As many commenters rightly found out, these devices are regenerative receivers. If you are interested in "real" radar sensors, I propose watching video #439
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!
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?
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!
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.
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.
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
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 !
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!
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
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.
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!
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 :)
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!
IRC these units don't work like a radar. IRC they don't receive a signal back from what they send out. They just emit a continuous wave and monitor how much power it is using to transmit. if something moves in it's "field" it changes the SWR standing wave ratio of the transmitter, causing it to us more or less power that the comparitor uses to cause a trip.
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"
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.
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!
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.
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.
Hello Andreas, Before I begin, I like your videos a lot. In your video at 15:04 min. you explain that the RCWL-0516 cannot work in a 3.3 volt environment, I make a mistake and put 3.3 volt as input voltage. So 3.3 volt on the 3.3 pin and GND on the GND pin then a diode connected on the Out pin and GND, and wonder the RCWL-0516 works also, it detects movements like before. I think that you can use the module from 3.3 volts and if you have 4 volts till 28 volts you must connect the input voltage on the VIN pin. www.elecrow.com/rcwl-0516-microwave-radar-sensor-switch-module-body-induction-module-4-28v-100ma.html Greetings from Holland, Jan-Henk van Kesteren
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.
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
Thank you for the video, Andreas! I love your channel! I want to report that the RCWL-0516 works great with the Sonoff Basic switch with the OUT pin on the Sonoff's GPIO14 pin and the 3.3V pin connected to the 3.3V of the Sonoff. I use it to report movement via MQTT.
I bought a sensor which is marked "2.7GHz" from Aliexpress and was quite surprised by the spectrum of signal which it emits. It is not a narrow "spike" but rather wide, maybe 1 MHz wide. Is that happening because of poor Q of PCB resonator?
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 taking the time to run through these. Wish I had found this video before I bought 5 of each of the RCWL and HFS boards. I need 3 working units (always buy extra from China). Looks like the cheaper boards will be the best fit. NBD. At the prices these things are going for these days I can throw the others in a drawer to use for something else some day. The HFS boards will be better if I need something to be directional.
Are you sure the RCWL-0516 does not work on 3.3V? I really cannot see a reason why it shouldn't work if you power it with 3.3V on the 3.3V pin. Usually a voltage regulator doesn't care much if you power its output with the right voltage and no input connected... Even if the voltage regulator is integrated within the IC. And I don't think the unregulated input voltage is used anywhere else except on the voltage regulator input. You should try it.
Great video Andreas! I found this GitHub repo that has a schematic of the RCWL-0516 : github.com/jdesbonnet/RCWL-0516/blob/master/README.md that you may find useful. Thank you for the great videos!
Genial! Justo acabo de comprar el RCWL-0516 para detectar la presencia de intrusos, una muy buen explicación amigo! Gracias por compartirlo con nosotros
Thanks for this comprehensive and systematic comparision. It comes very handy to me because I also received a sensor similar to XYC-WB-D1 for playing around and looking for a helpful application. Unfortunately (?) most helpful application are already covered in my environment. It is really an excellent work to do all that with just one (1) transistor and some passives. Chapeau!
I just found your channel, great video! I like how precise and concise your comments are. Brief, clear and to the point. You have a new subscriber! And you made me laugh so much at the end when you said "If true then like". 🤣
Nice introduction in Mircorwaves. I like your channel very much.Also becaues you are a swiss guy too :) It's very nice to see, that we have such brillant heads in our small country ;) Since 3 days I played around with the RCWL-0516 and I'm very happy with it. Stay healthy and I hope a lot more videos are coming up :) Next I want to build a LoRa Gateway because in my region no one have it. A liebe Gruess und sunnigs Wätter :)
@@AndreasSpiess Gerne, mache ich gleich mal :) Herzlichen Dank für den Link! Was ich wirklich so toll an deinen Videos finde ist, dass du es auf eine Weise rüber bringst, die selbst ein nicht-Elektroniker daraus schlau wird. Dafür ein herzliches Dankeschön. Behalte dein way-to-do bei, denn dieser ist wirklich genial. Schönes Wochenende und herzliche Grüsse aus Bern
Great video. Appreciate the effort to examine and compare the most important characteristics of each unit with a scientific approach. I agree with you, even if the units are simply measuring the variance in transmitter output to determine motion, some sort of return circuit is required. Thanks again.
