US20070021946A1 - Lamp monitoring and control unit and method - Google Patents

Abstract

A unit and method for remotely monitoring and/or controlling an apparatus and specifically for remotely monitoring and/or controlling street lamps. The lamp monitoring and control unit comprises a processing and sensing unit for sensing at least one lamp parameter of an associated lamp, and for processing the lamp parameter to monitor and control the associated lamp by outputting monitoring data and control information, and a transmit unit for transmitting the monitoring data, representing the at least one lamp parameter, from the processing and sensing unit. The method for monitoring and controlling a lamp comprises the steps of: sensing at least one lamp parameter of an associated lamp; processing the at least one lamp parameter to produce monitoring data and control information; transmitting the monitoring data; and applying the control information.

Description

• This application is a Continuation of Ser. No. 11/117,518, filed Apr. 29, 2005 (now U.S. Pat. No. 7,113,893), which is a Continuation of Ser. No. 10/811,855, filed Mar. 30, 2004 (now U.S. Pat. No. 6,889,174), which is a Continuation of Ser. No. 10/251,756, filed Sep. 23, 2002 (now U.S. Pat. No. 6,714,895), which is a Continuation of Ser. No. 09/605,027, filed Jun. 28, 2000 (now U.S. Pat. No. 6,456,960), which is a Divisional of Ser. No. 09/501,274, filed Feb. 9, 2000 (now U.S. Pat. No. 6,393,381), which is a Divisional of Ser. No. 08/838,302, filed Apr. 16, 1997 (now U.S. Pat. No. 6,119,076). The entire disclosure of the prior applications is considered as being part of the disclosure of the accompanying application and is hereby incorporated by reference therein.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• This invention relates generally to a unit and method for remotely monitoring and/or controlling an apparatus and specifically to a lamp monitoring and control unit and method for use with street lamps.
• 2. Background of the Related Art
• The first street lamps were used in Europe during the latter half of the seventeenth century. These lamps consisted of lanterns which were attached to cables strung across the street so that the lantern hung over the center of the street. In France, the police were responsible for operating and maintaining these original street lamps while in England contractors were hired for street lamp operation and maintenance. In all instances, the operation and maintenance of street lamps was considered a government function.
• The operation and maintenance of street lamps, or more generally any units which are distributed over a large geographic area, can be divided into two tasks: monitor and control. Monitoring comprises the transmission of information from the distributed unit regarding the unit's status and controlling comprises the reception of information by the distributed unit.
• For the present example in which the distributed units are street lamps, the monitoring function comprises periodic checks of the street lamps to determine if they are functioning properly. The controlling function comprises turning the street lamps on at night and off during the day.
• This monitor and control function of the early street lamps was very labor intensive since each street lamp had to be individually lit (controlled) and watched for any problems (monitored). Because these early street lamps were simply lanterns, there was no centralized mechanism for monitor and control and both of these functions were distributed at each of the street lamps.
• Eventually, the street lamps were moved from the cables hanging over the street to poles which were mounted at the side of the street. Additionally, the primitive lanterns were replaced with oil lamps.
• The oil lamps were a substantial improvement over the original lanterns because they produced a much brighter light. This resulted in illumination of a greater area by each street lamp. Unfortunately, these street lamps still had the same problem as the original lanterns in that there was no centralized monitor and control mechanism to light the street lamps at night and watch for problems.
• In the 1840's, the oil lamps were replaced by gaslights in France. The advent of this new technology began a government centralization of a portion of the control function for street lighting since the gas for the lights was supplied from a central location.
• In the 1880's, the gaslights were replaced with electrical lamps. The electrical power for these street lamps was again provided from a central location. With the advent of electrical street lamps, the government finally had a centralized method for controlling the lamps by controlling the source of electrical power.
• The early electrical street lamps were composed of arc lamps in which the illumination was produced by an arc of electricity flowing between two electrodes.
• Currently, most street lamps still use arc lamps for illumination. The mercury-vapor lamp is the most common form of street lamp in use today. In this type of lamp, the illumination is produced by an arc which takes place in a mercury vapor.
• FIG. 1 shows the configuration of a typical mercury-vapor lamp. This figure is provided only for demonstration purposes since there are a variety of different types of mercury-vapor lamps.
• The mercury-vapor lamp consists of anarc tube110 which is filled with argon gas and a small amount of pure mercury. Arctube110 is mounted inside a largeouter bulb120 which encloses and protects the arc tube. Additionally, the outer bulb may be coated with phosphors to improve the color of the light emitted and reduce the ultraviolet radiation emitted. Mounting ofarc tube110 insideouter bulb120 may be accomplished with an arctube mount support130 on the top and astem140 on the bottom.
• Main electrodes150aand150b, with opposite polarities, are mechanically sealed at both ends ofarc tube110. The mercury-vapor lamp requires a sizeable voltage to start the arc betweenmain electrodes150aand150b.
