Patent Publication Number: US-2005128093-A1

Title: Self-protected fire-sensing alarm apparatus and method

Description:
BACKGROUND  
      1. Field of the Invention  
      The present invention relates generally to flame or fire detection systems. More particularly, the present invention relates to a self-protected fire-sensing alarm that can detect and counter actions designed to degrade the fire detection performance of the alarm.  
      2. Background Information  
      There are many places where smoking or the lighting of matches and lighters is prohibited. This prohibition can result from, for example, a decision of the persons responsible for the room, compliance with local non-smoking laws or ordinances, or an incentive from an insurance carrier. The prohibition can also be the result of a concern for personal health and or the need to protect property. “No Smoking” areas can include public rest rooms and other areas of public schools, restaurants, office buildings, aircraft, airports, and the like. In addition, recent concerns related to the lighting of matches on aircraft are based on, for example, the fear of possible attempts to ignite a bomb or fire aboard a commercial aircraft.  
      Smoke detectors and/or flame detectors can be located in any or all of the aforementioned areas, rooms or other enclosed spaces. These devices generally provide a means to detect smoke or flame and notify those in the area via an alarm. In some instances, the notification can be sent to a remote location via a wire or wireless communications device, such as described in, for example, U.S. Pat. Nos. 6,195,003, 6,239,697 and 6,281,791.  
      Smoke detectors can use light scattering or other means to sense the smoke associated with a fire. Smoke detectors are described in, for example, U.S. Pat. No. 6,195,014. These devices generally require concentrations of smoke that are associated with a significant fire located in the room or vicinity. These smoke detectors are useful to save lives and property from fires that are not controlled.  
      Flame detectors make use of radiation emissions associated with flame. Flame detectors are described in, for example, U.S. Pat. Nos. 5,959,589 and 6,239,433. Radiation emissions that can be detected by flame detectors include, for example, infrared and ultraviolet radiation. The response time of flame detectors can be faster than that of smoke detectors and the probability of detection is better than smoke detectors since the flame detectors detect the flame emissions rather than the build-up of smoke. In particular environments, multiple wavelengths and statistical fluctuations can be used to reduce false alarms. Flame detectors that detect multiple wavelengths can be used in areas with, for example, explosive materials to reduce hazardous explosions. These multiple wavelength detection systems can be more expensive than smoke detectors or flame detectors using a single wavelength.  
      To be useful, the sensor systems can be coupled to an alerting system. Some alerting systems can use audible or visible signals to alert persons in the area of the danger. The alert can be local to the sensor. Alternatively, the alert can be sent via a wired or wireless transmission to a remote location, for example, to notify security personnel of the hazard.  
      To reduce missed detections and improve reliability, alarm systems have been designed with, for example, self-testing circuits or low battery indicators. However, a person attempting to smoke a cigarette or cause fire damage through the use of a flame may want to willfully and deliberately violate the prohibition against smoking and/or the use of flame in the given area. If aware of the presence of a monitoring device in the area, a person may attempt to deliberately negate the performance of such detectors placed in the area to monitor for an event related to fire or flame.  
      To counter such attempts at negating the performance of the smoke detector, the case of a smoke detector can be redesigned to prevent persons from placing a cup or plastic bag over the sensor in such a manner as to block smoke from entering the detector, as described, for example, in U.S. Pat. No. 5,339,072.  
      Existing smoke and/or flame detection devices are generally vulnerable to deliberate attempts to negate the performance of such a detector. Such attempts can include, for example, covering the sensing element, and smashing, removing, or otherwise damaging the detector.  
     SUMMARY OF THE INVENTION  
      A self-protected fire-sensing alarm system and method are disclosed. In accordance with exemplary embodiments, according to a first aspect of the present invention, the fire-sensing apparatus includes a flame sensor for detecting a presence of flame within a volume. The flame sensor can detect ultraviolet energy generated by flame to detect the presence of flame, but be insensitive to electromagnetic radiation that normally occurs within the volume. The apparatus can also include a smoke sensor for detecting the presence of smoke within the volume. The apparatus includes a tamper sensor for detecting tampering to the apparatus. The tampering prevents the apparatus from detecting the presence of flame within the volume. The tamper sensor can include a motion sensor for detecting motion to the apparatus, which can indicate an attempt to tamper with the apparatus. The tamper sensor can also include a visible light sensor. An absence of visible light to the visible light sensor can indicate an attempt to tamper with the apparatus. The visible light sensor can include means for generating electrical energy from the visible light that can be used to charge a power supply for powering the apparatus.  
      According to the first aspect, the apparatus includes an alarm indicator for indicating an alarm condition in response to i.) a detection of the presence of flame within the volume and/or ii.) a detection of tampering to the apparatus. The alarm indicator can indicate the alarm condition to persons within a vicinity of the apparatus using an audible alarm, a visual alarm and/or a tactile alarm. The apparatus can also include a transmitter for transmitting the alarm condition to a remote monitor. Receipt of the alarm condition by the remote monitor generates an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor to indicate the alarm condition to the remote monitor, such as remotely monitoring persons. The transmitter can also transmit a status message to the remote monitor at periodic intervals. The status message can include, for example, information for identifying the location of the source of the status message, the existence of the alarm condition, and the type of alarm condition. An alarm condition can be indicated if the remote monitor does not receive the status message within the periodic interval, and an audible alarm, visual alarm and/or tactile alarm can be generated at the location of the remote monitor to indicate the alarm condition. To camouflage the apparatus, the apparatus can have the appearance of an object used for a different purpose within the volume. The apparatus can also be resistant to shock which can be indicative of an attempt to tamper with the apparatus. One or more of the apparatus can be positioned within the volume to monitor the contents of the volume.  
      According to a second aspect of the present invention, a fire-sensing system includes a fire sensor for detecting the presence of flame and/or smoke within the volume. The fire sensor can include a flame sensor for detecting ultraviolet energy generated by flame, where the flame sensor is insensitive to electromagnetic radiation that normally occurs within the volume. The fire sensor can also include a smoke sensor for detecting the presence of smoke within the volume. The system includes tamper countering structure for countering attempts to prevent the fire sensor from detecting the presence of flame and/or smoke within the volume. The tamper countering structure can include a motion sensor for detecting motion to the system and/or a visible light sensor. For example, an absence of visible light to the visible light sensor can be indicative of an attempt to tamper with the system. The visible light sensor can also include means for generating electrical energy from visible light that can be used to charge a power supply used to power the system. The attempt countering structure can also include camouflage for camouflaging the appearance of the system by providing the system with the appearance of an object used for a different purpose within the volume. The attempt countering structure can also include a shock-resistant enclosure for the system for protecting the system against shock.  
