Patent Grant
9917644
The present disclosure relates to the communication of data using light, specifically the communicating of data based on imperceptible changes in the modulation of a visible light source.
The ability to use light to transmit information has been known for centuries. For example, the photophone uses modulated sunlight to transmit information, in that the brightness of a reflected beam of light observed at the receiver, varied based on audio-frequency variation in air pressure (e.g., sound wavers) which act upon the mirror. In this design, the transmitter has sunlight reflected off a surface of a over a thin mirror positioned at an end of a speaking tube, as words are spoken the mirror oscillates between convex and concave shapes, altering the amount of light reflected from its surface to the receiver. Another example of known communication techniques using light include Morse code in which the visible on/off switching (e.g., pulsing) of a light source is decoded by an observer to obtain the text information. Other techniques and implementations using modulated light to transmit information are known, however, in each of these techniques the modulation of the light source is perceptible by the human eye, which can enable the communicated data to be compromised.
The present disclosure provides a description of a systems and methods for communicating data using imperceptible changes in light.
An exemplary lighting system for data communication is disclosed, comprising: a light source configured to emit light; a processing device configured to receive data for communication and generate a signal encoded with the received data; and a modulator configured to modulate light emitted by the light source, wherein the modulation is imperceptible to the human eye, and the modulated light includes the encoded data.
An exemplary lighting system for communicating data is disclosed, comprising: an input device configured to receive data for communication; an encoding device configured to generate a signal encoded with the received data; a light source configured to emit light; a modulator configured to modulate light emitted by the light source, wherein the modulation is imperceptible to the human eye, and the modulated light includes the encoded data; a receiver configured to receive the modulated light signal including the encoded data and convert the received light to a current signal; a decoding device configured to obtain the encoded data from the current signal, decode the encoded data, and perform and identification or authentication based on the decoded data; and an interface configured to generate an output based on a result of the identification or authentication.
An exemplary method for communicating data using light is disclosed, comprising: identifying, by a processing device, data to be communicated; encoding, by the processing device, the data to be communicated into a signal; transmitting light via a light source; modulating, using an optical or electrical signal modulator, the transmitted light to transmit the encoded signal, wherein the modulation of the transmitted light is imperceptible to a human eye; receiving, by a receiving device, the modulated light; identifying, based on imperceptible changes in the modulated light, the encoded signal; and decoding the signal to obtain the encoded data.
Exemplary embodiments are best understood from the following detailed description when read in conjunction with the accompanying drawings. Included in the drawings are the following figures:
Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description of exemplary embodiments are intended for illustration purposes only and are, therefore, not intended to necessarily limit the scope of the disclosure.
The data to be communicated may be transmitted to an encoding device 104. The encoding device 104 may be configured to encode the data into a signal. Devices and circuits suitable for encoding the data will be apparent to persons having skill in the relevant art, and may include amplifiers, processors, microprocessors, etc.
In some embodiments, the input device 102 and the encoding device 104 may be a single device. In other embodiments, the input device 102 may transmit the data to the encoding device 104 via a network. Suitable types and configurations of the network will be apparent to persons having skill in the relevant art and may include Near Field Communications (NFC), Bluetooth, radio frequency, infrared, local area network (LAN), wireless area network (WAN), etc.
The encoded signal may then be transmitted to a light 106. The light 106 may include a light source 108 and a modulation device 110. In some embodiments, the modulation device 110 may be separate from the light 106. In a further embodiment, the modulation device 110 may be included in the encoding device 104. In an even further embodiment, the input device 102, the encoding device 104, and the modulation device 110 may be a single device.
The light source 108 may be any type of light source suitable for performing the functions as disclosed herein. In an exemplary embodiment, the light source 108 may be a solid-state light source, such as a light emitting diode (LED). In other embodiments, the light source 108 may be an incandescent light, iridescent light, halogen lamp, compact fluorescent lamp, a light-emitting electrochemical cell, or an infrared lamp. The light source 108 may emit light towards a receiving device 112. In some embodiments, the light source 108 may be directed (e.g., transmitted) in a specific direction or orientation. In one embodiment, the light 106 may include a filter 107 to filter the light emitted by the light source 108 (e.g., to emit a specific wavelength or range of wavelengths). The light source 108 may either be a visible light source or an invisible (e.g., to the human eye) light source.
