Patent Document

[0001]     This application is a Continuation of Ser. No. 10/811,855, filed Mar. 30, 2004, 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  
       [0002]     1. Field of the Invention  
         [0003]     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.  
         [0004]     2. Background of the Related Art  
         [0005]     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.  
         [0006]     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&#39;s status and controlling comprises the reception of information by the distributed unit.  
         [0007]     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.  
         [0008]     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.  
         [0009]     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.  
         [0010]     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.  
         [0011]     In the 1840&#39;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.  
         [0012]     In the 1880&#39;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.  
         [0013]     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.  
         [0014]     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.  
         [0015]      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.  
         [0016]     The mercury-vapor lamp consists of an arc tube  110  which is filled with argon gas and a small amount of pure mercury. Arc tube  110  is mounted inside a large outer bulb  120  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 of arc tube  110  inside outer bulb  120  may be accomplished with an arc tube mount support  130  on the top and a stem  140  on the bottom.  
         [0017]     Main electrodes  150   a  and  150   b,  with opposite polarities, are mechanically sealed at both ends of arc tube  110 . The mercury-vapor lamp requires a sizeable voltage to start the arc between main electrodes  150   a  and  150   b.    
         [0018]     The starting of the mercury-vapor lamp is controlled by a starting circuit (not shown in  FIG. 1 ) which is attached between the power source (not shown in  FIG. 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.  
         [0019]     During the starting operation, electrons move through a starting resistor  160  to a starting electrode  170  and across a short gap between starting electrode  170  and main electrode  150   b  of 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 polarity main electrodes  150   a  and  150   b.  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 between main electrode  150   b  and starting electrode  170 .  
         [0020]     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.  
         [0021]     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.  
         [0022]     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.  
         [0023]      FIG. 2  shows a lamp arrangement  201  with a typical lamp sensor unit  210  which is situated between a power source  220  and a lamp assembly  230 . Lamp assembly  230  includes a lamp  240  (such as the mercury-vapor lamp presented in  FIG. 1 ) and a starting circuit  250 .  
         [0024]     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.  
         [0025]     A typical street lamp assembly  201  includes a lamp sensor unit  210  which in turn includes a light sensor  260  and a relay  270  as shown in  FIG. 2 . Lamp sensor unit  210  is electrically coupled between external power source  220  and starting circuit  250  of lamp assembly  230 . There is a hot line  280   a  and a neutral line  280   b  providing electrical connection between power source  220  and lamp sensor unit  210 . Additionally, there is a switched line  280   c  and a neutral line  280   d  providing electrical connection between lamp sensor unit  210  and starting circuit  250  of lamp assembly  230 .  
         [0026]     From a physical standpoint, most lamp sensor units  210  use a standard three prong plug, for example a twist lock plug, to connect to the back of lamp assembly  230 . The three prongs couple to hot line  280 a, switched line  280   c,  and neutral lines  280   b  and  280   d.  In other words, the neutral lines  280   b  and  280   d  are 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 in  FIG. 2  since it is not relevant to the operation of lamp sensor unit  210 .  
         [0027]     Power source  220  may be a standard 115 Volt, 60 Hz source from a power line. Of course, a variety of alternatives are available for power source  220 . In foreign countries, power source  220  may be a 220 Volt, 50 Hz source from a power line. Additionally, power source  220  may be a DC voltage source or, in certain remote regions, it may be a battery which is charged by a solar reflector.  
         [0028]     The operation of lamp sensor unit  210  is fairly simple. At sunset, when the light from the sun decreases below a sunset threshold, the light sensor  260  detects this condition and causes relay  270  to close. Closure of relay  270  results in electrical connection of hot line  280   a  and switched line  280   c  with power being applied to starting circuit  250  of lamp assembly  230  to ultimately produce light from lamp  240 . At sunrise, when the light from the sun increases above a sunrise threshold, light sensor  260  detects this condition and causes relay  270  to open. Opening of relay  270  eliminates electrical connection between hot line  280   a  and switched line  280   c  and causes the removal of power from starting circuit  250  which turns lamp  240  off.  
         [0029]     Lamp sensor unit  210  provides an automated, distributed control mechanism to turn lamp assembly  230  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.  
         [0030]     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.  
         [0031]     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.  
         [0032]     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.  
         [0033]     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.  
         [0034]     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.  
         [0035]     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.  
         [0036]     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.  
