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Inside a $1 radar motion sensor

10maurycy10.github.io

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Re: Inside a $1 radar motion sensor

#81

Post by Aurornis »

farceSpherule wrote: post #77

You cannot try to rationalize the prices that China charges for goods. Everything is, more or less, state-owned and state-controlled. If the Chinese government wants to undercut an American product, they will tell the manufacturer to drop the price to X, and the manufacturer will comply. This also does not take into account Chinese currency manipulation. Profit or loss be damned.

The BOM of this circuit really is very minimal because it’s a clever circuit.

It’s not without flaws (regulatory approval is non-existent for this) but they really did combine some dirt cheap components on to a dirt cheap PCB.

You, too, could assemble this circuit at scale for extremely low prices, no government intervention necessary.

Re: Inside a $1 radar motion sensor

#82

Post by moffkalast »

marcosdumay wrote: post #72
moffkalast wrote: post #64

Earlier quoted context omitted.

Weren't microwave ovens invented because someone's chocolate melted in their pocket while operating a radio transmitter? Maybe it's just a lady godiva story since it seems weird that the person wouldn't feel overly hot as well, but maybe.

It's a well known story, he was doing maintenance: https://en.wikipedia.org/wiki/Microwave_oven#Discovery The thing is, you don't need a lot of extra heat to melt a chocolate bar on your pocket. It's perfectly possible that everybody felt hot when working on an active radar, but didn't discuss it or maybe even notice the correlation.

Oh wow it's even known what brand of a bar it was, funny that.

> The first food deliberately cooked with Spencer's microwave oven was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.

They were having a blast I see.

Re: Inside a $1 radar motion sensor

#83

Post by NavinF »

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.

“Practically everyone knows what veganism is, but vegans are actually a very small minority.

There are more Americans with gambling addictions than there are people committed to vegan diets!”

Chart: https://x.com/cremieuxrecueil/status/1805367282270433791?s=4...

Re: Inside a $1 radar motion sensor

#84

Post by ein0p »

marcinzm wrote: post #78
farceSpherule wrote: post #77

You cannot try to rationalize the prices that China charges for goods. Everything is, more or less, state-owned and state-controlled. If the Chinese government wants to undercut an American product, they will tell the manufacturer to drop the price to X, and the manufacturer will comply. This also does not take into account Chinese currency manipulation. Profit or loss be damned.

Isn't the US basically the same? The US government gives massive subsidies, tax breaks or just has the military buy components for 10x the price (to offset commercial loses and R&D).

And creates regulatory capture for the rest, e.g. healthcare and big pharma ($4T a year), both of which too charge nontrivial multiples of what the rest of the world pays.

Re: Inside a $1 radar motion sensor

#85

Post by transpute »

stavros wrote: post #44
Avamander wrote: post #42

Earlier quoted context omitted.

There are some that detect heartbeat, I guess those might work. But those are mmWave, not just cheap 2.4GHz radars or PIR.

I've got LD2410B, which are mmWave, so they should detect heartbeat (and do), but not from more than 2-3m away.

Is the LD2410B sensing range limited by the PCB antenna?

Re: Inside a $1 radar motion sensor

#86

Post by stavros »

transpute wrote: post #85
stavros wrote: post #44

Earlier quoted context omitted.

I've got LD2410B, which are mmWave, so they should detect heartbeat (and do), but not from more than 2-3m away.

Is the LD2410B sensing range limited by the PCB antenna?

I'm not sure, it always just made sense to me that the farther away someone is, the harder it'll be to detect their small movements.

Re: Inside a $1 radar motion sensor

#87

Post by transpute »

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…

> 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-he... & 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-s...

Re: Inside a $1 radar motion sensor

#89

Post by marcinzm »

dclowd9901 wrote: post #80
What2159 wrote: post #79

Earlier quoted context omitted.

You make China sound like a VC, Uber, AirBNB, etc ran at a loss to try to own the market.

The government also stands to benefit greatly if they throw their weight behind smart ideas, just like VCs. It would be interesting if the government could fund itself with investment.

VC returns are overall much worse than the S&P 500. The top firms are potentially better but that's a very limited investment pool. Softbank has shown what happens if you try the VC approach with a massive pool. Not good returns. The core value of VC has historically been due to it being uncorrelated with the stock market. That allows it to be a risk hedge for investors. The perception is that it is no longer uncorrelated so even that value is mostly gone.

The US government invests in growing the economy, or tries to, which increase tax revenue which gives the government more money.

edit: Also it's not that top VCs are better at finding investment but rather that their social capital means they provide values to companies beyond the investment money. As a result companies that are doing well which choose to take money from top VCs versus other VCs. As a result the model doesn't scale since there's a limited pool of top companies to invest in.

Re: Inside a $1 radar motion sensor

#90

Post by transpute »

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.

Intel Meteor Lake+ platforms can use NPU for WiFi 7 Sensing.

Presence (commercial): https://community.intel.com/t5/Blogs/Tech-Innovation/Client/...

Breathing (research): 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/

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