Abstract:
An electro-optical, automatic meter reader for enabling a consumer to view and manage power consumption through a browser. A sensor attached to a bracket is mounted to the outside cover of a utility meter without modification of the meter or removal of its housing. A data-collector stores data obtained from the sensor via a serial port which may also provide power for the sensor, thus avoiding use of a dedicated power supply. The data-collector connects to a computer which provides a centralized object through which to view and manage power consumption. The real-time and combined historic data can be used to forecast whether usage will fall above or below a predetermined usage level at the end of a given period of time. In response to a forecast exceeding the level, the computer displays the appropriate graph in a red colored bar within a quantity vs. time chart. The computer may control power consuming devices. A communication system may be established to the system for remote management by the consumer or by the utility company for its own billing and management purposes.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to a utility usage measurement system, and more particularly to a means of obtaining real-time utility consumption readings and also managing utility consumption by controlling end-use devices from the computer or personal digital assistant (PDA) of the consumer.  
       BACKGROUND OF THE INVENTION  
       [0002]     There are various types of automatic meter reading devices (AMR) which use optical light-sensing arrangements to provide remote utility readings for determining utility consumption and for billing purposes. These devices were typically developed as a cost-effective alternative to the existing meter reading methods and devices. For example, these AMR devices avoid having a person walk or drive from establishment to establishment and manually read each meter. However, the majority of methods using optical light-sensing devices are installed inside the existing meter and/or require professional installation. Thus, a skilled or trained individual must physically remove the glass housing present on such meter in order to install the automatic reading device. This process is inefficient and also very costly for either the utility company or the consumer.  
         [0003]     In U.S. Pat. No. 5,767,790, the device utilizes a photoelectric sensor for reading the watt-hour indicator of electricity service usage. A light source beams a light on a rotating disk in the meter. The disk reflects the light except for one darkened area, which absorbs the beam of light. The reflected light is sensed by the photoelectric sensor and a pulse is sent each time the reflected light is not sensed. Each pulse indicates one full rotation of the disk. All of the computing elements of the monitor system are contained within the utility watt-hour meter housing, and even the glass cover is replaced with a polycarbonate cover. Other similar devices installed within the existing meter housing are disclosed in U.S. Pat. No. 4,327,3625 and U.S. Pat. No. 5,506,404. A significant disadvantage typical of these devices is that the installation process requires the existing meter to be physically opened and/or the optical light sensing arrangement to be assembled with professional assistance. Thus, an ordinary consumer generally cannot set up the device, and therefore consumers would have to bear installation costs.  
         [0004]     In U.S. Pat. No. 5,880,464, infrared light sensors are used to detect the shadow of a meter pointer against a meter face to enable the meter reader to determine consumption rates. This automatic meter reader device is placed on the cover of the watt-hour meter. However, the device requires the angle and heights of the light source and sensor to be adjusted in a specific manner using a height adjustment carrier having a collar that must be tightened, which a typical customer most likely would find difficult to accurately adjust. Furthermore, no provision is made for powering the device and thus further installation problems may be created for the consumer.  
         [0005]     There are also certain utility-based applications in which a network controller or some other headend device located in a utility company interrogates the automatic meter reading device, in order to find out the utility usage for billing purposes. Typical drawbacks that are inherent in these systems are that customers cannot see their use in real-time, cannot access this information except when a billing statement is received and, cannot see data except in the standard format chosen by the utility company.  
         [0006]     In addition, there are various types of readers that can be utilized to manage the consumption of electrical power or fossil fuels. U.S. Pat. No. 6,167,389 allows the consumer, through the use of adapted end-use devices, to program these devices based on a pricing-tier billing system. The pricing-tier billing system sets a billing rate for power consumption based on the load levels on a power grid. A utility company may use a billing system with four-tiers: Normal Load, Medium Load, High Load, and Critical Load. Each tier has a different billing rate for power consumption with the Critical Load tier charging at the highest rate. The utility company may transmit data packets though an open network from a centralized headend to gateways at customer locations. These data packet cause the gateways to generate random startup time offsets, to control when end-use devices will be started. This is useful to protect the power grid from being loaded such that results in a blackout. However, this system does little to provide feedback to the consumer, let alone provide them with real-time data on their use and cost that allows the consumer to directly shed load voluntarily or with incentive, in order to help the utility balance its load demands. Thus, this device allows the utility company to obtain meter readouts are obtained for internal load and billing purposes only.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention provides an electro-optical, automatic meter reader (AMR) for enabling a consumer to view and manage power consumption on the consumer&#39;s computer, which may be a computer or PDA. The automatic meter reader is an apparatus for optically reading a meter using a sensor that can be used to monitor electricity consumption. A sensor of the apparatus may be attached to a bracket, which may be mounted to the outside cover of the meter. An installation process of the apparatus need not require modification of the existing meter nor require removal of the housing of the existing meter. An end-user may install the automatic meter reader without special skills or tools, in fact, with no additional hardware other than those included as a part of the system.  