         [0037]     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  
       [0038]     The present invention provides a lamp monitoring and control unit and method for use with street lamps which solves the problems described above.  
         [0039]     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.  
         [0040]     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.  
         [0041]     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.  
         [0042]     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.  
         [0043]     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.  
         [0044]     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.  
         [0045]     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.  
         [0046]     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.  
         [0047]     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.  
         [0048]     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.  
         [0049]     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.  
         [0050]     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.  
         [0051]     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.  
         [0052]     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.  
         [0053]     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  
       [0054]     The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:  
         [0055]      FIG. 1  shows the configuration of a typical mercury-vapor lamp.  
         [0056]      FIG. 2  shows a typical configuration of a lamp arrangement comprising a lamp sensor unit situated between a power source and a lamp assembly.  
         [0057]      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.  
         [0058]      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.  
         [0059]      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.  
         [0060]      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.  
         [0061]      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.  
         [0062]      FIG. 8  shows an example frequency channel plan for a lamp monitoring and control unit, according to another embodiment of the invention.  
         [0063]      FIG. 9  shows a typical directional discontinuity ring radiator (DDRR) antenna.  
         [0064]      FIG. 10  shows a modified DDRR antenna, according to another embodiment of the invention.  
         [0065]     FIGS.  11 A-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  
       [0066]     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.  
         [0067]      FIG. 3  shows a lamp arrangement  301  which includes lamp monitoring and control unit  310 , according to one embodiment of the invention. Lamp monitoring and control unit  310  is situated between a power source  220  and a lamp assembly  230 . Lamp assembly  230  includes a lamp  240  and a starting circuit  250 .  
         [0068]     Power source  220  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 for power source  220 . In foreign countries, power source  220  may be a 220 volt, 50 Hz source from a power line. Additionally, power source  220  may be a DC voltage source or, in certain remote regions, it may be a battery which is charged by a solar reflector.  
         [0069]     Recall that lamp sensor unit  210  included a light sensor  260  and a relay  270  which is used to control lamp assembly  230  by automatically switching the hot power  280   a  to a switched power line  280   c  depending on the amount of ambient light received by light sensor  260 .  
         [0070]     On the other hand, lamp monitoring and control unit  310  provides several functions including a monitoring function which is not provided by lamp sensor unit  210 . Lamp monitoring and control unit  310  is electrically located between the external power supply  220  and starting circuit  250  of lamp assembly  230 . From an electrical standpoint, there is a hot  280   a  with a neutral  280   b  electrical connection between power supply  220  and lamp monitoring and control unit  310 . Additionally, there is a switched  280   c  and a neutral  280   d  electrical connection between lamp monitoring and control unit  310  and starting circuit  250  of lamp assembly  230 .  
         [0071]     From a physical standpoint, lamp monitoring and control unit  310  may use a standard three-prong plug to connect to the back of lamp assembly  230 . The three prongs in the standard three-prong plug represent hot  280   a,  switched  280   c,  and neutral  280   b  and  280   d.  In other words, the neutral lines  280   b  and  280   d  are both connected to the same physical prong and share the same electrical potential.  
         [0072]     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.  
         [0073]      FIG. 4  shows lamp monitoring and control unit  310 , according to another embodiment of the invention. Lamp monitoring and control unit  310  includes a processing and sensing unit  412 , a transmit (TX) unit  414 , and an optional receive (RX unit  416 . Processing and sensing unit  412  is electrically connected to hot  280   a,  switched  280   c,  and neutral  280   b  and  280   d  electrical connections. Furthermore, processing and sensing unit  412  is connected to TX unit  414  and RX unit  416 . In a standard application, TX unit  414  may be used to transmit monitoring data and RX unit  416  may be used to receive control information. For applications in which external control information is not required, RX unit  416  may be deleted from lamp monitoring and control unit  310 .  
         [0074]      FIG. 5  shows a lamp monitoring and control unit  310 , according to another embodiment of the invention, with a configuration similar to that shown in  FIG. 4 . Here, however, lamp monitoring and control unit  310  of  FIG. 5  further includes a light sensor  518 , analogous to light sensor  216  of  FIG. 2 , which allows for some degree of local control. Light sensor  518  is coupled to processing and sensing unit  412  to provide information regarding the level of ambient light. Accordingly, processing and sensing unit  412  may receive control information either locally from light sensor  518  or remotely from RX unit  416 .  