The modulation device 110 may be any type of device suitable for modulating the light emitted by the light source 108. For example, the modulation device 110 may be a switch configured to turn the light source 108 on and off, a dimmer configured to dim or brighten the light emitted by the light source 108 by a predetermined amount, etc. The modulation device 110 may be implemented using components apparent to persons having skill in the relevant art, such as processors, microprocessors, etc. The modulation device 110 may modulate the light emitted by the light source 108 such that the changes in the light are imperceptible to the human eye. The modulation device 110 may use any modulation technique suitable for performing the functions as disclosed herein, such as frequency-shift keying, phase-shift keying, amplitude-shift keying, on-off keying, quadrature amplitude modulation, continuous phase modulation, etc. More specifically, the modulation technique could be selected from an analog-to-digital converter (if needed) and a square wave formation circuit to drive a power source to the light emitter, but can be much more complex including data security encryption (e.g., RSA 128 bit encryption) in addition to converting the signal into a modulated form suitable for the physical layer transmission. Physical layer modulation includes, by way of example only, such modulation techniques as analog modulation (e.g. AM, FM, PM, QAM, SM, and SSB), digital modulation (e.g., ASK, CPM, FSK, MFSK, MSK, OOK, PPM, PSK, QAM, SC-FDE, TCM) spread spectrum (e.g., CSS, DSSS, FHSS, THSS). The modulation device 110 may modulate the light emitted by the light source 108 such that the modulated light transmits the encoded signal including the data to be communicated.
The receiving device 112 may be configured to receive the modulated light emitted by the light source 108. The receiving device 112 may be any device suitable for performing the functions as disclosed herein, such as a photocell, etc. The receiving device 112 may be configured to convert the received light to a current. In some embodiments, the receiving device 112 may also include a filter, which may be configured to filter out noise based on ambient light or light from external light sources (e.g., the sun, street and parking lot lighting, overhead lighting, etc.). The receiving device 112 may include additional components as will be apparent to persons having skill in the relevant art, such as an amplifier. The receiving device 112 may transmit the processed signal of the emitted light to a decoding device 114.
The decoding device 114 may be configured to decode the signal as received and processed by the receiving device 112. Methods for decoding the signal will be apparent to persons having skill in the relevant art and may be based on the modulation technique employed by the modulation device 110. The decoding device 114 may use any components necessary to decode the signal, such as processor, microprocessors, etc., and obtain the encoded data. The decoding device 114 may then transmit the decoded data to a display device 116, which may display the decoded data to a user. It will be apparent to persons having skill in the relevant art that the receiving device 112 and decoding device 114 may be a single device. In one embodiment, the receiving device 112, the decoding device 114, and the display device 116 may be a single device.
The system 100 may be used to perform one-way or two-way communication of data using light. Suitable applications for the system 100 will be apparent to persons having skill in the relevant art and may vary widely. In one application, the system 100 may be used to authenticate a vehicle. For example, the headlights of a car may emit light that may be modulated using changes imperceptible to the human eye, but which may be read by a receiving device at a security checkpoint (e.g., for a controlled area, on a toll road, etc.). The receiving device may process the modulated light to determine the identity of the vehicle based on the modulation, which may be used for authentication. In some embodiments, the modulation may be specific to the vehicle. In other embodiments, the modulation may alternatively or additionally be specific to the operator of the vehicle, such as by the operator using an identification card or inputting authentication information on an input device 102 in the vehicle. The system 100 may be implemented in an aftermarket device in order to facilitate such an application, such as by installation into the headlight itself (e.g., as an intermediate add-on modulator between the power source and the head lamp, running lights, interior lights, etc.) at the connector to the headlight or other light source, or at the control for the headlights located in the interior of the vehicle.
The light source might be selected because it is a preexisting or common light source (head or running lights, flashlights, room lighting, etc.) that is not typically thought of as being useful for modern communications. Unlike light signally for human observation (e.g., ship-to-ship light signaling using Morse Code), the frequency of the light modulation, whether by on/off modulation of just controlling the light output level occurs at a speed faster that a human can perceive the pulsing or dimming or shifting of the light spectrum. Common electronic sensors, such as video or traffic cameras at common frame rates of 28-36 frames per second, would also not perceive the light signaling. Hence, the light signaling can be accomplished without human or accidental perception but common light sensors and recorders. For instance, the frequency can be in the range of a thousand or more hertz. This means that the photo sensor/receiver has to be specifically tuned or designed to detect the light signal, and most people would not think to inspect the light source for hidden signals, because they are common light sources. This is useful for toll and security gates in a vehicle environment, of example. Further still, the light source and/or receiver might be directional for greater signal to noise ratios and reduced chances of detection.
Other suitable applications of the system 100 will be apparent to persons having skill in the relevant art and may include, for example, the shipping industry, the airline industry, etc.
It will be apparent to persons having skill in the relevant art that the system 100 may be configured to perform both half duplex and full duplex communications.
Techniques consistent with the present disclosure provide, among other features, systems, and methods for the communicating data using imperceptible changes in light. While various exemplary embodiments of the disclosed system and method have been described above, it should be understood that they have been presented for purposes of example only, not limitations. It is not exhaustive and does not limit the disclosure to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practicing of the disclosure, without departing from the breadth or scope.
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| 20140099107 A1 | Apr 2014 | US |
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| 61711299 | Oct 2012 | US |