         [0008]     The photoelectric sensor beams a light onto a rotating disk, visible on the face of the meter, whose surface reflects the light. A marker such as a black dot or line placed on the rotating disk absorbs the beamed light resulting in an interval where a lower level of light is being reflected. The photoelectric sensor counts these intervals, representing the number of turns the disk rotates indicating utility usage during a given time period. The apparatus connects to a data-collection unit through a first serial port. The data-collection unit stores the data from the sensor. The serial port connection may also serve to supply power for the apparatus through one otherwise unused pin of that serial connector being assigned as a power carrier, thus avoiding the need for a dedicated power supply. The data collection unit may also be used to store data when the computer is turned off and can be powered by an external 12 volt DC power supply.  
         [0009]     The data-collection unit connects through a second serial port, located on the opposite side from the first serial port, to the user&#39;s computer. The computer provides the consumer with a centralized location to either directly or remotely view and manage his power consumption. The software collects the data and provides the end-user with information relating to power consumption such as real-time rate of usage and historical usage levels. For example, information is arranged in three graphs that are analogous to information common to automobile travel. These include the real-time rate-of-use, comparable to the speedometer of an automobile. This graph tells the user how much power they are consuming at this moment. The second graph, a monthly data graph displaying daily data, is comparable to the trip odometer. This graph shows the user how much power they have consumed on a day-to-date, daily and month-to-date basis. The final graph is comparable to the general odometer. It shows the total energy consumption through the life of the system. Each graph can be displayed in units of kilowatt hours or dollars or other forms of currency. By presenting this data in three logical and understandable formats, data can be used to forecast whether the consumer will be under his monthly baseline utility usage or cost level of consumption based on then-current requirements. Such forecasts are commonly used by trip computers in automobiles to tell the consumer whether they should adjust their speed to reduce fuel consumption, when they will arrive at their destination based upon present and average speed, and how many miles they have to go to complete their trip. If the power forecast indicates that the present usage will cause that consumer to exceed the baseline unit or cost level, the consumer may control the power usage of end-use devices from the computer to assure that they end the time below this requirement, especially during power crisis situations. A forecast rate for use is shown for the consumer as a red colored line on each graph. A second line, the rate of consumption that must be averaged in order to arrive at or under the base line, is also displayed on each graph. If a consumer is averaging under their baseline amount, for the period in question, the bar for that particular graph shall show as a green bar. If the consumer is averaging over the baseline amount for the period in question, the bar for that particular graph shall show as a red bar. For example, if the consumer is averaging a rate of consumption use on a daily basis that will exceed the monthly baseline level if continued for the rest of the cycle, the monthly bar shall show as red. If the consumer is averaging a rate of consumption on an hourly basis that will exceed the average daily baseline, that day&#39;s bar shall show as red in color. In this way the consumer is always aware of their status to achieve baseline levels for the hour, day, and month.  
         [0010]     Further, the consumer may program the computer to automatically control the rate of power consumption. Through commonly available products that accept commands to control thermostats, lighting and other household items, consumer may alert such products through automatic commands to adjust the thermostat on his air conditioning unit from his computer or program the computer to automatically adjust the temperature setting on the thermostat in response to the forecast. In addition, a communication system, such as the Internet, can also be utilized to allow the computer to communicate to the utility company for billing purposes or to allow the consumer to access and manage his power consumption from a remote computer or PDA. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The present invention will now be described in more detail with reference to preferred embodiments of the invention, given only by way of example and illustrated in the accompanying drawings in which:  
         [0012]      FIG. 1  illustrates a block schematic diagram of an apparatus for reading and managing power consumption in accordance with the present invention;  
         [0013]      FIG. 2A  provides an illustrated embodiment of the reader in a plan view;  
         [0014]      FIG. 2B  provides an illustrated embodiment of the reader in a side sectional view;  
         [0015]      FIG. 3A  depict the bracket attached to a conventional meter in a front view;  
         [0016]      FIG. 3B  depict the bracket attached to a conventional meter in a side view;  
         [0017]      FIG. 4  is an illustration of a preferred sensor;  
         [0018]      FIG. 5  provides an illustration of conventional utility meters;  
         [0019]      FIG. 6  illustrates a user interface displayed on the screen of the computer;  
         [0020]      FIG. 7  is an illustration of the computer connected to power consuming device through a serial port or Ethernet interface of the computer; and  
         [0021]      FIG. 8  provides an illustration of the computer connected to a communication system for remote access to the data stored and compiled on the computer.  
