Patent Application
20150326314
The application pertains to multi-modal communications systems. More particularly, the application pertains to such systems which incorporate multiple, wireless communications systems of substantially different wavelengths which can operate in tandem.
Various types of wireless RF communications 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.
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 same, and is not intended to limit the claims hereof to the specific embodiment illustrated.
Visible Light Communication (VLC) is a non-disruptive wireless communications 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, 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 communications service in addition to providing illumination.
In fact RF communications and VL communications 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 communications systems follow. The particular characteristics of the different types of communications systems can be selected and allocated to implement various functions which might be difficult or expensive to implement with one type of communications system but which 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 communications 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, all go sound operation is possible. Redundant operation preserves batteries in the RF emergency devices by using VLC communications 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 here 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.
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 as well as solenoids or other types of actuators all without limitation. For example, unit 12a can be implemented as a fire detector, 12b, could be implemented as a gas detector and 12c could be implemented as an intrusion detector. Unit 12d 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 communications mode which can compliment the above noted RF communications mode of operation. For example devices 18a, 18b, 18c . . . 18p can provide illumination to the respective adjacent regions such as S1-1, S1-2 . . . S1-n in space S1, or S2-1, S2-2 in space S2. 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, manually operable switch 20 can be used to turn on a light emitting diode source 18b which can not only provide illumination in sub-region S2-1 but also emit the above noted modulated, visible, radiant energy V which can in turn cause actuator 12d to open or close a curtain, or shade, C, or unlock a door. Radiant energy signals V from switch 20 could also provide synchronization signals to detectors, or output devices 12b,c. The devices 12b, c can then communicate via RF communication links R with the monitoring system 16 or other units in the building B.
Optionally, unit 18i can also include an RF transceiver 46 and one or more sensors 48 as desired. Those of skill will understand that exemplary illumination element 18i can implement a variety of communications modes in accordance herewith to maximize battery life of the various wireless units 12i or to provide additional “smart house” functionality as desired.
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.