         [0075]      FIG. 6  shows another configuration for lamp monitoring control unit  310 , according to another embodiment of the invention, but without RX unit  416 . This embodiment of lamp monitoring and control unit  310  can be used in applications in which only local control information, for example from light sensor  518 , is to be passed to processing and sensing unit  412 . In other words, remote monitoring data may be received via TX unit  414  and local control information may be generated via light sensor  518 .  
         [0076]      FIG. 7  shows a more detailed implementation of lamp monitoring and control unit  310  of  FIG. 6 , according to one embodiment of the invention.  
         [0077]      FIG. 7  shows one embodiment of a lamp monitoring and control unit  310  with a three-prong plug  720  to provide hot  280   a,  neutral  280   b  and  280   d,  and switched  280   c  electrical connections. The hot  280   a  and neutral  280   b  and  280   d  electrical connections are connected to an optional switching power supply  710  in applications in which AC power is input and DC power is required to power the circuit components of lamp monitoring and control unit  310 .  
         [0078]     Light sensor  518  includes a photosensor  518   a  and associated light sensor circuitry  518   b.  TX unit  414  includes a radio modem transmitter  414   a  and a built-in antenna  414   b.  Processing and sensing unit  412  includes microprocessor circuitry  412   a,  a relay  412   b,  current and voltage sensing circuitry  412   c , and an analog-to-digital converter  412   d.    
         [0079]     Microprocessor circuitry  412   a  includes any standard microprocessor/microcontroller such as the Intel 8751 or Motorola 68HC16. Additionally, in applications in which cost is an issue, microprocessor circuitry  412   a  may comprise a small, low cost processor with built-in memory such as the Microchip PIC 8 bit microcontroller. Furthermore, microprocessor circuitry  412   a  may be implemented by using a PAL, EPLD, FPGA, or ASIC device.  
         [0080]     Microprocessor circuitry  412   a  receives and processes input signals and outputs control signals. For example, microprocessor circuitry  412   a  receives a light sensing signal from light sensor  518 . This light sensing signal may either be a threshold indication signal, that is, providing a digital signal, or some form of analog signal.  
         [0081]     Based upon the value of the light sensing signal, microprocessor circuitry  412   a  may alternatively or additionally execute software to output a relay control signal to a relay  412   a  which switches switched power line  280   c  to hot power line  280   a.    
         [0082]     Microprocessor circuitry  412   a  may also interface to other sensing circuitry. For example, the lamp monitoring and control unit  310  may include current and voltage sensing circuitry  412   c  which senses the voltage of the switched power line  280   c  and also senses the current flowing through the switched power line  280   c.  The voltage sensing operation may produce a voltage ON signal which is sent from the current and voltage sensing circuitry  412   c  to microprocessor circuitry  412   a.  This voltage ON signal can be of a threshold indication, that is, some form of digital signal, or it can be an analog signal.  
         [0083]     Current and voltage sensing circuitry  412   c  can also output a current level signal indicative of the amount of current flowing through switched power line  280   c.  The current level signal can interface directly to microprocessor circuitry  412   a  or, alternatively, it can be coupled to microprocessing circuitry  412   a  through an analog-to-digital converter  412   b.  Microprocessor circuitry  412   a  can produce a CLOCK signal which is sent to analog-to-digital converter  412   d  and which is used to allow A/D data to pass from analog-to-digital converter  412   d  to microprocessor circuitry  412   a.    
         [0084]     Microprocessor circuitry  412   a  can also be coupled to radio modem transmitter  414   a  to allow monitoring data to be sent from lamp monitoring control unit  310 .  
         [0085]     The configuration shown in  FIG. 7  is intended as an illustration of one way in which the present invention can be implemented. For example, analog-to-digital converter  412   b  may be combined into microprocessor circuitry  412   a  for some applications. Furthermore, the memory for microprocessor circuitry  412   a  may either be internal to the microprocessor circuitry or contained as an external EPROM, EEPROM, Flash RAM, dynamic RAM, or static RAM. Current and voltage sensor circuitry  412   c  may either be combined in one unit with shared components or separated into two separate units. Furthermore, the current sensing portion of current and voltage sensing circuitry  412   c  may include a current sensing transformer  413  and associated circuitry as shown in  FIG. 7  or may be configured using different circuitry which also senses current.  
