Patent Publication Number: US-9905116-B2

Title: Method and apparatus for detecting a hazard alert signal

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application is a Divisional of U.S. patent application Ser. No. 14/793,421, filed on Jul. 7, 2015, which is a Continuation of U.S. patent application Ser. No. 14/173,445, filed on Feb. 5, 2014, which claims the benefit of U.S. provisional application Ser. No. 61/761,088 filed on Feb. 5, 2013. 
    
    
     BACKGROUND 
     I. Field of the Invention 
     The present invention relates to home security and, more particularly, to a method and apparatus for audible/visual detection of conventional consumer smoke or carbon monoxide detectors. 
     II. Description of Related Art 
     Many homes and businesses contain hazard alarms for detecting the presence of smoke and/or carbon monoxide. Such detectors are typically purchased by consumers at the retail level and installed in their homes and businesses. When a fire or excess carbon monoxide is detected, these detectors typically emit a piercing siren and/or visual effect (e.g., flashing light). However, older people often have hearing or mobility difficulty and remain at a significantly increased risk of injury even if the audible alarm sounds. 
     Home security monitoring vendors such as Ackerman or ADT™ offer networked detectors and failsafe deployment of first responders. Again, when an alarm condition is detected, these systems emit an audible local alarm and also send an alarm code to a central panel for alerting a remote monitoring station, which in turn dispatches proper authorities to the location where the alarm condition exists. However, these network detectors are typically system-specific, and are installed by a third party along with other detectors such as door and window monitors for unauthorized entry. These network systems and their dedicated alarms are expensive and not generally used for middle and low income housing. 
     Inexpensive consumer smoke or carbon monoxide detectors cannot communicate with home security systems, or vice versa, since these consumer-grade detectors generally lack the capability to wirelessly communicate with a centrally-located security panel. Further, most wireless security panels use proprietary protocols to reduce the ability for third party products to communicate with these panels. Consequently, when a consumer smoke or carbon monoxide detector sounds an alarm and no one is present inside the home, the alarm will not be acted on. 
     Consequently, there remains a need for an apparatus that would enable network monitoring of consumer-level fire and carbon monoxide alarms. 
     SUMMARY 
     Accordingly, it is an object of the present invention to provide a method and device for audibly and/or visually detecting activation of a conventional consumer smoke or carbon monoxide detector and for communicating that fact to a network security system for communication with a remote monitoring station. 
     It is another object to accomplish the foregoing in an environment where multiple different alarm types may be activated at once, and to be able to discriminate the different alarm types. 
     It is another object to accomplish the foregoing with a digital processor-based circuitry and a buffer for storing digital samples on a FIFO basis and for analyzing a contiguous subset of the digital samples stored in buffer memory to detect each cadence patterns. 
     In accordance with the foregoing and other objects, in one embodiment, the present invention comprises an apparatus for detecting a pattern warning signal from a hazard alarm and in response thereto sending an alert signal to a home security panel for notification to a remote monitoring station, comprising a receiver circuitry for converting said pattern warning signal from the hazard alarm into digital values, a user interface for providing user input to the apparatus, a memory for storing processor-executable instructions and at least one temporal pattern characteristic associated with a first temporal pattern, a processor coupled to the circuitry, the user interface and the memory for executing the processor-executable instructions that causes the apparatus to receive, by the processor via the user interface, an identification of a first hazard alarm proximate to the apparatus, receive, by the processor via the receiver circuitry, the digital values, determine, by the processor, that the digital values substantially match a first temporal characteristic of the at least one temporal characteristics stored in the memory, transmit the alert signal to the home security panel when the digital values substantially match at least one of the at least one temporal patterns; and transmit the identification of the first hazard alarm to the home security panel. 
     In another embodiment, an apparatus is described for detecting a pattern warning signal from a hazard alarm and in response thereto sending an alert signal to a home security panel for notification to a remote monitoring station, comprising, circuitry for converting the pattern warning signal from the hazard alarm to a stream of digital values, a user interface for providing user input to the apparatus, a memory device for storing processor-executable instructions and a long lull time period associated with a first temporal pattern, a processor coupled to the memory device for executing the processor-executable instructions that causes the apparatus to determine a first time when the stream of digital values transitions from a high state to a low state and then to a high state, determine a duration of the low state, compare the duration of the low state to the long lull time period, determine that a pattern warning signal is present if the duration of the low state is equal to the long lull time period, transmit the alert signal to the home security panel when the pattern warning signal is present, and transmit the identification of the first hazard alarm to the home security panel. 
