#181

[@MartinBgelund]

This is very interesting, I'm looking forward to see more of the innovative details. How about pedestrians, skaters runners, etc in the same speed range? How will you avoid counting those as bikes?

[@AndreasSpiess]

I think, It will not be universally usable. For bigger roads with lots of traffic maybe a stationary solution is affordable. For smaller roads, this might be a possibility.

[@anlumo1]

Skaters might be a problem, but pedestrians and runners are slower and it might be possible to filter them out (as long as you're not measuring close to an intersection). The bigger problem is probably groups of bicycles.

[@MartinBgelund]

anlumo1 There are fast walkers and slow bikers, so filtering will be based on assumptions, not on certain attributes.

[@anlumo1]

Yes, but I don't think that a 0% error rate is required. In addition to that, bicycles have a minimum speed they need to operate at, otherwise they topple over.

[@Sir_Trip-s-A-Lot]

Can easily be addressed by magnetic field sensor alongside. The only foolproof way is to distribute free cycle only RFID stickers at city hotspots. That will solve all the problems

[@JoeBee999]

To messure only frequency, the signal is very often staged throug a comparator. This gives a nice square frequency. As far as i know, Atmel AVRs have one build in. Or just use a OPamp. Then feed to an input capture pin and the time os messured.

[@AndreasSpiess]

That would then be version 1. I have also to check if the digital pins of the ESP32 are Schmitt-Triggers

[@Thesignalpath]

Thanks for pointing to my channel. :)

[@AndreasSpiess]

You deserve it. I like your channel!

[@schmohawk_]

this is hardcore!

[@randomhuman1965]

Great Video!! Could you not use two or more of those $6 sensors back to back for an easy direction count cheat? One may have to be detuned slightly via the screw to avoid interference...

[@AndreasSpiess]

Maybe this will be the solution at the end...

[@phinok.m.628]

Well, the problem with detecting the falling/rising frequency is that you have to a assume the bike is going at a constant speed. A quickly stopping bike may decrease the frequency more than it's changing proximity to the sensor increases the frequency, causing false readings, not to mention the angle from where the bike comes can change, since bikes don't always drive in straight lines. Another problem is, that multiple bikes driving very closely to each other would likely be counted as a single bike. So if you want accurate readings, this is probably not a very good way to count bikes. If you only want rough numbers however, I guess this would be a reasonable way to do it. And if you want accurate readings, I guess this method would still be useful, but combined with other measuring methods. Since no method is perfect, but many combined can probably eliminate a lot of errors. Anyway, I would be very interested in a way to measure distance to cars using for example radar. I've been looking for a reasonably cheap and reliable way to measure long distances (say up to 300 m) and preferably many times per second, but haven't found any way to do it so far.

[@AndreasSpiess]

I do not expect exact readings because of all the problems you mentioned. But I hope the errors will be tolerable for a certain purpose. And if not, we at least tried ;-)

[@phinok.m.628]

Yeah, it's certainly an interesting experiment. I hope you don't take me mentioning likely problems the wrong way. I think it's great what you and other youtubers like you do. Regardless of whether it works as intended or not, it's always good to share your experience with others so they can learn from it.

[@phinok.m.628]

@@AndreasSpiess Btw. what's wrong with measuring the change in amplitude to determine the direction the bike it going? Sure it's would be a little more complicated to do, but I think it would be a more reliable way to do it.

[@moses5407]

Did this ever go to completion? I haven't found a specific follow-up...?

[@AndreasSpiess]

No. The usable range was too short :-(

[@TomaszDurlej]

Rotation radar next time maby?

[@AndreasSpiess]

Then I first need a flying bike ;-)

[@hvanmegen]

2 years in: still loving the guy with the Swiss accent.. my #1 go-to guy when I want to be informed about IoT, electronics and home automation!

[@AndreasSpiess]

Thank you very much!

[@ErnestGWilsonII]

Wow, an awesome video! I am hoping that you can hook up a display or send a signal back to MQTT with the speed data from the object and maybe even trigger a camera based on the recorded speed of the object. My love of electronics and RF are always rekindled when I watch your awesome channel. As an old school electronics technician myself, I wish we were not separated by such a large geographic distance. I am slightly jealous of your assistant in the video, having access to the master Andreas Spiess, I hope he is aware of how lucky he is!. I am fondly reminded of days long ago when my old crew had a lab and we built various electronic devices, this is why I love this channel! I hope you win the contest! Thumbs up, loyal fan / subscriber, -Ernest 73s W3TCP

[@AndreasSpiess]

You see that my heart is also moving a little faster if RF is involved... Distances fortunately are no more as separating as they were 100 years ago. So, maybe we can once drink a beer together. You never know ;-)

[@Tarbard]

It makes a nice sci-fi noise too.