      According to the second aspect, the system includes a transmitter for transmitting an alarm notification upon detection of i.) the presence of at least one of flame and smoke within the volume and/or ii.) an attempt to prevent the fire sensor from detecting the presence of the at least one of flame and smoke within the volume. The transmitter can transmit the alarm notification to persons within the vicinity of the system using an audible alarm, a visual alarm and/or a tactile alarm. The transmitter can also transmit the alarm notification to a remote monitor. Receipt of the alarm notification by the remote monitor can generate an audible alarm, a visual alarm and/or a tactile alarm at the remote monitor&#39;s location to indicate the alarm notification to the remote monitor. The transmitter can also transmit a status message to the remote monitor at periodic intervals. An alarm condition can be indicated if the remote monitor does not receive the status message within the periodic interval, and an audible alarm, visual alarm and/or tactile alarm can be generated at the location of the remote monitor to indicate the alarm condition.  
      According to a third aspect of the present invention, a method for sensing fire within a volume comprises the steps of: i.) detecting a presence of flame within the volume; ii.) detecting tampering that prevents a detection of the presence of flame within the volume; and iii.) indicating an alarm condition in response to a.) the detection of the presence of flame within the volume and/or b.) the detection of tampering that prevents the detection of the presence of the flame within the volume. The method can also comprise the step of detecting the presence of smoke within the volume, wherein the step of indicating an alarm condition can further comprise the step of indicating the alarm condition in response to the detection of the presence of smoke within the volume. The method can also comprise the step of transmitting a status message to a remote monitor at periodic intervals. An alarm condition can be indicated if the remote monitor does not receive the status message within the periodic interval, and the step of transmitting the status message can include the step of generating an audible alarm, visual alarm and/or tactile alarm at the location of the remote monitor to indicate the alarm condition.  
      According to the third aspect, the step of detecting the presence of flame within the volume can include the steps of: i.) detecting ultraviolet energy generated by flame; and ii.) ignoring electromagnetic radiation that normally occurs within the volume. The step of detecting tampering can include the steps of: i.) detecting motion, where the motion can indicate tampering; and ii.) detecting an absence of visible light, where an absence of visible light can indicate tampering. The step of detecting an absence of visible light can include the step of generating electrical energy from the visible light to supply power to charge a power supply. The step of indicating an alarm condition can include the steps of: i.) indicating an alarm condition to persons within the vicinity of the volume using an audible alarm, a visual alarm and a tactile alarm; and ii.) transmitting the alarm condition to a remote monitor. The step of transmitting the alarm condition can include the step of generating an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor, upon receipt of the alarm condition by the remote monitor, to indicate the alarm condition to the remote monitor. The method can also include the step of countering attempts at tampering that prevent the detection of the presence of flame within the volume. For example, the step of countering attempts at tampering can include the steps of: i.) creating camouflage that has the appearance of an object used for a different purpose within the volume; and ii.) resisting shock that can be indicative of attempts at tampering.  
      According to a fourth aspect of the present invention, a method for sensing fire within a volume comprises the steps of: i.) detecting a presence of at least one of flame and smoke within the volume; ii.) countering attempts to prevent a detection of the presence of the at least one of flame and smoke within the volume; and iii.) transmitting an alarm notification upon detection of a.) the presence of the at least one of flame and smoke within the volume and/or ii.) an attempt to prevent the detection of the presence of the at least one of flame and smoke within the volume. The step of detecting the presence of flame and/or smoke can include the steps of: i.) detecting ultraviolet energy generated by flame to detect the presence of flame; ii.) ignoring electromagnetic radiation that normally occurs within the volume; and iii.) detecting the presence of smoke within the volume. The step of countering attempts can include the steps of: i.) detecting motion that can be indicative of an attempt to prevent the detection of the flame and/or smoke; ii.) detecting an absence of visible light, where the absence of visible light can be indicative of an attempt to prevent the detection of the flame and/or smoke; iii.) creating camouflage that has an appearance of an object used for a different purpose within the volume; and iv.) resisting shock that can be indicative of an attempt to prevent the detection of the flame and/or smoke. The step of detecting an absence of visible light can include the step of generating electrical energy from the visible light that can be used to charge a power supply.  
      According to the fourth aspect, the step of transmitting an alarm notification can include the steps of: i.) transmitting an alarm notification to persons within the vicinity of the volume, using an audible alarm, a visual alarm and/or a tactile alarm; and ii.) transmitting the alarm notification to a remote monitor. The step of transmitting the alarm notification to the remote monitor can include the step of generating an audible alarm, a visual alarm and/or a tactile alarm at the remote monitor&#39;s location, upon receipt of the alarm notification by the remote monitor, to indicate the alarm condition to the remote monitor. The method can also include the step of transmitting a status message to the remote monitor at periodic intervals. The absence of receipt of the status message by the remote monitor within the periodic interval can be indicative of an alarm condition. In such a situation, the step of transmitting a status message can include the step of generating an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor to indicate the alarm condition to the remote monitor.  
      According to a fifth aspect of the present invention, a system for sensing fire within a volume comprises means for detecting a presence of flame within the volume, means for detecting tampering that prevents a detection of the presence of flame within the volume, and means for indicating an alarm condition in response to a.) the detection of the presence of flame within the volume and/or b.) the detection of tampering that prevents the detection of the presence of the flame within the volume. The system can also comprise means for detecting the presence of smoke within the volume, wherein the means for indicating an alarm condition can indicate the alarm condition in response to the detection of the presence of smoke within the volume. The system can also comprise means for transmitting a status message to a remote monitor at periodic intervals. An alarm condition can be indicated if the remote monitor does not receive the status message within the periodic interval, and the system can include means for generating an audible alarm, visual alarm and/or tactile alarm at the location of the remote monitor to indicate the alarm condition.  