Just found your channel.. Great work! I appreciate the comprehensive analysis of these cheap sensors, as the ebay listings tend to give little information.
Hi Andrea thank you for the efforts in reviewing the sensors. For the proper working of the sensors perhaps you can cross check the hypothesis put by sirus o your spectrum analyser. The signal should be visible in the UHF band, based on the geometry of the antenna on the PCBA.
Hello, I am a radar systems engineer for 30 years. It looks like the antenna is a double-dipole and is intended to mount in a simple tube-like cylinder. In this mode it would be a simple motion detector which is what you said correctly at the beginning of the video. However the price is amazing and I will get some of these for proximity sensors around my home as the basis for a new security system. I am also subscribing to your channel. Thank you very much for this video!
Great to have such subscribers! Is this simple design with only one transistor something you know? Because so far, nobody was able to explain us how it works and which principle it uses. For example, I was able to prove, that the modules work ok even if other modules are in close proximity. But as soon as I switch one module off or on, the others trigger. Another question is, if it senses speed and in which direction (from-to or also across). I did not do any proper tests about that.
Yes, with a common ground signals can go in both direction on a wire in TEM mode, so TX mode signals to from the XO to the TX transistor, received signals go the other direction, through a circulator and into the RX front-end, in this simple setup harmonics and distortion are ignored since this is a simple switch motion/no motion based on Doppler signal which is what you said. These modules seem to be in the 5GHz band that is internationally not regulated it is the "other" ISM band that very few can use because of lack of range. In this case that is positive attribute since range-to-target is so close. For several units close together yes there is interference but since the unit only detects Doppler. It is like saying one unit can use another unit's TX signal as long as there is no motion. The other units trigger when a unit is switched off because they detect a change in this signal when a unit goes down the XO does not stop abruptly but changes frequency as power is removed and voltage from the power supply capacitor sags. That is what the other units are detecting.
Hi Andreas, I only comment now (quite a while after watching this for the first time). I got myself 10 RCWL-0516 sensors and I just LOVE them. I automated my lights in both my house and workshop. I even made an alarm sensor unit to monitor movement at my main gate. Thanks to this unit I was able to catch two thieves in the act of trying to break in (South Africa has very high crime rate, so you need to do anything possible to give you an early warning) I did however found that if you are running the RCWL-0516 over a long distance you need to add a PI filter. Two big sized capacitors (100-470uF) with a 10ohm resistor in series (two caps ground tied to ground, one cap receives the supply power, resistor in series to the next cap positive and that goes to VIn of the RCWL. That completely eliminated any false alarms. The unit is very sensitive.It picks up small animals such as pigeons and cats. Oh, and watch out for FOG. Moving moisture seriously affects the unit. That was the only time it failed (false alarms). So for people living in high fog areas, sorry, this will not work. Thanks for a great channel. Love your work. Keep it up.
Thanks for sharing your experience. I did not know about the fog. And maybe it would help to have two sensors in the same area to distinguish between small and bigger "animals". Only if both see something it is big enough.
Hello again, I found that these units are quite sensitive. I do have two units spaced about 6 meters apart (my original idea was to detect direction of movement). That works but it senses both human and small animals (i.e. the neighbors cat) with the same accuracy. I programmed my Arduino Nano to now count the number of triggers or monitor the duration of how long the unit is triggered before creating an alarm. This did eliminate many false animal triggers, but if the little critter decided to hang around the sensor, unfortunately then the alarm goes off. My HD Closed circuit camera system is then used to confirm friend (small animal) or foe (real criminal)
Yes, it worked for me in the hall all right but not in the bathroom, when I kept the unit on a plastic drum full of water. Somehow the effect was dampened and worked only within a few cm as opposed to 3-4 m in a open dry hall.
Movement is almost never detected by the red shift (frequency change) of the reflected radio wave. Speed is measured in a totally different way, with a so-called doppler radar. Doppler radar measures the distance of an object by measuring the time elapsed between sending out and receiving the same signal. It sends out two singals, and measure the change of distance between those two signals.