     In yet another embodiment, a method is described, performing by an alarm detector, comprising, receiving, by a processor via a user interface, an identification of a first hazard alarm proximate to the alarm detector, receiving, by the processor via receiver circuitry, a stream of digital values representative of a pattern warning signal, determining, by the processor, that the digital values substantially match a first temporal characteristic of at least one temporal characteristics stored in a memory, transmitting an alert signal to a home security panel when the digital values substantially match at least one of the at least one temporal patterns, and transmit, by the processor via a transmitter, the identification of the first hazard alarm to the home security panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments and certain modifications thereof when taken together with the accompanying drawings in which: 
         FIG. 1  illustrates one embodiment of a system for providing a hazard alert to a remote monitoring station using an alarm detector for detecting a hazard alarm in accordance with the teachings herein; and 
         FIG. 2  is a functional block diagram of the alarm detector of  FIG. 1 ; 
         FIG. 3  is a flow diagram illustrating one embodiment of alarm detection and transmission; 
         FIG. 4  illustrates a typical T-3 temporal pattern; 
         FIG. 5  illustrates a typical T-5 temporal pattern; and 
         FIG. 6  illustrates two overlapping temporal patterns that are out of phase from one another. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure describes a method and apparatus for audibly or visually detecting activation of one or more conventional consumer smoke, fire and/or carbon monoxide detectors, and for communicating that fact to a home security system for communication with a remote monitoring station. 
       FIG. 1  illustrates one embodiment of an alarm detector  100  for detecting the presence of an audio and/or visual alert in a home or business  106 , typically in the form of a pattern warning signal, generated by hazard alarm  102  when a hazardous condition has been detected by hazard alarm  102 , and for transmitting an alert signal to a home security panel  104  for communication to a remote monitoring station  107  via a network  108 , such as a PSTN, Wide Area network, such as the Internet, and/or cellular voice and/or data network. The term “pattern warning signal” as used herein refers to an audible or visual signal that comports to temporal pattern, such as an ISO 8201 and/or ANSI/ASA S3.41 temporal pattern, presenting the audible or visual signal in a series of timed “pulses” of sound or light. Most smoke detectors manufactured today comport to the ISO/ANSI/ASA standard, which requires an interrupted four count (three half second audio or visual pulses, followed by a one and one half second pause, commonly repeated for a minimum of 180 seconds). This is commonly known as a “Temporal Three” or T-3 pattern. Similarly, modern carbon monoxide detectors comport to a “Temporal Four” or T-4 format, comprising an interrupted five count (four half second audio or visual pulses, followed by a one and one half second pause). Thus, a type of hazard can be determined by knowing whether an alert signal comprises a T-3 or a T-4 temporal pattern.  FIG. 4  illustrates a typical T-3 temporal pattern, while  FIG. 5  illustrates a typical T-5 temporal pattern, each illustration showing a repeating, time-varying voltage comprising “pulses” or “peaks”  400 / 500 . These pulses represent an “envelope” of a high-frequency signal corresponding to a high-frequency audible tone produced by hazard alarm  102  if it has detected a hazard condition. The temporal characteristic comprises a number of pulses, followed by a “long lull period”, shown in  FIGS. 4 and 5  as long lull period  404  and  504 , respectively. 
     The hazard alarm  102  may comprise any one or more of a smoke detector, fire detector, carbon monoxide detector, natural gas detector, radon detector, or any other device that detects one or more hazardous conditions. For example, hazard alarm  102  may comprise a model KID442007 smoke detector manufactured by Kidde, Inc. of Mebane, N.C. and/or a carbon monoxide detector such as model C0400, manufactured by First Alert, Inc. of Aurora, Ill., or a model KN-COSM-B combination smoke detector and carbon monoxide detector also manufactured by Kidde. Hazard alarm  102  is typically battery-operated and generally has no native capability to send or receive wireless communication signals of any type, other than by audible warning and/or visually by illuminating a light that is part of hazard alarm  102 . 
     Security panel  104  is part of an overall security system for a home or business, for example, a Safewatch QuickConnect™ system sold by ADT™ of Boca Raton, Fla. Typically, these home security systems monitor door and windows of a home or business to detect unauthorized entry. If an unauthorized entry is detected by a sensor, an indication of the entry is transmitted to security panel  104 , which in turn may emit an audible and/or visual alert, and/or send an alert signal to remote monitoring station  107  so that the proper authorities may respond to the alarm condition. 
     Alarm detector  100  comprises a combination of hardware and software that determines when hazard alarm  102  has been activated (e.g., has detected a hazard condition such as smoke, fire, and/or carbon monoxide, etc.) and, in response, transmits an alert signal to security panel  104  so that security panel  104  may transmit a signal to the remote monitoring station  107 . 
     Alarm detector  100  generally comprises an audio detector including one or more microphones or other suitable audio transducers to detect an audible signal emanating from hazard alarm  102  and to convert same to an analog signal. Preferably, audio detector  204  comprises one or more conventional piezo microphones, typically small in size and well known in the art. In one embodiment, an array of two or more microphones are used in order to provide differential sound detection. This enhances the ability for alarm detector  100  to detect audio signals from hazard alarm  102  in an environment where the audio signals bounce off of walls, furniture, etc. This overcomes a problem where the reflected audio signals combine at the audio detector along with the original audio signal from the audio detector to form audio wave patterns whose amplitude rises and falls as the reflected audio signals combine with each other and the original signal emanating from the hazard alarm  102 . Using two or more microphones enables spatial-diversity to occur, thus increasing the ability of alarm detector  100  to detect an audio signal that may be tainted with such reflected signals. 