      According to the fifth aspect, the means for detecting the presence of flame within the volume can include means for detecting ultraviolet energy generated by flame, but which ignores electromagnetic radiation that normally occurs within the volume. The means for detecting tampering can include means for detecting motion, where the motion can indicate tampering, and means for detecting an absence of visible light, where an absence of visible light can indicate tampering. The means for detecting an absence of visible light can include means for generating electrical energy from the visible light to supply power to charge a power supply. The means for indicating an alarm condition can include means for indicating an alarm condition to persons within the vicinity of the volume using an audible alarm, a visual alarm and a tactile alarm, and means for transmitting the alarm condition to a remote monitor. The system can include means for generating an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor, upon receipt of the alarm condition by the remote monitor, to indicate the alarm condition to the remote monitor. The system can also include means for countering attempts at tampering that prevent the detection of the presence of flame within the volume. For example, the means for countering attempts at tampering can include means for creating camouflage that has the appearance of an object used for a different purpose within the volume, and means for resisting shock that can be indicative of attempts at tampering.  
      According to a sixth aspect of the present invention, a system for sensing fire within a volume comprises means for detecting a presence of at least one of flame and smoke within the volume, means for countering attempts to prevent a detection of the presence of the at least one of flame and smoke within the volume, and means for transmitting an alarm notification upon detection of a.) the presence of the at least one of flame and smoke within the volume and/or ii.) an attempt to prevent the detection of the presence of the at least one of flame and smoke within the volume. The means for detecting the presence of flame and/or smoke can include means for detecting ultraviolet energy generated by flame to detect the presence of flame, but which ignores electromagnetic radiation that normally occurs within the volume, and means for detecting the presence of smoke within the volume. The means for countering attempts can include: means for detecting motion that can be indicative of an attempt to prevent the detection of the flame and/or smoke; means for detecting an absence of visible light, where the absence of visible light can be indicative of an attempt to prevent the detection of the flame and/or smoke; means for creating camouflage that has an appearance of an object used for a different purpose within the volume; and means for resisting shock that can be indicative of an attempt to prevent the detection of the flame and/or smoke. The means for detecting an absence of visible light can include means for generating electrical energy from the visible light that can be used to charge a power supply.  
      According to the sixth aspect, the means for transmitting an alarm notification can include means for transmitting an alarm notification to persons within the vicinity of the volume, using an audible alarm, a visual alarm and/or a tactile alarm, and means for transmitting the alarm notification to a remote monitor. The means for transmitting the alarm notification to the remote monitor can include means for generating an audible alarm, a visual alarm and/or a tactile alarm at the remote monitor&#39;s location, upon receipt of the alarm notification by the remote monitor, to indicate the alarm condition to the remote monitor. The system can also include means for transmitting a status message to the remote monitor at periodic intervals. The absence of receipt of the status message by the remote monitor within the periodic interval can be indicative of an alarm condition. In such a situation, means for generating an alarm condition can generate an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor to indicate the alarm condition to the remote monitor.  
      Thus, exemplary embodiments of the present invention can automatically monitor a volume, room or other space for the presence of a flame, smoke or fire. In such a volume, the presence of a flame, smoke or fire may be unintentional, or caused by an individual intentionally creating a flame for the purposes of, for example, causing a hazard to property or persons, lighting a cigarette where smoking is not permitted, and the like. To prevent detection of the flame, smoke or fire, the individual may deliberately attempt to counter the performance of the fire-sensing system. Measures to counter the performance of the system can include, for example, attempts to blind the system, attempts to damage the system, attempts to move or remove the system, and the like. According to exemplary embodiments, the fire-sensing system incorporates several means to negate these and other countermeasures. Upon the presence of an event, such as the detection of flame, smoke or fire or the detection of an attempt to tamper with or otherwise negate the performance of the system, an alerting signal can be sent to a monitor or other person or persons. The monitor or other person or persons can be located locally or remotely to the system. The alerting signal can be an audible, visual or tactile signal. The alerting signal can be sent via a wire or a wireless communications system if the monitor or other person is located remotely to the system.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Other objects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments, in conjunction with the accompanying drawings, wherein like reference numerals have been used to designate like elements, and wherein:  
       FIG. 1  is a diagram illustrating a fire-sensing apparatus  100 , in accordance with an exemplary embodiment of the present invention.  
       FIG. 2  is a block diagram illustrating an electronic configuration of the fire-sensing apparatus, in accordance with an exemplary embodiment of the present invention.  
       FIG. 3  is a flowchart illustrating steps performed by a low-power microcontroller of the fire-sensing apparatus, in accordance with an exemplary embodiment of the present invention.  
       FIG. 4  illustrates an outer enclosure of the fire-sensing apparatus, in accordance with an exemplary embodiment of the present invention.  
       FIG. 5  illustrates positioning of the fire-sensing apparatus within a volume, in accordance with an exemplary embodiment of the present invention.  
       FIG. 6  is a diagram illustrating a monitor module, in accordance with an exemplary embodiment of the present invention.  
       FIG. 7  is a block diagram illustrating components that can comprise the monitor module, in accordance with an exemplary embodiment of the present invention.  
       FIG. 8  is a flowchart illustrating steps performed by a low-power microcontroller in the monitor module, in accordance with an exemplary embodiment of the present invention.  
       FIG. 9  is a flowchart illustrating steps for sensing fire within a volume, in accordance with an exemplary embodiment of the present invention.  
       FIG. 10  is a flowchart illustrating steps for detecting a presence of flame within a volume, in accordance with an exemplary embodiment of the present invention.  
       FIG. 11  is a flowchart illustrating steps detecting tampering, in accordance with an exemplary embodiment of the present invention.  
       FIG. 12  is a flowchart illustrating steps for indicating an alarm condition, in accordance with an exemplary embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Exemplary embodiments of the present invention are directed to a self-protected fire-sensing alarm system and method. According to exemplary embodiments, a volume, room or other space can be automatically monitored for the presence of a flame, smoke or fire. While the presence of a flame, smoke or fire in the volume may be unintentional, an individual may intentionally create a flame, smoke or fire in the volume for the purposes of, for example, causing a hazard to property or persons, lighting a cigarette where smoking is not permitted, and the like. Thus, the individual may deliberately attempt to counter the fire-sensing system&#39;s ability to detect the fire to prevent the system from detecting the flame or fire. Measures to counter the fire-sensing system can include, for example, attempts to blind the system, attempts to damage the system, attempts to move or remove the system, and the like. The self-protected fire-sensing system according to exemplary embodiments incorporates means to negate these and other countermeasures.  