I think there is a misunderstanding here? The RADAR I was working on cost just under £2,000,000 and use multiple pings etc. However, I understand these very low-cost units operate exactly as described in the video. I purchased mine for
Excellent video! Very informative. To make RCWL-0516's output pulse shorter, one needs to replace the capacitor that is next to the pins 3 and 4 of the IC. I replaced it with 100pF capacitor and now the output pulse is around 40ms. I think with larger values the ratio is closer to 0.25s/nF. Making the pulse longer can be done without removing the onboard capacitor. But like you said, these adjustments require SMD work.
I ordered some of the RCWL-0516 to try at home. If the microwave circuit is a regenerative receiver, it will transmit as well as receive. This was a problem with early regenerative receivers, they interfered with other receivers and could be detected easily. These may be detecting motion by moving objects interfering with the regeneration.
We've got a few radar sensors at work that we're working with (I'm in an mainly-automotive engineering firm) and they are really neat... it doesn't seem like they should work, but i can see the data from them, clear as day. crazy stuff!
I think the idea is to use them as vehicle and obstacle detection. The ones you're showing here seem to be essentially switches. The ones we have can generate a two-dimensional graph of distance vs velocity. You can tell motion towards and away from the sensor and where it is. It's pretty neat. www.d3engineering.com/solutions/autonomous-systems/auto NOTE: I am posting this as myself, not as a representative of this or any other company... It is neat technology though!
Hi Andreas Great video.. I bought a few of the RCWL 9196 based devices that you show in the video and I have been doing some experiments into the mode of operation and other uses for these devices. I've written the account in my blog, but to cut to the chase. Try soldering a wire to Pin 12 of the RCWL9196 and connect it to an oscilloscope or even better an Arduino board. (I'm using a STM32F103C8 aka Blue Pill board for this) The waveforms you'll see are very interesting What you see when an object moves towards or away from the sensor are a series of peaks and troughs, but also with superimposed smaller or larger peaks and troughs of different amplitude. So. My hypothesis, is that these devices operate by using wave propagation interference, where the reflected wave from the object, back to the oscillator / transmitter effects the amount of current it needs to draw in order to maintain its steady state oscillation. Unfortunately along with the fluctuations in voltage from the oscillator, the main IC (2 stage op-amp), causes additional complications as it effectively works as a differentiator with a period of around 0.1 sec. So even if the oscillator output voltage is moved to a higher or lower value by the reflection from a stationary object, the observed output from the op-amp, ends up at Vdd /2 (approx 1.6v) It may be possible to modify the analogue electronics to turn the op-amp into a pure amplifier, (with fixed offset to remove the fixed - mid point voltage from the oscillator), but I still can't think of a use for this apart from motion sensing. I would however recommend that people try using the voltage on Pin 12, as it allows a lot more flexibility in the trigger threshold, and also the output hold time, etc, as this can all be done in the MCU firmware (e.g. in an Ardiuno sketch) You can see the full write and some plots of the data in my blog www.rogerclark.net/investigating-a-rcwl-9196-rcwl-0516-radar-motion-detector-modules/
Nice to hear from you! Thank you fro your comment. You bring up a interesting topic. To do the logic inside the micro controller indeed gives much more flexibility to detect patterns. I think, we will see more of these interesting small chips in the near future. And maybe, a supplier even takes your idea to replace the chip with an ordinary opamp (and maybe even add a cheap I2C ADC), which would not be too complicated. Then, we would have a simple sensor with a wide range of usage.
I think if the device had a I2C DAC to set the voltage on the inverting input of the first opamp, it would make the device more flexible, and perhaps it may be possible to use several of these located in 3 corners of a triangle to perhaps help with navigation of small robots, as they will get different interference patterns from reflections to each other, and perhaps analysis of that data could be useful. But for now, I'm happy just to use it for a motion detector where I can select the sensitivity in the MCU code (by reading the analog output on pin 12)
Very good, thanks. Have you thought about using aluminium foil, say placing your module in a project box lined with foil on the sides but with "clear" lid? This should give a crude ~120° cone sensitivity.
Great video. Never new these existed. Would be interesting to see a video demonstrating when to use either radar, ir or microwave sensors. Also, would be great to see what can be achieved with them, like can the device give a different reading dependent on proximity
Here you may find all the answers you are looking for! Anyway the RCWL-0516 is not a radar and not Doppler effect based! Thanks for this great comparison!
