ฝัง
- เผยแพร่เมื่อ 11 ส.ค. 2018
- In this episode Shahriar demonstrates a full analysis of a CDM324 24GHz Doppler radar module from IC Station. Opening the module reveals a series of microwave PCB components and several active devices. A complete analysis of the module is presented. The unit is then measured and the impact of antenna impedance and power supply voltage on the output frequency is measured. The phase noise of the output signal is also measured. Using a series of servo motors, the radiation pattern of the antenna array in both azimuth and elevation is also presented.
Using the radar module the speed of a computer fan is remotely measure using an oscilloscope and FFT function.
You can buy your own module from (www.icstation.com/).
All proceedings from Patreon for this video will be donated.
The Signal Path
www.TheSignalPath.com
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Great stuff! That was a really fun and informative look at the radar module. Thanks!
Applied Science Thank you. It means a lot coming from you.
Hey Ben, any DIY RF ASIC stuff on the radar? :D
17:43 this circuit is as uploader describes......identical to parts used in Siemens LR250, LR260 radar units....my job was to tune the modules for production ...I have uploaded videos to my member areashowning this exactly....good work guy!
Thanks for the nice video!
As an RF Engineer working in sub 5GHz world I would really apreciate a second video going in more detail about how you as a mm expert would aproach such a design:
* Which tools would you use?
* How would you split the design problem and choose which aproach to go for?
* How much and what would you do in simulation, what would you do/tune by experiment?
* How would you actually experiment at 24GHz?
* Especially how would you estimate/measure boundary 24GHz RF aspects of the PCB, schielding, cross talk effects?
* Would you expect your first prototype to actually oscillate and do anything?
* If not, how would you probe and measure what is going on?
I'm glad to know that there exists people who actually know what they are doing at this RF range xDD
Thanks for everything you do. I doubled my Patreon support, because your are correct. I support so that everyone can learn as I do. I've been in a low earning spot in my life and couldn't support, now I'm in a good point and so I do. You do a lot in helping those of us with little to no RF understanding (and often even minimal electronics understanding) become more familiar with RF principles. Thanks again and keep up the good work!
I really love the fact that you're not just giving out valuable knowledge out for free and also doing a noble act of helping out those in need. Trust me, I'm really teary eyed right now but I'm elated, super duper happy. I will support your channel as much as I can. Lots of love. Keep doing good deeds, may not be financial but help anyway one can 😊👏👏👏👍👍👍✌️✌️😎
Thank you. :)
I did not watch the video yet, just the introduction and I have to say that I really support your attitude towards your viewers and your way of doing this stuff. It is obviously great that you give this much to the people but I mention it anyway
That wobbly oscillator and the super-simple circuit reminds me of a three-transistor super-regen 27 MHz walkie-talkie I built when I was 13 or so. Slighly bigger components, but it felt like dangerously high frequencies to me at the time. It went all of the place with hand capacitance, antenna loading, etc, too - and the receiver transmitted about as far as the transmitter did. But it worked, and with just three active devices, and I've never forgotten quite how much you can do with quite so little, if you put your mind to it. Lovely video.
Did you notice how the "quench rate" affected each other's super-regen receivers when in proximity too?
I don't have much money to donate but I have been supporting your patreon because I like what you do and I learn from it. Great videos deserve support and you make great videos.
You have a great way of explaining things, this was really fun to watch. Thank you.
Great way to measure antenna polarization! Excellent details as always... man, you've earned and deserve an endowment to perpetually fund your microwave systems reviews, tear downs and awesome frugal resourceful repairs. Thanks for sharing!
This is awesome. Cannot explain how much you help me learn microwave stuff. Thanks!
This is a really well presented video, as an RF student I'm glad I found this channel
Amazing video. I am always so excited when I see a new video from TSP! I can tell this was a lot of work. One suggestion - maybe when using RF jargon like rat-race or the name of that horn, put it in text on the screen when editing? I find a have a hard time hearing what was said since it is spoken quickly and have to rewind and play the video a few times to catch the name. Could just be me though so take it with a grain of salt. Thank you for the video, learned a ton.
That's greatest video what I seen from your last few months may be years! Thank you!
RF circuits were always interesting to me. Just like magic tricks. Btw this was another great, informative video!
Probabaly one of the best "Recommended Videos" in my feed in a very long time. This brings me back to the days when I worked at a satellite communications company testing their waveguide switches and multiplexers. Great analysis on the Doppler circuitry.
