If these devices are regenerative RECEIVERS do they need a licence? After all, they do actually radiate! thanks

@@andrewainger I do not think a license would help here. They are anyway illegal...

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Ketil Duna , Really good diction, I'm from Russia and I understood all the information. Good work!

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Lucky for him that his neighbour works as a ground controller at the local airport, so he's an expert at flapping his arms around :-P

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You are right. Most of the time, I think, we have to reduce sensitivity rather than to try to increase it...

They are really too sensitive. I tried connecting one(rcwl-0516) to a nodered counter node via a 8266 microcontroller to detect the number of detections and found that even with nobody present in the apartment it is still detecting movement at times.I live in an apartment building so I assume it is detecting movement through the walls in the other apartments.I did not try to reduce the sensitivity yet. Has anybody tried it with resistors to reduce sensitivity?

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Thanks!

Thanks!

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Thank you for your additions!

Will it be able to detect u if ur are not moving or sleeping

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Thanks for the feedback. Maybe I will try it once...

Unless the ground is dry, wouldn't the moisture swamp the return signal?

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:-)

Thank you!

You are probably right. There are a few ideas around in the comments. I do not know what is right or wrong...

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:-)

:-)

Thank you for your feedback!

Thank you!

This is one additional opinion on how these devices work. I stopped to try to understand. I just use them...

Baaaa

I agree with Sirus. This is very similar to the way shop lifting alarms work.

Depending of the distance between the transmitter and the reflections the signal arrives at the receiver either in phase, out of phase or in betwee at the receiver. The two signals are present on the transistor at the same time. As the transistor is a nonlinear device the two signals mix together and generate a DC offset dependant of their relative phase. When an object is moving in front of the sensor this DC offset oscillates at a very low frequency. This signal is amplified and detected by a chip which is very similar to the BISS0001 used in PIR sensors as the output signals of these sensors are nearly identical. The only difference is that this chip includes a built in 3.3v regulator.

@@keesterwee4890 They do not work the same way as the shop theft systems. They rely on the same technology used with prox or access control tags. The arches transmit an rf signal that sweeps a small bandwidth at around the 3.8ghz mark. The tags on the shop item have an antenna tuned to that frequency, a small capacitor and transistor in a smc package connect to the antenna. The RF energy from the arches powers the IC in the alarm tag and creates a simple oscillation resulting in a reflection of RF power at a slightly offset frequency or delay depending on the system type. The signal return to the arch triggers the alarm. It's just come over to the uk but stores in Japan have been using this for years with IC's that will return a pulsed code instead of just a "present" signal as with the theft alarms. These shops in Japan allow you to swipe your customer card and then go round the store filling your trolly. When you exit the store all the prox codes are read and you are billed for the goods. Sadly until all the packaging manufacturers and the industry incorporate smart IC technology we cannot switch to this system. I tested a product with a smart tag a while back and was not surprised to discover that the coded return from the product matched the bar code ! I assume this has been done to make life easier for any stores that have a barcode database. They only then need switch from a barcode reader to an RF based one. I can't see unmanned stores taking of in the UK just the stock itself ;-) With regards to how these little detectors do operate see my reply to "Sirus"

Thanks for your explanations. I only doubt if or how all these functions can be done with only one active component. That is the miracle for me... If you look at a newer video we use the principles you mentioned for a bicycle counter. But this device will have much more parts.

Dude - did you copy that out of a textbook? Nice explanation for doppler ranging radar. But that's not what this does. It just detects motion by mixing the transmitted and received signals together and detects a low-frequency beat. No ranging info. No speed info. Just detects motion.

That is not the principle how these work, though. They are simple regen style recievers

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Any links?