      Upon the presence of an event, such as the detection of flame, smoke or fire within the volume or the detection of an attempt to tamper with or otherwise negate the performance of the system, an alerting signal can be sent to a monitor or other person or persons. The monitor or other person can be located locally or remotely to the system. The alerting signal can be an audible, visual or tactile signal that can be generated locally to the system (e.g., to alert persons within a vicinity of the system of the presence of the event). If the monitor or other person is located remotely to the system, the alerting signal can be sent via a wire or a wireless communications system, and the audible, visual or tactile signal can be generated remotely at the location of the monitor or other person to alert the monitor or other person of the presence of the event.  
      These and other aspects of the present invention will now be described in greater detail.  FIG. 1  is a diagram illustrating a fire-sensing apparatus  100 , in accordance with an exemplary embodiment of the present invention. The apparatus  100  can include a flame sensor for detecting the presence of flame with a volume. The flame sensor can be, for example, an ultraviolet sensor  105  that can detect ultraviolet energy generated by flame to detect the presence of flame within the volume. The ultraviolet sensor  105  can be insensitive to electromagnetic radiation that normally occurs within the volume. Thus, the ultraviolet sensor  105  can respond to ultraviolet radiation emitted from a flame from a lighter or match, but absent from standard incandescent or fluorescent lighting and absent from sunlight. Ultraviolet radiation reflects from most standard surfaces. Thus, the ultraviolet sensor  105  does not require line of sight to the flame. By detecting ultraviolet radiation instead of the visible light that normally occurs within a volume such as an enclosed room, the ultraviolet sensor  105  can be extremely sensitive to flames in a volume where flames are prohibited, and not subject to false alarms from standard lighting such as may be expected in the volume or room. Any electronic sensor that is capable of detecting ultraviolet radiation can be used for the ultraviolet sensor  105 . However, any electronic sensor that is capable of detecting the presence of flame within a volume can be used for the flame sensor.  
      The apparatus  100  can include a tamper sensor for detecting tampering to the apparatus  100 . The tampering prevents the apparatus  100  from detecting the presence of flame within the volume. For example, the tamper sensor can include a visible light sensor  110 . Some level of visible light (e.g., sunlight, standard incandescent or fluorescent lighting, and the like) can be present in the volume of interest during the operation of the apparatus  100 . Thus, an absence of visible light to the visible light sensor  110  can be indicative of an attempt to tamper with the apparatus  100 . In other words, the absence of visible light can be an indication of deliberate attempts to blind the ultraviolet or flame sensor by covering some portion or all of apparatus  100 , including visible light sensor  105 , with an opaque object or any other material that blocks visible light from entering the visible light sensor  110 . Any electronic sensor that is capable of detecting visible light can be used for visible light sensor  110 .  
      According to an exemplary embodiment, the visible light sensor  105  can include means for generating electrical energy from the visible light. For example, a solar cell, photoelectric cell or any other electronic device that is capable of generating electricity from light can be used for the visible light sensor  110 . According to such an exemplary embodiment, the visible light sensor  110  can generate electrical energy. Thus, the means for generating electrical energy from the visible light can supply electrical energy to charge a power supply for powering the apparatus  100 . For example, the electrical energy can be used to extend the life of a rechargeable battery power supply  115 , in addition or alternatively to an AC power supply connected to apparatus  100  or to the use of a non-rechargeable battery power supply (e.g., standard alkaline batteries). Alternatively, the means for generating electrical energy can supply electrical energy to power the apparatus  100 .  
      According to an exemplary embodiment, the tamper sensor can include a motion sensor  120  for detecting motion to the apparatus  100 . Some level of motion or movement to the apparatus  100  can be present if attempts are made to remove or move the apparatus  100 . A detection of motion can be indicative of deliberate attempts to tamper with the apparatus  100  to prohibit the function of, for example, the ultraviolet sensor  105  by, for example, moving or removing the apparatus  100  from its position within the volume. Any electronic sensor that is capable of detecting motion can be used for motion sensor  120 .  
      The apparatus  100  can include an alarm indicator for indicating an alarm condition in response to i.) the detection of the presence of flame within the volume and/or ii.) the detection of tampering to the apparatus  100 . For example, electrical circuitry  125  can be used to manage and control the apparatus  100 . The circuitry  125  can be any combination of hardware, firmware and software. For example, the circuitry  125  can include a processor, such as, for example, any type of microprocessor or microcontroller, and/or firmware, software, or any other type of electrical circuitry or any combination thereof. The circuitry  125  can also include any type of computer memory. The circuitry  125  can monitor for events indicative of a fire or flame, such as can be sensed via the ultraviolet sensor  105 . The circuitry  125  can also monitor for deliberate attempts to degrade or otherwise negate the performance of apparatus  100 , such as can be indicated by loss of visible light to visible light sensor  110  or detection of motion by motion sensor  120 .  
      Upon detection of flame or fire and/or attempts at tampering with the apparatus  100 , the circuitry  125  can indicate the alarm condition to persons within a vicinity of the apparatus  100 . For example, the circuitry  125  can cause an audible alarm to be emitted through a speaker, buzzer, horn, siren or any other electrical device capable of emitting sound. Alternatively or additionally, the circuitry  125  can cause a visual alert to be emitted through a flashing light, a steady light, a strobe light, an alphanumeric display or any other electrical device capable of displaying a visual alert. Alternatively or additionally, the circuitry  125  can cause a tactile alert to be emitted by, for example, causing the apparatus  100  to vibrate using any type of electronic device that is capable of causing vibration.  