• The starting of the mercury-vapor lamp is controlled by a starting circuit (not shown inFIG. 1) which is attached between the power source (not shown inFIG. 1) and the lamp. Unfortunately, there is no standard starting circuit for mercury-vapor lamps. After the lamp is started, the lamp current will continue to increase unless the starting circuit provides some means for limiting the current. Typically, the lamp current is limited by a resistor, which severely reduces the efficiency of the circuit, or by a magnetic device, such as a choke or a transformer, called a ballast.
• During the starting operation, electrons move through astarting resistor160 to astarting electrode170 and across a short gap betweenstarting electrode170 andmain electrode150bof opposite polarity. The electrons cause ionization of some of the Argon gas in the arc tube. The ionized gas diffuses until a main arc develops between the two opposite polaritymain electrodes150aand150b. The heat from the main arc vaporizes the mercury droplets to produce ionized current carriers. As the lamp current increases, the ballast acts to limit the current and reduce the supply voltage to maintain stable operation and extinguish the arc betweenmain electrode150band startingelectrode170.
• Because of the variety of different types of starter circuits, it is virtually impossible to characterize the current and voltage characteristics of the mercury-vapor lamp. In fact, the mercury-vapor lamp may require minutes of warm-up before light is emitted. Additionally, if power is lost, the lamp must cool and the mercury pressure must decrease before the starting arc can start again.
• The mercury-vapor lamp has become the predominant street lamp with millions of units produced annually. The current installed base of these street lamps is enormous with more than 500,000 street lamps in Los Angeles alone. The mercury-vapor lamp is not the most efficient gaseous discharge lamp, but is preferred for use in street lamps because of its long life, reliable performance, and relatively low cost.
• Although the mercury-vapor lamp has been used as a common example of current street lamps, there is increasing use of other types of lamps such as metal halide and high pressure sodium. All of these types of lamps require a starting circuit which makes it virtually impossible to characterize the current and voltage characteristics of the lamp.
• FIG. 2 shows alamp arrangement201 with a typicallamp sensor unit210 which is situated between apower source220 and alamp assembly230.Lamp assembly230 includes a lamp240 (such as the mercury-vapor lamp presented inFIG. 1) and a startingcircuit250.
• Most cities currently use automatic lamp control units to control the street lamps. These lamp control units provide an automatic, but decentralized, control mechanism for turning the street lamps on at night and off during the day.
• A typicalstreet lamp assembly201 includes alamp sensor unit210 which in turn includes alight sensor260 and arelay270 as shown inFIG. 2.Lamp sensor unit210 is electrically coupled betweenexternal power source220 and startingcircuit250 oflamp assembly230. There is ahot line280aand aneutral line280bproviding electrical connection betweenpower source220 andlamp sensor unit210. Additionally, there is a switchedline280cand aneutral line280dproviding electrical connection betweenlamp sensor unit210 and startingcircuit250 oflamp assembly230.
• From a physical standpoint, mostlamp sensor units210 use a standard three prong plug, for example a twist lock plug, to connect to the back oflamp assembly230. The three prongs couple tohot line280a, switchedline280c, andneutral lines280band280d. In other words, theneutral lines280band280dare both connected to the same physical prong since they are at the same electrical potential. Some systems also have a ground wire, but no ground wire is shown inFIG. 2 since it is not relevant to the operation oflamp sensor unit210.
• Power source220 may be a standard 115 Volt, 60 Hz source from a power line. Of course, a variety of alternatives are available forpower source220. In foreign countries,power source220 may be a 220 Volt, 50 Hz source from a power line. Additionally,power source220 may be a DC voltage source or, in certain remote regions, it may be a battery which is charged by a solar reflector.
• The operation oflamp sensor unit210 is fairly simple. At sunset, when the light from the sun decreases below a sunset threshold, thelight sensor260 detects this condition and causes relay270 to close. Closure ofrelay270 results in electrical connection ofhot line280aand switchedline280cwith power being applied to startingcircuit250 oflamp assembly230 to ultimately produce light fromlamp240. At sunrise, when the light from the sun increases above a sunrise threshold,light sensor260 detects this condition and causes relay270 to open. Opening ofrelay270 eliminates electrical connection betweenhot line280aand switchedline280cand causes the removal of power from startingcircuit250 which turnslamp240 off.
• Lamp sensor unit210 provides an automated, distributed control mechanism to turnlamp assembly230 on and off. Unfortunately, it provides no mechanism for centralized monitoring of the street lamp to determine if the lamp is functioning properly. This problem is particularly important in regard to the street lamps on major boulevards and highways in large cities. When a street lamp burns out over a highway, it is often not replaced for a long period of time because the maintenance crew will only schedule a replacement lamp when someone calls the city maintenance department and identifies the exact pole location of the bad lamp. Since most automobile drivers will not stop on the highway just to report a bad street lamp, a bad lamp may go unreported indefinitely.
• Additionally, if a lamp is producing light but has a hidden problem, visual monitoring of the lamp will never be able to detect the problem. Some examples of hidden problems relate to current, when the lamp is drawing significantly more current than is normal, or voltage, when the power supply is not supplying the appropriate voltage level to the street lamp.
• Furthermore, the present system of lamp control in which an individual light sensor is located at each street lamp, is a distributed control system which does not allow for centralized control. For example, if the city wanted to turn on all of the street lamps in a certain area at a certain time, this could not be done because of the distributed nature of the present lamp control circuits.
