FIELD OF THE INVENTION  
         [0001]    The invention pertains to multi-unit monitoring systems. More particularly, the invention pertains to such units which are capable of wirelessly transmitting status information or parameter values to displaced observers.  
         BACKGROUND OF THE INVENTION  
         [0002]    Monitoring systems having a large number of interconnected detectors are known to be useful in monitoring various conditions in a region. Various maintenance and test procedures have been developed to facilitate servicing such systems. One testing vehicle has been disclosed in Bellavia et al. U.S. Pat. No. 4,827,244.  
           [0003]    Bellavia et al. teach the wireless initiation of a test function The transmission of information from a detector in both human perceptible and machine readable form is also known.  
           [0004]    It would be desirable to facilitate the wireless transfer of information to service personnel in the area of the respective detector. It would also be desirable to be able to implement such transmissions using, if possible, components already present on or in the respective detectors.  
         SUMMARY OF THE INVENTION  
         [0005]    An ambient condition detector incorporates a source of radiant energy, for example, an infrared emitting diode, to carry out a sensing function. The source is located within the detector and is not visible from locations outside of the detector.  
           [0006]    A control circuit within the detector drives the source with a modulated electrical signal. In a disclosed embodiment, one portion of the signal is associated with a sensing function. Another portion is associated with an external information transfer function. In other embodiments, the sensing related portion could also be modulated with the information to be transferred.  
           [0007]    The detector includes an opaque, radiant energy transmissive housing which contains the source. Radiant energy which is emitted from the source passes, in part, through the housing and is radiated from the housing into the surrounding ambient atmosphere. The radiated signal can be sensed and demodulated to extract the transmitted information.  
           [0008]    A variety of transmission protocols can be used. Parameter values or status indicators can be transmitted from the detector using analog modulation. Pulse amplitude, pulse position, pulse width or frequency modulation can be used. Other analog modulation processes could be used including phase modulation. Alternately, a binary representation can be transmitted.  
           [0009]    In another embodiment, information could be transmitted, using one or more analog protocols, from a light emitting diode. This diode could be located at an exterior peripheral surface of the detector.  
           [0010]    In this embodiment, parameter values and status information can be wirelessly transmitted using the modulated waveform. Periods of transmitted signals can be in a range on the order of 3-10 seconds.  
           [0011]    In yet another aspect, a portable unit can receive and demodulate the modulated signals. Parameter values or status indicators can be displayed at the unit  
           [0012]    Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a diagram of a system in accordance with the present invention;  
         [0014]    [0014]FIG. 2 is a side sectional view of a detector in accordance with the present invention;  
         [0015]    [0015]FIG. 3 is a timing diagram which illustrates aspects of the operation of the detector of FIG. 2;  
         [0016]    FIGS.  4 A- 4 B are diagrams of a hand held, portable reader usable with the detector of FIG. 2;  
         [0017]    [0017]FIG. 5 is a block diagram of components of the reader of FIG. 4;  
         [0018]    [0018]FIG. 6 is a timing block diagram which illustrates aspects of the operation of the reader of FIG. 4A;  
         [0019]    [0019]FIG. 7A is a flow diagram illustrating processing carried out by the reader of FIG. 4A;  
         [0020]    [0020]FIG. 7B is a flow diagram illustrating a method of using the reader of FIG. 4A;  
         [0021]    [0021]FIG. 8 is an alternate embodiment of a detector in accordance with the present invention; and  
         [0022]    FIGS.  9 A- 9 D are timing diagrams which illustrate alternate analog modulation processes in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated.  
         [0024]    [0024]FIG. 1 illustrates a system  10  in accordance with the present invention. The system  10  incorporates a common element  12 , which could be implemented with one or more programmed processors. The element  12  is coupled to a bi-directional wired medium such as electrical cable or optical fiber  14 . A plurality of devices  16  is coupled to the medium  14  and in bi-directional communication with the control element  12 . The devices  16  can include one or more detectors, such as detector  16   i,  as well as audible or visible output devices  16   j  and/or various types of control devices  16   k,  all of which would be known to those of skill in the art.  