      Alternatively or additionally, the alarm condition can be sent to a monitor that is located remotely to the apparatus  100 . Consequently, the apparatus  100  can include a transmitter for transmitting the alarm condition to a remote monitor. For example, the apparatus  100  can include a transmitter  130  for transmitting information via wireless radio communication. Any type of wireless transmitter unit can be used for transmitter  130  that is capable of wirelessly transmitting electrical information to a remote receiver using any type of information transmission protocol, such as, for example, a radio frequency transmitter and accompanying antenna. The apparatus  100  can also include a receiver for wirelessly receiving electrical information from a remote transmitter (e.g., a reset signal to reset apparatus  100  (e.g., after an alarm condition has been activated), a software and/or firmware update for circuitry  125  (e.g., if circuitry  125  is at least partially implemented using software and/or firmware), and the like). However, the apparatus  100  can also or alternatively be connected to a remote monitor via a wired electrical connection. The wired electrical connection that can be any type of wired electrical connection that is capable of communicating electrical information, such as a wire, cable, network connection, fiber optic connection, or any other type of wired electrical connection.  
      Thus, for example, using transmitter  130 , upon detection of the presence of ultraviolet radiation by ultraviolet sensor  105 , the circuitry  125  can transmit the alarm condition to the remote monitor, such as remotely monitoring person or persons. Upon the detection of the absence of visible light by visible light sensor  110 , the circuitry  125  can transmit the alarm condition to the remote monitor. Upon the detection of the presence of motion by the motion sensor  120 , the circuitry  125  can transmit the alarm condition to the remote monitor. The transmitted alarm condition can include information such as, for example, an identification code to identify a particular apparatus  100  when multiple volumes or rooms are being monitored by multiple apparatus  100 , an indication of the type of event that caused the alarm condition, or any other type of information that can assist in alerting the remote monitor to the alarm condition and assist the remote monitor in assessing the situation.  
      The apparatus  100  can also include a smoke sensor for detecting the presence of smoke within the volume. Thus, upon detection of smoke within the volume, the circuitry  125  can transmit the alarm condition to the remote monitor and/or indicate the alarm condition to persons within the vicinity of the apparatus  100  using an audible alarm, a visual alarm and/or a tactile alarm. Any electronic sensor that is capable of detecting smoke can be used for the smoke sensor.  
      The transmitter  130  can also transmit a status message to the remote monitor at periodic intervals. The status message can be, for example, a binary code word, where each bit or bits in the code word can represent a particular piece of information (e.g., if a bit is set, then the information associated with that bit is true, otherwise it is false; a combination of bits can indicate a unique identifier). For example, by setting an appropriate bit in the status message code word, the status message can indicate that the apparatus  100  is performing as designed. However, the status message can be any type of electronic message. The status messages can be sent periodically, but pseudo-randomly. The transmission period can be varied to minimize message traffic collisions in the situation where multiple rooms are being monitored by different apparatus  100 . The status message can include, for example, information for identifying the location of the source of the status message to the remote monitor (e.g., an identification code to identify a particular apparatus  100  when multiple volumes or rooms are being monitored by multiple apparatus  100 ), information for identifying the existence of an alarm condition to the remote monitor (e.g., a code indicating that the apparatus  100  detects no events or detects an event), information for identifying a type of alarm condition to the remote monitor (e.g., a code indicating if flame or fire has been detected or tampering to the apparatus  100  has been detected), or any other type of information that can assist the remote monitor in determining the status of the apparatus  100 . Thus, the status message can include information that can be contained in the alarm condition, in addition or alternatively to the alarm condition.  
      According to exemplary embodiments, if the remote monitor does not receive a status message within a predetermined interval, then an alarm condition associated with apparatus  100  can be indicated. The cause of a missing status message can be, for example, a low battery (preventing effective information transmission), a defective apparatus  100 , or a deliberate attempt to damage the apparatus  100 .  
       FIG. 2  is a block diagram illustrating an electronic configuration of the fire-sensing apparatus  100 , in accordance with an exemplary embodiment of the present invention. Ultraviolet sensor  105  can be sensitive in the near-ultraviolet part of the spectrum and can be, for example, a solid state device or a gas ionization device. The ultraviolet sensor  105  can provide an electrical signal to preamplifier  210 . Preamplifier  210  can perform necessary signal conditioning on the electrical signal prior to analog-to-digital (A/D) conversion by A/D converter  235 . A motion sensor  120  can be included to detect tampering or other motion to the apparatus  100 . The motion signal can be amplified by preamplifier  215  prior to A/D conversion by A/D converter  235 .  
      Photocell  205  can serve multiple purposes. For example, the photocell  205  can detect visible light as a method of identifying tampering when visible light to the photocell  205  is blocked. The photocell  205  can output an electrical signal that can be amplified by preamplifier  220  and then digitized by A/D converter  235 . The resulting signal can represent the intensity of visible light in the vicinity of the apparatus  100 . Ultraviolet sensor  105  and photocell  205  can be configured or otherwise positioned in the apparatus  100  such that an attempt to block the ultraviolet sensor  105  will also block the photocell  205 , indicating that tampering is likely. Photocell  205  can also supply current to battery charger  225  for recharging rechargeable battery  115 . One or more photocells  205  can be selected to have sufficient output current to fully supply the power requirements of the apparatus  100 .  
      The A/D converter  235  can send a multiplexed digital data stream to a low-power microcontroller  230 . The low-power microcontroller  230  can be any type of processor, such as, for example, any type of microprocessor, microcontroller, digital signal processor (DSP), application-specific integrated circuit (ASIC), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), or the like, preferably one that operates at low power. The low-power microcontroller  230  can be connected to any form of computer memory, for example, to store computer instructions or other data or information. The low-power microcontroller  230  can perform, for example, data value measurements, range checking, and the like, and can execute the logic that determine whether an alarm, a tamper, or, for example, and an “ALL CLEAR” message should be transmitted via radio link  240  and antenna  245 . Thus, circuitry  125  can include, for example, preamplifiers  210 ,  215  and  220 , battery charger  225 , low-power microcontroller  230  (and an accompanying computer memory, if desired) and A/D converter  235 , while transmitter  130  can include radio link  240  and antenna  245 . Additionally, status messages can be transmitted occasionally at intervals of, for example, five to ten seconds, or at any desired interval. The transmission interval can be randomized so that messages from multiple apparatus  100  do not persistently collide and interfere with each other.  