[@AndreasSpiess]

:-))

[@alana314]

Hi Andreas! I bought the same CDM323 and amplifier and got it to work like your first part, making sound at a distance of a few inches. But I can't get it to work with objects more than a foot away like your bicycle. How did you get that part to work? Did you modify the pitch of the sensor somehow?

[@AndreasSpiess]

It is all about building a low-noise high gain amplifier. Not easy, though.

[@peterleather6866]

Another fascinating and informative videos Andreas! I wonder how the sensor will cope with more than one bicycle at the same time? Will the sensor output multiple frequencies for the different speeding objects? Also if two bicycles were close to the same speed (side by side for example) would it be impossible for the sensor to tell. A very small limitation perhaps but a very interesting sensor.

[@AndreasSpiess]

It will have its problems with multiple bicycles, for sure. But maybe it will be exact enough for smaller roads where a cheap temporary solution is just right.

[@charlesdorval394]

That was an awesome video Andreas! Thank you!

[@AndreasSpiess]

You are welcome!

[@ThomasHaberkorn]

now I know where Knight Rider got their sound effects :)

[@AndreasSpiess]

:-))

[@gweliver]

Great project, can anyone direct me to the follow-up video (pt2), thanks for all the great content and detail(s) you provide. You are someone we can trust, for sure!!!

[@AndreasSpiess]

There is none for the moment.

[@tylerrourke50]

I would also like to see a part 2. Great video!

[@steven_jahn]

I won an 2 channel oscilloscope last year after someone was caught cheating. They let me know in May I had won on the redraw and I got my scope in July!

[@AndreasSpiess]

Thanks for your feedback!

[@BitsOfBoris]

I got one for the fun of it but I get no IF signal... 0v with a light offset. Certainly not 400mv waves :'( Meh. Tried with two 5V regulator and double checked the pinout between you and ali. Anyone got the same issue?

[@rodinsocaciu]

Highly appreciated your videos. Great when such initiative could get helping. Have you considered looking over a AC Volt&Amp&Watt Meter WiFi logger?

[@AndreasSpiess]

You can buy one from Sonoff. I made once a video about it. But maybe I will cover this topic in the future again.

[@gandsnut]

The change in towards/away sound (in this demo) seems opposite to 'Doppler' effect... As the ambulance siren comes towards, its pitch sounds higher, when the siren is just by us, it sounds 'normal', then when siren passes away, the pitch sounds lower. But this is a moot point, because we can interpret the radar sensor output however we want.

[@AndreasSpiess]

The relevant for me is my measurements. And there direction does not matter ;-)

[@joinedupjon]

the difference between this radar and sound waves is that you can hear the pitch change directly for the ambulance whereas the radar reflection is processed to produce a 'difference' output and it's the difference output that you hear in the video. negative difference sounds exactly like positive difference. also we'd expect the difference signal to be zero at the instant the bike passes closest to the radar - for the siren this would be the instant we heard the 'true' frequency.

[@dl8cy]

What an incident - yesterday in the evening i thought about that and now the Swiss guy shows solutions. Keen on part 2 of the Video. Thank you and 73 from Germany

[@AndreasSpiess]

Maybe it is not the complete solution. Still a way to go ;-)

[@АнтонАнтонов-ь5щ6н]

First of all, thank you, Andreas, very much for such cool videos. You teach us a lot!) Please, correct me. 1) "Two zero crosings of the wave" - is a half-period? 2) Period is 150ms. So 1/150 ms = 1/0.150 s = 6.6(6) Hz, not 67 Hz?

[@AndreasSpiess]

1. Yes, correct

[@spikeydapikey1483]

Looking forward to part two. Cheers :o)

[@AndreasSpiess]

Will take some time...

[@sylvainlazare1114]

Good work and very convincing presentation. What happens in the caseof more than one moving target? you would need a more discriminating software? or do you have simple solution?

[@AndreasSpiess]

I do not think we can discriminate several bicycles.