         [0025]    The members of the plurality  16  can transmit, wirelessly, status information to a hand-held unit  20  carried by an operator or maintenance person U. The unit  20  enables the maintenance person U to walk through regions monitored by the system  10  and to wirelessly download from the respective units, such as units  16   i,    16   j  or  16   k  status information, parameter values and the like without having to physically contact the respective device or disconnect it from the medium  14 .  
         [0026]    Alternately, or in addition to, the system  10  can include a plurality of wirelessly coupled electrical units  24 . These units, as illustrated by the representative electrical unit  24   i  carry wireless transmitters and, in the case of using RF communication respective RF antennae  24   i - 1 . In this embodiment, control element  12  also carries a wireless antenna of an appropriate type  12 - 1  so as to carry on wireless communication with the unit  24   i.  The portable reader  20  can be used to download status and parameter information from the members of the plurality  24  just as for the members of the plurality  16 .  
         [0027]    [0027]FIG. 2 illustrates an exemplary detector  16   i  which includes a housing  16   i - 1 . Housing  16   i - 1  carries a photoelectric smoke chamber  16   i - 2 .  
         [0028]    The chamber  16   i - 2  includes a radiant energy emitter  16   i - 3  which could be implemented using a laser diode or light emitting diode. The radiant energy can be emitted at a variety of frequencies all without limitation of the present invention except as noted below.  
         [0029]    Radiant energy  18   i - 1  is projected into the smoke chamber  16   i - 2  by the emitter  16   i - 3 . A portion of that radiant energy is scattered by smoke in the chamber, as understood by those of skill in the art, and is detected by photosensor  16   i - 4 . The emitter  16   i - 3  and the sensor  16   i - 4  are coupled to control circuitry  16   i - 5  of a type which would be known to those of skill in the art.  
         [0030]    The circuitry  16   i - 5 , in addition to energizing the emitter  16   i - 3  and reading the signal back from the sensor  16   i - 4 , can include bi-directional interface circuitry for communicating with the medium  14  or an antenna corresponding to the antenna  24   i - 1  for wireless communication with the control element  12 . The control element  16   i - 5  can be implemented, at least in part, with a programmed processor.  
         [0031]    When the control element  16   i - 5  energizes the emitter  16   i - 3  in addition to emitting the desired radiant energy  18   i - 1 , the emitter leaks radiant energy  18   i - 2 . A portion of the leakage radiation  18   i - 3  passes through the plastic housing  16   i - 1  and can be sensed at hand-held unit  20 .  
         [0032]    In one embodiment, a wall portion of the housing  16   i - 1  can be formed with a reduced thickness on the order of 0.35 through 0.045 inches to facilitate transmissivity of the leakage radiation  18   i - 2  through the housing. Plastic such as polycarbonate (available commercially as FR110) is transmissive of leakage radiation  18   i - 2 , in a wavelength range of 820 nm to 950 nm (nano-meters) so as to be detected by hand-held unit  20 . Polypropylene can also be used.  
         [0033]    With appropriate drive signals, as would be understood by those with skill in the art, a broader range, including 500 to 950 nm, can be expected to emit sufficient stray radiation for detection by an appropriate handheld unit.  
         [0034]    [0034]FIG. 3 illustrates a timing diagram of a representative modulated signal used to drive emitter  16   i - 3 , which in turn produces leakage radiation  18   i - 3  for detection by unit  20 . The source of  16   i - 3 , which might be an infrared emitting laser diode or infrared light emitting diode is driven by control circuitry  16   i - 5  for on the order of  207  microseconds to produce a stabilized sample interval for the sensor  16   i - 4  to detect smoke scattered radiant energy. Two subsequent pulse position modulated indicators, identified in FIG. 3 as “marker bit” and “stop bit” can be used to transmit detector parameter values, such as sensitivity data status or advisory messages such as in an analog format and message data in an analog format. Exemplary messages include status or advisory messages such as “replace”, “good”, and variations of“dirty” or “service”.  