     Alarm detector  100  may, alternatively or in addition, comprise a visual detection device including one or more photo-sensitive LEDs or other suitable device(s) capable of sensing illumination produced by hazard alarm  102  in response to hazard alarm  102  detecting a hazard condition. Such illumination may be turned on and off, or modulated, to produce a pattern warning signal in conformance with a T-3 or T-4 cadence. 
     If hazard alarm  102  detects a hazard condition, it typically will emit a high-decibel pattern warning signal with standardized parameters including frequency, volume, and cadence. 
     The pattern warning signal emitted by hazard alarm  102  comprises an audible signal usually around 3200 Hz at 45 dB to 120 dB, weighted for human hearing. The pattern warning signal typically complies with the well-known Temporal-Three alert signal, often referred to as T3 (ISO 8201 and ANSI/ASA 53.41 Temporal Pattern) which is an interrupted four count (three half second pulses, followed by a one and one half second pause, repeated for a minimum of 180 seconds). CO2 (carbon monoxide) detectors are specified to use a similar pattern using four pulses of tone (often referred to as temporal-4 or T4). 
     Alarm detector  100  detects the presence of sound and/or light emanating from one or more hazard alarms  102  by evaluating the decibel level, frequency, cadence, and/or other characteristics of the signals. 
     For example, in the embodiment of  FIG. 1 , the audio detector of alarm detector  100  receives the audio signal produced by hazard alarm  102 , and then determines whether the audio signal comports to, for example, an audio signal having a T-3 or T-4 temporal characteristic or cadence. If so, alarm detector  100  transmits a signal to security panel  104 , using wired or wireless communication methods, indicating that one or more hazards have been detected. Preferably, alarm detector  100  is configured to distinguish the type of alarm condition based on the type of signal detected from hazard alarm  102 . For example, if a T-3 cadence is detected, alarm detector  100  may transmit a signal to security panel  104  indicating that a smoke or fire hazard has been detected. If a T-4 cadence is detected, alarm detector  100  may transmit a signal to security panel  104  indicating that a carbon monoxide hazard has been detected. 
     Security panel  104  is programmed to contact a remote monitoring station  107  upon receipt of a signal from alarm detector  100  or from any of the door or window sensors, to inform the remote monitoring station that an alarm condition has been detected and, in one embodiment, an indication of the type of alarm, such as smoke, carbon monoxide, etc. 
       FIG. 2  is a functional block diagram of one embodiment of alarm detector  100 . In this embodiment, alarm detector  100  comprises a processor  200 , a memory  202 , an audio and/or optical detector  204 , an amplifier  206 , a filter  208 , a comparator  210 , a buffer  212 , a user interface  214 , and a transmitter  216 . It should be understood that not all of the functional blocks shown in  FIG. 2  are required for operation of alarm detector  100  in all embodiments (for example, amplifier  206  or buffer  212 ), that the functional blocks may be connected to one another in a variety of ways, that additional function blocks may be used (for example, additional amplification or filtering), and that not all functional blocks necessary for operation of the alarm detector  100  are shown for purposes of clarity, such as a power supply. 
     Processor  200  is configured to provide general operation of alarm detector  100  by executing processor-executable instructions stored in memory  202 , for example, executable code. Processor  200  typically comprises a general purpose processor, such as an ADuC7024 analog microcontroller manufactured by Analog Devices, Inc. of Norwood Mass., although any one of a variety of microprocessors, microcomputers, microcontrollers, and/or custom ASICs suitable for use in a power-limited, limited space design may be used alternatively. 
     Memory  202  comprises one or more information storage devices, such as RAM, ROM, EEPROM, UVPROM, flash memory, SD memory, XD memory, or virtually any other type of electronic, optical, or mechanical memory device. Memory  202  is used to store the processor-executable instructions for operation of alarm detector  100  as well as any information used by processor  200  to detect whether an audio and/or optical pattern warning signal has been generated by hazard alarm  102 . Memory device  202  could, alternatively or in addition, be part of processor  200 , as in the case of a microcontroller comprising on-board memory. 
     Audio/optical detector  204  comprises one or more microphones or other suitable audio transducers to detect an audible signal emanating from hazard alarm  102  and to convert same to an analog signal. Preferably, audio/optical detector  204  comprises one or more conventional piezo microphones, typically small in size and well known in the art. In one embodiment, an array of two or more microphones is used in order to provide differential sound detection. This enhances the ability for alarm detector  100  to detect audio signals from hazard alarm  102  in an environment where the audio signals bounce off of walls, furniture, etc. 