This one is the original of the cheaper LiDARs on the market but currently sold out: www.3dxr.co.uk/product/benewake-tfmini America: www.seeedstudio.com/Seeedstudio-Grove-TF-Mini-LiDAR-p-2996.html America 2: www.robotshop.com/en/benewake-tfmini-micro-lidar-module-12-m.html This one is a China knockoff but perhaps the same: www.aliexpress.com/item/RCmall-Lidar-Range-Finder-Sensor-Single-Point-Micro-Module-for-Arduino-Pixhawk-Cable-Benewake-TFmini-Drone/32852024277.html High Quality LiDAR for reference (older) : www.robotshop.com/en/lidar-lite-3-laser-rangefinder.html

Thanks for your links. I will look into the matter.

Thanks for liking. I hope, I did not request it. I just know, that many people forget it..

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No. These modules only detect presence.

I do not know, because I was not able to see much spectrum below 3 GHz.

1 MHz isn't that bad for these type of devices. with an arduino your frequency can vary as much as 0.5% - at 3 GHz that would be 1.5 MHz just from inaccuracy.

Thanks for the nice words!

Are Jayem He's speaking to a specialized group with this subject matter. He is very good at what he does, but there are not many who have an interest in sensors.

Besides the particular topic (sensors) - which is gaining traction with many makers and electronics diy hobbyists - I find a good number of our host's presentations balanced, informative and accessible, and creatively interesting. By doing this, what would be specialized subject is delivered for a wider audience to ponder and spark ideas.

Are Jayem I definitely agree with you.

Thanks. You too!

Thank you for your feedback. I am sure it will help other viewers!

+Chris B You are right. But here, you only find one transistor. This is, what amazes me.

Most of the stuff for filters would be in the chip. I need to go to the shed to check the transistor system use in this circuit, Andreas. As I do remember there was a simplified, radar which used one transistor, but have not been doing radar 11 year not so a bit rusty.

+Chris B The chip seems to be a digital PIR sensor timing chip. No RF, no filters there.

No the chip would be audio processing if used for filtering range.

Worked it out the transistor is mixer and mode suppressor. Clock is generated by the chip which must pass it to a solid state drive unless it is in the chip. If you need to know more msn me mate.

Thanks for your link. Maybe there are different versions of the same modules around, as in many other cases. Or I did something wrong, which also happens from time to time.

That is what I think, too...

Thanks!

You are right. I tried it again now and it works. I do not know what I did last time... BTW: I did not see a voltage regulator chip on board.

@Roter . If I understand you well, the 3.3V pin can also be used as an INPUT (on +3.3V) as long as the Vin pin is not used ... am I right ?

Yes

Thanks, then I'll try to power the radar sensor from the 3.3V output of my ESP8266 board.

Yann M I'd like to know how you get on.

Thanks for your link!

I thought youtube didn't allow links in the comments?

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Thanks!

Thanks for the hint. This is well possible because one was close by.

Thanks for the link.

Thank you very much. Appreciated.

Thank you for your nice words!

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:-)

Nice to read. Thank you!

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Thanks! :-)

Maybe it has a coating. But I do not think so. It is more than 20 years old and back then, coating was quite expensive.

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Thanks!

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:-)

Thank you!

Enjoy!

I have the HFS-DC06 and I'm trying to get it working but no luck. I apply 5volt at vcc. LED goes on and goes out again. After a 5 seconds it goes on and stays on. No luck in getting it working. Any tips or tricks? Thanks in advanced.

Maybe then I also have some more experience with them...

Thank you and welcome to the channel!

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Thanks!

:-)

Thank you!

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Welcome to the channel!

Glad you enjoyed it

Glad it was helpful!

Danke!

Nothing changed on these cheap sensors. The ones I have in mind for a new video are more expensive.

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As shown they can detect through walls. But they are only DC, no 220 volts

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Thanks!

Standard radars do not measure distance, they only measure speed.

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As usual, you are welcome!

:-)

Good idea. They are very interesting...

I can not do a video about the working, because it seems to be a big mystery...

Andreas Spiess I'm sure you can! To me it's a big confusing theme, but you seems to be totally capable :)

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AFAIK they use very complex Radar sensors.

You have to ask the guy which did this video, I think.

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Radar detects changes in speed, not distances. So you have to use ultrasound for measuring distance.