         [0035]    [0035]FIGS. 4A and 4B are illustrations of an exemplary hand-held sensing unit  20 . The unit  20 , depending on the form of wireless transmission, can include an antenna (RF) or optical collector or focusing surface  20   a  (infra-red) which is carried by a housing  20   b.  The housing  20   b  also carries a visual display, which could be implemented as a liquid crystal display  20   c.  Those of skill will understand that the antenna or collecting surface  20   a  would be configured so as to be consistent with the form of radiant energy to be sensed. A plurality of user controls, discussed subsequently, is carried by housing  20   b.    
         [0036]    [0036]FIG. 5 illustrates additional details of the hand-held unit  20  usable to detect infrared. Incident, modulated infrared is detected at a radiant energy sensor, such as a photodiode or phototransistor  20   d  whose output is in turn coupled to an amplifier  20   e.  An amplified output is processed in signal processing and control circuitry  20   f.  The signal processing circuitry  20   f,  in response to detecting the presence of protocol, previously discussed in FIG. 3, in the leakage radiation  18   i - 3  can in turn demodulate same to determine a numeric value of a parameter, such as sensitivity, and status information, such as a range such that the numeric value and range can be, for example, alternately displayed on display  20   b.    
         [0037]    User control element  20   g  can include pushbuttons for turning the unit  20  on and off as well as for selecting the type of information to be displayed as would be understood by those of skill in the art. The reader or unit  20  can be powered by a replaceable battery and can include a status indicating audible output device.  
         [0038]    As illustrated in FIG. 6, the processing circuitry  20   f  could in a step  100  display sensitivity in a numeric form for a period of time such as three seconds. In a step  102 , the display can be darkened for a predetermined interval.  
         [0039]    In a step  104 , a maintenance indicating status message can be displayed for a predetermined period of time followed by another darkened interval, step  106 , whereupon the display process repeats itself. It will be understood that the process illustrated in FIG. 6 is exemplary only and variations therefrom do not depart from the spirit and scope of the present invention.  
         [0040]    It will also be understood, that the unit  20  could incorporate if desired an audible output device which would indicate to the user that valid data had been read and is available for presenting either numerically or in the form of a status message. Other messages can be presented on display  20  to display the reader unit&#39;s own status. These include ready and a low-battery message. It will also be understood that the received parameter data or associated maintenance message could be continuously displayed subject to user control using one or more of the user control elements  20   g.    
         [0041]    The following data representations, messages and related reader functionality information are exemplary only and are not limitations of the present invention:  
                                       Parameter Value Or   Sensitivity data can be continuous displayed       Values Such As Sensitivity   in % per foot (2 digits and decimal point).       X.X %/FT   Valid range can be 0.0 to 9.9.       Status messages   Maintenance condition has been reached.       SERVICE   The device under test should be cleaned.           Display is continuous.       DIRTY   Pre-high maintenance condition has been           reached. The device under test should be           cleaned soon. Display is continuous.       GOOD   The device under test is within its           sensitivity limit. Display is continuous.       REPLACE   Low maintenance condition has been           reached. The device under test needs to be           replaced right away. The display is           continuous.                  
 
         [0042]    While the reader is on, any time the battery voltage falls too low, the display will change to read LOW BATT. The display is continuous. Once in this mode, the reader  20  stays in this mode until a time period, 30 minutes, has expired or the reader  20  is turned off. No data can be transferred to the reader in this mode.  
         [0043]    While the reader  20  is on, and not in low battery mode, anytime a pushbutton is momentarily pressed and released within 2 seconds, the display will change to a continuous READY to indicate it is ready for another data transfer.  
         [0044]    Any time the reader  20  is on, 30 minutes of inactivity (no button pushes), the reader will automatically turn off.  
         [0045]    Any time the reader  20  is on, if the pushbutton is pressed and held for 2 seconds, the horn will beep, for example for 600 mS, and the reader will turn off.  
         [0046]    Whenever the display changes from one message to the next message, there a 200 mS period of no display separates the messages.  