[@ZlayaCo6aka]

The purpose of the "unknown material" at 12:10 is to prevent any resonance within or oscillation due to the shielded enclosure; in this case, it appears to be the ubiquitous "conductive foam."

[@AndreasSpiess]

Thanks for clarification!

[@TheRealKitWalker]

2:04 "...in wrong hands can cost us a lot of money ": shows a picture of policeman. Hahaha clever and rightly said. 🤭🤭😂😂😂👏👏👏👍👍

[@AndreasSpiess]

:-)

[@TheRealKitWalker]

@@AndreasSpiess hehe :P but I'm glad that you actually make the gadgets I think of making but I never find the right sensors for them. The buying links you provided are a life and time saver. Thanks so much. Love your videos always. At present I'm researching to make a similar project using a 60 Ghz RF CMOS sensor to track and position a moving object in the field of sight and also measure their size, weight, heart beat, etc... with it. Possibly an idea for your next video? ;)

[@AndreasSpiess]

I thought these modules are still too expensive...

[@TheRealKitWalker]

@@AndreasSpiess Hmmm yes, I just found out the exact price + shipping. turns out there's hope for cdm324 to achieve what I want with the help deep learning. Hopefully, I'll start soon on this. Thanks Andreas.

[@mbaker335]

A very interesting video in an area I will experiment with myself. I lived in CH for seven years returning last October to retire in the UK. The pictures make me feel homesick in a strange way. Lovely country. I miss it a lot.

[@AndreasSpiess]

Thank you for your nice words about my country. You are always welcome as a guest here in CH ;-)

[@spacechicken2756]

This is a very interesting project! I am interested in making a little speed gun that would be able to measure tennis serves / baseball pitches. Do you think these components would be accurate enough? If not, do you have any suggestions for better radar sensors?

[@AndreasSpiess]

So far we abandoned this project because better sensors are over 100 dollars.

[@davidkempton2894]

I was so worried about you on that bike that I decided that I had better become a Patreon!

[@AndreasSpiess]

To support my widow if I crash? ;-) I drive around 4000km per year with my bike. So no problems for these short tests.

[@davidkempton2894]

Andreas Spiess I was hoping that it would encourage you to drive even faster! 😂

[@rickseiden1]

Your picture with the waves compressed and stretched out is reversed. It would be compressed in front of the police car and stretched behind it.

[@AndreasSpiess]

I think the drawing is relative to the ear, not the car.

[@EpicLPer]

So this sensor can only detect up to 6 km/h? Aaaw man :( Would need one that can detect up to 50-70...

[@AndreasSpiess]

It detects at least 6 km/h. 70 should be no problem.

[@EpicLPer]

@@AndreasSpiess Aaaah okay. I wanna build a LED matrix display like they have on the streets with this so drivers here in my area won't drive 100 in a 50 zone... Still on my ground but visible from the road so should be legal. Don't want to lose another cat to stupid speeders :(

[@AndreasSpiess]

The problem is the detection distance. It is max. 10 Meters

[@penversity]

@@AndreasSpiess Is there a way to increase the detection distance? Does it have something to do with raising the amplification?

[@klassichd10]

Thanks for this introduction and the Pictures from inside the CDM324. I did not open the mine. I only had to open one of my HB100 arriving with a loose rattling disk of this dielectric resonance oscillator. The arduino FFT works with the ESP32 just fine out of the box. Even with 1024 and 2048 samples. I am very curious how the InnoSenT quadrature radars will perform and what they cost. Also the AGC amplifier could help. Sounds promising.

[@AndreasSpiess]

I also played a little with FFT and the ESP32. So far I do not yet know which amplitude gives the best result nor which is the right sampling speed or # of samples to get max speed for the frequency range needed. Do you have any info about these factors? The InnosenT costs around 30 Euros at Conrad. AGC amplifier is on order... BTW: I opened mine because I killed it somehow. Don’t know how :-(

[@klassichd10]

