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> Your comment is a good example of exactly why the way this article (and the original paper) uses the word "Wi-Fi" and "connection" is a big problem. The main

> Your comment is a good example of exactly why the way this article (and the original paper) uses the word "Wi-Fi" and "connection" is a big problem. The main point of the article was : "University of Washington researchers are the first to make this a reality by 3-D printing plastic objects and sensors that can collect useful data and communicate with other WiFi-connected devices entirely on their own." Um I don't understand if you look at the flow chart this paper is narrowly speaking about wifi that it is Wifi TX --> 3D Printed Object --> Wifi RX I am talking about how this is 100% wifi communication and sure the Wifi RX is where the success of this relays. Sure it will work with other protocols but this is about them specifically using it as a way for Wifi RX > > Actually it does. It manipulates the WiFi signal. > Actually, it doesn't. "backscatter" the Wifi signal isn't manipulation? If you follow the "Backscatter" link in the article they actually state the following: "This new “interscatter communication” works by converting Bluetooth signals into Wi-Fi transmissions over the air." http://www.washington.edu/news/2016/08/17/interscatter-communication-enables-first-ever-implanted-devices-smart-contact-lenses-credit-cards-that-talk-wi-fi/ http://www.washington.edu/news/2016/08/17/interscatter-commu... So they can convert signals from bluetooth to Wifi isn't manipulation? Your statement of > It scatters back some radio frequencies, including 2.4GHz, which happens to be used by Wi-Fi... Seems off to their own "backscatter" definition. This is not simple reflections of radio signals these technically are new signals physically manipulated by the non-electronic devices.