       FIG. 3  is a flowchart illustrating steps that can be performed by the low-power microcontroller  230 , in accordance with an exemplary embodiment of the present invention. In step  302 , the digitized value from the ultraviolet sensor  105  can be compared with a threshold value to determine whether ultraviolet radiation is present. If ultraviolet radiation is present, then in step  304 , a ten second timer (or any desired length timer) can be set and a bit in the status message code word can be set to indicate flame detection. As long as the timer value is greater than zero, this bit can remain set. In step  306 , the digitized value of the photocell  205  voltage can be compared with a threshold value to determine if visible light is present. If the light intensity is below the threshold, then at least the photocell  205  has been blocked in an attempt to disable the apparatus  100 . If visible light is not present, then in step  308 , a ten second timer (or any desired length timer) can be set and another bit in the status message code word can be set to indicate tampering. This bit can remain set as long as the timer value is greater than zero. In step  310 , the digitized value of the motion sensor  120  can be compared to a threshold value. If the motion intensity is greater than the threshold value, motion is present that indicative of tampering. In step  312 , a ten second timer (or any desired length timer) can be set and a bit in the status message code word can be set to indicate tampering. This bit can remain set as long as the timer value is greater than zero.  
      After constructing the status message code word, in step  314 , a random time delay can be generated. The random time delay can be used to vary the transmission period to minimize message traffic collisions in the situation where multiple volumes or rooms are being monitored by different apparatus  100 . Once the random time delay has expired, the transmitter can be turned on in step  316 . In step  318 , a data synchronization pattern can be transmitted. The data synchronization pattern can be used by the receiver of the remote monitor to establish, for example, proper bit rate synchronization and word framing, and will depend on the type of communication protocol used to transmit the status message. In step  320 , an identification code can be transmitted to distinguish which apparatus  100  is transmitting among a potentially large number of different apparatus  100 . The identification code can be any type of information that can uniquely identify a particular apparatus  100 . In step  322 , the status message code word can be transmitted. In step  324 , the transmitter can be turned off, for example, to conserve power. After transmitting the data, in step  326 , all of the timers can be decremented by one second or any fixed amount of time appropriate to the length of the timer chosen. The process of measurement and evaluation can then be repeated starting at step  302 .  
       FIG. 4  illustrates an outer enclosure  410  of the fire-sensing apparatus  100 , in accordance with an exemplary embodiment of the present invention. According to exemplary embodiments, the apparatus  100  can be of rugged construction, making it difficult to damage the apparatus  100  through means such as, for example, striking the apparatus  100  with a hard object. Thus, the apparatus  100  can have an enclosure  410  made of, for example, high-impact plastic or any other rugged material, so that the apparatus  100  can be resistant to shock, where shock to the apparatus  100  can be indicative of an attempt to tamper with the apparatus  100 . The enclosure  410  can have a radiation transparent window  405  that allows visible light, ultraviolet radiation, and other electromagnetic radiation to pass through to the ultraviolet sensor  105  and the visible light sensor  110 . The enclosure  410  can also have one or more slots or other openings to allow smoke to enter the enclosure  410  for the purpose of detecting smoke by the smoke sensor.  
      Additionally, the apparatus  100  can have the appearance of an object used for a different purpose within the volume, to camouflage the apparatus  100 . For example, the apparatus  100  can be enclosed in an object typically present in the volume to conceal its intent, or the enclosure  410  can be shaped into the form and made to look like an object expected to be present in the volume or room of interest, such as a sprinkler head, light fixture, or other common device.  
       FIG. 5  illustrates positioning of the fire-sensing apparatus  100  within a volume, in accordance with an exemplary embodiment of the present invention. According to exemplary embodiments, the volume to be monitored by the apparatus  100  can be any volume, room or space, either open or enclosed, that can be monitored for the presence of flame, smoke or fire. The apparatus  100  can be positioned within the volume such that the apparatus  100  monitors substantially the entire contents of the volume. Multiple apparatus  100  can be positioned within the volume (and, for example, given the same identification) so as to provide complete or substantially complete coverage of the volume. For example, the apparatus  100  can be used in a restroom  505  of a public school, although the apparatus  100  can be used in any number of variations and configurations, such as, for example, in a restaurant, an aircraft seating area or rest room, or any number of other volumes where a fire or flame is prohibited but may be deliberately ignited. The apparatus  100  can be securely attached to, for example, a wall or ceiling. According to exemplary embodiments, a fire  510  causes an effect such as, for example, the emission of ultraviolet radiation  515  that can be detected at the apparatus  100 . Upon the ignition of the fire  510  in the restroom  505  or upon an attempt to degrade or otherwise negate the performance of the apparatus  100 , the apparatus  100  can detect such event and can communicate this information, for example, via wireless communication  520 , to a monitor module that can be located remotely to the apparatus  100 . The information can include information, for example, for identifying the location of the event in the instance where the facility has multiple volumes or rooms under surveillance. Upon receipt of the information, the remote monitor or other individual can be dispatched to investigate the restroom  505 . The apparatus  100  can also or alternatively issue an audible, visible and/or tactile alert to persons within the vicinity of the apparatus  100  to indicate the alarm condition to the persons located near the apparatus  100 .  
       FIG. 6  is a diagram illustrating a monitor module, in accordance with an exemplary embodiment of the present invention. According to exemplary embodiments, an alarm condition can be transmitted to a remote monitor. The remote monitor can be any person or persons, located either locally or remotely to the apparatus  100 , who have responsibility for overseeing the volume under surveillance and who are be notified upon detection of flame, smoke or fire and/or upon detection of tampering to the apparatus  100 , such as, for example, security personnel, the fire department, the police department, and the like.  
      To notify the remote monitor, a monitor module  600  can be used. The monitor module  600  can provide a display or message window  605  (e.g., an alphanumeric display) and an alert indicator  610  (e.g., a light, LED, or other visual indicator) of the condition at the single or multiple volumes or rooms being monitored. Upon receipt of a periodic signal indicative of the wellness of apparatus  100 , no alert need be indicated (e.g., alert indicator  610  does not flash or otherwise light up). However, upon the receipt of a signal indicative of an alarm condition, the monitor module  600  can generate an audible alarm (e.g., through a speaker, buzzer, horn, siren or the like), a visual alarm (e.g., a flashing light, a steady light, a strobe light, or the like via alert indicator  610 , or an alphanumeric message display through message window  605 ), and/or a tactile alert (e.g., an electronic device that causes the monitor module  600  to vibrate) to indicate the alarm condition and alert the remote monitor. Additionally, based on the information contained in the signal received by the monitor module  600 , the location of the event can be indicated to the remote monitor via the message window  605 , such as, for example, by displaying a predefined identification code. Other information can be displayed to the remote monitor through message window  605 , such as, for example, the type of event generating the alarm condition, or any other information that can assist in alerting the remote monitor to the alarm condition and that can be transmitted via a status message or alert notification.  