     Audio/optical detector  204  may also comprises an optical detector comprising one or more photo-sensitive LEDs or other suitable device(s) capable of sensing an illumination signal produced by hazard alarm  102  in response to hazard alarm  102  detecting a hazard condition. 
     Amplifier  206  comprises circuitry used to amplify the magnitude of the analog signal from audio/optical detector  204  to a level suitable for filter  208  to process. Amplifier  206  may comprise one or more of any number of well-known amplifiers, such as in the form of discreet components (e.g., one or more transistors, op-amps, resistors, capacitors, etc.), an integrated circuit, or part of a custom ASIC. In one embodiment, amplifier  206  amplifies the signal from audio/optical detector  204  by a factor of 40, resulting in a signal to filter  208  between 0 and the voltage limit of the amplifier, typically 3 volts. 
     Filter  208 , in one embodiment, comprises a bandpass filter centered at a frequency equal to a frequency of the pattern warning signal. For example, filter  208  may comprise a Chebyshev filter, centered at 3.1 kHz, as many smoke or carbon monoxide detectors in use emit an audio pattern warning signal at 3.1 kHz, with some variation expected. In other embodiments, filter  208  could alternatively comprise a highpass filter or a lowpass filter. The bandpass of filter  208  is wide enough to allow for such variation between different smoke/carbon monoxide detectors, such as a bandpass of 2 kHz, but narrow enough to attenuate any extraneous audible signals, such as sound from TVs, people, animals, and generally sounds other than the audio pattern warning signal from hazard alarm  102 . Filter  208  may comprise discreet components such as one or more transistors, op-amps, resistors, capacitors, etc., an integrated circuit, or part of a custom ASIC. 
     The output from filter  208  is provided to comparator  210 . Comparator  210  is used to present digital “1”s and “0”s to processor  200  for use in determining whether a pattern warning signal is present. Typically, a fixed DC voltage is also presented to comparator  210  for comparison to the signal from filter  208 . The fixed DC voltage is selected at some point greater than the mid-point between the voltage supplied to comparator  210  and ground, or between two supply voltages. The voltage may be selected by such factors as the decibel level of hazard alarm  102 , the location of hazard alarm  102  in proximity to alarm detector  100 , the gain of amplifier  206 , the type of audio/optical detector  204 , other factors, or a combination thereof, in order to present a signal within the input voltage range of processor  200 . When a voltage greater than the threshold voltage is presented to comparator  210 , a digital “1” is produced, and when the voltage to comparator  210  is less than the threshold voltage, a digital “0” is produced. The threshold voltage is chosen high enough so that a small magnitude sound wave presented to audio/optical detector  204  result in a “0”, such as sounds from a TV or conversation, or even by loud sounds (e.g., dog barking, boiling tea kettles) located some distance away from hazard alarm  102 . Additionally, the threshold voltage is chosen low enough to ensure that large magnitude sound waves presented to audio/visual detector  204 , such as those from hazard alarm  102  in close proximity to alarm detector  100 , results in a “1” being produced. In this way, comparator  102  acts like a one-bit, variable-threshold A/D converter, converting an analog signal from filter  210  to a digital signal determined by the voltage level of the analog signal compared to the threshold voltage. 
     Buffer  212  comprises one or more information storage devices, such as a RAM memory, or other type of volatile electronic, optical, or mechanical memory device. Buffer  212  could, alternatively or in addition, be part of processor  200 , as in the case of a microcontroller comprising on-board memory, or a custom ASIC. Buffer  212  is used to store the digital information generated by comparator  210 . Buffer  212  includes a predetermined number N memory locations each configured to store a digital value from comparator  210 , and as all N locations become populated with digital information, new samples begin replacing the oldest samples in a first-in-first-out (FIFO) manner. In one embodiment, the use of DMA by processor  200  allows storage independent of the processes being executed by processor  200 , effectively freeing processor  200  to perform other functions as digital information from comparator  210  is generated. The number of memory locations comprising buffer  212  will vary in one embodiment vs. another, as will be described later herein. Typically, digital information generated by comparator  210  is stored in buffer  212  at predetermined time intervals, for example every 20 milliseconds. 
     User Interface  214  may be provided which generally comprises hardware and/or software necessary for allowing a user of alarm detector  100 , such as a homeowner, to perform various tasks such as to check the status of a battery, send a test signal to the security panel  104 , put the alarm detector  100  into a particular mode of operation such as “armed mode” where alarm detector  100  transmits a signal to security panel  104  upon detection of an audible/visual alarm produced by hazard alarm  102 , among others. Such hardware and/or software may comprise switches, pushbuttons, touchscreens, and other well-known devices. 
     Transmitter  216  comprises circuitry necessary to transmit signals from alarm detector  100  to one or more remote destinations, such as security panel  104  and/or some other remote entity, such as to a cellular network for delivery to a personal communication device, such as a wireless smartphone. Such circuitry is well known in the art and may comprise BlueTooth, Wi-Fi, Sigsbee, X-10, Z-wave, RF, optical, or ultrasonic circuitry, among others. Alternatively, or in addition, transmitter  216  comprises well-known circuitry to provide signals to a remote destination via wiring, such as telephone wiring, twisted pair, two-conductor pair, CAT wiring, or other type of wiring. 