         [0022]      FIG. 9  illustrates an alternative embodiment of the present invention using wireless communication to transmit the data obtained by the reader. 
     
    
     DETAILED DESCRIPTION  
       [0023]      FIG. 1  illustrates a block schematic diagram of an apparatus  100  for reading and managing power consumption in accordance with the present invention. As shown in  FIG. 1 , a reader  104  is attached to a typical utility meter  102  such as an analog or digital power meter commonly found on homes, apartment buildings and commercial buildings. The reader  104  provides a means for automatically reading power consumption and may eliminate the need for manually reading the meter  102 . The data generated by the reader  104  may be continuously transferred through a connection such as a serial cable  120 , to a data collection unit  106  or alternatively directly to the monitoring device  110 , such as a computer.  
         [0024]     The data collector  106  is therefore optional. When provided, the data collection unit stores data generated by the reader  104 . The data collection unit  106  may store data for a limited time when the monitoring device (computer)  110  is shut off or in the event of a power failure. With appropriate memory, the unit  106  may be able to store data for up to a year. The preferred embodiment of the data-collection unit  106  for a household may include a single serial port interface from the reader  104 , such as a RJ-11 or RJ45 and a single serial port out, to the computer  110 , such as a DB-9. The preferred data-collection unit  106  is approximately 2″ wide and 3″ long and includes a 12 volt input, such as from a wall mounted AC to DC converter  108 . A battery, such as a standard watch battery, may be provided for backup. Further, the data collection unit  106  may be powered by the serial driver of one pin on the serial port of the computer. The preferred data-collection unit  106  includes a microprocessor such as a PIK Microprocessor including non-volatile memory and a timer crystal. It will be apparent that any microprocessor or controller could be used.  
         [0025]     In a preferred application of the invention where multiple power meters are monitored, such as an apartment building or a commercial building, may be similar to the household application described above. However, the data collection unit  106  may be provided with inputs for additional readers  104 , such as four to eight inputs and an optional Ethernet connector for networking to a single monitoring device  110 .  
         [0026]     The preferred embodiment of the monitoring device  110  may be a conventional general-purpose computer system or a serial server containing one or more serial ports and an Ethernet port, and need not be specific to this application. The monitoring device  110  receives the data from a cable  118 , such a serial cable, which connects directly to the reader  104 . Alternatively, a cable  116  may be a serial cable connecting to the optional data-collection unit  106  through a serial port in, such as a RJ-45 or RJ-11 connector and a serial port out, such as a DB-9 connector. The monitoring device  110  will not lose information during power failure as it stored its data in non-volatile memory and real-time data is only gathered when power is present and being consumed. In addition, when employed, the data collector  106  will not lose its data during an outage because it holds historic values in non-volatile memory and real-time data is only gathered when power is present and, thus, being consumed.  
         [0027]     The monitoring device  110  may be connected to a communication system  112  or network, such as the Internet to allow remote access  114  of the data. For example, a utility company may obtain the data for billing purposes or by the end-user who wants to control his power consumption from his PDA or computer from a remote location, such as his office.  
