Abstract:
A system having first and second different communication systems can include a plurality of illumination devices having modulatable optical output signals. A plurality of building control units are in wireless communication with one another. Representative units could include ambient condition detectors, intrusion detectors, output devices, or actuators. At least some of the units include optical sensors responsive to the modulatable optical output signals, wherein, in response to received, modulated optical output signals, a respective control unit carries out a predetermined function.

Description:
FIELD 
     The application pertains to multi-modal communication systems. More particularly, the application pertains to such systems that incorporate multiple, wireless communication systems of substantially different wavelengths that can operate in tandem. 
     BACKGROUND 
     Various types of wireless RF communication systems are known for use in building automation, monitoring, and control systems. While useful, there are limitations as to the type of functionality that such systems can provide. Such systems can also suffer from eavesdropping and exposure to foreign third parties along with power related limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a system in accordance herewith; 
         FIG. 2  is a block diagram of an illumination element in accordance herewith; and 
         FIG. 3  is a block diagram of a radio frequency enabled device in accordance herewith. 
     
    
    
     DETAILED DESCRIPTION 
     While disclosed embodiments can take many different forms, specific embodiments hereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles hereof as well as the best mode of practicing the same and is not intended to limit the claims hereof to the specific embodiment illustrated. 
     Visible Light Communication (VLC) is a non-disruptive wireless communication solution made possible by the advent of light emitting diode (LED) building illumination systems. A key property of LED lighting is that it can be amplitude modulated at very high rates, providing good data transmission without affecting the illumination function itself. 
     VLC has several advantages over traditional RF communication systems; the operation is unlicensed, and the transmission path is contained (by walls) so spatial re-use is not an issue nor is eavesdropping beyond the room/building walls a problem. Further, the cost of transmission and reception is low. Since wavelengths are short, there are good ranging and location opportunities. The downsides of VLC are short operating range and, of course, the lights need to be powered and modulated to operate as a communication service in addition to providing illumination. 
     In fact, RF communication and VL communication operating together offer several complementary properties. As discussed below, complementary or tandem operation offers additional control configurations not available with a single wireless system. 
     Examples of functionality available with multi-modal communication systems follow. The particular characteristics of the different types of communication systems can be selected and allocated to implement various functions that might be difficult or expensive to implement with one type of communication system, but that can be very cost effectively provided with the second type of system. 
     Those of skill will understand that the following are exemplary only and are not limitations hereof. Numerous additional possibilities are available with multiple complimentary communication systems. 
     In particular, the following exemplary functionality is possible with VLC and RF communication systems operating in tandem. The following examples contribute to extending battery life of wireless units. Synchronized sirens or sounders can be provided for battery-powered smoke detectors. In such instances, if one goes, then all go sound operation is possible. Redundant operation preserves batteries in the RF emergency devices by using VLC communication when the lights are on and RF when they are not. 
     Synchronizing optical signals can be sent to RF transceivers at much lower operating current in the battery powered device than would be possible if synchronization was via the RF signals. In-building location services can be provided. In this regard, a security system portable tablet control unit or phone could use its built-in camera to detect the nearest modulated LED light fixture and, therefore, its location, again enabling smart room operation. 
     In yet another aspect, smart room RF based functionality can be augmented. For example, a manually operated light switch can indicate occupancy and can trigger other devices in the illuminated area when the light is turned on or energized. A shade or blind can automatically be closed when the light is turned on. Similarly, the heat could be turned on or up or a door locked or unlocked in response to a light being turned on. Status requests to remote detectors could reduce overall quiescent current if the request to the battery powered detector was via VLC with the sensor response via RF. Those of skill will understand that these are examples and not limitations hereof. 
     In principle, the enabling technology includes an ability to amplitude modulate individual LED light fixtures in conjunction with the capability of high speed photo diodes to detect messages in building control products and portable devices. As those of skill will understand, the examples disclosed herein require various data protocols—both RF and visible light—to enable timing accuracy for timing and synchronization. Addressable lighting fixtures and control devices that can detect RF and/or VLC signals are useful in the present context. 
     Further, elements of the VLC system can transmit a change of status indication, for example, “turning-off”, to alert local RF devices. Alternately, a change of status message indicating “light on” could also be transmitted. 
       FIG. 1  illustrates a system  10  in accordance herewith installed in a building B. The building B has two floors indicated by spaces S 1 , S 2 . A plurality  12  of detectors and/or output devices  12   a ,  12   b ,  12   c  . . .  12   n , which can be in wireless RF communication R, are illustrated scattered throughout the building B as would be understood by those of skill in the art. 
     The plurality  12  can include fire or gas detectors, intrusion or other security monitoring detectors, output devices, such as audible or visual alarm indicating devices, or solenoids or other types of actuators all without limitation. For example, the unit  12   a  can be implemented as a fire detector, the unit  12   b  could be implemented as a gas detector, and the unit  12   c  could be implemented as an intrusion detector. The unit  12   d  can be an actuator, which could implement a linear motion in response to a received command. All such devices can be in wireless RF communication R with a displaced monitoring system control unit  16 . 
     Other devices in a plurality  18  can emit visible light and provide both an illumination function as well as modulated beams of radiant energy V, which can provide a second communication mode that can compliment the above noted RF communication mode of operation. For example, the devices  18   a ,  18   b ,  18   c  . . .  18   p  can provide illumination to the respective adjacent regions, such as S 1 - 1 , S 1 - 2  . . . S 1 - n  in space S 1  or S 2 - 1 , S 2 - 2  in space S 2 . In addition, such devices can emit modulated beams of visible radiant energy V, which can provide additional or different control functions than provided by the wireless RF system. 
     For example, a manually operable switch  20  can be used to turn on a light emitting diode source  18   b , which can not only provide illumination in sub-region S 2 - 1 , but also emit the above noted modulated, visible, radiant energy V, which can, in turn, cause the actuator  12   d  to open or close a curtain or shade C or unlock a door. Radiant energy signals V from the switch  20  could also provide synchronization signals to the detectors or output devices  12   b,c . The devices  12   b, c  can then communicate via RF communication links R with the monitoring system  16  or other units in the building B. 
       FIG. 2  is a block diagram of an illumination element, such as  18   i , in accordance herewith. The element  18   i  includes a housing  40 , which carries a source  42  of visible light, for example, one or more light-emitting-diodes. Control circuits  44  can energize the source  42  to provide both visible light for illumination and a modulated, coded, data sequence, which can be detected and responded to by other units in the vicinity of the element  18   i.    
     Optionally, the unit  18   i  can also include an RF transceiver  46  and one or more sensors  48  as desired. Those of skill will understand that the exemplary illumination element  18   i  can implement a variety of communication modes in accordance herewith to maximize battery life of the various wireless units  12   i  or to provide additional “smart house” functionality as desired. 
       FIG. 3  is a block diagram of a detector or actuator  12   i , such as  12   a - 12   d . The unit  12   i  can be carried by a housing  50  and include light sensors  52 , which can respond to coded messages from the element  18   i  as described above. Control circuits  54  can decode messages received from the sensors  52  and/or RF messages received from a transceiver  56 . The units, such as  12   i , can carry one or more condition sensors and/or actuators as at  58  all without limitation. The units, such as  12   i , can be energized by batteries B whose life can be extended by the above described processes of using multi-model communication. 
     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.