         [0047]    [0047]FIG. 7A is a flow diagram illustrating exemplary data acquisition and processing by processing circuitry  20   f  utilizing the communication protocol previously discussed in FIG. 3. In a step  112 , the circuitry awaits receipt of an initial pulse, corresponding for example to the 207 μS sample pulse of FIG. 3. Upon receipt thereof, in a step  114 , circuitry  20   f  zeros out a timer and enables that timer.  
         [0048]    In a step  116 , the circuitry waits for the beginning of the next pulse, which, with respect to the protocol of FIG. 3, corresponds to the marker bit. If the time in the timer is less than 247 μS, step  118 , the marker bit will not yet have arrived. If the time in the timer exceeds 247 μS, but is less than 422 μS, step  120 , a valid marker bit pulse has probably been received. In this event, the current value of the timer is saved, step  122 , the timer is zeroed and again enabled.  
         [0049]    The next pulse is awaited, step  124 . If the lapsed time in the timer is less than 40 μS, step  126 , the expected stop bit will have not as yet arrived. If the pulse has arrived and the time is less than 70 μS, step  128 , a valid stop bit has been detected. The second value is saved as T 2 , step  130 , and the timer is zeroed and re-enabled.  
         [0050]    The next pulse is awaited, step  132 . If a pulse arrives within 100 μS, the process returns to step  112  and repeats. Alternately, if 100 μS passes and no additional pulses are received, step  134 , the processing circuitry  20   f  can up-date the display  20   b  based on the contents of the T 1  and T 2  registers, step  136 .  
         [0051]    It will be understood that the above processing methodology of FIG. 7A can be varied to take into account the amount and types of data transmitted, the number and nature of the pulses as well as other analog transmission protocols without departing from the spirit and scope of the present invention.  
         [0052]    [0052]FIG. 7B illustrates the steps of a method  140  of using the reader  20 . In an initial step  142 , the reader is activated by turning it on. Where the reader  20  incorporates an audible output device, the device can be activated to produce an audible alarm and the display  20   b  can be activated to display a “ready” visual indicator, step  144 .  
         [0053]    In a step  146 , the user U positions the reader so as to pick up the relevant radiation from the unit whose parameters or status are being read, such as exemplary unit  16   i.  If the processing circuitry  20   f  determines that valid data from the respective electrical unit has been detected and processed, step  148 , both audible and visible indications will be presented by the unit  20 , step  150 .  
         [0054]    In a step  152 , the display  20   b  can be driven in a toggle mode so as to alternately display, for example, a parameter value such as sensitivity value and a status message. It will be understood that the type of parameter value being displayed is dependent upon the type of electrical unit whose transmission is being sensed. Other types of parameters and messages can be received, demodulated and displayed by the unit  20  without departing from the spirit and scope of the present invention.  
         [0055]    The reader  20  can be turned off by pressing an on/off button, step  154  for a two second interval, step  156 . In such event, the audible device can provide an audible turn off tone step  158  prior to the reader turning off step  160 . Alternately, it will be understood that if the on/off button is held for less than two second, step  156 , alternate functions can be indicated such as freezing the current representation of the display  20   b  or other related functions as would be understood by those of skill in the art.  
         [0056]    Low battery conditions can be indicated by the display  20   b.  Additionally, the unit  20  can be automatically inactivated after a predetermined time interval, such as 30 minutes, to promote a longer battery life.  
         [0057]    It will be understood that alternate embodiments of the unit  20 , responsive to, for example, visible light, come within the spirit and scope of the present invention. Similarly, alternate analog protocols, which might be used with visible light, also come within the spirit and scope of the present invention.  
         [0058]    [0058]FIG. 8 illustrates a detector  16   j,  an alternate embodiment to the detector  16   i.  The detector  16   j  includes a plastic housing  16   j - 1  which carries a smoke chamber  16   j - 2 . The chamber  16   j - 2  could be implemented as a photoelectric smoke chamber or as an ionization-type smoke chamber.  