My project with these OWL sensors as a movement sensor, with an ESP8266 to send data, was frustrating with false signals and unreliability until I ensured the WiFi was OFF for most of the sensing time loop while movement pulses were counted and only turned on briefly to transmit the counts! Results:= lower current draw and great reliability. Not surprising but it look time for me to figure that out. Thanks for your inspiration.
Thank you for sharing your experience. Looking at the Spectrum analyzer in my newest video you saw that they work around 3 GHz. Which is very close to 2.4GHz Wi-Fi. So it is no wonder that you get cross-talk.
Once again a *very* interesting video Andreas! .. Think I have to order some devices immediate just to have them at hand for future projects! I have such a Radar system in my car (VW) where it works really great at distances even >100 Meter .. but wasn't aware that for smaller distances these devices can used at very low cost now in own projects! The type of 'sonsors' we have available nowadays is astonishing!, and thanks to Andreas we now how to use them ;-) Thanks for the info!!
As many commenters rightly found out, these devices are regenerative receivers. If you are interested in "real" radar sensors, I propose watching video #439
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...
Mystery gadgets! Nice writeup. You have a very comfortable voice and clear, easy to understand diction. Good job!
Thanks!
Ketil Duna , Really good diction, I'm from Russia and I understood all the information. Good work!
excellent comparison video, I can see allot of work went into making this.
Thanks!
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
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!
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?
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!
Thank you for your nice words!
Sir your videos are gold, it reflects how much work you put into these masterpiece review videos.
Thank you!
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.
Thank you for your additions!
Will it be able to detect u if ur are not moving or sleeping
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.
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
You are welcome!
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 !
You are welcome!
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!
You are welcome!
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
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
Andreas Spiess, you are putting out very good content. Thank you! You are having an impact on the world.
Nice to read. Thank you!
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!
You are welcome!
Thanks Andreas, I always enjoy your videos.
You are welcome!
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 :)
Thanks for the feedback. Maybe I will try it once...
Unless the ground is dry, wouldn't the moisture swamp the return signal?
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!
You are welcome!
IRC these units don't work like a radar. IRC they don't receive a signal back from what they send out. They just emit a continuous wave and monitor how much power it is using to transmit. if something moves in it's "field" it changes the SWR standing wave ratio of the transmitter, causing it to us more or less power that the comparitor uses to cause a trip.
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"
Super Vergleich! :) Die Neugier auf die Module ist geweckt und alle wichtigen Fragen sind in einem Video beantwortet! Klasse Arbeit!
Danke!
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.
You are probably right. There are a few ideas around in the comments. I do not know what is right or wrong...
Andreas , Thank you for your articulate understanding of this technology.
You are welcome!
I don't usually like videos on request, but I had to make an exception.
Thanks for liking. I hope, I did not request it. I just know, that many people forget it..
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!
You are welcome!
thank you for your effort. this was interesting AND useful!
Thanks!
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.
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.
With outstanding content like this, it's really a crime that AS doesn't have 200,000 subs. Soon, I trust!
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.
Thorough review that answered all my questions.
Thank you!
"of course the technology can also be used against us" LOL
:-)
Thank you for your thorough analysis of the devices. A fine video presentation of your results.
You are welcome!
Cool stuff. I might buy a few to play with
:-)
Excellent! Very professional and comprehensive. Saved me tons of work... and money! Thank you, Andreas. I'm looking forward to your next video.
Thank you for your feedback!
Hello Andreas,
Before I begin, I like your videos a lot.
In your video at 15:04 min. you explain that the RCWL-0516 cannot work in a 3.3 volt environment, I make a mistake and put 3.3 volt as input voltage.
So 3.3 volt on the 3.3 pin and GND on the GND pin then a diode connected on the Out pin and GND, and wonder the RCWL-0516 works also, it detects movements like before.
I think that you can use the module from 3.3 volts and if you have 4 volts till 28 volts you must connect the input voltage on the VIN pin.
www.elecrow.com/rcwl-0516-microwave-radar-sensor-switch-module-body-induction-module-4-28v-100ma.html
Greetings from Holland,
Jan-Henk van Kesteren
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.
Top notch video. Practical, succinct, objective. A benchmark for review vids.
Thanks! :-)
@Andreas, some new LiDAR models entered the market, you could test them maybe?
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.
Thank you for the video, Andreas! I love your channel!
