5 ms·

Through-wall 2.4Ghz Wi-Fi CSI radar can be done with $20 ESP32 boards, https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing https://github.com/Marsrocky/Awesom

Through-wall 2.4Ghz Wi-Fi CSI radar can be done with $20 ESP32 boards, https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing & https://www.cnx-software.com/2022/08/08/esp-wifi-csi-detects-humans-with-wifi-signals-only-no-sensor-needed/ https://www.cnx-software.com/2022/08/08/esp-wifi-csi-detects... > Espressif claims it can also capture subtle movements caused by small movements such as breathing and chewing of people or animals in a static environment.. works with all ESP32 series microcontrollers including ESP32, ESP32-S2, and ESP32-C3, and does not require any changes to the hardware 2024 AI/NPU laptops with Wi-Fi 7 from Intel and Qualcomm can combine RF radar and on-device inference to identify human activity. Related: DIY Radio Telescope: Building a Camera That Can See WiFi (2019) https://www.youtube.com/watch?v=g3LT_b6K0Mc https://www.youtube.com/watch?v=g3LT_b6K0Mc Wi-Fi devices set to become object sensors by 2024 via IEEE 802.11bf standard (2021), https://news.ycombinator.com/item?id=40458766 https://news.ycombinator.com/item?id=40458766 How automotive radar measures the velocity of objects (2024) https://news.ycombinator.com/item?id=40768959 https://news.ycombinator.com/item?id=40768959 How Wi-Fi sensing of movement became usable (2024) https://www.technologyreview.com/2024/02/27/1088154/wifi-sensing-tracking-movements/ https://www.technologyreview.com/2024/02/27/1088154/wifi-sen...