         [0059]    It will also be understood that the unit  16   j  could carry other types of ambient condition sensors without departing from the spirit and scope of the present invention. These include thermo sensors, gas sensors, position sensors, intrusion sensors, velocity sensors and the like, all without limitation.  
         [0060]    Where the smoke chamber  16   j - 2  is implemented as a photoelectric smoke chamber, it incorporates an emitter  16   j - 3  which could be implemented as an infrared laser diode or light emitting diode. A sensor of scattered radiant energy  16   i j - 4  is carried in chamber  16   j - 2  and is coupled to control circuitry  16   j - 5 .  
         [0061]    The unit  16   j  can be in wireless communication with input/output interface circuitry in control circuits  16   j - 5  which are in turn coupled to bi-directional wired medium  14 . Alternately, at the unit  16   j  can incorporate a wireless antenna, such as the exemplary wireless antenna  24   i - 1  corresponding to wireless communication exhibited by the members of the plurality  24 .  
         [0062]    The electrical unit  16   j  also carries a light emitting diode  16   j - 6  which is carried by housing  16   j - 1  such that the diode  16   j - 6  directly emits radiant energy, such as radiant energy  18   j - 4  into the region in which the unit  16   j  is located. The emitted radiant energy  18   j - 4  which could be emitted as visible light or if desired, as infrared can in turn be sensed by hand-held reader  20 ′. Other alternates include RF or sonic transmission.  
         [0063]    The reader  20 ′ is configured as is the reader  20  for the type of radiant energy, visible or infrared that it is intended to sense. The reader  20 ′ includes processing circuitry  20   f ′ which acquires and demodulates data, such as parameter values, general conditions or status information from electrical units such as the unit  16   j.    
         [0064]    FIGS.  9 A- 9 D illustrate alternate forms of analog modulation processable by processing circuitry  20   f ′, using methodologies which are variations of the processing methodology of FIG. A as would be understood by those of skill in the art. FIG. 9A illustrates a protocol which incorporates pulse position modulation. A start pulse is followed by three positioned defined data intervals. Pulse width in this protocol may not be important. Using the analog modulation scheme of FIG. 9A, three pieces of data can be transferred from the respective electrical unit in an analog format. It will be understood that less than or more than three pieces of information can be transferred without departing from the spirit and scope of the present invention.  
         [0065]    [0065]FIG. 9B illustrates frequency modulation wherein pluralities of pulses are frequency modulated, to indicate various values of parameters or status. With this protocol, neither the pulse width nor the pulse amplitude are necessarily critical.  
         [0066]    [0066]FIG. 9C illustrates transfer of three parameter values or status indicators using pulse width modulation. The widths of the respective pulses are modulated by the information being transferred. With this modulation, pulse amplitude may not be critical.  
         [0067]    [0067]FIG. 9D illustrates transfer of information from an electrical unit to the reader  20 ′ using pulse amplitude modulation. In this protocol, the amplitude of the respective pulses is modulated in accordance with the information to be transmitted. Pulse width may not be critical in this modulation scheme.  
         [0068]    It will be understood that one or more of the protocols of FIGS. 9A through 9D can be combined and used to transfer additional information in a single transmission. For example, pulse width and pulse amplitude-type modulation can be combined in a common transmission. Similarly, pulse position modulation could be combined with pulse amplitude modulation to improve transmission efficiency.  
         [0069]    It will also be understood that the reader  20 ′ could be used to decode parameter values or status information from electrical units which incorporate a wide variety of ambient condition sensors. In addition, parameter values or status information can be read from other types of electrical units such as output devices which control audible or visible output devices, lock or unlock doors, or the like all without limitation.  
         [0070]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.
An ambient condition detector incorporates a common radiant energy source to carry out a first, sensing, function and a second, information transmitting function. The source can generate a beam to implement a fire sensing function. In addition, modulated radiant energy emitted from the source can be remotely sensed to determine detector status or internal parameter values. In an alternate embodiment, a source of radiant energy can be configured at an exterior periphery of the detector and information can be wirelessly transmitted therefrom using one or more analog modulation processes.