D-Light Project,working Principle
D-Light Project
D-Light, which means
“data through illumination”, A invention of Professor Harald Hass. He says
that his invention can produce data rates faster than 10 Mbps, which is
speedier than average broadband connection. He visualizes a future where data
for laptops, smartphones, and tablets is transmitted through the light in a
room, but Haas says that this version is limited by existing LEDs and by the
usage of LEDs as transmitters and detectors at the same time. However, he has
created a better LED, which provides a data rate close to 4 Gbps operating on
just 5 milliwatt of optical output power and using high bandwidth photo diodes
at the receiver. Haas says that we can send data with a distance of 10 meters
at up to 1.1 Gbps with a simple lens, and soon they will increase that up to 15
Gbps. The 802.11ad Wi-Fi standard for the 60 GHz radio band reaches just under
7 Gbps, so Li-Fi would more than double of that rate.
D-Light
system uses Orthogonal Frequency Division Multiplexing (OFDM) techniques, which
allows us to vary the intensity of the LEDs output at a very fast rate,
invisible to the human eye; for the eye, the bulb would simply be on and
providing light. The signal can be picked up by simple receivers. He says: “It
should be so cheap that it is everywhere. Using the visible light spectrum,
which comes for free”.
Working Principle
Li-Fi technology is
implemented using white LED light bulbs used for illumination by applying a
constant current. However, by fast variations of the current, the light output
can be made to vary at extremely high speeds. If the LED is on, it transmits a
digital 1 otherwise it transmits a digital 0. The LEDs can be switched on and
off quickly to transmit data that can't be detected by a human eye.
So what we need at all for sending data
are some LEDs and a controller that cods data into those LEDs and for receiving
data, we need an Image Sensor, Photodiode which is used as a detector.
The LED bulb will
hold a micro-chip that will do the job of processing the data. The light
intensity can be manipulated to send data by tiny changes in amplitude. for data transmission; it can be
done by single LED or multi LED. On the receiver side there is a photo
detector, which convert this light into electric signals and it will give the
electric signals to the device connected to it. Voltage regulator and level
shifter circuits are used on both sides to convert or maintain a voltage level
between transmitter and receiver.
NAXT COMING:::Advantages