I want to report that the RCWL-0516 works great with the Sonoff Basic switch with the OUT pin on the Sonoff's GPIO14 pin and the 3.3V pin connected to the 3.3V of the Sonoff. I use it to report movement via MQTT.
Thank you for your feedback. I am sure it will help other viewers!
I bought a sensor which is marked "2.7GHz" from Aliexpress and was quite surprised by the spectrum of signal which it emits. It is not a narrow "spike" but rather wide, maybe 1 MHz wide. Is that happening because of poor Q of PCB resonator?
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 taking the time to run through these. Wish I had found this video before I bought 5 of each of the RCWL and HFS boards. I need 3 working units (always buy extra from China). Looks like the cheaper boards will be the best fit. NBD. At the prices these things are going for these days I can throw the others in a drawer to use for something else some day. The HFS boards will be better if I need something to be directional.
I hope they will work for you. Keep the power lines very clean (there are a few discussions about that)
Are you sure the RCWL-0516 does not work on 3.3V? I really cannot see a reason why it shouldn't work if you power it with 3.3V on the 3.3V pin. Usually a voltage regulator doesn't care much if you power its output with the right voltage and no input connected... Even if the voltage regulator is integrated within the IC. And I don't think the unregulated input voltage is used anywhere else except on the voltage regulator input. You should try it.
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.
You continue to read my mind and post the videos just when I need them. Thanks
:-)
Great video Andreas!
I found this GitHub repo that has a schematic of the RCWL-0516 : github.com/jdesbonnet/RCWL-0516/blob/master/README.md that you may find useful. Thank you for the great videos!
Thanks for your link!
I thought youtube didn't allow links in the comments?
Genial! Justo acabo de comprar el RCWL-0516 para detectar la presencia de intrusos, una muy buen explicación amigo! Gracias por compartirlo con nosotros
You are welcome!
Great hands-on test ! Thanks !
More info here: github.com/jdesbonnet/RCWL-0516
Thanks for the link.
Thank you very much. Appreciated.
Very nicely done - appreciate your thoroughness on the testing; gave me some background on what they might do.
Thank you!
The 1.8 GHz could be a DECT phone
Thanks for the hint. This is well possible because one was close by.
Thanks for this comprehensive and systematic comparision. It comes very handy to me because I also received a sensor similar to XYC-WB-D1 for playing around and looking for a helpful application. Unfortunately (?) most helpful application are already covered in my environment.
It is really an excellent work to do all that with just one (1) transistor and some passives. Chapeau!
That is what I think, too...
Awesome! I have been waiting for this video since you mentioned it in one of your mail bags, thanks for coming through with the usual great content.
Thanks!
Excellent comparison Andreas. I will be using in my future projects.
Thanks!
I just found your channel, great video! I like how precise and concise your comments are. Brief, clear and to the point. You have a new subscriber!
And you made me laugh so much at the end when you said "If true then like". 🤣
Welcome aboard the channel!
Nice introduction in Mircorwaves. I like your channel very much.Also becaues you are a swiss guy too :) It's very nice to see, that we have such brillant heads in our small country ;) Since 3 days I played around with the RCWL-0516 and I'm very happy with it. Stay healthy and I hope a lot more videos are coming up :) Next I want to build a LoRa Gateway because in my region no one have it. A liebe Gruess und sunnigs Wätter :)
Wenn es dich interessiert kannst du hier mal reinhören: www.srf.ch/sendungen/digital-plus/ue60-influencer-landet-grosserfolg-mit-elektronik-videos
@@AndreasSpiess Gerne, mache ich gleich mal :) Herzlichen Dank für den Link! Was ich wirklich so toll an deinen Videos finde ist, dass du es auf eine Weise rüber bringst, die selbst ein nicht-Elektroniker daraus schlau wird. Dafür ein herzliches Dankeschön. Behalte dein way-to-do bei, denn dieser ist wirklich genial. Schönes Wochenende und herzliche Grüsse aus Bern
Vielen Dank!
Great video. Appreciate the effort to examine and compare the most important characteristics of each unit with a scientific approach. I agree with you, even if the units are simply measuring the variance in transmitter output to determine motion, some sort of return circuit is required. Thanks again.
You are welcome!
Just found your channel.. Great work! I appreciate the comprehensive analysis of these cheap sensors, as the ebay listings tend to give little information.