• Because of these limitations, a new type of lamp control unit is needed which allows centralized monitoring and/or control of the street lamps in a geographical area.
• One attempt to produce a centralized control mechanism is a product called the RadioSwitch made by Cetronic. The RadioSwitch is a remotely controlled time switch for installation on the DIN-bar of control units. It is used for remote control of electrical equipment via local or national paging networks. Unfortunately, the RadioSwitch is unable to address most of the problems listed above.
• Since the RadioSwitch is receive only (no transmit capability), it only allows one to remotely control external equipment. Furthermore, since the communication link for the RadioSwitch is via paging networks, it is unable to operate in areas in which paging does not exist (for example, large rural areas in the United States). Additionally, although the RadioSwitch can be used to control street lamps, it does not use the standard three prong interface used by the present lamp control units. Accordingly, installation is difficult because it cannot be used as a plug-in replacement for the current lamp control units.
• Because of these limitations of the available equipment, there exists a need for a new type of lamp control unit which allows centralized monitoring and/or control of the street lamps in a geographical area. More specifically, this new device must be inexpensive, reliable, and easy to install in place of the millions of currently installed lamp control units.
• Although the above discussion has presented street lamps as an example, there is a more general need for a new type of monitoring and control unit which allows centralized monitoring and/or control of units distributed over a large geographical area.
• The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
SUMMARY OF THE INVENTION
• The present invention provides a lamp monitoring and control unit and method for use with street lamps which solves the problems described above.
• While the invention is described with respect to use with street lamps, it is more generally applicable to any application requiring centralized monitoring and/or control of units distributed over a large geographical area.
• These and other objects, advantages and features can be accomplished in accordance with the present invention by the provision of a lamp monitoring and control unit comprising: a processing and sensing unit for sensing at least one lamp parameter of an associated lamp, and for processing the at least one lamp parameter to monitor and control the associated lamp by outputting monitoring data and control information; and a transmit unit for transmitting the monitoring data, representing the at least one lamp parameter, from the processing and sensing unit.
• These and other objects, advantages and features can also be achieved in accordance with the invention by a lamp monitoring and control unit comprising: a processing unit for processing at least one lamp parameter and outputting a relay control signal; a light sensor, coupled to the processing unit, for sensing an amount of ambient light, producing a light signal associated with the amount of ambient light, and outputting the light signal to the processing unit; a relay for switching a switched power line to a hot power line based upon the relay control signal from the processing unit; a voltage sensor, coupled to the processing unit, for sensing a switched voltage in the switched power line; a current sensor, coupled to the switched power line, for sensing a switched current in the switched power line; and a transmit unit for transmitting monitoring data, representing the at least one lamp parameter, from the processing unit.
• These and other objects, advantages and features can also be achieved in accordance with the invention by a method for monitoring and controlling a lamp comprising the steps of: sensing at least one lamp parameter of an associated lamp; processing the at least one lamp parameter to produce monitoring data and control information; transmitting the monitoring data; and applying the control information.
• A feature of the present invention is that the lamp monitoring and control unit may be coupled to the associated lamp via a standard three prong plug.
• Another feature of the present invention is that the processing and sensing unit may include a relay for switching the switched power line to the hot power line.
• Another feature of the present invention is that the processing and sensing unit may include a current sensor for sensing a switched current in the switched power line.
• Another feature of the present invention is that the processing and sensing unit may include a voltage sensor for sensing a switched voltage in the switched power line.
• Another feature of the present invention is that the transmit unit may include a transmitter and a modified directional discontinuity ring radiator, and the modified directional discontinuity ring radiator may include a plurality of loops for resonance at a desired frequency range.
• Another feature of the present invention is that in accordance with an embodiment of the method, the step of processing may include providing an initial delay, a current stabilization delay, a relay settle delay, to prevent false triggering.
• Another feature of the present invention is that in accordance with an embodiment of the method, the step of transmitting the monitoring data may include a pseudo-random reporting start time delay, reporting delta time, and frequency. The pseudo-random nature of these values may be based on the serial number of the lamp monitoring and control unit.
• An advantage of the present invention is that it solves the problem of providing centralized monitoring and/or control of the street lamps in a geographical area.
• Another advantage of the present invention is that by using the standard three prong plug of the current street lamps, it is easy to install in place of the millions of currently installed lamp control units.
• An additional advantage of the present invention is that it provides for a new type of monitoring and control unit which allows centralized monitoring and/or control of units distributed over a large geographical area.
• Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
• The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:
• FIG. 1 shows the configuration of a typical mercury-vapor lamp.
• FIG. 2 shows a typical configuration of a lamp arrangement comprising a lamp sensor unit situated between a power source and a lamp assembly.
• FIG. 3 shows a lamp arrangement, according to one embodiment of the invention, comprising a lamp monitoring and control unit situated between a power source and a lamp assembly.
• FIG. 4 shows a lamp monitoring and control unit, according to another embodiment of the invention, including a processing and sensing unit, a Tx unit, and an Rx unit.
