Light is better than radio waves
when it comes to some wireless communications, a new study has
found.
Optical communications systems could provide faster,
more secure communications with wider bandwidth and would be
suitable for restricted areas like hospitals, aircraft and
factories.
Sending information via light waves either in
physical light guides or wirelessly is not new, but existing
wireless systems either require direct line of sight or are diffused
and have low signal strength.
Penn State University (PSU)
engineers chose to take a different approach using multi-element
transmitters and multi-branch optical receivers in a quasi-diffuse
configuration.
The system uses a high-powered laser diode --
a device that converts electricity into light -- as the optical
transmitter and an avalanche photo diode, a device that converts
light to electricity, as the receiver. The light bounces off the
walls and is picked up by the receiver.
'Unless the walls are
painted solid black, there is no need to worry about transmission
within a room,' said Jarir Fadlullah, PSU graduate student in
electrical engineering.
The researchers tested infrared
light, but the system will also work with visible light and
ultraviolet light.
'The optical system we have offers a very
large bandwidth thus a very high speed,' said Fadlullah. 'We can
send one gigabit per second or more over a gigahertz
band.'
The researchers, including Mohshen Kavehrad, PSU
professor of electrical engineering, think this looks like an ideal
system.
Radio frequency systems do not require line of sight
transmission, but can pass through some substances and so present a
security problem, said a release.
The study was presented
Wednesday at SPIE Phonotics West Conference in San Francisco.
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Word on the street in the Gulf
is that the Israeli army is preparing for a new war in either
the Palestinian territories or Lebanon. The talk is Syria
might also be drawn in, turning any conflict into a regional
war. Whatever the situation, Israel is not giving anything
away.
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Breaking News
Friday 5th February, 2010
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