         [0086]     The frequencies to be used by the TX unit  414  are selected by microprocessor circuitry  412   a.  There are a variety of ways that these frequencies can be organized and used, examples of which will be discussed below.  
         [0087]      FIG. 8  shows an example of a frequency channel plan for lamp monitoring and control unit  310 , 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 in  FIG. 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.  
         [0088]     The mapping between channel numbers and frequencies can either be performed in microprocessor circuitry  412   a  or TX unit  414 . In other words the data signal sent to TX unit  414  from microprocessor circuitry  412   a  may either consist of channel numbers or frequency data. To transmit at these frequencies, TX unit  414  must have an associated antenna  414   b.    
         [0089]      FIG. 9  shows a typical directional discontinuity ring radiator (DDRR) antenna  900 . DDRR antenna  900  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 antenna  900  in applications such as lamp monitoring and control unit  310  is that the antenna dimension for resonance in certain frequency ranges, such as the IVDS frequency range, is too large.  
         [0090]      FIG. 10  shows a modified DDRR antenna  1000 , according to a further embodiment of the invention. Modified DDRR antenna  1000  is mounted on a PC board  1010  and includes a metal shield  1020 , a coil segment  1060 , a looped wire coil  1040 , a first variable capacitor C 1 , and a second variable capacitor C 2 . Additionally, a plastic assembly (not shown) may be included in modified DDRR antenna  1000  to hold looped wire coil  1040  in place.  
         [0091]     The RF energy to be radiated is fed into an RF feed point  1050  and travels through wire segment  1060  through a hole  1030  in metal shield  1020  to variable capacitor C 2 . Variable capacitor C 2  is used to match the input impedance of modified DDRR antenna 1000 to 50 ohms. Looped wire coil  1040  is looped several times, as opposed to typical DDRR antenna  900  which only has one loop. Looped wire coil  1040  may be coupled to wire segment  1060 , or both looped wire coil  1040  and wire segment  1060  may be part of a continuous piece of wire, as shown. The end of wire coil  1040  is coupled to capacitor C 1  which tunes modified DDRR antenna  1000  for resonance at the desired frequency.  
         [0092]     Modified DDRR antenna  1000  has multiple loops in wire coil  1040  which allow the antenna to resonate at particular frequencies. For example, if typical DDRR antenna  900  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 antenna  900  has a 4″ diameter, it will have poor resonance in the IVDS frequency range. In contrast, if modified DDRR antenna  1000  has a 4″ diameter, it will have excellent resonance in the IVDS frequency range. Accordingly, modified DDRR antenna  1000  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 modified DDRR antenna  1000  depends on the frequency range selected.  
         [0093]     Furthermore, if lamp monitoring and control unit  310  includes RX unit  416 , as shown in  FIG. 4 , modified DDRR antenna  1000  can be shared by TX unit  414  and RX unit  416 . Alternatively, RX unit  416  and TX unit  414  may use separate antennas.  
         [0094]     FIGS.  11 A-E show methods for implementation of logic for lamp monitoring and control unit  310 , according to a further embodiment of the invention. These methods may be implemented in a variety of ways, including software in microprocessor circuitry  412   a  or customized logic chips.  
         [0095]      FIG. 11A  shows one method for energizing and de-energizing a street lamp and transmitting associated monitoring data. The method of  FIG. 11A  shows a single transmission for each control event. The method begins with a start block  1100  and proceeds to step  1110  which involves checking AC and Daylight Status . The Check AC and Daylight Status step  1110  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 the step  1120  which is a decision block based on the change.  
         [0096]     If a change occurred, step  1120  proceeds to a Debounce Delay step  1122  which involves inserting a Debounce Delay. For example, the Debounce Delay may be 0.5 seconds. After Debounce Delay step  1122 , the method leads back to Check AC and Daylight Status step  1110 .  
         [0097]     If no change occurred, step  1120  proceeds to step  1130  which is a decision block to determine whether the lamp should be energized. If the lamp should be energized, then the method proceeds to step  1132  which turns the lamp on. After step  1132  when the lamp is turned on, the method proceeds to step  1134  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. After step  1134 , the method leads back to step  1110  which checks AC and Daylight Status.  
         [0098]     Returning to step  1130 , if the lamp is not to be energized, then the method proceeds to step  1140  which is a decision block to check to deenergize the lamp. If the lamp is to be deenergized, the method proceeds to step  1142  which involves turning the Lamp Off. After the lamp is turned off, the method proceeds to step  1144  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. After step  1144 , the method returns to step  1110  to check the AC and Daylight Status.  
