technology used to see through walls

1. WI-VI TECHNOLOGY
-Seeing through walls….
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2. CONTENTS:
Introduction
What can Wi Vi do?
Basic principle
How it works?
Applications
Advantages
Limitations
Future scope
Conclusion 2

3. INTRODUCTION
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4. 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
- 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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5. KEY IDEA
Wi-Vi
Device
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6. 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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7. 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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8. 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.
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9. receiver
obstacle
180˚ inverse
DIRECTION OF
SIGNAL
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10. • 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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11. WI-VI SETUP
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12. • 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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13. ALL REFLECTIONS FROM STATIC OBJECTS ARE CANCELLED OUT, AND THE ONLY
THING REGISTERED BY THE DEVICE IS THE MOVING HUMAN.
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14. Applications
Police avoids ambush Firefighters check for humans
Personal Security Gesture Interface from behind a wall
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15. 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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16. 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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17. 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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18. 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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19. 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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20. THANK YOU
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