Yet another big thanks for your great video series
Admirable personality, amazing knowledge - you really are the right person in the right place.
Thank you for educating us and offering us a glimpse into your field. It encourages the next generation to progress in learning
excellent explanation, such a simple design
Great video, thank you for sharing this information in an understandable en fun way.
This was a fantastic video, very well done and thank you!
Great video. A quick note about the antenna design: The displaced/inset feed point on each patch changes the patch impedence and not the bandwidth. The patch bandwidth is a strong function of the substrate dielectric constant and lambda/h (where h is the dielectric thickness).
the width of cutout did effect the bandwidth/gain
Wonderful video - thankyou. Just seeing what is available in these microwave modules. First time I've seen one of your videos; very well done and love the equipment, ...reminds me of my younger years in the lab doing design engineering.
Wow! So fascinating! I’m just a hobbyist but your instruction is so good even I can understand it.
Shahriar, thank you so much for your calm and crystal clear explanations.
Of course I knew one needs an active device for an oscillator. Your few words “it really doesn’t matter” really brightened my horizon. Thank you Shahriar! 😊
Man, if I were to go back to school microwave RF is what I would study. I looks like so much fun. You have a dream job, too. Keep up the great videos. Thanks for sharing your knowledge.
I realy like what you say in the beginning here, more people shuold do so.
Really smart guy! I enjoy these videos!
This was great. Thank you so much!
I sincerely like all your videos - yet this type of videos are my favourite. The device in the video has nothing but a BJT and two diodes in it, and it gives you the capability to measure distance, rpm and various other things.
Again, your other teardown videos are of excellent quality as well. However, this kind of simplistic looking devices mesmerize me.
They kinda remind me that engineering is applied physics, and not just connecting some modules together
Good to know that this thing can be FM modulated by changing the supply voltage. Also, if some sliding doors has this sensor, probably it is possible to make 'remote door opener' (supermarket...). Just bought one device for $6.33. Will be fun to see does it works as intended - as if ghost passing through the door. :D
I received a notification, didn't have time to watch the video yet, but already left my usual like!
Another awesome video. Thanks
Super nice video. Very informative. Thank you!
Great review, thank you, it was very interesting!
Great a voltage controlled oscillator at 24GHz.
I saw a paper (20 years ago) from a university where they extracted the reflected radar signal from turbine blades of aeroplanes. This was a masters or doctoral thesis but half of the results were not published because they related to identification of the turbine type of military aircraft. Basically it could extract the integer ratios of all the moving turbine blades to determine engine type and the power setting of the target.
Thanks! great video!
Pretty awesome! Much appreciated!
Excellent! Keep it up.
Amazing video!
Love the wooden Mini Circuits boxes
Using an FFT of a radar output to measure fan RPM on a 6GHz scope is the most awesome thing ever.
Here I was foolishly thinking you would use measurement markers in the time domain. Silly me. :(
Its interesting to see the different reflections coming back from each blade due to the differences in the copper foil on each.
Amazing job here! Very detailed!!
What i would like to ask if we know the impedance of the output pin? At least at category of let say few ohms, hundreds of ohm, thousands etc
I had not seen this one. Interesting. Had never heard of a Rat Race Coupler.
Looks like I missed another one too!
How cute the rotator is!
Great stuff!
Great video! Although I miss the more in depth videos with multiple experiments.
Demystifying the blackmagic voodoo that is RF modules! Thanks for sharing!
Useful video
just recently found your channel, Loving it, it immediately became my goto channel on youtube.
Thank you for the videos, and may ask what is your technical background ? in other words where did you study this stuff ?
عالی شهریار جان
Excellent video as usual. You need a wacom to overlay photo and sketch :)
Fascinating video as always. Any chance you could do a design series? It would be so interesting to see you design a discrete multi-GS/s ADC (say, 4 bit) with HEMTs (GaN would be neat). I was thinking “simple” projects might not run afoul of work conflicts, but would still be a unique and deeply insightful learning resource.
Very good video thanks
Excellent presentation. I have two of these and have been waiting for this day. For $3 I got myself a mini- RADAR. It's cheap and unstable, but it's super cool. I believe your test Did show that "Arc" in the sweep VS the Y axis with the crisp change. Also, the signal quality was good for using the shaky pan tilt device. I also believe the beam pattern maybe narrow. Recheck the X axis again by mounting it on the shaft of the servo. I'd do it but I'm no longer on the Navy and don't have access to that kind of test equipment. It's a mini- RADAR, Fascinating...
