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Inside a $1 radar motion sensor

10maurycy10.github.io

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Re: Inside a $1 radar motion sensor

#21

Post by 037 »

t0mas88 wrote: post #20
037 wrote: post #15

A little tangential, but are these things safe for humans? I have a couple of LD2410 devices and I’d like to use one of them with ESPHome in the bedroom. I did some research and they seem to be very low power and safe, but you know, before sleeping with a radar pointing at us all night long, I’m looking for as much feedback as possible.

I have these all around the house, but not in the bedrooms. I use weight sensors to detect that someone is in bed and traditional PIR for motion in bedrooms. Probably overly careful, but I didn't want to point a radar at my sleeping kids (and myself) for 12 hours per day. Similar for the WiFi access point upstairs, it's only in the hallway and not at maximum power.

I agree with you, especially regarding children and anyone who hasn’t explicitly made this choice, which is why I asked the question. The only thing is, I suspect we get scared by certain words, like “radar” and “microwaves”, and then we might spend all day with our heads next to a Wi-Fi router or a phone constantly downloading files on 4G.

For example: maybe the ESP32 transmitting the bed weight exposes us to more danger than the radar sensor (that can also be placed very far from the bed)? Maybe with our smartphones charging on the nightstand too.

I’m not a big fan of fear-based, illogical decisions. But, again, I understand perfectly.

Re: Inside a $1 radar motion sensor

#22

Post by 037 »

transpute wrote: post #2

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

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-...

2. https://arxiv.org/abs/1908.05108

Re: Inside a $1 radar motion sensor

#23

Post by stavros »

t0mas88 wrote: post #18
transpute wrote: post #2

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

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 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.

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.

Re: Inside a $1 radar motion sensor

#24

Post by stavros »

tstrimple wrote: post #16
silisili wrote: post #13

Earlier quoted context omitted.

I think you could go cheaper. A sound detection sensor is a bit cheaper, and it just needs to detect the word 'vegan.'

Strangely enough I've heard far more people make this "joke" than actual vegans speaking up. Even when living in LA.

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.

Re: Inside a $1 radar motion sensor

#25

Post by stavros »

zer00eyz wrote: post #9

USB C mm wave "radars" that hook to home automation are a thing. Priced between 11 and 20 bucks they are fairly feature rich... If you want to roll your own check out what the folks over at ESP home have going on (google esp home mm wave).

The actual component costs about $5, if you want to roll your own with an ESP32.

Re: Inside a $1 radar motion sensor

#26

Post by stavros »

mrcsharp wrote: post #10

The LD2410 (B) is another option and it operates over UART. It is a bit more expensive ~$5 but has more configuration options.

Get the B variant, you can configure it over Bluetooth from your phone. Otherwise it's a huge hassle.

That said, it doesn't work very well for me when sitting still 4-5m away, it thinks I've left.

Re: Inside a $1 radar motion sensor

#27

Post by amelius »

transpute wrote: post #2

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

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

Re: Inside a $1 radar motion sensor

#28

Post by amelius »

037 wrote: post #22
transpute wrote: post #2

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

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 reason…

Interesting. I'd be interested in a breathing sensor that can work on someone working at a computer.

Re: Inside a $1 radar motion sensor

#29

Post by amelius »

stavros wrote: post #26
mrcsharp wrote: post #10

The LD2410 (B) is another option and it operates over UART. It is a bit more expensive ~$5 but has more configuration options.

Get the B variant, you can configure it over Bluetooth from your phone. Otherwise it's a huge hassle. That said, it doesn't work very well for me when sitting still 4-5m away, it thinks I've left.

These radars are designed to detect motion, not someone sitting still.

Re: Inside a $1 radar motion sensor

#30

Post by 037 »

amelius wrote: post #28
037 wrote: post #22

Earlier quoted context omitted.

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 reason…

Interesting. I'd be interested in a breathing sensor that can work on someone working at a computer.

I’m sure it can be done with a normal camera and enough light, especially with the advancement of AI technologies in recent years. I haven’t had time to experiment, but if you have an iPhone, you can try this app [1] I installed yesterday to study its feasibility.

On the homepage, there is a video [2] explaining more as well, and their paper [3].

1. https://www.rouast.com/vitallens/

2. https://www.youtube.com/watch?v=_0HHjovI8hc

3. https://arxiv.org/pdf/2312.06892

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