       FIG. 3  is a flow diagram illustrating one embodiment of alarm detection and transmission. The method is implemented by processor  200  executing processor-readable instructions stored in the memory  202  shown in  FIG. 1 . It should be understood that in some embodiments, not all of the steps shown in  FIG. 3  are performed and that the order in which the steps are carried out may be different in other embodiments. It should be further understood that some minor method steps have been omitted for purposes of clarity. Finally, it should be understood that although much of the discussion related to  FIG. 3  references audible signals sensed by an audio detector only, it is intended that such discussion additionally relate to light signals and the use of optical detectors either additionally, or in the alternative. 
     The process begins at block  300 , where the audio/optical detector  204  receives audio signals in the form of sound pressure waves from the general surroundings where alarm detector  100  is located and audio signals from hazard alarm  102  if hazard alarm  100  has detected a hazard condition. These audio signals are converted into analog signals and provided to amplifier  206 . In another embodiment, audio/optical detector  204  comprises means for detecting light signals produced by hazard alarm  102 , such as one or more photodiodes, phototransistors, or other light-sensitive devices. In one embodiment, the photodiodes, phototransistors, or other light-sensitive devices are chosen to detect light signals in a frequency range produced by a typical hazard alarm  102 . In any case, audio/optical detector  204  converts the optical signals into electronic signals for use by amplifier  206 . In an embodiment where audio/optical detector  204  comprises both an audio detector and an optical detector, two streams of analog signals are produced and processed separately, in one embodiment, by adding another amplifier, filter, and comparator similar to amplifier  206 , filter  208 , and comparator  210  and providing the output of the second comparator to processor  200 . 
     At block  302 , the analog signal from audio/optical detector  204  is provided to amplifier  206 , where amplifier  206  amplifies the magnitude of the electronic analog signal. In one embodiment, the electronic analog signal is amplified by a factor of 40. In other embodiments, an automatic gain control feature may be incorporated into the circuitry of amplifier  206 , to maintain a signal that is within a usable voltage range of filter  208 . In some cases, amplifier  206  may actually attenuate the analog signal if, for example, hazard alarm  102  is located very close to alarm detector  100  and/or the audible signal from hazard alarm  102  is very loud. In any case, the amplified analog signal is the provided to filter  208 . 
     At block  304 , filter  208  attenuates frequencies in the amplified analog signal outside the passband of filter  208  to produce a filtered, amplified, analog signal. The passband center frequency and bandpass are selected to attenuate sounds other than those produced by hazard alarm  102 . 
     At block  306 , the filtered, amplified, analog signal is provide to comparator  210 , where it is compared with a threshold voltage that is also provided to comparator  210 , as discussed previously. Comparator  210  converts the filtered, amplified, analog signal into a digital signal comprising digital “1”s and “0”s and provides the digital signal to processor  200 . Alternatively, the digital signal may be stored directly into buffer  212 , rather than provided to processor  200 . 
     At block  308 , in one embodiment, processor  200  receives the digital signal from comparator  210  and stores digital samples from the digital signal into buffer  212  in a first-in, first-out (FIFO) manner, as discussed previously. In one embodiment, the digital samples are stored using DMA that allows storage of the digital samples independent of other processes executed by processor  200 , effectively freeing the processor  200  to determine if a pattern warning signal has been received based on the digital samples stored in buffer  212 . In one embodiment, buffer  212  comprises 64 memory locations, and processor  200  stores each new digital sample in a first memory location, while shifting any previously-stored digital samples to a next respective, adjacent memory location. When buffer  212  is full, processor  200  continues storing new data samples in the first memory location and shifting each of the previously-stored digital samples to the next, sequential memory location, causing the last digital sample in buffer  212  to be ejected from buffer  212 . Thus, buffer  212  acts as an evaluation window of time equal to the number of memory locations multiplied by the rate at which digital samples are added to buffer  212 . For example, if buffer  212  comprises 100 memory locations and processor  200  stores digital samples at a rate of one sample every 20 milliseconds, buffer  212  essential captures a 2 second window of time (100 memory locations times 20 milliseconds) of audio information received by audio/optical detector  204 . 
     At block  310 , in one embodiment, processor  200  determines if a pattern warning signal has been received based on some or all of the digital samples stored in buffer  212 , in some embodiment, over a predetermined time period. In one embodiment, processor  200  evaluates some or all the digital samples stored in buffer  212  at predetermined time periods, such as once every 20 milliseconds, every 30 milliseconds, or some other time period typically at least an order of magnitude less than the period of the temporal signal, shown in  FIG. 4  as temporal pattern period  406  and in  FIG. 5  as period  506 . Taking periodic sample of some or all of buffer  212  acts as a low-pass filter, smoothing the output of comparator  210  due to noise at the comparator&#39;s input. 