Hi, do you think this module can trigger a car radar detector at some meaningful distance, let say 50-100m?
@@ivanilarionov1893 not enough RF power.
You're the best, thanks!
Good video.
Thank you very march
great outside-of-box experiment!
Still i am clueless about the orientation of the (mixing?) diode in receiver as drawn in vid.
Nice video
Amazing!
Good video as usual. I have been reading a little bit about microwave photonics which seems to be an application of lasers to creating and processing microwave signals. Demonstrations seem to be hard to come by though. Maybe it is something you may able to do with the equipment in your lab.
Didn't understand most of it (someday I will), but that demo at the end was neat!
the poster in the background looks a lot like Vector's Terminal Redux album cover. I was excited about it
I believe that is a painting a viewer sent him.
Great job ! Enjoyed and shared your presentation.
Question: If we add a saw tooth to a VCO (4-5 V) and that VCO links to the DC input, we would have an FMCW Output and theoretically the Beat frequency in the IF would give us the Distance, right?
You could try making CW-FM radar out of that by applying some kind of modulation to power supply like sine or sawtooth
and then measure the spectrum of the IF output or frequency of IF output
awesome video, can you explain how the shape of wire so critical for RF designing
I gees that the high radar feedback event 17/2 clock, comes from the noise from the wire from the power supply, that you use for both the fan and the radar sensors, that resonance get amplified. :) have you done a video on different PCB material for RF signals and microstrip?
Building circuits in the GHz world is sure different. Would have been interesting to see the effect or lack of effect a piece of quarter inch plywood placed between source and fan would have. Thanks for the video once again.
plywood is mostly transparent at 24 GHz.
Wonderful video. I am actually going to use this in a product. One issue that I like to confirm is the material for the PCB. It looks like some sort of Ceramic filled substrate. If it is then the dielectric variation concerns may be somewhat diminished
As he said in the video, it appears to be thin generic FR4. This is an $11 item (including shipping).
My Idol!
I wonder what type of transistor/amplifier is used.
Great fun!
What kind of sorcery are this?!
Where I can find some magic books about it?
great video!, hey, a bit off topic, This may be something you would like to do a video on. I have always wondered how those Old-school storage CRT's worked. I used them back in the day (I'm old) and never gave it a thought. Now I'm building a lab and can't afford all new equipment, so I pick up 2 HP spectrum analyzers for stuff above 8 GHz to about 25 GHz, got them both working and they have the storage CRT's in them. They work great, but I never knew how they worked.
Is that possible to ramp the input VDD to create a ramp output signal? Would it be useful for extract more information from this poor little module?
Nice video. BTW: do you known what the high frequency transistor is? with 24Ghz the ft of the transistor is 3 times of 24Ghz
Good man.. Information WANTS to be free, and shared
Question, is the rf absorption (adsorption?..semantics) material as conductive foam... Like what some ic's are shipped in? I imagine that stuff would contain rf pretty well
Thank you for the video, excellent information. Would it be possible to modify this CDM324 to be just a receiver? I'm looking for something small and cheap that will detect 24GHz and output to and Arduino analog input. Any help or guidance would be greatly appreciated, this is way outside my wheelhouse.
What can I do to use this module only as a receiver module?
I want to cancel the transmitter part. I just need to work with the receiver part that detects microwave signals.
Thank you.
RF, mágico e muito interessante
Since this module is affected so much by the quality of the power supply, what would happen if you purposely feed it ramped voltage? If you operated this module using a high-speed sawtooth voltage source would you be able to get range information in addition to (or instead of) doppler information? What if the I/Q signals were separated? I have found a module similar to this one called "CFK024-5A" which has separate I/Q outputs. Thanks for doing this video, I learned so much!
The idea behind the rough adjustment quality of that osc is that all computation happens in the frequency/spectral domain so you might not care so much about the fine tuning of emitting freq as long as you get sharp and distinguishable peaks for both (transmitted+recieved) signals. Another possibility is that you can tune the working frequency by the voltage a little.