         [0028]      FIGS. 2A and 2B  provides an illustrated embodiment of the reader  104  in both a plan view ( FIG. 2A ) and a side sectional view ( FIG. 2B ). The reader  104  includes a bracket  202  and a sensor  210  such as a photoelectric sensor. The bracket  202  preferably is a unitary body and lacks movable parts thus being relatively cost effective and also being easy to install. The preferred material for the bracket  202  is either rubber or plastic but it may be made out of any suitable material. Included in the bracket  202  may be an aperture  208  for accepting the sensor  210 . The sensor  210  may be threaded into a nut  216  attached to the meter  102 . For example, the nut  216  may be plastic and secured using glue or epoxy to the meter face. The nut  216  may fit into a recessed portion  218  of the bracket  202 . In addition, a heat and moisture dissipation channel  212  may be included to allow ventilation of the heat generated by the sensor  210 . The heat generated from the sensor  210  may be used to melt ice in cold-weather climates in which case melted ice may escape through the channel  212 . In addition, the channel  212  acts as a temperature equalization path between the sensor  210  and the outside elements, thus preventing the fogging of the lens in the sensor aperture  406 . The bracket  202  may also incorporate a fastener  204  and  206 , for example a hook and loop such as Velcro or double-sided tape or other adhesive to attach to the meter  102 . As illustrated in  FIG. 2B , the back of the bracket  202  may follow the same contour as the meter  102  to ensure proper alignment and secure mounting to the meter.  
         [0029]      FIGS. 3A and 3B  depict the bracket  202  attached to a conventional meter  102  in both a front view ( FIG. 3A ) and also a side view ( FIG. 3B ). The bracket  202  may attach to the translucent (typically glass), outside cover  306  of the meter  102  conventional to most existing electric utility meters. As mentioned above, the shape  214  of the bracket  202  may follow the same contour as the translucent outside cover  306  of the existing meter  102  ensuring proper alignment with the existing meter  102 . An installation process of the bracket  202  to the translucent outside cover  306  of the existing meter  102  need not require modification of the existing meter  102  nor removal of the translucent outside cover  306 . Furthermore, the installation may only require one part of the bracket  202  to be rigidly attached to the translucent outside cover  306  allowing an end-user to install the reader  102  without special skills or tools.  
         [0030]      FIG. 4  is an illustration of a preferred sensor. The reader  104 , in a preferred embodiment, utilizes a photoelectric sensor  210  such as the Mini-Beam 2 from the Banner Engineering Corp. of Minneapolis, Minn. to read the existing meter. The sensor  210  includes a light source and a photo receptive element. The preferred size of the sensor  210  is about a 1″ square but is not limited to that size. The preferred sensor also includes a threaded member  406  which may be screwed into a nut  216  secured to the meter housing  306  as mentioned above. The nut  218  may also secure the sensor  210  to the bracket  202  as shown in  FIG. 2B . For example, the nut  216  may fit into a recessed portion  218  of the bracket  202 . A light emitting diode (LED)  402  may be placed on the back of the sensor  210  to provide a visual indication that the sensor  210  is picking up the correct signal such as to aid in installation of the reader  104 . The sensor  210  may incorporate a cable  404 , such as a serial cable, that supplies the power preferably with 10V or 12 V but may range from 10-30V. The cable  404  may also provide the means for transferring data.  
         [0031]      FIG. 5  provides an illustration of conventional utility meters  102  such as a digital meter  506  and an analog meter  508 . The sensor  210  ( FIG. 4 ) is oriented to beam a light, such as a visible red 660 nm, or another wavelength, onto a rotating disk  502  located in the meter  102 . The beam of light passes through the translucent outside cover  306  of the meter  102 . The surface of the disk  502  reflects the light; the reflected light is sensed by the photo receptive element of the sensor  210 . A marker  504 , such as a darkened area, normally found on the rotating disk  502  absorbs the beamed light resulting in an interval where a lower level of light is being reflected to the sensor  210 . The number of intervals, counted by the sensor  210 , represents the number of turns the disk rotates indicating utility usage during a given time period. The time between each interval is inversely proportional to the rate of power consumed. Further, the aforementioned LED  402  may turn on to indicate whether the sensor  210  has made contact with the rotating disk  502  and turn off when the black marker  504  is being sensed, thus a consumer with no special skills, will be sure of the proper alignment of the sensor  210 .  
         [0032]     The reader  104  may use software algorithms to avoid spurious data in which light sensors are vulnerable to such as may be caused by sunlight striking the rotating disk  502 . The rotating disk  502  in a meter  102 , may have a maximum number of rotations per second and the reader  104  may be programmed to ignore certain detections. For example, if a sensor detects more then 2 passes per second from a rotating disk  502  with a 2 rotations per second maximum, the reader  104  may be programmed to ignore the second pass. The reader  104  also may have the capability to alert the end user that an adjustment may need to be made to the sensor  210 .  
         [0033]     The reader  210  may also use a software algorithm that avoids spurious data based on the time interval between each pass. For example, if a long-short-long pattern of the intervals between passes is sensed by the reader  210  may be programmed to ignore the middle short reading. Again, an alert signal may be sent to the end user that an adjustment may need to be made to the sensor  210 .  