     In one embodiment, processor  200  assigns a “1” or “high” buffer state to the signal provided by comparator  210  when the number of “1”s stored in these memory locations exceeds a first predetermined threshold number, or if a predetermined percentage of memory locations contain a digital “1” (i.e., 75% of the number of digital values read, or a numerical value, such as 50 memory locations or, conversely, whether a percentage of “0”s in the sampled memory locations is less than a second predetermined threshold such as 25% or 50 memory locations). In one embodiment, processor  200  samples enough memory locations in buffer  212  to cover the period of a temporal signal. In one embodiment, all of the memory locations are evaluated by processor  200 . If the number or percentage of “1”s in buffer  212  exceed the threshold, this is indicative of the presence of energy within the passband of filter  208 , which in turn indicates that a first pattern warning signal is sounding from hazard alarm  102 , for example an audible alert signal that follows a T-3 cadence, indicating the presence of a first hazard condition, such as the presence of smoke. Alternatively, or in addition, processor  200  evaluates the digital samples at predetermined time intervals to determine if the number or percentage of “1”s in the sample exceeds a third predetermined threshold (i.e., 85% of the number of digital values read, or a numerical value, such as 70 memory locations or, conversely, whether a percentage of “0”s in the sampled memory locations is less than a fourth predetermined threshold such as 25% or 70 memory locations). If so, this is indicative that a second pattern warning signal is sounding from hazard alarm  102  (or from a different hazard alarm), for example an audible alert signal that follows a T-4 cadence, indicating the presence of a second hazard condition, such as the presence of an abnormal level of carbon monoxide. In the just-described embodiment, the sampling rate of comparator  210  and the period of the temporal signal may be used to select the size, or number of memory locations, of buffer  212 . For example, in this embodiment, it is desirable to evaluate enough samples to cover at least one period of the temporal signal. If the period is 5 seconds, and the sampling rate is 20 milliseconds, buffer  212  would be selected to be at least 250 memory locations, or bits, long. In another embodiment, processor  200  does not determine that a hazard alarm has been detected until processor  200  determines that a predetermined number of “high” buffer states have occurred within a predetermined time period or that a predetermined number of “high” buffer states have occurred consecutively. 
     In another embodiment, processor  200  reads or samples some or all of buffer  212  at predetermined time intervals, assigns a buffer state or digital value to each sample, determine the occurrence of “events” based on the samples, and then compare the events to one or more temporal pattern characteristics to determine if a pattern warning signal is present. 
     A first “event” can be defined as a predetermined percentage or number of memory locations in a sample having a “1” stored therein, indicating energy within the passband of filter  208 , for example a percentage greater than 70%. A second event could be defined as a predetermined percentage or number of memory locations having a “0” stored therein, indicating a minimal, or no, energy inside the passband of filter  208 , for example a percentage less than 30% (of course, the assignment of events could be reversed, e.g., the first event defined as a predetermined number of percentage of memory locations contain a “0” and the second event defined as a predetermined number of percentage of memory locations contain a “1”). Other events can be defined by combining the events described and/or by combining the events described above with time. For example, events such as the following could be defined: 
     Third Event: a first event followed by another first event (indicates continued energy within the passband) 
     Fourth Event: a first event followed by a second event (indicates energy in the passband followed by minimal, or no, energy in the passband) 
     Fifth Event: a second event followed by a first event (indicates a minimal, or no, energy in the passband followed by energy present in the passband) 
     Sixth Event: a second event followed by a second event (indicates continued minimal, or no, energy in the passband) 
     Seventh Event: the fourth event, followed by a number of second events, followed by either a first event or the fifth event 
     Of course, many other events could be defined and not all of the events described above are necessary for the operation of pattern warning detection in this embodiment. Processor  200  may also determine a time that each event occurs and record the event and the time that each event occurred in memory  202 . It should also be understood that while use of “events” may simplify and/or reduce processing necessary by processor  200 , in other embodiments, the use of events is not used. In these cases, processor  200  may make state determinations of the samples from buffer  212  and then compare the determinations with each other and/or to time in order to determine whether the output of comparator  210  comports to one or more characteristics of a pattern warning signal. 
     If events are used, processor  200  can compare events to one or more characteristics of a temporal pattern stored in memory  202  to determine when a pattern warning signal is present. The characteristics may comprise one or more of a) three energy peaks within a predetermined time period, b) four energy peaks within a predetermined time period, c) three (or four) energy peaks within a predetermined time, each peak having a duration of a predetermined time, d) a “long lull time period” having a duration substantially equal to long lull  404  or  504  in  FIGS. 4 and 5 , respectively (i.e., a lack of energy in the passband between two detections of energy in the passband), e) a temporal pattern period (e.g., period  406  or  506 ), measured by one or more re-occurrences of any one or more of items a-d. Of course, a number of other temporal pattern characteristics could be used, either alternatively or in conjunction with the aforementioned characteristics, to determine whether a pattern warning signal is present. 