Thank you!
I very like your videos and how you do explain the comparison. You're now my favorite youtuber.
Thank you and welcome to the channel!
Very nice comparison, Andreas!
Thanks!
wie immer auf den Punkt!
Danke!
Nice work. It was pleasure to watch. Many thanks.
Glad you enjoyed it
this video was incredibly informative! Keep it up, man
Thanks!
thank you so much for doing this test its very important for many useful applications !
You are welcome!
Very useful comparison video . Great effort is done .
Thank you!
Congratulations for your work. This type of videos are very useful when making a purchase decision.
Thank you!
Great video as always. Thanks Andreas. Have a great Sunday!
Thanks. You too!
Great video. FWIW, I'm using 3.3v input via Arduino on the RCWL-0516 with no problems, so it is definitely the sensor of choice for me.
Thanks for the feedback.
Hi Andrea thank you for the efforts in reviewing the sensors. For the proper working of the sensors perhaps you can cross check the hypothesis put by sirus o your spectrum analyser. The signal should be visible in the UHF band, based on the geometry of the antenna on the PCBA.
Their frequency is above the limits of my SA :-(
This is very helpful video Andreas. Nicely done.
Thanks!
Never heard of those fantastic little radar sensors. Thank you.
You are welcome!
Hello, I am a radar systems engineer for 30 years. It looks like the antenna is a double-dipole and is intended to mount in a simple tube-like cylinder. In this mode it would be a simple motion detector which is what you said correctly at the beginning of the video. However the price is amazing and I will get some of these for proximity sensors around my home as the basis for a new security system. I am also subscribing to your channel. Thank you very much for this video!
Great to have such subscribers! Is this simple design with only one transistor something you know? Because so far, nobody was able to explain us how it works and which principle it uses. For example, I was able to prove, that the modules work ok even if other modules are in close proximity. But as soon as I switch one module off or on, the others trigger. Another question is, if it senses speed and in which direction (from-to or also across). I did not do any proper tests about that.
Yes, with a common ground signals can go in both direction on a wire in TEM mode, so TX mode signals to from the XO to the TX transistor, received signals go the other direction, through a circulator and into the RX front-end, in this simple setup harmonics and distortion are ignored since this is a simple switch motion/no motion based on Doppler signal which is what you said. These modules seem to be in the 5GHz band that is internationally not regulated it is the "other" ISM band that very few can use because of lack of range. In this case that is positive attribute since range-to-target is so close. For several units close together yes there is interference but since the unit only detects Doppler. It is like saying one unit can use another unit's TX signal as long as there is no motion. The other units trigger when a unit is switched off because they detect a change in this signal when a unit goes down the XO does not stop abruptly but changes frequency as power is removed and voltage from the power supply capacitor sags. That is what the other units are detecting.
Thanks for your explanations!
Video was very interesting to watch and the comments contained more interesting information, subscribed.
Welcome to the channel!
I didn't even know there are devices like these out there, but they seem pretty cool. The video was excellent, too.
Thanks!
Wow, such a solid video - respect to You Andreas
:-)
i`m from Brazil, your explanation is excellent, congratulations and thank you
You are welcome!
Great Comparison! I'm anxious about the next video explaining how they work! Please do it :) Thanks a lot!!
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 :)
Hi Andreas,
I only comment now (quite a while after watching this for the first time).
I got myself 10 RCWL-0516 sensors and I just LOVE them. I automated my lights in both my house and workshop. I even made an alarm sensor unit to monitor movement at my main gate. Thanks to this unit I was able to catch two thieves in the act of trying to break in (South Africa has very high crime rate, so you need to do anything possible to give you an early warning)
I did however found that if you are running the RCWL-0516 over a long distance you need to add a PI filter. Two big sized capacitors (100-470uF) with a 10ohm resistor in series (two caps ground tied to ground, one cap receives the supply power, resistor in series to the next cap positive and that goes to VIn of the RCWL. That completely eliminated any false alarms.
The unit is very sensitive.It picks up small animals such as pigeons and cats. Oh, and watch out for FOG. Moving moisture seriously affects the unit. That was the only time it failed (false alarms). So for people living in high fog areas, sorry, this will not work.
Thanks for a great channel. Love your work. Keep it up.
