#135 Radar Sensors / Switches: Comparison and Tests

The invention of radar influenced the way World War two went because it was possible to detect planes of the enemy and shoot them down. And since then, this technology made civil aviation as we know it possible because it can detect the movement of metallic surfaces over distance. Of course, technology can also be used against us, for example, if we are trapped while speeding…

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[AndreasSpiess]

As many commenters rightly found out, these devices are regenerative receivers. If you are interested in "real" radar sensors, I propose watching video #439

[waltsteinchen]

Today my RCWL-0516 's arrived from ali-express, could'nt wait to do some experiments .. (did'nt add any additional components)
Wow .. these things are unbelievable sensitive especially moving to or away from them. Over the entire distance of my buro (~4 Meter) a movement of 2 cm's of my hand is enough to trigger it.
Thanks a lot Andreas for making this great video!

[KetilDuna]

Mystery gadgets! Nice writeup. You have a very comfortable voice and clear, easy to understand diction. Good job!

[voltlog]

excellent comparison video, I can see allot of work went into making this.

[PaulJaros]

Hi. I've recently discovered the RCWL-0516 and in search of more specifics I've then found your video.Your extensive tests are very helpful. Especially the needed voltage to run it, the diagnosis if the devices interfere with each other, the directionality and what they penetrate.

Viele Grüsse aus dem Hackerspace Ruum42 aus der Ostschweiz.

[dishendra.]

Sir your videos are gold, it reflects how much work you put into these masterpiece review videos.

[Dronebotworkshop]

Thank you so much for doing this, prior to this video I was not aware of these cheap radar sensors (the rcwl-0516 is on eBay for about a dollar). As usual your testing was detailed and your explanation was perfect. Another excellent video!

[AbqMichaelMcDonald]

I have been using RCWL-0516 Microwave Radar Sensors in a smart lighting application (integrated with ESP32 developer boards) for several months now. To this video I would add a couple notes. The first is that though the sensors do not interfere with each other, they can get false triggered from the ESP32. This effect falls off after a centimeter or two. Lesson learned, be careful mounting the sensors to the same circuit board as your controller. The lack of directionality and ability to penetrate wood is amazing and perfect for my application. The sensors often detect me just before I enter the rooms with my lights.

My sensors appear to work through regular glass. I mounted some of my smart lights on my double pane window and the detectors see me from outside my house. My different experience may be explained by the sensors penetrating the wood but it may be that I’m using traditional glass and your video reported testing against acrylic glass. The later makes sense as acrylic would act more like water than silicate.

A final note on voltages... Though it does take 5V to power the sensors, the sensor output voltage is 3.2-3.4V. This is perfect if you’re powering your circuit with a 5V supply and reading the signal with a CMOS device like the ESP32.

[Absolutelyautomation]

I discovered those modules recently, and still waiting for them to arrive. You saved me a lot of time, i don't have to make a comparative test. Thank you

[amali]

Excellent details. Thank you. It will be great if you can make a video on using those as metal detectors! Like detecting metal hidden underground or maybe behind a large lump of sand. Those treasure hunters will love the video :)

[dougmanatt]

Thanks for checking out these various sensors. I think I will find them very useful and it is great to be able to rely on you to sort the features of the many choices available!

[Peter_S_]

Perfect timing! I just received four RCWL-0516 units. I could not decide which variety to get and it appears randomness intervened to select a good choice for me.

These evaluations of similar products are both interesting and useful. Thank you!

[PhG]

I keep repeating myself... great video !
A very good comparison which is very usefull. It will defenately help me
for choosing the right one.
Thanks Andreas !

[edwardrf]

First of all, great video! These motion detection radars most likely works in doppler mode, which is sensitive to frequency close to its emitting frequency, which explains why 2 of the same model do not interfere with each other, and why they don't detect stationary object.

[ralfjahns]

The long awaited radar sensor comparision you promised to do! You have not forgotten it! Now I know these devices work and which one to buy. Thank you so much!

[raymondvanrykel]

Andreas,
The working principle of these type of radars (radio detection and ranging) is well understood and used in many applications already for many years.
In a nutshell:
These radars typically work in the L to X band : 1GHz-12.5GHz
They are frequency modulated continuous waves radars typically with linear frequency sweeps, say 100Mhz
Example: a saw tooth frequency of 100kHz changes the frequency linearly from 2.4GHz to 2.5GHz in 10 microseconds
The transmitted signal is sent into the world via the antenna
The received signal that bounced back from an object on a distance d from the antenna is received back with a delay of 2d/c seconds (c speed of light 3*10E8m/sec).
Example: if d is 3m, the delay is 20 nanoseconds. During this delay the frequency of the transmitter has increased 200kHz versus the received signal. (100MHz*20nsec/10usec)
The transmitted and received signal are combined (mixed) and passed through a highly nonlinear element, i.e a diode. The output of this process are waveforms that include the sum and difference of the 2 signals and their harmonics
Through proper filtering we can isolate the frequency difference (200kHz), calculate the delay (20 nsec) and the related object distance (3m)
Kind regards

[BikerCaf]

Very good, thank you.
You have to bare in mind that a lot of double glazing windows have an aluminium coating all over the glass for thermal insulation/reflection, and so this will no doubt explain away a lot of the RF attenuation you found when doing the double glazing window through tests.

[claudiog.]

"of course the technology can also be used against us" LOL

[MaxintRD]

Good video. I like how you compared these units and gave a clear overview of their main advantages. (Good to see I picked the right one when randomly ordering the cheapest radar-sensor I could find). Thanks!

[gandsnut]

With outstanding content like this, it's really a crime that AS doesn't have 200, 000 subs. Soon, I trust!