I used a biased signal with 1.6V virtual GND. Try to get the signal in front of the output cap. The ADC of the ESP32 is poor (www.esp32.com/viewtopic.php?t=1045) , so you have to use the preamp to get several hundred mV. Using 24GHz you get a Doppler shift of 3400Hz @76km/h and 40Hz @0.9km/h. To avoid aliasing you should sample at least 6400 samples/s (Nyquist-Shannon). Try 8000 samples/s which could work. Otherwise use 4000samples/s which works but limits you to ca. 37km/h. If your radar also sees faster vehicles like cars, you should use a low pass filter as an anti-aliasing filter. To be precise @ low speed you should measure 40Hz with maybe 10%, that means 4Hz. To achive a resolution of 4Hz @ 8000 samples/s you need N> 2000, that means 2048 samples per conversion, or 1024 @ 4000samples/s. This leads to a window time of ca. 1/4 sec in which the speed should be approximately constant. Looks reasonable. You find some formulas e.g. in home.zhaw.ch/~rur/dsv1/unterlagen/dsv1kap3dftfft.pdf public.beuth-hochschule.de/~mixdorff/mmt1/files/spektralanalyse.pdf home.zhaw.ch/~dqtm/dsv1/vorlesung/dsv1kap3_dftfft.pdf You should use a Hanning window (arduino FFT provides it) to reduce the effect of a finite oberservation time (rectangular window). arduino FFT is a complex FFT. You feed the ADC samples in the real part and flood the imaginary part with 0 - when using the cheap radars. Using the the quadrature radars you feed the quadrature signal to the imaginary part. arduino FFT performs the complex FFT and has a function to calculate the magnitude vs. frequency and to pick the highest magnitude. This maybe a bit crude and you may add a function finding several local minima. And extracting the phase (leading to the direction) is not provided by arduino FFT out of the box as far as I remember.

[@lnbt1]

Can you recommend what type of sensor can be used to measure the pingpong ball / badminton birdie smashing speed? Thank you!

[@AndreasSpiess]

I think only radar would be fast enough and also has a certain beam width (see my last video about Laser speed gun). But I do not know if a small ping-pong ball will create a signal big enough. And I do not know how you can deal with the different angles the ball might take in relation to the sensor. So you have to experiment.

[@PhG1961]

Great and surprisingly interesting video. Btw, I defenately would like to have that Keysight equipment. I remember the HP and Agilent as being excellent... but also very expensive.

[@AndreasSpiess]

Yes, it is a nice device. And I am happy with it :-)

[@WolframWebers]

I seriously like your videos and learned a lot about electronics (I'm more into software engineering). Please, keep up. You're awesome.

[@AndreasSpiess]

Thank you!

[@augurelite]

This was one of the most interesting videos I've seen in a long time! Very cool!!

[@AndreasSpiess]

Glad you enjoyed it!

[@joinedupjon]

I was going to suggest you fabricate an inside corner cube reflector to increase the detection range... but if you're interested in detecting general cycle traffic rather than optimising your own speeding it's not relevant :) Audio output sounded like an old fashioned bicycle dynamo IMO

[@AndreasSpiess]

You are right: It sounds like a dynamo!

[@joinedupjon]

I've remembered a humorous suggestion for defeating speed radar in an old motorcycle magazine... attaching corner cube reflectors to the wheels to produce strong return signals with varying frequency shift, the theory was that this would confuse the receiver. doubt it was ever tried - it doesn't seem practical.

[@maximilianibel]

Interesting idea. Maybe install a larger rotating disk with cubes mounted on outside rim on top of car (wheels are probably too low). Could use this project to measure effectiveness of that strategy (or just use the US style speed indicators). I don't know how focused radar based speed guns are, plus I thought many speed guns now work with lasers pointed at number plates and directly measure return times (like lidar/rangefinders). That's much harder to fool.

[@CroutonBrown]

Abso-smurfly wonderful video you’ve got here, mon capitain! Thank you for providing this content!

[@AndreasSpiess]

My pleasure!

[@gasperh.9800]

hello Andreas, First I would like to say great video. I am doing school project with arduino trough this school year. i decided to make a portable car speed detector using microwave radar sensor(hb100/cdm324/..), amplifier, arduino UNO and LCD display... i am still not profesional with arduino software/hardware and will try to learn more trough this school year. i would really appreciate if you could take 5min and answer this questions: -are microwave sensor, amplifier and arduino enough to measure speed or do i need other components? -are arduinos capable of measuring frequency for this project (using FreqCount library)? -is arduino UNO fast enough? what about arduino NANO? do i need faster microcontroler? -do hb100/cmd324 substract transmited and received signal or do i need another component to make it happpen? hope you can help me, thanks

[@AndreasSpiess]

You get a quite small signal (proportional to speed) from the hb100/cdm324 and need to amplify. See limpkin.fr/index.php?post/2017/02/22/Making-the-Electronics-for-a-24GHz-Doppler-Motion-Sensor for help

[@rklauco]

Excellent idea! I have to test it. Fun fact: I thought it's elektrovelo before I realized the sound is produced by the amplifier and speaker :)

[@AndreasSpiess]

I am still too young for an e-bike ;-)

[@zeljkodujmovic]

Hi Andras I'm also from Switzerland :-) I was interested in a radar gun for measuring the speed from a ball (volleyball). What is the speed range of this radar? Do you think we could build a radar gun for this purpose? Volleyball speeds can be 20 130 km/h. Could this device measure it? I would like to detect the top speed of a serve or spike for example.