Thanks for sharing your experience. I did not know about the fog. And maybe it would help to have two sensors in the same area to distinguish between small and bigger "animals". Only if both see something it is big enough.
Hello again,
I found that these units are quite sensitive. I do have two units spaced about 6 meters apart (my original idea was to detect direction of movement). That works but it senses both human and small animals (i.e. the neighbors cat) with the same accuracy. I programmed my Arduino Nano to now count the number of triggers or monitor the duration of how long the unit is triggered before creating an alarm. This did eliminate many false animal triggers, but if the little critter decided to hang around the sensor, unfortunately then the alarm goes off.
My HD Closed circuit camera system is then used to confirm friend (small animal) or foe (real criminal)
Yes, it worked for me in the hall all right but not in the bathroom, when I kept the unit on a plastic drum full of water. Somehow the effect was dampened and worked only within a few cm as opposed to 3-4 m in a open dry hall.
Thank you and your neighbour as well for this demonstration of these interesting devices ;-)
:-)
Thank you, very helpful comparison.
Glad it was helpful!
Very interesting and complete comparison. Thank you!
Thanks!
A very comprehensive review! Thank you for your hard work!
You are welcome!
Movement is almost never detected by the red shift (frequency change) of the reflected radio wave. Speed is measured in a totally different way, with a so-called doppler radar. Doppler radar measures the distance of an object by measuring the time elapsed between sending out and receiving the same signal. It sends out two singals, and measure the change of distance between those two signals.
I think there is a misunderstanding here? The RADAR I was working on cost just under £2,000,000 and use multiple pings etc. However, I understand these very low-cost units operate exactly as described in the video. I purchased mine for
I must thank you for these videos, they are great.
You are welcome
Excellent video! Very informative.
To make RCWL-0516's output pulse shorter, one needs to replace the capacitor that is next to the pins 3 and 4 of the IC. I replaced it with 100pF capacitor and now the output pulse is around 40ms.
I think with larger values the ratio is closer to 0.25s/nF. Making the pulse longer can be done without removing the onboard capacitor.
But like you said, these adjustments require SMD work.
Thanks for the info. Maybe I will try it with one of the devices for my next experiments.
Excellent video. I just bought some of these myself. Looking forward to testing them out when they arrive.
:-)
Thanks for all the hard-won information! Great study.
You are welcome!
Thank you very much for this review!
You are welcome!
Many thanks for the great summary - exactly what I needed to know :) Best regards from DE
You are welcome!
Excellent review. This is how it's done people. Subscribed.
Welcome aboard the channel!
Thanks for your video. I need to use motion detection for my project. I appreciate your effort and infos.
You are welcome!
I ordered some of the RCWL-0516 to try at home. If the microwave circuit is a regenerative receiver, it will transmit as well as receive. This was a problem with early regenerative receivers, they interfered with other receivers and could be detected easily. These may be detecting motion by moving objects interfering with the regeneration.
Well possible. BTW I built such a (tube) regen receiver in another video...
Good to follow the thought process.
Thank you!
Fantastic video. you are as thorough as ever. thanks for your big use off time to make this video 👍😀
Thanks for your feedback!
We've got a few radar sensors at work that we're working with (I'm in an mainly-automotive engineering firm) and they are really neat... it doesn't seem like they should work, but i can see the data from them, clear as day. crazy stuff!
+Scott Lawrence What kind of applications do you use them?
I think the idea is to use them as vehicle and obstacle detection. The ones you're showing here seem to be essentially switches. The ones we have can generate a two-dimensional graph of distance vs velocity. You can tell motion towards and away from the sensor and where it is. It's pretty neat.
www.d3engineering.com/solutions/autonomous-systems/auto
NOTE: I am posting this as myself, not as a representative of this or any other company... It is neat technology though!
These are nice devices! But I assume, they cost also more than 50 cents ;-)
Yes. Very much more than $0.50. ;)
Interesting video which gives a lot of useful information about these devices.
Glad you think so!
Nice video. Have not come across these modules yet. Very interesting, will have to add one to my collection.
:-)
Hi Andreas
Great video.. I bought a few of the RCWL 9196 based devices that you show in the video and I have been doing some experiments into the mode of operation and other uses for these devices. I've written the account in my blog, but to cut to the chase.