      According to exemplary embodiments, the absence of receipt of the status message by the remote monitor within the periodic interval can generate an audible alarm, a visual alarm and/or a tactile alarm at the location of the remote monitor to indicate the alarm condition to the remote monitor. The absence of the receipt of a scheduled periodic status message can be indicative of deliberate damage to the apparatus  100 , or a low power (i.e. battery) condition at the apparatus  100 . In either case, an audible, visual and/or tactile alarm signal can be generated by monitor module  600  to alert the remote monitor of the alarm condition resulting from the absence of receipt of the status message.  
      The monitor module  600  can be a portable unit that can be carried by the remote monitor, or a fixed unit that can be placed in a room generally in communication with the remote monitor. The portable unit embodiment can have, for example, a low battery indicator  615 . The fixed unit embodiment can have, for example, a corresponding power indicator.  
       FIG. 7  is a block diagram illustrating components that can comprise the monitor module, in accordance with an exemplary embodiment of the present invention. Signals received from fire-sensing apparatus  100  by antenna  705  can be processed by radio receiver  710  to extract a digital bit stream representing transmissions from the apparatus  100 . The radio receiver  710  can be any type of receiver that is capable of receiving wireless communications. For wired communications, a receiver that is capable of receiving electrical information over any type of wired transmission medium (e.g., a wire, cable, network connection, fiber optic cable, and the like) can be used. The bit stream can be sent to a low-power microcontroller  720  for analysis and reporting. The low-power microcontroller  720  can be any type of processor, such as, for example, any type of microprocessor, microcontroller, DSP, ASIC, PROM, EPROM, EEPROM, or the like, preferably one that operates at low power.  
      The status of all apparatus  100  being monitored by the monitor module  600  and a history of the status of each of the monitored apparatus  100  can be stored in a memory  725  in connection with the low-power microcontroller  720 . The memory  725  can be any type of computer memory or any other type of electronic storage medium that is located either internally or externally to low-power microcontroller  720 , such as, for example, read-only memory (ROM), random access memory (RAM), cache memory, compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, or the like. As will be appreciated based on the present description, the memory  725  of low-power microcontroller  720  can, for example, be programmed using conventional techniques known to those having ordinary skill in the art of computer programming. For example, the actual source code or object code of a computer program for performing any or all of the functions described herein for low-power microcontroller  720  can be stored in the memory  725 . The remote monitor using the monitor module  600  can access memory  725  to locate alarm and tampering events that occurred previously. For example, the remote monitor can access the information through message window  605  using any type of input access device, such as a keyboard or keypad, or any type of computer pointing device attached or otherwise connected to monitor module  600 . Alternatively or additionally, status indicator  730  and alarm indicator  735  can display, for example, the most recent apparatus data. A rechargeable battery  715  can be used to power the radio receiver  710 , low-power microcontroller  720  and memory  725 , although non-rechargeable batteries or an AC power supply can be used to power monitor module  600 .  
       FIG. 8  is a flowchart illustrating steps that can be performed by the low-power microcontroller  720  in the monitor module  600 , in accordance with an exemplary embodiment of the present invention. In step  805 , the low-power microcontroller  720  can loop waiting for a signal from the radio receiver  710 . When a signal is detected in step  810 , the low-power microcontroller  720  can search for and acquire the synchronization pattern in step  815  to, for example, establish word boundaries. In step  820 , the identification code can be read, while in step  825 , the status code can be read. In step  830 , the identification and status codes can be stored in the memory  725  along with, for example, the time that they were received, or any other desired information. In step  835 , the memory  725  can be searched to retrieve the elapsed time from the last report for each apparatus  100 . In step  840 , if one or more reports have been missed from a particular apparatus  100 , it can be considered overdue, for example, due to tampering. The tamper alarm can then be reported to the remote monitor in step  845 . In step  850 , the current report can be checked for the presence of a fire alarm code. If the fire alarm code is present, then in step  855 , the flame alarm can be reported to the remote monitor. In step  860 , the current report can be checked for the presence of a tamper code. If the tamper code is present, then in step  865 , the tamper alarm can be reported to the remote monitor. The monitor module can then return to the search loop of step  805  to wait for the next signal.  
      According to an alternative exemplary embodiment of the present invention, a fire-sensing system can include a fire sensor for detecting the presence of flame and/or smoke within a volume. The fire sensor can include a flame sensor for detecting ultraviolet energy generated by flame to detect the presence of flame within the volume. However, the flame sensor can be insensitive to electromagnetic radiation that normally occurs within the volume, such as sunlight, standard incandescent or fluorescent lighting, and the like. For example, referring to  FIG. 1 , the ultraviolet sensor  105  can be used to detect the ultraviolet energy generated by flame, such as from a candle, a match, a lighter, or any other source of flame. However, any type of flame sensor can be used that is capable of detecting the presence of flame within the volume. The fire sensor can also include a smoke sensor for detecting the presence of smoke within the volume. Any type of smoke sensor can be used that is capable of detecting the presence of smoke within a volume.  
      According to the present alternative exemplary embodiment, the system can include tamper countering structure for countering attempts to prevent the fire sensor from detecting the presence of flame and/or smoke within the volume. The tamper countering structure can include, for example, a motion sensor  120  for detecting motion to the system. A detection of motion to the system can be indicative of an attempt to prevent the fire sensor from detecting the presence of flame and/or smoke within the volume.  
      The tamper countering structure can include, for example, a visible light sensor  110 . An absence of visible light to the visible light sensor  110  can be indicative of an attempt to prevent the fire sensor from detecting the presence of flame and/or smoke within the volume. The visible light sensor  110  can include, for example, means for generating electrical energy from the visible light, such as, for example, a solar cell, a photoelectric cell, or any other electronic device that is capable of generating electrical energy from light. The means for generating electrical energy from visible light can supply electrical energy to charge a power supply used to power the system, such as, for example, rechargeable battery  115 .  
