Radio Signals | Wi-Fi

Notes by Alfe Corona on the presentation of Dr. Alam at Fordham University on 24 January 2018.

Watching Ubiquitous Radio Signal Activities

Sensing and Security Application Perspectives.

Using signals we may be able to detect if others are alive. For rescue operations. I.E. : Building collapse, fire event.

The types of signals we may use for detection are:

  • Modulated magnetic signal
  • Ambient sound
  • FM
  • Bluetooth
  • Modulated lights
  • Wi-Fi

Each signal has its pros and cons.

We will focus on Wi-Fi.

Using Wi-Fi we are able to see through walls using Wi-Vi.

  • WiSee: Able to see body movements. I.E. Kicking, walking, etcetera.
  • AllSee
  • WiHear
  • WiTrack:I.E. Single person seating.
  • Wi-Draw: We are able to create a drawing based on where the person moves.
  • KeyStroke: We are able to detect what people are typing on their computers.
  • EQ-Radio: We can detect peoples emotional state. I.E. Happy, sad, angry, etcetera.

You use yourself as a remote controller for changing TV channels, changing apartment temperature, turning lights on or off, etcetera.

Touchless heart beat and breadth monitoring. Useful for rescue operations. I.E. Landslide, fire, earthquake, trap and healthcare monitoring.

CSI is Channel State Information. Has to do with send and receive signals status.


Physical security to CyberSecurity:

  • There are good applications and bad applications. I.E. Capture of finger movements and mouth movement to detect what is being communicated.
  • Some of the future works to be used in our favor are: Physical Security Gun detection. Because police can't search without a search warrant. And cameras don't work which raise and security concern.
  • We can have Wi-Fi surveillance. Used for home security. Online Intrusion Detection.
  • Can be used for spying, monitoring people movements, personal security‚ĶAnd military surveillance.
  • For Law enforcement.
  • For Gaming.
  • Can be used for smart fall detection. It can alert you if the floor is going down or up to save you from falling.

Challenges/Solutions:

  • Some of the challenges we have are to remove noise from radio signals to have better accuracy of detection.
  • The use of machine learning, data mining, signal acquisition.
  • Ensure router, mobile are not monitoring/tracking you.


In lame terms, the experience of Wi-Fi signal to detect people's body movement and tracking can be compared to the radio communication that Naval Submarines use. Where the Submarine sends a signal underwater which travels hundreds of miles and in the radio control room the Submarine is able to detect everything under water from shrimps, sharks, other submarines, surface ships, distance from point A to point B, the exact position of things, etcetera...

It was a very interesting topic. And a scary one if we are not proactive and secure our signals so that others with malicious intent do not invade our privacy at home or anywhere else!



Here's What Wi-Fi Would Look Like If We Could See It


Originally posted on Creators

Austrian artist and architect Peter Jellitsch measured radio waves to record the wifi activity in a New York apartment over 45 days. (You know, the maddening pattern of how it cuts out and then comes back and is really strong and then is barely working again.) He used the data to sculpt an object that's a physical depiction of a wifi signal.

A couple years before that, a team from the from the Oslo School of Architecture and Design visualized wifi signals in a Norwegian town by "light painting" them. They created a long rod with 80 lights that lit up according to the signal strength of the wifi network, and filmed the result.

Wifi occupies the radio frequency band of the electromagnetic spectrum between actual radio waves and microwaves (used to listen to the game, and cook your dinner, respectively). This frequency band means that wifi boxes and computers can send and receive data as electromagnetic wave that have a 3 to 5 inch distance distance between each pulse of the wave. The wifi pulses are shown here as multicolored spheres radiating out from the source, near the right of the image. Wifi transmitters are basically an antenna equipped with a transmission protocol that splits the frequency band into several segments, referred to as channels. Data can be transmitted over each channel or in order to send and receive greater quantities of data at faster rates. Although color represents its own unique, visible segment of the electromagnetic spectrum, we use red, orange, yellow and other colors to show the invisible wifi channels that make up the overall wifi signal. Wifi fields are usually spherical (like the one here) or ellipsoidal and extend about 20-30 meters, assuming a typical off the shelf wifi box.

The wi-fi visualizations are set in Washington, DC. Lamm used data from a map on DC.gov to approximate the size and shapes of wi-fi networks over the National Mall.

Wifi waves travel through space as rapid, data encoded pulses or waves. A freeze frame of these pulses would show that the pulses are about 6 inches apart (as shown by the lightly colored bands traveling through space in this image). Wifi routers are basically antenna that can send data over multiple frequencies all at the same time. These multiple frequencies are shown as blue, green, yellow, and red colors that pervade the space around the mall. The data from these multiple frequencies swirls around in space as shown here, but can be translated using a common tag system understood by wireless devices.