         [0099]     Returning to step  1140 , if the lamp is not to be deenergized, the method proceeds to step  1150  in which an error bit is set, if required and proceeds to step  1160  in which an A/D is read. For example, the A/D may be the analog-to-digital converter  412   d  for reading the current level as shown in  FIG. 7 .  
         [0100]     The method then proceeds from step  1160  to step.  1170  which checks to see if a transmit is required. If no transmit is required, the method proceeds to step  1172  in which a Scan Delay is executed. The Scan Delay depends upon the circuitry used and, for example, may be 0.5 seconds. After step  1172 , the method returns to step  1110  which checks AC and Daylight Status.  
         [0101]     Returning to step  1170 , if a transmit is required, then the method proceeds to step  1180  which performs a transmit operation. After the transmit operation of step  1180  is completed, the method then returns to step  1110  which checks AC and Daylight Status.  
         [0102]      FIG. 11B  is analogous to  FIG. 11A  with one modification. This modification occurs after step  1120 . If a change has occurred, rather than simply executing step  1122 , the Debounce Delay, the method performs a further step  1124  which involves checking whether daylight has occurred. If daylight has not occurred, then the method proceeds to step  1126  which executes an Initial Delay. This initial delay may be, for example, 0.5 seconds. After step  1126 , the method proceeds to step  1122  and follows the same method as shown in  FIG. 11A .  
         [0103]     Returning to step  1124  which involves checking whether daylight has occurred, if daylight has occurred, the method proceeds to step  1128  which executes an Initial Delay. The Initial Delay associated with step  1128  should be a significantly larger value than the Initial Delay associated with step  1126 . For example, an Initial Delay of 45 seconds may be used. The Initial Delay of step  1128  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). After step  1128 , the method proceeds to step  1122  which executes a Debounce Delay and then returns to step  1110  as shown in  FIGS. 11A and 11B .  
         [0104]      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 and control unit  310  does not have a RX unit  416  for receiving acknowledgements of transmissions.  
         [0105]     The method begins with a transmit start block  1182  and proceeds to step  1184  which involves initializing a count value, i.e. setting the count value to zero. Step  1184  proceeds to step  1186  which involves setting a variable x to a value associated with a serial number of lamp monitoring and control unit  310 . For example, variable x may be set to 50 times the lowest nibble of the serial number.  
         [0106]     Step  1186  proceeds to step  1188  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.  
         [0107]     Step  1188  proceeds to step  1190  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 in microprocessing circuitry  412   a.    
         [0108]     Step  1190  proceeds to step  1192  in which a packet is transmitted on channel y. Step  1192  proceeds to step  1194  in which the count value is incremented. Step  1194  proceeds to step  1196  which is a decision block to determine if the count value equals an upper limit N.  
         [0109]     If the count is not equal to N, step  1196  returns to step  1188  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.  
         [0110]     If the count is equal to N, step  1196  proceeds to step  1198  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.  
         [0111]      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.  
         [0112]     The method begins with a transmit start block  1110 ′ and proceeds to step  1112 ′ which involves initializing a count value, i.e., setting the count value to 1. The method proceeds from step  1112 ′ to step  1114 ′ 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 unit  510 .  
         [0113]     The method proceeds from step  1114 ′ to step  1116 ′ which involves checking to see if the count equals 1. If the count is equal to 1, then the method proceeds to step  1120 ′ 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 step  1118 ′ 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 unit  510 .  
         [0114]     After either step  1118 ′ or step  1120 ′, the method proceeds to step  1122 ′ 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 unit  510 .  
         [0115]     The method proceeds from step  1122 ′ to step  1124 ′ 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 step  1118 ′ or the reporting start time delay selected in step  1114 ′, if the count equals 1. The use of separate randomization steps  1114 ′ and  1118 ′ is important because it allows the use of different randomization functions for the reporting start time delay and the reporting delta time, respectively.  
         [0116]     After step  1124 ′ the method proceeds to step  1126 ′ which involves transmitting a packet on the transmit channel selected in step  1122 ′.  
         [0117]     The method proceeds from step  1126 ′ to step  1128 ′ which involves incrementing the counter for the number of packet transmissions.  