      The tamper countering structure can include, for example, camouflage for camouflaging the appearance of the system. According to exemplary embodiments, the camouflage can provide the system with the appearance of an object used for a different purpose within the volume. For example, the system can be enclosed in a sprinkler head, light fixture or other common device to conceal its intent, or the system can be shaped into the form and made to look like such an object. The tamper countering structure can include, for example, a shock-resistant enclosure (such as enclosure  410  of  FIG. 4 ) for the system for protecting the system against shock. A shock to the system, such as, for example, hitting the system with a hard object, can be indicative of an attempt to disable, damage or otherwise negate the performance of the system. Thus, the system can be enclosed in a rugged material, such as, for example, a high-impact plastic, to protect the system from such shocks.  
      According to the present alternative exemplary embodiment, the system can include a transmitter for transmitting an alarm notification upon detection of i.) the presence of flame and/or smoke within the volume, and/or ii.) an attempt to prevent the fire sensor from detecting the presence of flame and/or smoke within the volume. The transmitter can transmit the alarm notification to persons within the vicinity of the system using, for example, an audible alarm, a visual alarm, and/or a tactile alarm. Additionally or alternatively, the transmitter can transmit the alarm notification to a remote monitor. For example, transmitter  130  can be used to transmit the alarm notification to a remote monitor or other person or persons located remotely from the system. The alarm notification can be transmitted to the remote monitor via wireless or wired communication. Upon receipt of the alarm notification by the remote monitor, an audible alarm, a visual alarm and/or a tactile alarm can be generated at the location of the remote monitor to indicate the alarm notification to the remote monitor. For example, monitor module  600  can be used to generate the alarm to indicate the alarm notification to the remote monitor.  
      The transmitter can transmit a status message to the remote monitor at periodic intervals. The status message can include, for example, information for identifying the location of the source of the status message, information for identifying the existence of an alarm condition associated with the system, information for identifying the type of alarm condition associated with the system, or any other type of information that can assist the remote monitor in assessing the situation. According to the present alternative exemplary embodiment, if the remote monitor does not receive the status message within the periodic interval, then an alarm condition is indicated. Consequently, the absence of receipt of the status message by the remote monitor within the periodic interval can generate an audible alarm, a visual alarm, and/or a tactile alarm at the location of the remote monitor to indicate the alarm condition to the remote monitor.  
       FIG. 9  is a flowchart illustrating steps for sensing fire within a volume, in accordance with an exemplary embodiment of the present invention. In step  905 , the presence of flame within the volume can be detected. If the presence of flame is not detected in step  905 , then in step  910  the presence of smoke within the volume can be detected. If the presence of smoke is not detected in step  910 , then in step  915  tampering can be detected that prevents the detection of the presence of flame, smoke or fire within the volume. If no tampering is detected in step  915 , then in step  925 , a status message can be transmitted to a remote monitor at periodic intervals. The status message can indicate, for example, that no alarm conditions have been detected. If flame is detected in step  905 , or smoke detected in step  910 , or tampering detected in step  915 , then in step  920 , an alarm condition can be indicated. The indication of the alarm condition can form part of the status message transmitted to the remote monitor in step  925 . For example, the status message can include, for example, information for identifying the location of the source of the status message, information for identifying the existence of the alarm condition, information for identifying the type of alarm condition, or any other information. Exemplary embodiments can then continue monitoring the volume at step  905 .  
       FIG. 10  is a flowchart illustrating steps for the step  905  of  FIG. 9  of detecting a presence of flame within a volume, in accordance with an exemplary embodiment of the present invention. In step  1000 , substantially the entire contents of the volume can be monitored for the presence of flame within the volume. In step  1005 , electromagnetic radiation that normally occurs within the volume (e.g., sunlight, standard incandescent and fluorescent lighting, and the like) can be ignored. In step  1010 , ultraviolet energy generated by flame can be detected. If ultraviolet energy is detected in step  1010 , then an alarm condition can be indicated in step  920  of  FIG. 9 . Otherwise no flame has been detected and the process can continue with step  910  in  FIG. 9 .  
       FIG. 11  is a flowchart illustrating steps for step  915  of  FIG. 9  of detecting tampering, in accordance with an exemplary embodiment of the present invention. In step  1105 , motion can be detected. The motion can indicate tampering that prevents the detection of the presence of flame, smoke or fire within the volume. If no motion is detected, then in step  1110 , an absence of visible light can be detected. For step  1110 , electrical energy can also be generated from the visible light. The generated electrical energy can be used to, for example, charge a power supply. If visible light is detected, then no tampering has been detected, and the process can continue with step  925  of  FIG. 9 . If motion or an absence of visible light is detected, then the process can continue with step  920  of  FIG. 9  to indicate an alarm condition. Exemplary embodiments of the present invention can counter attempts at tampering that prevent the detection of the presence of flame, smoke or fire within the volume. For example, camouflage can be created that has the appearance of an object used for a different purpose within the volume, or shock can be resisted that can be indicative of attempts at tampering.  
       FIG. 12  is a flowchart illustrating steps for step  920  of  FIG. 9  of indicating an alarm condition, in accordance with an exemplary embodiment of the present invention. In step  1205 , the alarm condition can be indicated to persons within the vicinity of the volume using an audible alarm, a visual alarm and/or a tactile alarm. In step  1210 , the alarm condition can be transmitted to a remote monitor. Upon receipt of the alarm condition by the remote monitor, an audible alarm, a visual alarm and/or a tactile alarm can be generated at the location of the remote monitor to indicate the alarm condition to the remote monitor. In addition, according to exemplary embodiments, the absence of receipt of the status message by the remote monitor within the periodic interval can be indicative of an alarm condition. Therefore, if the remote monitor does not receive the status message within the periodic interval, an audible alarm, visual alarm and/or tactile alarm can be generated at the location of the remote monitor to indicate the alarm condition to the remote monitor.  
      The steps of a computer program as illustrated in  FIGS. 3 and 8 - 12  can be embodied, in whole or at least in part, in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. As used herein, a “computer-readable medium” can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium can include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CDROM).  
      It will be appreciated by those of ordinary skill in the art that the present invention can be embodied in various specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence thereof are intended to be embraced.  
      All United States patents and applications, foreign patents, and publications discussed above are hereby incorporated herein by reference in their entireties.