[@AndreasSpiess]

I do not think this is the right technology. Firstly, it would probably not detect any non-conducting material. And secondly, its reach is way too small for such fast moving things.

[@Daniel-fw5gu]

Great video, as always... BTW, Channel 3Blue1Brown did an excellent video about Fourier-Transformation...

[@AndreasSpiess]

Thanks for the link. Excellent explanation of FFT

[@NorbertHarrer]

Yes, I also saw that video recently. Amazing stuff. So far FT was only a magic black box to me. That video really gives some insight.

[@korokw]

Did you ever think, why frequency is changing when the vehicle is passing?? Because cos α is changing - while the velocity is constant! This is a very important fact!

[@AndreasSpiess]

Of course. Usually you can only use a part of the data where the angle is small

[@wowtah]

Very interesting! Can you please go into more detail on the direction detection? With the Ali sensors in particular :) keep up the good work!

[@AndreasSpiess]

We will share our results in a later video.

[@rjrodrig]

Why can you look at the phase of the signal. You can use a down converter approach by using I and Q signal split and get the phase information. I suspect you can detect direction. Using an FPGA you could implement a down converter

[@AndreasSpiess]

May

[@dusterl1472]

Probably too late to cment and expect a reply but here goes... You mentioned increasing amplification, what amplifier would you start with or suggest to avoid clipping? Also, where pray tell, did you source those other sensors you plan(ned) to try? Last two questions, but they're related... For increasing performance of these modules, would a different antenna be practical? And what about increasing the actual output power/wattage?

[@AndreasSpiess]

Clipping is not a problem because you are interested in the frequency. Changing the design is very tricky because the high frequency.

[@gijsqwerasdf]

This is so awesome, thank you! One question: is it possible to only detect metal objects? Is it depending on the frequency perhaps? I'd like to detect bikes and cars, but not pedestrians.

[@AndreasSpiess]

Conductivity is what counts. So it will not be easy to distinguish between humans and bikes using radars. A camera is probably better.

[@luom23]

considering detecting multiple objects, I would suggest multiple receivers

[@AndreasSpiess]

I am not sure if this would work or if they would disturb each other

[@timothyivan2427]

Is it possible to detect slow movement (10 Km/h) of small silicone rubber tube (D=1 cm ) about 5 cm away from the sensor. Does it require any changes in the circuit due to size and proximity of the sensor?

[@AndreasSpiess]

I do not know if it is able to detect silicone. The good has to reflect the waves. So you have to try.

[@gregorybolin4672]

What is needed to make this module work ld306s radsr module aliexpress. Could it be used for golfballs or baseballs Thanks

[@AndreasSpiess]

I do not think it will detect things without metal or water.

[@raghu9270]

Hello Guy with the Swiss accent, I am a great fan of your channel and thanks to you I have built a lot of projects and Every one was successful. You are truly a great guy.. Can you do a project on building a speed gun radar detector to be used in the car using commonly available sensors and microprocessors. It will be really great project. The currently available sensors in the market are pretty expensive. Also as a maker it will be great fun to build one on our own. Thanks

[@AndreasSpiess]

Unfortunatly, the cheap modules are not good enough for that purpose and the good ones are very expensive :-(

[@transient0126]

Since frequency can be used to determine speed, then how do you explain calculating speed when the frequency is changing over distance? Your calculation is dependent on when you sample the frequency. This is confusing to me.

[@AndreasSpiess]

If the frequency changes the speed or the angle the radar sees the object also changed.

[@ebb2421]

the screw of the HB sensor does shift the freq, confirmed with HP5350B, have fun

[@AndreasSpiess]

Thanks for the feedback!