         [0118]     The method proceeds from step  1128 ′ to step  1130 ′ 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 from step  1130 ′ back to step  1118 ′ which involves randomizing the reporting delta time for the next transmission. If the count is greater than N, then the method proceeds from step  1130 ′ to the end block  1132 ′ for the transmission method.  
         [0119]     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.  
         [0120]      FIG. 11E  shows a further method for transmitting monitoring data multiple times from a monitoring and control unit  510 , according to another embodiment of the invention.  
         [0121]     The method begins with a transmit start block  1140 ′ and proceeds to step  1142 ′ which involves initializing a count value, i.e., setting the count value to 1. The method proceeds from step  1142 ′ to step  1144 ′ 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 in  FIG. 8 .  
         [0122]     Step  1144 ′ proceeds to step  1146 ′ which makes a decision based upon whether Group A or B is being used. If Group A is being used, step  1146 ′ proceeds to step  1148 ′ which involves setting a base channel to the appropriate frequency for Group A. If Group B is to be used, step  1146 ′ proceeds to step  1150 ′ which involves setting the base channel frequency to a frequency for Group B.  
         [0123]     After either Step  1148 ′ or step  1150 ′, the method proceeds to step  1152 ′ 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 unit  510  by 50 and using the resulting value, x, as the number of milliseconds for the reporting start time delay.  
         [0124]     The method proceeds from step  1152 ′ to step  1154 ′ which involves waiting x number of seconds as determined in step  1152 ′.  
         [0125]     The method proceeds from step  1154 ′ to step  1156 ′ which involves setting a value z=0, where the value z represents an offset from the base channel number set in step  1148 ′ or  1150 ′. Step  1156 ′ proceeds to step  1158 ′ which determines whether the count equals 1. If the count equals 1, the method proceeds from step  1158 ′ to step  1172 ′ which involves transmitting the packet on a channel determined from the base channel frequency selected in either step  1148 ′ or step  1150 ′ plus the channel frequency offset selected in step  1156 ′.  
         [0126]     If the count is not equal to 1, then the method proceeds from step  1158 ′ to step  1160 ′ 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 from step  1160 ′ to step  1172 ′ which involves transmitting the packet on a channel determined from the base channel frequency selected in either step  1148 ′ or step  1150 ′ plus the channel number offset selected in step  1156 ′.  
         [0127]     If the count is not equal to N, indicating that the count is a value between 1 and N, then the method proceeds from step  1160 ′ to step  1162 ′ which involves reading a real time counter (RTC) which may be located in processing and sensing unit  412 .  
         [0128]     The method proceeds from step  1162 ′ to step  1164 ′ 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 step  1164 ′ to step  1166 ′ which involves waiting x seconds and returning to step  1162 ′.  
         [0129]     If the value of the RTC is less than the maximum value, then the method proceeds from step  1164 ′ to step  1168 ′ 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.  
         [0130]     The method proceeds from step  1168 ′ to step  1170 ′ 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 y times 25 KHz.  
         [0131]     The method then proceeds from step  1170 ′ to step  1172 ′ which involves transmitting the packet on a channel determined from the base channel frequency selected in either step  1148 ′ or step  1150 ′ plus the channel frequency offset computed in step  1170 ′.  
         [0132]     The method proceeds from step  1172 ′ to step  1174 ′ which involves incrementing the count value. The method proceeds from step  1174 ′ to step  1176 ′ 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 from step  1176 ′ back to step  1154 ′ which involves waiting x number of milliseconds. If the count is equal to N+1, the method proceeds from step  1176 ′ to the end block  1178 ′.  
         [0133]     The method shown in  FIG. 11E  is similar to that shown in  FIG. 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.  
         [0134]     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.  
         [0135]     For example,  FIG. 4  shows a light monitoring and control unit  310  in which there is no light sensor but rather an RX unit  416  for receiving control information. Light monitoring and control unit  310  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 and control unit  310  of  FIG. 4  allows for a centralized control mechanism. For example, RX unit  416  could receive centralized energize/deenergize signals which are sent to all of the street lamp assemblies in a particular geographic region.  
         [0136]     As another alternative, if lamp monitoring and control unit  310  of  FIG. 4  contains no RX unit  416 , the control functionality can be built directly in the processing and sensing unit  412 . For example, processing and sensing unit  412  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 either RX unit  416  or light sensor  518 .  
         [0137]     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.

Technology Category: 5