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WI-VI TECHNOLOGY-Seeing through walls….
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CONTENTS:IntroductionWhat can Wi Vi do?Basic principleHow it works?ApplicationsAdvantagesLimitationsFuture scopeConclusion
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INTRODUCTION
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Wi-Vi
- Wireless Device- Captures moving objects behind the wall
- Through Wall Imaging
- Relatively Low power
- Low Cost- Low Bandwidth
- It is 3 antenna MIMO Device
- Two transmitting and one receiving antenna.
- Limits itself to a 20 MHz-wide Wi-Fi channel, and avoids ultra-wide band solutions
- Two modes of use:- Image moving
objects behind the wall
- Gesture based interface
- Uses Wi-Fi signals in ISM band(2.4Ghz)
- Typically Wi-Fi Hardware
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KEY IDEA
Wi-ViDevice
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WHAT CAN WI VI DO?
Detect the Number of Moving Humans in a Closed Room.
Determine the Relative Locations of Moving Humans.
Enable Communication through a Wall without Carrying a
Wireless Device.
Identify Simple Gestures from Behind a Wall.
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BASIC PRINCIPLE:Based on the principle of RADAR and SONAR
imaging.WI-VI is potentially an X-RAY vision created with low
power Wi-Fi signals.This tech uses reflected Wi-Fi signals to track the
movement of people behind walls.See through movement behind walls.
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HOW IT WORKS: WI-VI uses two transmitting antennas and a single
receiver. Transmitting signals are low power Wi-Fi signals. The two antennas transmit almost identical signals,
except the second antenna's signal is the inverse of the first, resulting in interference.
9receiver
obstacle180˚ inverse
DIRECTION OF SIGNAL
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• Any static objects that the signals hit including the wall create identical reflections, they too are cancelled out by this nulling effect.
• Only those reflections that change between the two signals, such as those from a moving object, arrive back at the reciever.
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WI-VI SETUP
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• As the person moves through the room, his or her distance from the receiver changes, meaning the time it takes for the reflected signal to make its way back to the receiver changes.
• The system then uses this information to calculate where the person is at any one time.
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ALL REFLECTIONS FROM STATIC OBJECTS ARE CANCELLED OUT, AND THE ONLY THING REGISTERED BY THE DEVICE IS THE MOVING HUMAN.
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Applications Police avoids ambush Firefighters check for humans
Personal Security Gesture Interface from behind a wall
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Advantages Wi-Vi requires only few MHz of bandwidth and operates in
the same range as Wi-Fi. It operates in ISM band.
Wi-Vi can perform through-wall imaging without access to
any device on the other side of the wall.
Wi-Vi employs signals whose wavelengths are 12.5 cm.
Extend human vision beyond the visible electromagnetic
range, allowing us to detect objects in the dark or in smoke.
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Limitations
Display has very low resolution.
We cannot detect humans behind concrete walls thicker
than 8".
To achieve a narrow beam the human needs to move by
about 4 wavelengths (i.e., about 50 cm).
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Future Scope Wi-Vi could be built into a Smartphone or a special
handheld device.
Can be used in search-and-rescue missions and law
enforcement
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Conclusion
Smart hand held device which gives an insight vision through walls.
Could prove to be very powerful and effective device for defence purposes.
Possibly the next generation RADAR.
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Bibliography
http://people.csail.mit.edu/fadel/wivi/
Fadel Adib and Dina Katabi, See Through Walls with Wi-Fi,
ACM SIGCOMM'13, Hong Kong August 2013.
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THANK YOU
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