         [0034]      FIG. 6  illustrates a user interface displayed on the screen of the computer  110  ( FIG. 1 ). As Illustrated in  FIG. 6 , the computer  110  may provide a central location for the end-user to remotely connect to or use directly to view the data collected by the reader  104 . Software stored in the computer  110  memory causes the computer  110  to compile counted intervals from the reader. The software may be compliant to all automatic meter reading devices, and therefore might not be specific to the aforementioned reader  104 . In addition, the software may incorporate an adjustable architecture to optimize for various sizes and complexities fitting to the end-user&#39;s need.  
         [0035]     An interface  602  such as web-based interface (e.g. a browser), allows the end-user to monitor the information relating to power consumption. The interface  602  may, for example, render all graphic data as line or bar graphs  608  using Macromedia Corporation&#39;s Flash program. By choosing to render data via flash, the vast majority of the program overhead for rendering the interface  602  is handled directly in the browser of the computer used to display the interface  602 . Thus, the computer  110  may be an inexpensive device such as a serial server or other device which contains one or more serial ports. Because an end user might want to view monthly bar graphs  608  of power consumption, Macromedia Flash provides the ability to present real-time moving graphs or pictures. This might be utilized when providing real-time power consumption rate  606  such as a line graph or chart depicting power usage over time or up-to-date/cost per billing cycle costs. In addition the interface  602  may be provide other data such as peak demand rate including date and time of the peak demand. The interface  602  is structured in automobile-familiar methods for ease of use and so that an end-user need not require special training or skills to use.  
         [0036]     Illustrated in  FIG. 7  are devices  702  such as Heating Ventilation Air Condition (HVAC) systems and other power consuming devices that may be connected to the computer  110  through a serial port or Ethernet interface of the computer  110 . The interface  602  may provide the end-user with information on what devices are being currently used, the rate of power consumption the device operates at, and the ability to control these devices based on measured consumption. Therefore, allowing the end-user to manage the rate of consumption for that household.  
         [0037]     The ability to manage the rate of consumption may be especially advantageous when dealing with utility companies that use a penalty-level billing system. In this system, if a customer exceeds a predetermined level of power consumption or baseline level, then the utility company may charge a premium rate for the power consumed above the baseline. Some utility companies may also provide rebates on future bills when a customer falls below a predetermined level of usage for a given period. The interface  602  may provide a forecast based on a real-time rate of consumption to determine whether the end-user will be under his monthly baseline utility usage level of consumption or other predetermined level. The forecast may be computed by taking the average power consumption used per day of the current billing cycle and multiplying it by the number of days in a billing cycle. So, for example, if the customer was on day  5 , the forecast will divide the total power usage at that time by 5 to compute a daily average and then multiply the daily average by the number of days in the billing cycle. A new forecast may be computed continuously based upon present and historical usage. If the forecast indicates that the usage will exceed the baseline level the consumer may control the power usage of end-use devices from the computer  110  to fall below this requirement, especially during power crisis situations. For example, the end-user may turn off unnecessary lights or decrease the length of time certain devices will run such as a dryer or a HVAC system from the computer  110 .  
         [0038]     Further, the consumer may program the computer  110  to automatically manage the rate of power consumption. For example, if the forecast is indicating that the consumer will exceed the baseline level if continued for the entire billing cycle, the end-user might program the computer  110  to automatically raise or lower the temperature on the thermostat a few degrees. This may provide the end-user with the consumption rate of each device and plan use of certain devices accordingly. This may be useful in setting up exact budgets and strictly adhering to them in an automated manner using the computer  110 .  
         [0039]     In addition to avoid being charged a premium rate for power consumption, the forecast can allow the end user to fully utilize all of the non-premium power allocated to him. For example, rather then shutting off the HVAC system and enduring an uncomfortable climate, the end user can use the forecast to determine a adjust the thermostat at a certain temperature the forecast may allow the end user to adjust the temperature so that he can stay under the baseline and yet enjoy in a comfortable temperature.  
         [0040]     Using the interface  602  provided by the software stored on the computer  110 , the end-user may also determine an optimization schedule for running the devices  702 . The end-user may obtain data such as cost per hour device used or cost/cycle (washing machine). This may help determine whether the device is properly running as efficient as intended by the manufacturer. Also based on this information, the end-user may program or choose from created device-operating schedules to maximize cost effectiveness and power conservation.  
