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Inside a $1 radar motion sensor

10maurycy10.github.io

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Re: Inside a $1 radar motion sensor

#101

Post by hippich »

aeonik wrote: post #96
hippich wrote: post #67

Earlier quoted context omitted.

Just to clarify - I changed transmitters antenna.

I'm pretty curious if you could sketch something up. Sounds like you might have inadvertently created a wave guide. If you are feeling adventurous you might want to try dropping your creation into an Antenna Simulation software like NEC or something similar. https://www.xnec2c.org/

https://imgur.com/qelKWpL

Here is youtube video someone fixing broken unit to get an idea what it looks like inside - https://www.youtube.com/watch?v=-k_6NsqFAdc

Not sized properly. Transmitter is sitting on a pretty tall pole right now and getting it off is a bit of a hassle. And I also already covered cap with a glued heatshrink to protect against elements, so accurate measurements are not possible without destroying it... But I hope it can give an idea what I came up with.

Thanks for the link to the simulation tool!

Re: Inside a $1 radar motion sensor

#102

Post by hippich »

RF_Savage wrote: post #99
hippich wrote: post #45

Almost not related, but reminded me about recent RC hack I was working on. I have an driveway alarm from mighty mule, which uses 433Mhz radio powered by two AA batteries to communicate signal from the coil sensor detection sitting next to the driveway to the base station in the house using OOK modulation. The stock PCB antenna was not very good at the distance I had it to work with, so I started experimenting with ex…

A capacitance hat is a legit way to electrically lengthen an antenna. I have had decent success with them when finetuning antennas for lower bands.

thanks for the "capacitance hat" search term. from googling it looks like this hat is electrically connected to the antenna? In my case if the "cap" touches the copper wire of the antenna - signal strength decreased. Only when I kept the cap close but not touching the antenna it performed well.

Re: Inside a $1 radar motion sensor

#103

Post by mianos »

stavros wrote: post #100
mianos wrote: post #97

Earlier quoted context omitted.

here is the ld2450 multi object tracker: https://github.com/mianos/mqttradar It's pretty complete. There was some other guy who wanted an ld2450 tracker so I worked with him to get it going.

This is very exciting, thanks!

ps, it uses the esp-idf. I'm not using the Arduinio framework anymore. Any trouble getting it going or feature, put a ticket in.

Re: Inside a $1 radar motion sensor

#104

Post by InvisGhost »

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.

The bit on that wikipedia page about reanimating frozen hamsters is a bit of a sci-fi nightmare

Re: Inside a $1 radar motion sensor

#105

Post by RF_Savage »

hippich wrote: post #102
RF_Savage wrote: post #99

Earlier quoted context omitted.

A capacitance hat is a legit way to electrically lengthen an antenna. I have had decent success with them when finetuning antennas for lower bands.

thanks for the "capacitance hat" search term. from googling it looks like this hat is electrically connected to the antenna? In my case if the "cap" touches the copper wire of the antenna - signal strength decreased. Only when I kept the cap close but not touching the antenna it performed well.

Sure, but that does not stop it from capacitively coupling it.

Even tape or insulation from a wire can, be used to electrically lengthen or fine tune an antenna. But thats less about capacitance and more about the electrical lenght being longer in the dielectric.

Re: Inside a $1 radar motion sensor

#106

Post by moffkalast »

InvisGhost wrote: post #104
marcosdumay wrote: post #72

Earlier quoted context omitted.

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.

The bit on that wikipedia page about reanimating frozen hamsters is a bit of a sci-fi nightmare

Tom Scott has a great video on that: https://www.youtube.com/watch?v=2tdiKTSdE9Y

Re: Inside a $1 radar motion sensor

#107

Post by fennecfoxy »

Don't like these cheap sensors most of the time since most can't tell between a moving person and a fan rotating or curtain moving in a breeze. They are configurable to some degree but seems like not enough.

I'm sure there are more expensive options but they're more locked down/limited as well.

Re: Inside a $1 radar motion sensor

#108

Post by rpaddock »

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.

The site Microwave News keeps up on the latest health aspects of such things.

https://www.microwavenews.com

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