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Morse Code Hidden In The Light: Visible Light Communication

Mar 12, 2018

The wireless vanguard is "blue"

From the propagation characteristics of visible light communication still belongs to a kind of wireless communication, information transmission carrier is not only the traditional radio waves (3 hz ~ 3000 hz frequency range), but the terahertz frequencies as high as 384 ~ 769 of visible light waves.It is a kind of to transmit data using visible light spectrum as a carrier to a new wireless transmission technology, through to the LED bulb installed microchips, can control its flickering millions of times per second, which represents a "1" the light is bright, on behalf of the "0" lights are out, binary data is encoded into light fast and effective transmission.

And light mobile phones, tablets, and other kinds of terminal equipment, through the integration of photosensitive sensor can be read in light of the "Moore Smith code", so as to achieve the purpose of high-speed information transmission.From this point of view, compared with the "big brother" of radio wave communication, visible light communication is not very different in basic principle, but has a special advantage of "blue out of blue".

More bandwidth.At present, the traditional radio wave communication is facing the dilemma of "spectrum shortage", and the trend of preemption is more obvious with the available spectrum of 10 ~ 60 GHZ.The spectrum width of optical communication is 4 orders of magnitude higher than that of existing radio waves, and there is no need to worry about the problem of insufficient spectrum.

Networking is more alive.The traditional network of radio wave communication network is complex, which requires the installation of information infrastructure and terminal equipment of a large number of radio-frequency signals, and it is extremely easy to generate electromagnetic compatibility and interference problems.And visible light communication does not need to establish base station, also need not spectrum licensing, simply add chip in LED bulbs, you can make it a "communications base station" "wireless router" "GPS satellite navigation, and other functions, so as to realize where there is a light, there is a network signal, realize" end through "" pan on the Internet.For the cabin interior, surface ships and submarines, underground tunnels, such as radio waves propagation limited environment, can greatly make up for the inadequacy of electromagnetic coverage, and effectively avoid the electromagnetic compatibility and interference problems.

Better confidentiality.Due to the visible light communication must be in LED light source is open to transfer, the functions of close communication will fail, so just add shading devices, but did not make the light through a closed communication network can be formed, its security level is higher than other wireless transmission technology.In addition, due to the visible light is only transmitted along a straight line, and the uplink and downlink channel is run independently, hackers must be in the same room, and into two channels at the same time to complete a real sense of attack, to the outside of the light transmission lines to steal signals and interference is very difficult.

International competition is heating up.

Japan initiated the study of visible light communication.As early as 2000, the research office of nakagawa put forward an indoor communication system test using LED lighting as the communication base station for wireless transmission of information.In 2014, Japan's TAKAYA company developed an optical communication system with a speed of 10 megabits per second.In may of the same year, Japan's dongyang electric machine developed an underwater visible high-speed communication device, which peaked at 50 megabits per second.

European countries are not far behind. Their work in visible light communication is driven by the OMEGA program of more than 20 universities, research institutes and businesses in Europe.In November 2015, Velmenni, Estonia, demonstrated a prototype light bulb with a peak data transmission rate of 224 gigabits per second under laboratory conditions.

As the world's leading scientific and technological power, the United States is seeking to seek the dominant position in global optical communication technology and market.Giant of science and technology, represented by Google and ERC Boston university center, the university of California at UC - Light, Penn state university COWA center, scientific research institutions, is gearing up for visible Light communication standard protocols and related systems research and development work, and start the mechanism and strategy of related market research.

Although the vision of optical communication is beautiful, it still needs to break through a series of technical bottlenecks, which is expected to be widely used.For example, how to convert the potential of visible light bandwidth into broadband capacity is currently constrained by the modulation bandwidth of white leds, which requires further technological breakthroughs.For example, both the signal control of LED lights and the real-time processing after receiving the signal need special integrated chip, which is still very weak in this field.For example, the wavelength of visible light signal is very short, and it is very easy to attenuate rapidly in the transmission medium, which directly leads to the limitation of communication distance, and it is difficult to realize high-speed transmission at long distance.

In this regard, countries around the world have launched the key technology of visible light communication, and strive to seize the first opportunity in the slice of this cake.

There is much to be done in the future.

In the future, it is not easy to meet the growing demand for wireless communication in the military field: large transmission capacity, flexible networking, good electromagnetic compatibility, high confidentiality requirements...The traditional radio wave communication faces severe challenges.However, the special advantages of optical communication enable it not only to integrate with radio wave communication, but also to demonstrate its ability in other fields.

The communication expert of "heaven", "go to earth" and "go to sea".In the internal communications of aircraft, underground tunnels, surface ships, submarines and other special places, the use of radio equipment is often strictly limited in order to prevent the interference of rf signals.O the falklands war in 1982, the British "Sheffield" because of the shipboard wireless communication system compatible with between ship-borne warning radar is difficult to share, so that the radar to fail to boot and found that the incoming missiles "flying fish", a direct result of the ship capsized during the catastrophic consequences.And with visible light communication, only in the special place with central controller, and a series of LED light source, can effectively avoid electromagnetic interference, while a communication so as to realize the fast communication for the inside of a combat platform, communication, underwater special operations for communication, etc. Provide efficient and safe means of communication.

"Expert" in high-precision navigation and positioning.Visible light communication is through the central controller to send the LED information navigation information node, to within the scope of visible light as a carrier to light weapons platform terminal, the terminal USES built-in photosensitive detector can obtain the most timely dynamic battlefield environment, the optimal route and coordinates navigation and positioning information.According to the research, it can be used to achieve the accuracy of visible light navigation in centigrade by taking measures such as the network scientific layout, algorithm design and signal processing optimization of the battlefield LED information node.

Target identification and battlefield anti - injury weapon.Through to get all kinds of weapons platform equipped with LED lights recognition device, platform and platform, platform and the LED information between nodes can rely on a specific signal coding to conduct real-time communication and identification, weapons platform through to read received LED lights flashing patterns, can effectively determine the signal against property, so as to make effective measures in time, the greatest degree to ensure their own safety.