• FIG. 5 shows a lamp monitoring and control unit, according to another embodiment of the invention, including a processing and sensing unit, a Tx unit, an Rx unit, and a light sensor.
• FIG. 6 shows a lamp monitoring and control unit, according to another embodiment of the invention, including a processing and sensing unit, a Tx unit, and a light sensor.
• FIG. 7 shows a lamp monitoring and control unit, according to another embodiment of the invention, including a microprocessing unit, an A/D unit, a current sensing unit, a voltage sensing unit, a relay, a Tx unit, and a light sensor.
• FIG. 8 shows an example frequency channel plan for a lamp monitoring and control unit, according to another embodiment of the invention.
• FIG. 9 shows a typical directional discontinuity ring radiator (DDRR) antenna.
• FIG. 10 shows a modified DDRR antenna, according to another embodiment of the invention.
• FIGS.11A-E show methods for one implementation of logic for a lamp monitoring and control unit, according to another embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• The preferred embodiments of a lamp monitoring and control unit (LMCU) and method, which allows centralized monitoring and/or control of street lamps, will now be described with reference to the accompanying figures. While the invention is described with reference to an LMCU, the invention is not limited to this application and can be used in any application which requires a monitoring and control unit for centralized monitoring and/or control of devices distributed over a large geographical area. Additionally, the term street lamp in this disclosure is used in a general sense to describe any type of street lamp, area lamp, or outdoor lamp.
• FIG. 3 shows alamp arrangement301 which includes lamp monitoring andcontrol unit310, according to one embodiment of the invention. Lamp monitoring andcontrol unit310 is situated between apower source220 and alamp assembly230.Lamp assembly230 includes alamp240 and a startingcircuit250.
• Power source220 may be a standard 115 volt, 60 Hz source supplied by a power line. It is well known to those skilled in the art that a variety of alternatives are available forpower source220. In foreign countries,power source220 may be a 220 volt, 50 Hz source from a power line. Additionally,power source220 may be a DC voltage source or, in certain remote regions, it may be a battery which is charged by a solar reflector.
• Recall thatlamp sensor unit210 included alight sensor260 and arelay270 which is used to controllamp assembly230 by automatically switching thehot power280ato a switchedpower line280cdepending on the amount of ambient light received bylight sensor260.
• On the other hand, lamp monitoring andcontrol unit310 provides several functions including a monitoring function which is not provided bylamp sensor unit210. Lamp monitoring andcontrol unit310 is electrically located between theexternal power supply220 and startingcircuit250 oflamp assembly230. From an electrical standpoint, there is a hot280awith a neutral280belectrical connection betweenpower supply220 and lamp monitoring andcontrol unit310. Additionally, there is a switched280cand a neutral280delectrical connection between lamp monitoring andcontrol unit310 and startingcircuit250 oflamp assembly230.
• From a physical standpoint, lamp monitoring andcontrol unit310 may use a standard three-prong plug to connect to the back oflamp assembly230. The three prongs in the standard three-prong plug represent hot280a, switched280c, and neutral280band280d. In other words, theneutral lines280band280dare both connected to the same physical prong and share the same electrical potential.
• Although use of a three-prong plug is recommended because of the substantial number of street lamps using this type of standard plug, it is well known to those skilled in the art that a variety of additional types of electrical connection may be used for the present invention. For example, a standard power terminal block or AMP power connector may be used.
• FIG. 4 shows lamp monitoring andcontrol unit310, according to another embodiment of the invention. Lamp monitoring andcontrol unit310 includes a processing andsensing unit412, a transmit (TX)unit414, and an optional receive (RX)unit416. Processing andsensing unit412 is electrically connected to hot280a, switched280c, and neutral280band280delectrical connections. Furthermore, processing andsensing unit412 is connected toTX unit414 andRX unit416. In a standard application,TX unit414 may be used to transmit monitoring data andRX unit416 may be used to receive control information. For applications in which external control information is not required,RX unit416 may be deleted from lamp monitoring andcontrol unit310.
• FIG. 5 shows a lamp monitoring andcontrol unit310, according to another embodiment of the invention, with a configuration similar to that shown inFIG. 4. Here, however, lamp monitoring andcontrol unit310 ofFIG. 5 further includes alight sensor518, analogous to light sensor216 ofFIG. 2, which allows for some degree of local control.Light sensor518 is coupled to processing andsensing unit412 to provide information regarding the level of ambient light. Accordingly, processing andsensing unit412 may receive control information either locally fromlight sensor518 or remotely fromRX unit416.
• FIG. 6 shows another configuration for lampmonitoring control unit310, according to another embodiment of the invention, but withoutRX unit416. This embodiment of lamp monitoring andcontrol unit310 can be used in applications in which only local control information, for example fromlight sensor518, is to be passed to processing andsensing unit412. In other words, remote monitoring data may be received viaTX unit414 and local control information may be generated vialight sensor518.
• FIG. 7 shows a more detailed implementation of lamp monitoring andcontrol unit310 ofFIG. 6, according to one embodiment of the invention.
