2. Outline:-
Introduction
what can wi-vi do?
Working
Challenges faced
Flash effect
Tracking human movements
Methods used to overcome the challenges
how we can track using reflections?
Applications
Advantages & limitations
future scope
Reference
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3. Introduction
Wi-Vi was created by Dina Katabi , a professor in MIT,
and her graduate student Fadel Adib.
Wi-vi stands for wireless vision.
It captures moving objects behind the wall.
Device uses typically wi-fi hardware.
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4. 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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5. Working
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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7. Flash effect:
When you take a device, point it at a wall, and transmit
Wi-Fi signals, a huge amount of reflection is going to
come from the wall itself.
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8. Tracking human movement:
when we get reflections from behind the wall ,we will get
reflections from everything in the environment: the chairs
,tables , and so on. How can we tease out the person’s
reflections from all of these reflections? And once we do
that, how can we track a person based on these reflections.
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9. Method used to overcome the
challenges:
Idea: transmit two waves that cancel each other when they
reflect off static objects but not moving objects
wall is static disappears
people tend detectable
to move
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13. How can we track using
reflections?
• Human reflects the signal, it’s as if he is the source of
that signal.
• We know that if you want to track an RF source, you can
do that using an antenna array.
• By steering the beam of the array, we can find the
direction of from which the signal is coming.
• Now, when a person moves, that direction would change,
and we are able to track him.
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18. Advantages:
Wi-vi require same bandwidth & operates in the same
range as wi-fi.
Wi-vi can perform through wall imaging without access
to any device on the other side of the wall.
Wi-vi employs signals whose wavelength 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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19. 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 about 50 cm.
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20. Future scope:
Wi-vi could be built into a smartphones or a special
handheld device.
Evolution of seeing humans through denser building
material and with a longer range.
High quality images.
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