     For example, in one embodiment, processor  200  determines whether a pattern warning signal is present by determining whether the output of comparator  210 , or the buffer states, substantially matches a long lull time of a temporal pattern, such as a T-3 or T-4 pattern. Typically, the long lull time is such patterns is one and a half (1.5) seconds. This greatly simplifies the process of determining whether the output from comparator  210  matches a temporal pattern, because only one characteristic need be examined. This embodiment may be particularly useful to eliminate problems of detection due to the presence of a second pattern warning signal from a second hazard alarm  102  located some distance away from a first hazard alarm  102  located closer to alarm detector  100 . In this case, two overlapping temporal patterns may make it difficult to determine the presence of one of the temporal audio patterns using the techniques previously discussed (such as peak or pulse detection, temporal pattern period detection, width of pulses or peaks, etc.), because the peak and lull times of each temporal signal overlap, as shown in  FIG. 6 . In  FIG. 6 , a first temporal pattern is shown in solid lines and a second temporal pattern is shown in dashed lines, the second temporal pattern having an amplitude that is less than the amplitude of the first temporal pattern. The signals shown in  FIG. 6  may be representative of the signal from comparator  212 , in which case both temporal signals are being processed simultaneously. This causes difficulty in determining the timing characteristics of a temporal pattern, such as 3, half-second peaks, followed by a longer lull time, such as one and a half seconds, because of the interfering nature of the overlapping signals. Fortunately, the phase of each hazard alarm  102  is typically not the same. So, over a relatively short time period, on the order of minutes, two temporal signals from two different hazard alarms may briefly be in-phase with each other, allowing alarm detector  100  to determine that at least one temporal signal is present, simply by detecting the long lull period. 
     Processor  200  may use events to determine when a long lull period has occurred, or it can determine individual states of buffer  212  and match the buffer states to the long lull characteristic. For example, after determining that buffer  212  has transitioned from a high buffer state to a low buffer state, processor  200  may determine that buffer  212  has transitioned from a low buffer state to a high buffer state at some later time. Upon occurrence of the transition from low to high, processor  200  may determine the elapsed time between the first transition and the second transition and compare that time to the long lull time associated with either a T-3 temporal pattern or a T-4 temporal pattern as shown in  FIGS. 4 and 5  as long lull  404  and  504 , respectively, in one embodiment, 1 and a half seconds. If the elapsed time between the transitions is substantially equal to the long lull time (e.g., +/−10%), processor  200  declares that either a T-3 or a T-4 signal is present. In one embodiment, processor does not declare that a T-3 or a T-4 signal is present unless at least two long lulls periods are detected, spaced apart in time from one another by a time approximately equal to a temporal pattern period  406  or  506  of either a T-3 or a T-4 signal. For instance, in a typical T-3 signal, the temporal time period is approximately 4 seconds. A typical T-4 signal comprises a temporal time period of approximately 5 seconds. Therefore, processor  200  will only declare a T-3 signal present if two long lulls occur about 4 seconds from each other, and a T-4 only if two long lulls occur about 5 seconds from each other. 
     Of course, in other embodiments, processor  200  can determine other characteristics of a temporal pattern, alternatively or in addition to the long lull as described above. For example, processor  200  could determine when one or more “pulses” or “peaks” occur, shown in  FIG. 4  as pulses  400  and in  FIG. 5  as pulses  500 , and the relative times between such pulses. Thus, if processor  200  determines that three pulses have occurred, each spaced 1 second apart, a T-3 temporal pattern could be declared. Various combinations of temporal characteristics could be used by processor  200  to determine whether a temporal pattern has occurred, using the events determined by the buffer sampling described above. For example, a temporal pattern could be declared if just one pulse is detected, followed by a long lull within the period of either a T-3 or T-4 temporal pattern. 
     In another embodiment, buffer  212  is not used. Rather, processor  200  determines whether one or more pattern warning signals are present by periodically sampling comparator  210 , such as once every 20 milliseconds. When a “1” is present, indicating energy within the passband of filter  208  (or, alternatively, when an uninterrupted, or nearly uninterrupted, sequence of “1”s are received, for example 5 consecutive “1”s), processor  200  starts a clock (implemented in either hardware or, more typically, software). In another embodiment, sampling by processor  200  continues until a “0” is received, indicating that no audio signal from hazard alarm  102  is present. A second clock may be started at this point. Processor  200  determines the elapsed time between when the “1” was detected and the time when the first “0” was detected in order to determine if the time that the output of comparator  210  was high matches to a “pulse” characteristic of a temporal signal, shown in  FIGS. 4 and 5  as pulse  400  and pulse  500 , respectively. In another embodiment, processor may wait to make the elapsed time measurement until a predetermined number of “0”s are generated sequentially by comparator  210 , such as five samples, to ensure that signal has, indeed, dropped off, in order to prevent false readings due to, for example, transient events such as noise. 