• FIG. 7 shows one embodiment of a lamp monitoring andcontrol unit310 with a three-prong plug720 to provide hot280a, neutral280band280d, and switched280celectrical connections. The hot280aand neutral280band280delectrical connections are connected to an optionalswitching power supply710 in applications in which AC power is input and DC power is required to power the circuit components of lamp monitoring andcontrol unit310.
• Light sensor518 includes a photosensor518aand associatedlight sensor circuitry518b.TX unit414 includes aradio modem transmitter414aand a built-inantenna414b. Processing andsensing unit412 includesmicroprocessor circuitry412a, arelay412b, current andvoltage sensing circuitry412c, and an analog-to-digital converter412d.
• Microprocessor circuitry412aincludes any standard microprocessor/microcontroller such as the Intel 8751 or Motorola 68HC16. Additionally, in applications in which cost is an issue,microprocessor circuitry412amay comprise a small, low cost processor with built-in memory such as theMicrochip PIC 8 bit microcontroller. Furthermore,microprocessor circuitry412amay be implemented by using a PAL, EPLD, FPGA, or ASIC device.
• Microprocessor circuitry412areceives and processes input signals and outputs control signals. For example,microprocessor circuitry412areceives a light sensing signal fromlight sensor518. This light sensing signal may either be a threshold indication signal, that is, providing a digital signal, or some form of analog signal.
• Based upon the value of the light sensing signal,microprocessor circuitry412amay alternatively or additionally execute software to output a relay control signal to arelay412awhich switches switchedpower line280ctohot power line280a.
• Microprocessor circuitry412amay also interface to other sensing circuitry. For example, the lamp monitoring andcontrol unit310 may include current andvoltage sensing circuitry412cwhich senses the voltage of the switchedpower line280cand also senses the current flowing through the switchedpower line280c. The voltage sensing operation may produce a voltage ON signal which is sent from the current andvoltage sensing circuitry412ctomicroprocessor circuitry412a. This voltage ON signal can be of a threshold indication, that is, some form of digital signal, or it can be an analog signal.
• Current andvoltage sensing circuitry412ccan also output a current level signal indicative of the amount of current flowing through switchedpower line280c. The current level signal can interface directly tomicroprocessor circuitry412aor, alternatively, it can be coupled tomicroprocessing circuitry412athrough an analog-to-digital converter412b.Microprocessor circuitry412acan produce a CLOCK signal which is sent to analog-to-digital converter412dand which is used to allow A/D data to pass from analog-to-digital converter412dtomicroprocessor circuitry412a.
• Microprocessor circuitry412acan also be coupled toradio modem transmitter414ato allow monitoring data to be sent from lampmonitoring control unit310.
• The configuration shown inFIG. 7 is intended as an illustration of one way in which the present invention can be implemented. For example, analog-to-digital converter412bmay be combined intomicroprocessor circuitry412afor some applications. Furthermore, the memory formicroprocessor circuitry412amay either be internal to the microprocessor circuitry or contained as an external EPROM, EEPROM, Flash RAM, dynamic RAM, or static RAM. Current andvoltage sensor circuitry412cmay either be combined in one unit with shared components or separated into two separate units. Furthermore, the current sensing portion of current andvoltage sensing circuitry412cmay include acurrent sensing transformer413 and associated circuitry as shown inFIG. 7 or may be configured using different circuitry which also senses current.
• The frequencies to be used by theTX unit414 are selected bymicroprocessor circuitry412a. There are a variety of ways that these frequencies can be organized and used, examples of which will be discussed below.
• FIG. 8 shows an example of a frequency channel plan for lamp monitoring andcontrol unit310, according to one embodiment of the invention. In this example table, interactive video and data service (IVDS) radio frequencies in the range of 218-219 MHz are shown. The IVDS channels inFIG. 8 are divided into two groups, Group A and Group B, with each group having nineteen channels spaced at 25 KHz steps. The first channel of the group A frequencies is located at 218.025 MHz and the first channel of the group B frequencies is located at 218.525 MHz.
• The mapping between channel numbers and frequencies can either be performed inmicroprocessor circuitry412aorTX unit414. In other words the data signal sent toTX unit414 frommicroprocessor circuitry412amay either consist of channel numbers or frequency data. To transmit at these frequencies,TX unit414 must have an associatedantenna414b.
• FIG. 9 shows a typical directional discontinuity ring radiator (DDRR) antenna900. DDRR antenna900 is well known to those skilled in the art, and detailed description of the operation and use of this antenna can be found in the American Radio Relay League (ARRL) Handbook, the appropriate sections of which are incorporated by reference. The problem with using DDRR antenna900 in applications such as lamp monitoring andcontrol unit310 is that the antenna dimension for resonance in certain frequency ranges, such as the IVDS frequency range, is too large.
• FIG. 10 shows a modifiedDDRR antenna1000, according to a further embodiment of the invention. ModifiedDDRR antenna1000 is mounted on aPC board1010 and includes ametal shield1020, acoil segment1060, a loopedwire coil1040, a first variable capacitor C1, and a second variable capacitor C2. Additionally, a plastic assembly (not shown) may be included in modifiedDDRR antenna1000 to hold loopedwire coil1040 in place.