Try soldering a wire to Pin 12 of the RCWL9196 and connect it to an oscilloscope or even better an Arduino board. (I'm using a STM32F103C8 aka Blue Pill board for this)
The waveforms you'll see are very interesting
What you see when an object moves towards or away from the sensor are a series of peaks and troughs, but also with superimposed smaller or larger peaks and troughs of different amplitude.
So. My hypothesis, is that these devices operate by using wave propagation interference, where the reflected wave from the object, back to the oscillator / transmitter effects the amount of current it needs to draw in order to maintain its steady state oscillation.
Unfortunately along with the fluctuations in voltage from the oscillator, the main IC (2 stage op-amp), causes additional complications as it effectively works as a differentiator with a period of around 0.1 sec. So even if the oscillator output voltage is moved to a higher or lower value by the reflection from a stationary object, the observed output from the op-amp, ends up at Vdd /2 (approx 1.6v)
It may be possible to modify the analogue electronics to turn the op-amp into a pure amplifier, (with fixed offset to remove the fixed - mid point voltage from the oscillator), but I still can't think of a use for this apart from motion sensing.
I would however recommend that people try using the voltage on Pin 12, as it allows a lot more flexibility in the trigger threshold, and also the output hold time, etc, as this can all be done in the MCU firmware (e.g. in an Ardiuno sketch)
You can see the full write and some plots of the data in my blog
www.rogerclark.net/investigating-a-rcwl-9196-rcwl-0516-radar-motion-detector-modules/
Nice to hear from you! Thank you fro your comment. You bring up a interesting topic. To do the logic inside the micro controller indeed gives much more flexibility to detect patterns. I think, we will see more of these interesting small chips in the near future. And maybe, a supplier even takes your idea to replace the chip with an ordinary opamp (and maybe even add a cheap I2C ADC), which would not be too complicated. Then, we would have a simple sensor with a wide range of usage.
I think if the device had a I2C DAC to set the voltage on the inverting input of the first opamp, it would make the device more flexible, and perhaps it may be possible to use several of these located in 3 corners of a triangle to perhaps help with navigation of small robots, as they will get different interference patterns from reflections to each other, and perhaps analysis of that data could be useful.
But for now, I'm happy just to use it for a motion detector where I can select the sensitivity in the MCU code (by reading the analog output on pin 12)
Very good, thanks. Have you thought about using aluminium foil, say placing your module in a project box lined with foil on the sides but with "clear" lid? This should give a crude ~120° cone sensitivity.
If you look at other comments: This should work. Of course, it depends on the application.
Great video. Never new these existed. Would be interesting to see a video demonstrating when to use either radar, ir or microwave sensors.
Also, would be great to see what can be achieved with them, like can the device give a different reading dependent on proximity
You can do your tests. these devices are not expensive ;-)
I recently did a video about the new 24GHz sensors, BTW
Excellent video. I can better understand you than a native English speaker. Good job, keep going.
Thanks!
I just come across one of those sensors and landed here after googling. Geat info!
Thank you!
Here you may find all the answers you are looking for! Anyway the RCWL-0516 is not a radar and not Doppler effect based! Thanks for this great comparison!
I agree!
My project with these OWL sensors as a movement sensor, with an ESP8266 to send data, was frustrating with false signals and unreliability until I ensured the WiFi was OFF for most of the sensing time loop while movement pulses were counted and only turned on briefly to transmit the counts! Results:= lower current draw and great reliability. Not surprising but it look time for me to figure that out.
Thanks for your inspiration.
Thank you for sharing your experience. Looking at the Spectrum analyzer in my newest video you saw that they work around 3 GHz. Which is very close to 2.4GHz Wi-Fi. So it is no wonder that you get cross-talk.
Really good video. Clear and very informative. Thank you.
:-)
Once again a *very* interesting video Andreas! .. Think I have to order some devices immediate just to have them at hand for future projects!
I have such a Radar system in my car (VW) where it works really great at distances even >100 Meter .. but wasn't aware that for smaller distances these devices can used at very low cost now in own projects! The type of 'sonsors' we have available nowadays is astonishing!, and thanks to Andreas we now how to use them ;-)
Thanks for the info!!
I agree concerning the possibilities. However, these sensors do not measure distance, just "the fact", that something is in range.
Good point!
so touching for an excellent video
Glad you enjoyed it