detaro 9y ago
While I'd agree that they "manipulate" the Wifi signal, I also have a hard time calling something that doesn't generate Wifi frames or packets "Wi-Fi communication". It merely changes the signal strength of existing packages (or packages specifically generated to fill air-time, which seems like another large downside of this). It does not generate new frames or insert data into them.
- baldfat 9y ago
  But it is a new signal originating from the 3D object. They even convert Bluetooth to Wifi signals with this technique. Read about comment of mine for source.
  - TeMPOraL 9y ago
    The technique you mention is realized through an FPGA chip. It is not used in the 3D-printed backscatter devices this article is about.
    - baldfat 9y ago
      Not this is through the Printed 3D Device From the paper "We 3D print a cup anemometer as shown in Fig. 2 to measure wind speeds. The entire setup is sufficiently light that even wind speeds as low as 2.3 m/s will cause it to spin. The hub of the anemometer is attached to backscatter gear that encodes an alternating sequence of zero one bits. When the hub spins, the backscatter gear pushes against the spring switch. The switch makes contact with the antenna and generates the backscatter signal. Wind speed can be inferred from the rate at which bit transitions occur."
  - detaro 9y ago
    That's a totally different project than the one this submission is about, using totally different technology. The 3d-printing one is modulating things in the range of few Hz, you're not making packets with that.
    - baldfat 9y ago
      Backscatter is the same technology in both projects. Yes, scientifically they are new packets. See https://youtu.be/4tmatoD0I1o?t=3m48s https://youtu.be/4tmatoD0I1o?t=3m48s They could do it with a radio signal of a clean sine wave and through the 3D object they could convert the sine wave into wifi. Just like they could take a bluetooth wave and make a wifi signal. The big advantage to this is they can just take a Wifi and use it to do the same thing. No need for new hardware.
      - detaro 9y ago
        They are similar in a very high-level view, but that's exactly what's causing the confusion here. Yes, the video you link is about a project that is actually generating Wifi signal. The article discussed here is not, and it's IMHO irresponsible by (what I assume was) the PR department of the university to present them as doing the same. Take a few minutes and compare the papers (printed Wifi http://printedwifi.cs.washington.edu/printedwifi.pdf http://printedwifi.cs.washington.edu/printedwifi.pdf and Hitchhike https://web.stanford.edu/~pyzhang/papers/sensys16_back_comm.pdf https://web.stanford.edu/~pyzhang/papers/sensys16_back_comm.... or interscatter http://interscatter.cs.washington.edu/files/interscatter.pdf http://interscatter.cs.washington.edu/files/interscatter.pdf), the principles used are very different. The 3D printed objects only switch an antenna which attentuates (=modulates the signal strength of) Wifi signals with a few Hz frequency at max, HitchHike and interscatter involving electronics completely transform the signal at HF level, retransmitting full packets at a different frequency. They are both "backscatter" in that they change an existing signal and thus require less energy than if they generated it themselves, but that's about it when it comes to similarities.
TeMPOraL 9y ago
> Wifi TX --> 3D Printed Object --> Wifi RX No, it's: Wifi TX --> 3D Printed Object --> general 2.4GHz RX through a specialized device or driver for an existing 2.4GHz device They're not magically encoding new Wi-Fi packets; they're changing the amplitude of Wi-Fi packets - and everything else that's on 2.4GHz - seen by the receiver. Contrast with the interscatter you mention, which uses an electronic device to encode new Wi-Fi packets. Interscatter is not what's happening here.
- baldfat 9y ago
  No I quoting a fact not an opinion. Please read my comment and sources before claiming I am factually wrong. "In this backscatter system, an antenna embedded in a 3-D printed object (middle) reflects radio signals emitted by a WiFi router (left) to encode information that is “read” by the WiFi receiver in a phone, computer or other device (right).University of Washington" Screenshot: https://i.imgur.com/rzX4RXX.png https://i.imgur.com/rzX4RXX.png > They're not magically encoding new Wi-Fi packets Yes, these are NEW signals powered by the radio signals that specifically in this article is wifi since it is so widely used. "The chip uses a technique called long-range backscatter to communicate with other devices. Instead of creating signals from scratch, it is able to selectively reflect radio waves that are already passing through space to create a new signal." https://www.technologyreview.com/the-download/608869/a-new-mobile-chip-beams-data-for-miles-using-almost-no-power/ https://www.technologyreview.com/the-download/608869/a-new-m... Just because they are using residual radio signals (They could use TV, Wifi or FM signals) doesn't mean the new singals aren't new. They are just using the energy in the signal itself doesn't make them magic. Instead of using electricity from a battery or a cord they are using the power of the radio wave. They can even power themselves off of the Gollakota’s radio frequency power scavenging technology. You could light up a led without any on board electricity and communicate between two devices https://www.youtube.com/watch?v=gX9cbxLSOkE https://www.youtube.com/watch?v=gX9cbxLSOkE Here is a speech about HitchHike: Practical Backscatter Using Commodity WiFi at (SenSys 2016) https://youtu.be/4tmatoD0I1o?t=3m48s https://youtu.be/4tmatoD0I1o?t=3m48s
  - detaro 9y ago
    You quote yourself "reflects radio signals". If you look at the paper, they are reading signal strengths with which they receive the packets the first station sends and are using the change between different packets to read the data. From the paper: > At a high level, a Wi-Fi transmitter sends a sequence of Wi-Fi packets and the Wi-Fi receiver uses the changes to the amplitude of the Wi-Fi packets, caused due to the backscatter operation, to extract the backscatter information > So we decode the backscatter information from the amplitude variations in the received Wi-Fi signal across packets. Your other links again are about totally different projects, doing different things (they involve chips for instance, not just 3D printed components. "Of course" chips can actually send/manipulate data at the speed necessary to generate packets, nobody is arguing against that)

detaro 9y ago

While I'd agree that they "manipulate" the Wifi signal, I also have a hard time calling something that doesn't generate Wifi frames or packets "Wi-Fi communication". It merely changes the signal strength of existing packages (or packages specifically generated to fill air-time, which seems like another large downside of this). It does not generate new frames or insert data into them.