• The RF energy to be radiated is fed into anRF feed point1050 and travels throughwire segment1060 through ahole1030 inmetal shield1020 to variable capacitor C2. Variable capacitor C2 is used to match the input impedance of modifiedDDRR antenna1000 to 50 ohms. Loopedwire coil1040 is looped several times, as opposed to typical DDRR antenna900 which only has one loop. Loopedwire coil1040 may be coupled towire segment1060, or both loopedwire coil1040 andwire segment1060 may be part of a continuous piece of wire, as shown. The end ofwire coil1040 is coupled to capacitor C1 which tunes modifiedDDRR antenna1000 for resonance at the desired frequency.
• ModifiedDDRR antenna1000 has multiple loops inwire coil1040 which allow the antenna to resonate at particular frequencies. For example, if typical DDRR antenna900 with approximately a 5″ diameter is modified to include three to six loops, then the diameter can be decreased to less than 4″ and still resonate in the IVDS frequency range. In other words, if typical DDRR antenna900 has a 4″ diameter, it will have poor resonance in the IVDS frequency range. In contrast, if modifiedDDRR antenna1000 has a 4″ diameter, it will have excellent resonance in the IVDS frequency range. Accordingly, modifiedDDRR antenna1000 provides for an efficient transformation of input RF energy for radiation as an E-M field because of its improved resonance at the desired frequencies and an impedance match (such as 50 ohms) to the input RF source. The exact number of additional loops and spacing for modifiedDDRR antenna1000 depends on the frequency range selected.
• Furthermore, if lamp monitoring andcontrol unit310 includesRX unit416, as shown inFIG. 4, modifiedDDRR antenna1000 can be shared byTX unit414 andRX unit416. Alternatively,RX unit416 andTX unit414 may use separate antennas.
• FIGS.11A-E show methods for implementation of logic for lamp monitoring andcontrol unit310, according to a further embodiment of the invention. These methods may be implemented in a variety of ways, including software inmicroprocessor circuitry412aor customized logic chips.
• FIG. 11A shows one method for energizing and de-energizing a street lamp and transmitting associated monitoring data. The method ofFIG. 11A shows a single transmission for each control event. The method begins with astart block1100 and proceeds to step1110 which involves checking AC and Daylight Status. The Check AC andDaylight Status step1110 is used to check for conditions where the AC power and/or the Daylight Status have changed. If a change does occur, the method proceeds to thestep1120 which is a decision block based on the change.
• If a change occurred,step1120 proceeds to aDebounce Delay step1122 which involves inserting a Debounce Delay. For example, the Debounce Delay may be 0.5 seconds. AfterDebounce Delay step1122, the method leads back to Check AC andDaylight Status step1110.
• If no change occurred,step1120 proceeds to step1130 which is a decision block to determine whether the lamp should be energized. If the lamp should be energized, then the method proceeds to step1132 which turns the lamp on. Afterstep1132 when the lamp is turned on, the method proceeds to step1134 which involves Current Stabilization Delay to allow the current in the street lamp to stabilize. The amount of delay for current stabilization depends upon the type of lamp used. However, for a typical vapor lamp a ten minute stabilization delay is appropriate. Afterstep1134, the method leads back to step1110 which checks AC and Daylight Status.
• Returning to step1130, if the lamp is not to be energized, then the method proceeds to step1140 which is a decision block to check to deenergize the lamp. If the lamp is to be deenergized, the method proceeds to step1142 which involves turning the Lamp Off. After the lamp is turned off, the method proceeds to step1144 in which the relay is allowed a Settle Delay time. The Settle Delay time is dependent upon the particular relay used and may be, for example, set to 0.5 seconds. Afterstep1144, the method returns to step1110 to check the AC and Daylight Status.
• Returning to step1140, if the lamp is not to be deenergized, the method proceeds to step1150 in which an error bit is set, if required and proceeds to step1160 in which an A/D is read. For example, the A/D may be the analog-to-digital converter412dfor reading the current level as shown inFIG. 7.
• The method then proceeds fromstep1160 to step1170 which checks to see if a transmit is required. If no transmit is required, the method proceeds to step1172 in which a Scan Delay is executed. The Scan Delay depends upon the circuitry used and, for example, may be 0.5 seconds. Afterstep1172, the method returns to step1110 which checks AC and Daylight Status.
• Returning to step1170, if a transmit is required, then the method proceeds to step1180 which performs a transmit operation. After the transmit operation ofstep1180 is completed, the method then returns to step1110 which checks AC and Daylight Status.
• FIG. 11B is analogous toFIG. 11A with one modification. This modification occurs afterstep1120. If a change has occurred, rather than simply executingstep1122, the Debounce Delay, the method performs afurther step1124 which involves checking whether daylight has occurred. If daylight has not occurred, then the method proceeds to step1126 which executes an Initial Delay. This initial delay may be, for example, 0.5 seconds. Afterstep1126, the method proceeds to step1122 and follows the same method as shown inFIG. 11A.
