changed by an amount exceeding a predetermined threshold, and wherein the processor is configured to report the last received sensed value from the sensor.

[0083] In other embodiments, the modular sensor tower comprises multiple sensors and multiple data lines, wherein the multiple data lines allow for communication between different sensors and the processor with different communication protocols.

[0084] It will be appreciated that the base module and/or head module may only have one complementary surface configured to connect to a corresponding complementary surface of an intermediary module, the base module configured to support the sensor tower. That is, each intermediary module has to allow the transfer of power and data signals between modules on either side of the intermediary module. The head and base modules may connect to the intermediary modules to transmit power and data signals directly with the connected intermediary modules and any other modules connected to the ground, power and data lines, but they do not necessarily need to carry signals between opposing surfaces as they may be considered to be the termini of the lines.

[0085] In some embodiments, one or more of the modules has an electrical component that can be controlled by another component in the sensor tower via the lines (e.g., the data line). The electrical component may be connected to the lines of the module via a removable submodule in the same manner or a similar manner to how the sensor submodule is connected to the lines (e.g., by using a physical connector having electrical terminals that impinge the lines). For example, the electrical component may be a fan having a motor and motor starter. A temperature sensor connected to the lines may have a controller configured to control the motor starter, thus being able to start the fan when a predetermined threshold temperature is reached to cool one or more components internal or external to the sensor tower.

[0086] Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.