baldfat 9y ago
But it is a new signal originating from the 3D object. They even convert Bluetooth to Wifi signals with this technique. Read about comment of mine for source.
- TeMPOraL 9y ago
  The technique you mention is realized through an FPGA chip. It is not used in the 3D-printed backscatter devices this article is about.
  - baldfat 9y ago
    Not this is through the Printed 3D Device From the paper "We 3D print a cup anemometer as shown in Fig. 2 to measure wind speeds. The entire setup is sufficiently light that even wind speeds as low as 2.3 m/s will cause it to spin. The hub of the anemometer is attached to backscatter gear that encodes an alternating sequence of zero one bits. When the hub spins, the backscatter gear pushes against the spring switch. The switch makes contact with the antenna and generates the backscatter signal. Wind speed can be inferred from the rate at which bit transitions occur."
- detaro 9y ago
  That's a totally different project than the one this submission is about, using totally different technology. The 3d-printing one is modulating things in the range of few Hz, you're not making packets with that.
  - baldfat 9y ago
    Backscatter is the same technology in both projects. Yes, scientifically they are new packets. See https://youtu.be/4tmatoD0I1o?t=3m48s https://youtu.be/4tmatoD0I1o?t=3m48s They could do it with a radio signal of a clean sine wave and through the 3D object they could convert the sine wave into wifi. Just like they could take a bluetooth wave and make a wifi signal. The big advantage to this is they can just take a Wifi and use it to do the same thing. No need for new hardware.
    - detaro 9y ago
      They are similar in a very high-level view, but that's exactly what's causing the confusion here. Yes, the video you link is about a project that is actually generating Wifi signal. The article discussed here is not, and it's IMHO irresponsible by (what I assume was) the PR department of the university to present them as doing the same. Take a few minutes and compare the papers (printed Wifi http://printedwifi.cs.washington.edu/printedwifi.pdf http://printedwifi.cs.washington.edu/printedwifi.pdf and Hitchhike https://web.stanford.edu/~pyzhang/papers/sensys16_back_comm.pdf https://web.stanford.edu/~pyzhang/papers/sensys16_back_comm.... or interscatter http://interscatter.cs.washington.edu/files/interscatter.pdf http://interscatter.cs.washington.edu/files/interscatter.pdf), the principles used are very different. The 3D printed objects only switch an antenna which attentuates (=modulates the signal strength of) Wifi signals with a few Hz frequency at max, HitchHike and interscatter involving electronics completely transform the signal at HF level, retransmitting full packets at a different frequency. They are both "backscatter" in that they change an existing signal and thus require less energy than if they generated it themselves, but that's about it when it comes to similarities.

TeMPOraL 9y ago

> Wifi TX --> 3D Printed Object --> Wifi RX No, it's: Wifi TX --> 3D Printed Object --> general 2.4GHz RX through a specialized device or driver for an existing 2.4GHz device They're not magically encoding new Wi-Fi packets; they're changing the amplitude of Wi-Fi packets - and everything else that's on 2.4GHz - seen by the receiver. Contrast with the interscatter you mention, which uses an electronic device to encode new Wi-Fi packets. Interscatter is not what's happening here.

baldfat 9y ago
No I quoting a fact not an opinion. Please read my comment and sources before claiming I am factually wrong. "In this backscatter system, an antenna embedded in a 3-D printed object (middle) reflects radio signals emitted by a WiFi router (left) to encode information that is “read” by the WiFi receiver in a phone, computer or other device (right).University of Washington" Screenshot: https://i.imgur.com/rzX4RXX.png https://i.imgur.com/rzX4RXX.png > They're not magically encoding new Wi-Fi packets Yes, these are NEW signals powered by the radio signals that specifically in this article is wifi since it is so widely used. "The chip uses a technique called long-range backscatter to communicate with other devices. Instead of creating signals from scratch, it is able to selectively reflect radio waves that are already passing through space to create a new signal." https://www.technologyreview.com/the-download/608869/a-new-mobile-chip-beams-data-for-miles-using-almost-no-power/ https://www.technologyreview.com/the-download/608869/a-new-m... Just because they are using residual radio signals (They could use TV, Wifi or FM signals) doesn't mean the new singals aren't new. They are just using the energy in the signal itself doesn't make them magic. Instead of using electricity from a battery or a cord they are using the power of the radio wave. They can even power themselves off of the Gollakota’s radio frequency power scavenging technology. You could light up a led without any on board electricity and communicate between two devices https://www.youtube.com/watch?v=gX9cbxLSOkE https://www.youtube.com/watch?v=gX9cbxLSOkE Here is a speech about HitchHike: Practical Backscatter Using Commodity WiFi at (SenSys 2016) https://youtu.be/4tmatoD0I1o?t=3m48s https://youtu.be/4tmatoD0I1o?t=3m48s
- detaro 9y ago
  You quote yourself "reflects radio signals". If you look at the paper, they are reading signal strengths with which they receive the packets the first station sends and are using the change between different packets to read the data. From the paper: > At a high level, a Wi-Fi transmitter sends a sequence of Wi-Fi packets and the Wi-Fi receiver uses the changes to the amplitude of the Wi-Fi packets, caused due to the backscatter operation, to extract the backscatter information > So we decode the backscatter information from the amplitude variations in the received Wi-Fi signal across packets. Your other links again are about totally different projects, doing different things (they involve chips for instance, not just 3D printed components. "Of course" chips can actually send/manipulate data at the speed necessary to generate packets, nobody is arguing against that)