[@ON7ARQ]

Nice explanation, but you need a licence to use it and I doubt if it is legal 1 to use the frequency 2 to use it as radar, I have also the HB100 module but for use as radio-amateur for ATV ( amateur television ) or phone

[@AndreasSpiess]

These modules are used in many buildings to open doors. But I am no lawyer... How far can you transmit with this module and how stable is its frequency?

[@betojasz]

Mannn, your videos are magic!! Great idea to put sound to hear the distance!! This is more than just science!! its fun!! Thanx a lot!!

[@AndreasSpiess]

You are right. We had some fun, too...

[@AdilKhan-jp7hn]

Excellent video and very interesting sensors. Please let's build a radar gun. Awesome

[@AndreasSpiess]

Thank you!

[@filipsimurda5236]

12:38 The same goes for amplitude, which means that we could detect the direction of motion by amplitude, right?

[@AndreasSpiess]

Yes, you can try it. It is not always easy if the area of the car for example changes with the angle if it moves. With a bicycle it was possible.

[@richardphillips2405]

Great video. I will have to try this. I was wondering about using the microwave sensors for range detection (distance).

[@AndreasSpiess]

These sensors only detect speed, no distance.

[@richardphillips2405]

@@AndreasSpiess This is sort of what I thought. It probably could get real complicated to build (diy) a distance measuring radar. What about FMCW (frequency modulated continuous wave type sensors).

[@AndreasSpiess]

The FMCW shoud do the trick. I one bought one, but unfortunately do not find it in my lab anymore :-( They are quite expensive...

[@tecnoactivaitservices1864]

Would this sensor measure pellet speed from an airgun , let say 300 fps to 1200 fps? positioning it close to the barrel it is important to measure speed not far than 2 yd.

[@AndreasSpiess]

I do not think so. Too small object and too small available distance.

[@offgridsweden]

Great video! Greetings from Andreas on Off Grid Sweden

[@AndreasSpiess]

Greetings back!

[@FedericoMorenoCh]

Very interesting video Andreas! Do you have any update on this proyect?

[@AndreasSpiess]

No. The range of these small devices was too short. And the bigger ones still are quite expensive.

[@imranrajjad7028]

Sir Mr Swiss accent guy, is it possible to hook a Cantena to these modules to increase range and directionality?

[@AndreasSpiess]

I do not think so. Maybe a horn antenna. But you need knowhow and instruments to do so.

[@Gunshot115]

This is a wonderful video. Thank you sir!

[@CShand]

What are the sensors used by traffic lights and toll bridges that only detect metal? Also how does this cope with say trees blowing around it.

[@AndreasSpiess]

I do not know.

[@justin3594]

How can we now take this and convert it to a digital speed? Like with an ADC and microcontroller?

[@AndreasSpiess]

Yes, you can use an ADC.

[@harrybowman5245]

What is the name of the directional radar you were planning to use? I couldnt see the video for it, thanks!

[@AndreasSpiess]

You usually find all links in my video description

[@bigendertroll]

are the calculations the same for the CDM324 radar module?

[@AndreasSpiess]

Yes.

[@muditgupta3520]

Can you tell me name of the sensor which you ordered for your second video, I am really looking forward to it.

[@AndreasSpiess]

Unfortunately, I never made a second video :-(

[@josephocampo]

Hi sir.. Is there a way to measure flow (discharge) of the river using sensors?

[@AndreasSpiess]

I only know they used distance sensors below bridges to measure the height of the river and create warnings.

[@MushFarmer]

when are you going to get a Bitcoin, etc address like Mr. Dave Jones?

[@AndreasSpiess]

No hurry. I first have to understand it ;-)

[@juanmanueldiflorio845]

Hi! Can the amp you used be replaced by the LM358? Thank you

[@aldob5681]

Image recognition seems better suited for people count. And could be trained to report the direction also.

[@AndreasSpiess]

True. But probably more expensive.

[@trzl6634]

in the speed calculation why 44 for km ?? from where you get it

[@AndreasSpiess]

It is a calculation of physical constants. You find it in the internet.

[@argcargv]

I like the direction this project is going. :-D

[@AndreasSpiess]

:-)

[@erickgutierrez6471]

Thanks for the information, do you think I can use any of these radar sensors to measure the heart rate and respiratory rate of a person? it is for a project. Thanks

[@AndreasSpiess]

I do not know if the speed of the object is fast enough. Maybe you have a look at my videos where I hacked an SPO2 sensor (which also measures heart rate) or where I hacked the Polar pulse sensor.