     When a “0” is detected from comparator  210  after detecting a “1”, processor  200  determines the elapsed time from when the “1” was first determined, and compares the elapsed time to an expected time period of a temporal signal pulse, for example, one-half second (shown as pulse  400  and pulse  500 ) as stored in memory  202 . Similarly, processor  200  continues to evaluate the output of comparator  210  to determine how long an uninterrupted (or nearly uninterrupted) sequence of “0”s occur after start of the second clock, to determine if the signal from comparator  210  remains low for a time period corresponding to a lull  402 / 502  in a temporal pattern, such as one-half second. Processor  200  continues to monitor the output of comparator  210 , using clocks to determine time periods of pulses and lulls, then matches the results to determine if a pattern warning signal is being emitted by hazard alarm  102 . For example, processor  200  may indicate the presence of a pattern warning signal when the output of comparator  210  has followed one or more T-3 or T-4 temporal patterns. For example, processor  200  may require 2 full periods of a temporal pattern before it declares that a pattern warning signal is present. 
     In another embodiment where buffer  212  is not used, processor  200  determines whether one or more pattern warning signals are present by, again, periodically sampling comparator  210 , such as once every 20 milliseconds, to determine if a “long lull” period of a temporal patter is present, e.g., long lull  404  or long lull  504 . In this embodiment, processor  200  evaluates the output of comparator  210  to determine if the “long lull” characteristic of a T-3 or T-4 signal is present. This is accomplished by noting a change in state of comparator  210  from a “1” to a “0”, then either starting a clock or counting the number of uninterrupted (or nearly uninterrupted) “0” that occur after the transition from “1” to “0”. When processor  200  determines that the output of comparator  210  has changed from a “0” to a “1” after detecting the change from “1” to “0”, the elapsed time between this event and the change from “0” to “1” is determined then compared to an expected lull time of a temporal signal associated with a pattern warning signal from hazard alarm  102 . In the embodiment where uninterrupted “0” s are tracked, processor  200  simply multiplies the number of uninterrupted (or near uninterrupted) “0”s that occur between the “1” to “0” transition and the “0” to “1” transition and multiply by the sample period to arrive at the time that the signal from comparator  210  has remained low. Again, this time period is compared to an expected lull time of a temporal signal associated with a pattern warning signal from hazard alarm  102  as stored in memory  202 . If a match is found, processor  200  determines that a pattern warning signal is present. 
     At block  312 , processor  200  may determine a type of hazard condition based on a comparison of signal using any of the evaluation embodiments presented above to information stored in memory  202 . For example, processor  200  may determine that 4 “pulses” have been detected, indicative of a T-4 cadence, which means that carbon monoxide has been detected by at least one carbon monoxide detector. 
     At block  314 , processor  200  generates an alert signal indicative that a hazard condition has been detected by one or more hazard alarms  102  and provides the alert signal to transmitter  216 . Processor  200  may also provide an indication of the type of hazard condition detected as determined at block  312 . In yet another embodiment, processor  200  may additionally transmit an indication of an identity of the hazard alarm that generated the detected pattern warning signal. This may be accomplished by entering a description of a hazard alarm  102  in proximity to alarm detector  100  using user interface  214 . For example, a user could enter “Zone  19 ”, “Smoke Detector in Master Bedroom”, “Smoke detector in zone  16 ”, “Carbon monoxide detector in zone  17 ”, or any other description that may help identify a location within a structure that the hazard event is occurring. 
     At block  316 , transmitter  216  transmits the alert signal generated by processor  200  at block  306  to a remote entity, such as a smartphone and/or security panel  104 , indicating that a hazard condition exists that has been detected by hazard alarm  102  and alarm detector  100 . The signal may additionally comprise the type of hazard condition sensed, and/or an indication of a location of the hazard or a location or identification of the hazard alarm that detected the hazard condition. In response, the security panel  104  may transmit a signal to a remote monitoring station alerting the remote monitoring station that a hazard condition has been detected and in some embodiments, the type of hazard condition, and/or location of the hazard or a location or identification of the hazard alarm that detected the hazard condition. 
     At block  318 , the processor determines if no audio information has been received from the audio/optical detector  204  and/or comparator  210  within the frequency band of filter  208  for a time period greater than a “long lull” time period associated with one or more temporal patterns, such as 5 seconds, or some other extended period of time. If so, this may indicate that the hazard condition no longer exists. In this case, processor  200  generates an indication of this event and transmits it to the smartphone and/or security panel  104 , informing the smartphone and/or security panel  104  that the hazard no longer exists. In response, the security panel  104  may send an indication to the remote monitoring station that the hazard seems to no longer exists. 
     Therefore, having now fully set forth the preferred embodiment and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that the invention may be practiced otherwise than as specifically set forth in the appended claims.