         [0041]     In addition to monitoring and controlling of power-consuming devices, the monitoring device  110  may perform other control functions. For example home security systems and fire alarm systems may be connected. The end-user may control these devices through the interface and program the monitoring device to treat to signals sent by these systems.  
         [0042]     Illustrated in  FIG. 8 , the computer  110  may be connected to a communication system  804 , such as the Internet. This may allow remote access to the data stored and compiled on the computer  110 . By allowing remote access to the data on the computer  110 , the end-user may control power consuming devices and other devices from any location such as a computer at work  808  or from his PDA  810 . For example, the end-user may want to raise or lower the temperature of his house before coming home.  
         [0043]     There may be situations when the end-user wants to make sure that no power is being consumed, when the end-user is on vacation or business trip or when a house or baby sitter is at the premises, for instance. Remote access to power consumption information may provide the end-user with information on whether power is being consumed, at what rate it is being consumed, what device is consuming the power and the ability to control that device.  
         [0044]     The utility company  806  may also communicate with the computer  110  to obtain the data for billing purposes. The utility company  806  may download the monthly power consumption information from the Internet and bill the end-user accordingly. In addition the utility company  806  may set up an on-line billing service and thus cut down on costs incurred in mailing the bill. Further, this may allow utility company  806  to forecast when more power is going to be consumed each day and to send emergency alerts to households or apartment/office buildings to control the power usage during a crisis situation.  
         [0045]     Remote access to the data may provide landlords of apartment/commercial buildings with readily available utility cost information. Landlords can provide potential lessees current and historic monthly averages of utility bills from their PDA/computer/laptop  814 . Also, landlords live in locations far from the property they own, possibly in a different state. Also the landlord may use the data to determine at what rate each tenant is consuming power and can adjust their rent or utility charges accordingly.  
         [0046]     By having remote access to control power-consuming devices, the landlord or utility company might regulate the rate of power consumption while not physically going there. For example, the landlord may control the temperature of the common area of the building from his home computer  814  or even programming the lights to turn off at certain times during the day when sunlight is adequate. The utility company  806  may turn off certain devices such as HVAC systems when the power-grid is approaching maximum capacity.  
         [0047]      FIG. 9  illustrates an alternative embodiment of the present invention. Unless specifically stated, all elements, of  FIG. 9  have a one-to-one functional correspondence with those of  FIG. 1 .  FIG. 9  differs form  FIG. 1  in that the serial cable  120  (from  FIG. 1 ) that connects the reader  104  and the data-collection unit  106  is replaced with a wireless communication channel. A transmitter  906  for sending wireless communications may be attached to the reader  104  using a shorter serial cable. A receiver  908  may be attached via another shorter serial cable to the data-collection unit  106  for accepting the transmitted communications from the transmitter  906 . The transmitter  906  may send data via a wireless carrier frequency, such as 433 MHz, which is standard for garage door openers. It will be apparent, however that another frequency (e.g., 900 MHz) could be used. The signals sent via the transmitter  906 , may be in the format of pulses that are created directly from the intervals of lower levels of reflected light sensed by the sensor  210 . Thus, each pulse formed by the reader may result in a pulse at the carrier frequency communicated by the transmitter  906 . To communicate the pulse to the data-collection unit  106 , the transmitter  906  may send a burst of the carrier frequency to represent each revolution of the rotating disk  502 . The wireless signal from the transmitter  906  may be encoded with identification information placed on the carrier frequency to prevent interference from other sources. It will be apparent that a number of different schemes may be used for communicating the revolution of the rotating disk  502  via the transmitter  906  and receiver  908 . The transmitter  906  and the receiver  908  may receive operating power from a battery or a wall-mounted AC to DC converter.  
         [0048]     Similarly to the embodiment of  FIG. 1 , the reader  104  may communicate directly with the computer  110 . In which case, the receiver and cable  904  may be mounted to the computer  110  rather than the data collection unit  106 . In addition, the data collection unit  106  may be omitted.  
         [0049]     Wireless communication may be used to help eliminate routing problems when using serial cables such as length of the cable needed and outdoor to indoor routing. The wireless communication device would also be helpful for small businesses in which there are multiple readers which all have to be connected to a monitoring device  110 .  
         [0050]     While the foregoing has been with reference to particular embodiments of the invention, it will be appreciated by those skilled in the art that changes in these embodiments may be made without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.