• Returning to step1124 which involves checking whether daylight has occurred, if daylight has occurred, the method proceeds to step1128 which executes an Initial Delay. The Initial Delay associated withstep1128 should be a significantly larger value than the Initial Delay associated withstep1126. For example, an Initial Delay of 45 seconds may be used. The Initial Delay ofstep1128 is used to prevent a false triggering which deenergizes the lamp. In actual practice, this extended delay can become very important because if the lamp is inadvertently deenergized too soon, it requires a substantial amount of time to reenergize the lamp (for example, ten minutes). Afterstep1128, the method proceeds to step1122 which executes a Debounce Delay and then returns to step1110 as shown inFIGS. 11A and 11B.
• FIG. 11C shows a method for transmitting monitoring data multiple times in a lamp monitoring and control unit, according to a further embodiment of the invention. This method is particularly important in applications in which lamp monitoring andcontrol unit310 does not have aRX unit416 for receiving acknowledgements of transmissions.
• The method begins with a transmitstart block1182 and proceeds to step1184 which involves initializing a count value, i.e. setting the count value to zero.Step1184 proceeds to step1186 which involves setting a variable x to a value associated with a serial number of lamp monitoring andcontrol unit310. For example, variable x may be set to 50 times the lowest nibble of the serial number.
• Step1186 proceeds to step1188 which involves waiting a reporting start time delay associated with the value x. The reporting start time is the amount of delay time before the first transmission. For example, this delay time may be set to x seconds where x is an integer between 1 and 32,000 or more. This example range for x is particularly useful in the street lamp application since it distributes the packet reporting start times over more than eight hours, approximately the time from sunset to sunrise.
• Step1188 proceeds to step1190 in which a variable y representing a channel number is set. For example, y may be set to the integer value of RTC/12.8, where RTC represents a real time clock counting from 0-255 as fast as possible. The RTC may be included inmicroprocessing circuitry412a.
• Step1190 proceeds to step1192 in which a packet is transmitted on channel y.Step1192 proceeds to step1194 in which the count value is incremented.Step1194 proceeds to step1196 which is a decision block to determine if the count value equals an upper limit N.
• If the count is not equal to N,step1196 returns to step1188 and waits another delay time associated with variable x. This delay time is the reporting delta time since it represents the time difference between two consecutive reporting events.
• If the count is equal to N,step1196 proceeds to step1198 which is an end block. The value for N must be determined based on the specific application. Increasing the value of N decreases the probability of a unsuccessful transmission since the same data is being sent multiple times and the probability of all of the packets being lost decreases as N increases. However, increasing the value of N increases the amount of traffic which may become an issue in a lamp monitoring and control system with a plurality of lamp monitoring and control units.
• FIG. 11D shows a method for transmitting monitoring data multiple times in a monitoring and control unit according to a another embodiment of the invention.
• The method begins with a transmitstart block1110′ and proceeds to step1112′ which involves initializing a count value, i.e., setting the count value to 1. The method proceeds fromstep1112′ to step1114′ which involves randomizing the reporting start time delay. The reporting start time delay is the amount of time delay required before the transmission of the first data packet. A variety of methods can be used for this randomization process such as selecting a pseudo-random value or basing the randomization on the serial number of monitoring and control unit510.
• The method proceeds fromstep1114′ to step1116′ which involves checking to see if the count equals 1. If the count is equal to 1, then the method proceeds to step1120′ which involves setting a reporting delta time equal to the reporting start time delay. If the count is not equal to 1, the method proceeds to step1118′ which involves randomizing the reporting delta time. The reporting delta time is the difference in time between each reporting event. A variety of methods can be used for randomizing the reporting delta time including selecting a pseudo-random value or selecting a random number based upon the serial number of the monitoring and control unit510.
• After either step1118′ orstep1120′, the method proceeds to step1122′ which involves randomizing a transmit channel number. The transmit channel number is a number indicative of the frequency used for transmitting the monitoring data. There are a variety of methods for randomizing the transmit channel number such as selecting a pseudo-random number or selecting a random number based upon the serial number of the monitoring and control unit510.
• The method proceeds fromstep1122′ to step1124′ which involves waiting the reporting delta time. It is important to note that the reporting delta time is the time which was selected during the randomization process of step1118′ or the reporting start time delay selected instep1114′, if the count equals 1. The use ofseparate randomization steps1114′ and1118′ is important because it allows the use of different randomization functions for the reporting start time delay and the reporting delta time, respectively.
• Afterstep1124′ the method proceeds to step1126′ which involves transmitting a packet on the transmit channel selected instep1122′.
• The method proceeds fromstep1126′ to step1128′ which involves incrementing the counter for the number of packet transmissions.
• The method proceeds fromstep1128′ to step1130′ in which the count is compared with a value N which represents the maximum number of transmissions for each packet. If the count is less than or equal to N, then the method proceeds fromstep1130′ back to step1118′ which involves randomizing the reporting delta time for the next transmission. If the count is greater than N, then the method proceeds fromstep1130′ to theend block1132′ for the transmission method.
• In other words, the method will continue transmission of the same packet of data N times, with randomization of the reporting start time delay, randomization of the reporting delta times between each reporting event, and randomization of the transmit channel number for each packet. These multiple randomizations help stagger the packets in the frequency and time domain to reduce the probability of collisions of packets from different monitoring and control units.