throwup238 2y ago
> chewing of people or animals The ESP32 can detect the difference between a cannibal and a vegan? That's impressive.
- lopis 2y ago
  How can you tell someone is a vegan? Don't worry, this 1$ radar motion sensor can tell you.
  - silisili 2y ago
    I think you could go cheaper. A sound detection sensor is a bit cheaper, and it just needs to detect the word 'vegan.'
    - tstrimple 2y ago
      Strangely enough I've heard far more people make this "joke" than actual vegans speaking up. Even when living in LA.
      - nothacking_ 2y ago
        That's the trick, you invert the logic. If you hear the word vegan, assume the person saying it is not.
      - stavros 2y ago
        The issue with this joke is that it's 100% confirmation bias. You know that all the vegans tell you they're vegan because you don't know about the ones that didn't.
        LoganDark 2y ago
        I think it's also survivorship bias. All the people who tell you they're vegan being vegan does not mean that all the people who are vegan will tell you they're vegan, just like all the people who won the lottery probably having bought lots of tickets does not mean that buying lots of tickets will win you the lottery.
        stavros 2y ago
        That's what I meant, maybe I used the wrong bias name.
        TeMPOraL 2y ago
        I know this under "selection bias", so now we have three contenders. Still, I'm not sure if it's a big factor. You likely know who is vegan in your circles, because veganism is unusual enough to be a good topic for gossip, you can easily see it when sharing a meal with someone, and it's also something you'd like to know when inviting people over, if you want to be a good host. So I think a more relevant estimate would be number of vegans you know vs. how many of them announce their veganism at the earliest opportunity.
  - the_third_wave 2y ago
    Come on, that's simple, just use voice recognition since the vegan won't stop telling the sensor about it.
slicktux 2y ago
Great links! I recall seeing somewhere that AMEX was investing in WiFi object detection…can’t remember exactly for what or how…
t0mas88 2y ago
Wifi sensing is interesting, but you can combine a $3 ESP chip with one of these for a much easier project at lower cost: https://www.dfrobot.com/product-2795.html https://www.dfrobot.com/product-2795.html I use those for presence detection in my house. 3D print a small case and for < $20 you have highly accurate presence detection that also works when sitting still. Ideal for automatic light and climate control.
- stavros 2y ago
  My problem with similar sensors is that they don't work very well if you're sitting still around 3m away. Maybe my sensor isn't great, but when I'm sitting still at the computer, it frequently thinks I'm not there any more, which ruins any benefit.
  - squarefoot 2y ago
    Pairing them with PIR detection should help to also detect stationary warm objects.
    - stavros 2y ago
      I did pair them, unfortunately PIR sensors are even worse at detecting stationary objects (less sensitive to body micromovements).
    - Avamander 2y ago
      It's difficult to find good PIR sensors though. The commonly found cheap modules don't include a thermistor to compensate for room temperature. Finding one with analog output or continuous detection is even more difficult, most detect changes.
  - Avamander 2y ago
    There are some that detect heartbeat, I guess those might work. But those are mmWave, not just cheap 2.4GHz radars or PIR.
    - 2y ago
037 2y ago
The “Vital Sign Detection & Healthcare”[1] section is very interesting, thank you! I am looking for a way to measure the heartbeat of a single person in a completely non-invasive manner (so without contact) and I see that it can be done with Wi-Fi (2019 Paper [2]). However, I’ve noticed that there are a lot of methods (video analysis, thermal camera, etc.), but they are hard to find as ready-made products at a reasonable price. The simplest solution is under-mattress sleep trackers, but unfortunately they are not an option for me. 1. https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing#vital-sign-detection--healthcare https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing#vital-... 2. https://arxiv.org/abs/1908.05108 https://arxiv.org/abs/1908.05108
- transpute 2y ago
  > measure the heartbeat of a single person in a completely non-invasive manner NIST, "Monitoring Respiratory Motion with Wi-Fi CSI" (2022), https://www.nist.gov/news-events/news/2022/12/wi-fi-could-help-identify-when-youre-struggling-breathe https://www.nist.gov/news-events/news/2022/12/wi-fi-could-he... & https://doi.org/10.1109/ACCESS.2022.3230003 https://doi.org/10.1109/ACCESS.2022.3230003 Google: Nest Hub sleep sensing for one person, with Fitbit Premium, https://www.techradar.com/health-fitness/how-to-track-your-sleep-with-google-nest-hub https://www.techradar.com/health-fitness/how-to-track-your-s...
- amelius 2y ago
  Interesting. I'd be interested in a breathing sensor that can work on someone working at a computer.
  - transpute 2y ago
    Intel Meteor Lake+ platforms can use NPU for WiFi 7 Sensing. Presence (commercial): https://community.intel.com/t5/Blogs/Tech-Innovation/Client/Wi-Fi-Sensing-Adding-Sensing-Capability-To-Intel-Wireless/post/1416624 https://community.intel.com/t5/Blogs/Tech-Innovation/Client/... Breathing (research): https://www.intel.com/content/www/us/en/research/respiration-detection-using-wi-fi-sensing.html https://www.intel.com/content/www/us/en/research/respiration... For older Intel wifi radios, there is custom firmware and many research papers: https://dhalperi.github.io/linux-80211n-csitool/ https://dhalperi.github.io/linux-80211n-csitool/
amelius 2y ago
These $1 boards also work through walls (I tried this).
- withinboredom 2y ago
  I always go through walls. — kool aid man
roger_ 2y ago
You can also use a single ESP and your WiFi AP as a source of packets.
utensil4778 2y ago
The gesture recognition sounds incredibly interesting. I work with vision based band tracking, and performance really isn't good enough for my application. I wonder what kind of resolution you can reasonably achieve? Is it good enough to detect finger pose? Aside: is there a way around IEEE paywall? I'd really love to read some of these papers

throwup238 2y ago

> chewing of people or animals The ESP32 can detect the difference between a cannibal and a vegan? That's impressive.

lopis 2y ago
How can you tell someone is a vegan? Don't worry, this 1$ radar motion sensor can tell you.
- silisili 2y ago
  I think you could go cheaper. A sound detection sensor is a bit cheaper, and it just needs to detect the word 'vegan.'
  - tstrimple 2y ago
    Strangely enough I've heard far more people make this "joke" than actual vegans speaking up. Even when living in LA.
    - nothacking_ 2y ago
      That's the trick, you invert the logic. If you hear the word vegan, assume the person saying it is not.
    - stavros 2y ago
      The issue with this joke is that it's 100% confirmation bias. You know that all the vegans tell you they're vegan because you don't know about the ones that didn't.
      - LoganDark 2y ago
        I think it's also survivorship bias. All the people who tell you they're vegan being vegan does not mean that all the people who are vegan will tell you they're vegan, just like all the people who won the lottery probably having bought lots of tickets does not mean that buying lots of tickets will win you the lottery.
        stavros 2y ago
        That's what I meant, maybe I used the wrong bias name.
        TeMPOraL 2y ago
        I know this under "selection bias", so now we have three contenders. Still, I'm not sure if it's a big factor. You likely know who is vegan in your circles, because veganism is unusual enough to be a good topic for gossip, you can easily see it when sharing a meal with someone, and it's also something you'd like to know when inviting people over, if you want to be a good host. So I think a more relevant estimate would be number of vegans you know vs. how many of them announce their veganism at the earliest opportunity.
- the_third_wave 2y ago
  Come on, that's simple, just use voice recognition since the vegan won't stop telling the sensor about it.