[@CookiePepper]

look at the equation again. transmitter frequency stability matter.

[@AndreasSpiess]

Short-term for sure.

[@GeoMikeCache]

Nice oscilloscope! A little bit pricey, but good. thumbs up.

[@AndreasSpiess]

Depends on where you get it from ;-)

[@extrastuff9352]

Can anyone explain the factor of 44 in the speed calculation?

[@AndreasSpiess]

You find it in the Limpkin's blog link in the description

[@roryfarrell7292]

Looking forward to seeing your implementation of the theory.

[@AndreasSpiess]

It will take a while

[@BloodBlight]

Was waiting for this video!!! Awesome! Looking forward to knowing the accuracy of these two sensors at different speeds!

[@AndreasSpiess]

They are accurate. But the range is quite limited.

[@koherer3732]

You don't need an expensive microwave osciloscope to watch the frequency of HB 100. You can get a satellite tv LNB, inject 12v into coaxial using a bias tee (inductor to stop RF getting into power line and a capacitor to block 12v from receiver). And then connect it to RTL SDR receiver. Then tune to 600-700 mhz range. Signal is well... not that unstable to jump to 9 GHz. If you feed the audio trought a capacitor to +5v in of HB-100 while powering it at the same time, you will get FM radio at 10.5 ish ghz. Device is low powered but if you worry about how legal it is, there is 3cm ham radio band you can think you're using, if you already has a license. I think any polarization LNB will work, I used linear. And aware of harmonics, because i've received some weak signal at 400 mhz and thought it's working that bad, but real signal was higher. SAT LNB lowers frequency by 9750 Mhz (i guess, google for precise value). BTW, this signal is slightly out of LNB band, but everything works ok.

[@koherer3732]

PS. Yes, signal is drifting when you touch the module, and has wery low drift when just listening. I don't know if it's a HB100 or LNB, maybe they both drift. I have to tune frequency when listening to WFM audio, but I saw a guy using some sort of "peak hold" function in SDRSharp on youtube.

[@AndreasSpiess]

These modules are used to open doors. So I assume the power is below the law. But I am no layer ;-) Thanks for the tip with the LNB. BTW, I have a HAM license (since 40 years).

[@Steve211Ucdhihifvshi]

Now can you build a radar detector thats in detectable???

[@AndreasSpiess]

No

[@FANDOMFUSIONS2007]

Can I check the ascent rate of my weather balloon by this

[@AndreasSpiess]

I do not think so. The range is only a few meters

[@LatinDanceVideos]

Really keen to hear if anyone has extended this project, made it more error proof and filtered out pedestrians from bicycles.

[@AndreasSpiess]

It is still in our lab and we work from time to time on it.

[@glewiss6696]

Hello, Thanks for the video. Does the device work if the source is not moving and that is the observer that is moving? Thanks

[@AndreasSpiess]

Since Einstein, we know that movements are "relative". So it should work.

[@glewiss6696]

@@AndreasSpiess Many thanks, Haven't got in touch recently with Albert but it seems logical indeed and much more than quantique physiques. So I might be able to convert it into to a car obstacle detection device...

[@mkomma179]

can l use the cdm 324 with a raspberry pi

[@AndreasSpiess]

I think so. It has a digital output.

[@AvinashRaiG]

Awesome , Guru of electronic knowledge..🙏 Sir I want to know if we can use these high frequency radar sensors for Cars to avoid collision from front at about 10 meter in advance and/or back?Please share some knowledge on this topic.

[@AndreasSpiess]

The reach of those sensors is not long enough. And they only detect movement.

[@garyhalsey7693]

If the sensor was mounted to a vehicle, pointing at say, 45 degrees to the ground, could you make a radar speedometer? This would then give you a far more accurate measurement of speed than the vehicle’s own uncalibrated speedometer possibly?

[@AndreasSpiess]

I do not think so. The speed would be 0 and probably just vary with the bumps ahead of you.

[@garyhalsey7693]

@@AndreasSpiess Ah, okay. Thank you for replying, love the channel!!