• FIG. 11E shows a further method for transmitting monitoring data multiple times from a monitoring and control unit510, according to another embodiment of the invention.
• The method begins with a transmitstart block1140′ and proceeds to step1142′ which involves initializing a count value, i.e., setting the count value to 1. The method proceeds fromstep1142′ to step1144′ which involves reading an indicator, such as a group jumper, to determine which group of frequencies to use, Group A or B. Examples of Group A and Group B channel numbers and frequencies can be found inFIG. 8.
• Step1144′ proceeds to step1146′ which makes a decision based upon whether Group A or B is being used. If Group A is being used,step1146′ proceeds to step1148′ which involves setting a base channel to the appropriate frequency for Group A. If Group B is to be used,step1146′ proceeds to step1150′ which involves setting the base channel frequency to a frequency for Group B.
• After eitherStep1148′ orstep1150′, the method proceeds to step1152′ which involves randomizing a reporting start time delay. For example, the randomization can be achieved by multiplying the lowest nibble of the serial number of monitoring and control unit510 by50 and using the resulting value, x, as the number of milliseconds for the reporting start time delay.
• The method proceeds from step1152′ to step1154′ which involves waiting x number of seconds as determined in step1152′.
• The method proceeds fromstep1154′ to step1156′ which involves setting a value z=0, where the value z represents an offset from the base channel number set instep1148′ or1150′.Step1156′ proceeds to step1158′ which determines whether the count equals 1. If the count equals 1, the method proceeds fromstep1158′ to step1172′ which involves transmitting the packet on a channel determined from the base channel frequency selected in eitherstep1148′ orstep1150′ plus the channel frequency offset selected instep1156′.
• If the count is not equal to 1, then the method proceeds fromstep1158′ to step1160′ which involves determining whether the count is equal to N, where N represents the maximum number of packet transmissions. If the count is equal to N, then the method proceeds fromstep1160′ to step1172′ which involves transmitting the packet on a channel determined from the base channel frequency selected in eitherstep1148′ orstep1150′ plus the channel number offset selected instep1156′.
• If the count is not equal to N, indicating that the count is a value between 1 and N, then the method proceeds fromstep1160′ to step1162′ which involves reading a real time counter (RTC) which may be located in processing andsensing unit412.
• The method proceeds fromstep1162′ to step1164′ which involves comparing the RTC value against a maximum value, for example, a maximum value of 152. If the RTC value is greater than or equal to the maximum value, then the method proceeds from step1164′ to step1166′ which involves waiting x seconds and returning to step1162′.
• If the value of the RTC is less than the maximum value, then the method proceeds from step1164′ to step1168′ which involves setting a value y equal to a value indicative of the channel number offset. For example, y can be set to an integer of the real time counter value divided by 8, so that Y value would range from 0 to 18.
• The method proceeds fromstep1168′ to step1170′ which involves computing a frequency offset value z from the channel number offset value y. For example, if a 25 KHz channel is being used, then z is equal to ytimes 25 KHz.
• The method then proceeds fromstep1170′ to step1172′ which involves transmitting the packet on a channel determined from the base channel frequency selected in eitherstep1148′ orstep1150′ plus the channel frequency offset computed instep1170′.
• The method proceeds fromstep1172′ to step1174′ which involves incrementing the count value. The method proceeds from step1174′ to step1176′ which involves comparing the count value to a value N+1 which is related to the maximum number of transmissions for each packet. If the count is not equal to N+1, the method proceeds fromstep1176′ back to step1154′ which involves waiting x number of milliseconds. If the count is equal to N+1, the method proceeds fromstep1176′ to theend block1178′.
• The method shown inFIG. 11E is similar to that shown inFIG. 11D, but differs in that it requires the first and the Nth transmission to occur at the base frequency rather than a randomly selected frequency.
• Although the above figures show numerous embodiments of the invention, it is well known to those skilled in the art that numerous modifications can be implemented.
• For example,FIG. 4 shows a light monitoring andcontrol unit310 in which there is no light sensor but rather anRX unit416 for receiving control information. Light monitoring andcontrol unit310 may be used in an environment in which a centralized control system is preferred. For example, instead of having a decentralized light sensor at every location, light monitoring andcontrol unit310 ofFIG. 4 allows for a centralized control mechanism. For example,RX unit416 could receive centralized energize/deenergize signals which are sent to all of the street lamp assemblies in a particular geographic region.
• As another alternative, if lamp monitoring andcontrol unit310 ofFIG. 4 contains noRX unit416, the control functionality can be built directly in the processing andsensing unit412. For example, processing andsensing unit412 may contain a table with a listing of sunrise and sunset times for a yearly cycle. The sunrise and sunset times could be used to energize and deenergize the lamp without the need for eitherRX unit416 orlight sensor518.
• The foregoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

Claims (1)

1. A system, comprising:

a plurality of fixed transmit/receive units each having an antenna and capable of transmitting and receiving digital packets of information;

at least one remote transmitting and receiving unit with a remote antenna capable of communicatively coupling to at least one of said plurality of fixed transmit/receive units via said digital packets of information.

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