slicktux 2y ago

Great links! I recall seeing somewhere that AMEX was investing in WiFi object detection…can’t remember exactly for what or how…

t0mas88 2y ago

Wifi sensing is interesting, but you can combine a $3 ESP chip with one of these for a much easier project at lower cost: https://www.dfrobot.com/product-2795.html https://www.dfrobot.com/product-2795.html I use those for presence detection in my house. 3D print a small case and for < $20 you have highly accurate presence detection that also works when sitting still. Ideal for automatic light and climate control.

stavros 2y ago
My problem with similar sensors is that they don't work very well if you're sitting still around 3m away. Maybe my sensor isn't great, but when I'm sitting still at the computer, it frequently thinks I'm not there any more, which ruins any benefit.
- squarefoot 2y ago
  Pairing them with PIR detection should help to also detect stationary warm objects.
  - stavros 2y ago
    I did pair them, unfortunately PIR sensors are even worse at detecting stationary objects (less sensitive to body micromovements).
  - Avamander 2y ago
    It's difficult to find good PIR sensors though. The commonly found cheap modules don't include a thermistor to compensate for room temperature. Finding one with analog output or continuous detection is even more difficult, most detect changes.
- Avamander 2y ago
  There are some that detect heartbeat, I guess those might work. But those are mmWave, not just cheap 2.4GHz radars or PIR.
  - 2y ago

037 2y ago

The “Vital Sign Detection & Healthcare”[1] section is very interesting, thank you! I am looking for a way to measure the heartbeat of a single person in a completely non-invasive manner (so without contact) and I see that it can be done with Wi-Fi (2019 Paper [2]). However, I’ve noticed that there are a lot of methods (video analysis, thermal camera, etc.), but they are hard to find as ready-made products at a reasonable price. The simplest solution is under-mattress sleep trackers, but unfortunately they are not an option for me. 1. https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing#vital-sign-detection--healthcare https://github.com/Marsrocky/Awesome-WiFi-CSI-Sensing#vital-... 2. https://arxiv.org/abs/1908.05108 https://arxiv.org/abs/1908.05108

transpute 2y ago
> measure the heartbeat of a single person in a completely non-invasive manner NIST, "Monitoring Respiratory Motion with Wi-Fi CSI" (2022), https://www.nist.gov/news-events/news/2022/12/wi-fi-could-help-identify-when-youre-struggling-breathe https://www.nist.gov/news-events/news/2022/12/wi-fi-could-he... & https://doi.org/10.1109/ACCESS.2022.3230003 https://doi.org/10.1109/ACCESS.2022.3230003 Google: Nest Hub sleep sensing for one person, with Fitbit Premium, https://www.techradar.com/health-fitness/how-to-track-your-sleep-with-google-nest-hub https://www.techradar.com/health-fitness/how-to-track-your-s...
amelius 2y ago
Interesting. I'd be interested in a breathing sensor that can work on someone working at a computer.
- transpute 2y ago
  Intel Meteor Lake+ platforms can use NPU for WiFi 7 Sensing. Presence (commercial): https://community.intel.com/t5/Blogs/Tech-Innovation/Client/Wi-Fi-Sensing-Adding-Sensing-Capability-To-Intel-Wireless/post/1416624 https://community.intel.com/t5/Blogs/Tech-Innovation/Client/... Breathing (research): https://www.intel.com/content/www/us/en/research/respiration-detection-using-wi-fi-sensing.html https://www.intel.com/content/www/us/en/research/respiration... For older Intel wifi radios, there is custom firmware and many research papers: https://dhalperi.github.io/linux-80211n-csitool/ https://dhalperi.github.io/linux-80211n-csitool/

amelius 2y ago

These $1 boards also work through walls (I tried this).

withinboredom 2y ago
I always go through walls. — kool aid man

roger_ 2y ago

You can also use a single ESP and your WiFi AP as a source of packets.

utensil4778 2y ago

The gesture recognition sounds incredibly interesting. I work with vision based band tracking, and performance really isn't good enough for my application. I wonder what kind of resolution you can reasonably achieve? Is it good enough to detect finger pose? Aside: is there a way around IEEE paywall? I'd really love to read some of these papers