[@poulmartinmller4094]

Thanks Andreas, you guys solve everything with sensors and hardware. Could three directional microphones and modest efforts from an "AI" not produce some algorithms to answer these questions in more detail (a bit of ml, add a bit of statistics (cluster & var), throw in some 3D sound mapping ... ). Or is it just to cumbersome to span that wide yet with nn and ml? Also it could possibly answer more of them and and in ways the hard encoded logic (in my world "hardware") is way too rigid to engulf? If not Amazon must be getting around to it by now like all the big tech companies, that ventures out into a sensor fuelled sensemaking mission in early chaos :-) Merry Christmas and what a lucky break to find the only piece of flat road in all of Swizz... It's must definitely be christmas now :-) just a year later. That's how good your shit is. Thanks.

[@AndreasSpiess]

Merry Christmas to you, too!

[@skewedmaker]

Great video! Would weather conditions have any effect on these sensors?

[@AndreasSpiess]

They are used to detect rain and snow. So I assume it has

[@TurkishLoserInc]

From what I've read on the advertisement page for the sensors: No, nor do most objects short of concrete walls and metal shielding in front of the sensor. It does say to install it away from moving conductors and magnetic fields however.

[@faidularcs]

Awesome project

[@AndreasSpiess]

Thanks.

[@ZlayaCo6aka]

The "small screw" you mentioned is not part of a capacitor. At about 6:08 in the video you see a small circular white object; that's a ferro-resonator. The "small screw" is ferrite and its proximity to the resonator adjusts the resonant frequency.

[@AndreasSpiess]

So I was „half right„ with the purpose at least. Thanks for the clarification!

[@JerryEricsson]

In 1974 the Department I was working for got our first updated digital display radar. It was X-Band. I was on duty one morning (read night shift near ending) and since there was nothing happening in the town, I parked the squad car under the sun shield over the A&W drive in, to watch traffic on the Highway that went through town. I was not running Radar at the time since the angle was too great to get any accurate readings, but it was on, and the volume on the head was turned up a bit. I began to hear ZIP! and a bit later ZIP! there were no cars but on the digital read out I was getting 104 MPH and faster flashes. As I studied this phenomenon I noticed that the swallows who nested in the over head cover were diving down to the ground after worms or insects, the radar was reading their speed. I began aiming the cone at the particular birds and the readings got faster as the angle decreased. It was actually a fun thing to do with the big old units.

[@AndreasSpiess]

Nice story! So this radar was quite sensitive. Detecting the water in these small birds.

[@learningtofullest6125]

Will it detect Birds?

[@learningtofullest6125]

like small objects?

[@AndreasSpiess]

I do not think so. At least over distance.

[@learningtofullest6125]

@@AndreasSpiess thank you!

[@deltaxcd]

Rather than doppler effect, it is easier to understand as interferometry because you are sending and receiving the same signal. So this sensor can do a very accurate measurement of movement distance, just count output pulses

[@AndreasSpiess]

These sensors only can detect speed, not distances.

[@deltaxcd]

@@AndreasSpiess well, you should just try it then. like I said rather than connecting speaker connect led and you will see how it will flash when you move reflector by about 1.5 cm I tried it and it works, although it was lower frequency radar

[@cdevidal]

Andreas, how do you spell the word that you say at the beginning of every episode? "Grietsie KZbinrs"? I always enjoy that "Swiss" accent, which I imagine must be German or Romansh :)

[@AndreasSpiess]

It is Swiss German (Grützi) and means "hello"

[@alfredzhong9014]

Hi Andreas, I was thinking about using one of these sensors to create a speed gun for a baseball. Do you know if these sensors handle small objects well? Another question is what is the max speed these sensors are effective in measuring? Love your videos, thanks!

[@AndreasSpiess]

I do not think they will cover small/non-metallic objects in a distance.

[@phizicks]

Come on Andreas, faster FASTER!!

[@AndreasSpiess]

:-))

[@marwans4018]

I need your help plz , i have hb100 sensor and i did make it work on my arduino and now i need to count number of cars that passing can i count the cars using hb100 ?

[@AndreasSpiess]

I am not sure if you will be successful. The range of the HB100 is quite small.

[@chuxxsss]

Msybe I should have done this, by the way use the 24 Ghz and some range sensor in software. That is correct the screw is a fine adjustment. You need range gates for distance as well. Doppler radar maybe you could use pulse radar. Nice work Andreas.

[@AndreasSpiess]

In the description, they talk about pulsing the radar. I do not know why I should do that other than saving energy.

[@bostonmacosx]

So we now have a device that makes sound... how can we read that back into the Arduino or ESP32 to get a useable speed out of it?

[@AndreasSpiess]

You can use Fast Fourier Transformation on an ESP32 to find the frequency. It works.