AFAIK in radar theory range information ideally suppose minimal or even 0 pulse width (Dirac's delta) of emitting signal and a precise calculation of TOF/delay time thus both high rise and attenuation of the oscillator are required. This particular circuit isn't suited for such yet you could attach a fine discriminator and counter for fun. Forcing it to emit short spikes with minimal FWHM you'd get a coarse TOF but the precision strongly depends on time-domain characteristics e.g. attack/decay parameters of the ckt.
When 24Ghz is in the title....I click on it.
Popcorn.......
Great!
Thank you for the video! This kind of format is absolutely the best!
But I have some questions left.
1.Am I correct that there are 4 layers on the board and the internal ones are connected to the ground?
2. Is the transistor in common base configuration and the resistors connected to the collector and the emitter are setting the DC operation point?
3. You were talking about biasing of the mixer. I don't see how it is done. Do you have to apply DC via IF input? But there are back-to-back diodes. Makes no sense for me...
Similar question: if the rat-race would give the difference on port 4 anyway, why not just tap the doppler signal from there? Why the diodes? Probably someone cand answer both at once.
1) I think so.
2) Yes.
3) They are cold biased at around 0V. The LO signal swings above and below GND. Save as RF.
Diodes are the non-linear devices required for frequency conversion. The linear difference alone would not be at IF, it would still be at the same frequencies as RF and LO.
Thank you very much for the response!
any idea where you could buy such rf absorber materials?
Wow, these scopes.
Firstly thank you for your great work.
I'm kinda confused at some point, so on FM transmission you detect the signal (on the receiver) by having an oscillator that gets in sync with the sender frequence, and when data is transmitted, what happens? The receiver signal gets attenuated by the data or amplified? Or I'm still confused?
For CW you're measuring only doppler. You transmit a signal at a steady frequency, say 24.000000000 GHz. That signal goes out, bounces off a moving object and comes back either slightly higher or lower in frequency, depending on if the object is moving toward you or away from you. The amount it shifts depends on the speed of the object. Lets say the frequency shifts up by 100 Hz, to 24.000000100 GHz. When it comes back, you mix the reflected signal with the transmitted signal, and you get the sum and the difference between them. You filter it so only the difference comes out, and you get a 100 Hz signal on the IF. That tells you the speed of the object. This is how police traffic radar works.
Now for FM (not what was done in this video), if you constantly vary the transmit frequency in a linear sawtooth way, the frequency going out is constantly changing. If it hits a stationary object and reflects back, the time delay between when it left and when it gets back means there's a difference in frequency between the transmitter and the receiver. That frequency difference determines the length of time the signal took round trip, and therefore determines the distance to the object. You measure the frequency difference like you did with CW, and the output if tells you the distance to the object. This is how the adaptive cruise control in your car keeps you 3 car lengths from the vehicle in front of you.
do you have an ultra-noob RF circuitry 101 introduction-level tutorial for a normal physics major person who has never dealt with RF? i'm primarily interested in why these waveguides are shaped the way they are.
Maybe your best video yet! You have the absolute best lab I have ever seen! Some of that gear is probably worth more than my house.
You can tell you’re doing OK in life when you can use kapton tape as Scotch tape! :-).
Gimme da Keysight signal analyser and I’ll give you a kidney or stem cells should you ever need them. I hope you don’t ever need them, I hasten to add...
ProdigalPorcupine Yea, I noticed the tape also. wish I even had some...
I thought the notch in along the feedpoints of the antennas was to get the feedline impedance correct? Notches on the other sides (90 deg. off) would be for trying to increase bandwidth?
You are right, it does affect the impedance. That also in turn can affect the BW. Notches on the other side would excite the other polarization.
Having tuned RHCP patches on a hi-K PCB dielectric, everything affects everything else in some way :) even giving the antenna too nasty of a glare. its almost maddening at times. All of those are coax fed from underneath, so I'd imagine shifting the feed there has less of an effect than matching the microstrip in. The in-depth videos are definitely enjoyed though. RF stuff on coax is 'easy' once you know the devices gotchas. Electrically large/distributed stuff can be a good mental exercise in 'thinking like RF'
TSP, given the oscillator frequency changes when the input voltage is varied, how come does the circuit in the module not function as an FMCW radar? I modulated the input voltage as a triangle waveform that varied from 4V to 5V at 10kHz. Given the observed frequency shift of about 6MHz when going from 4V to 5V, I was expecting to see a distance component on the IF output of about 800Hz per meter to the target. However, when I tested this hypothesis there was no distance component in the output and the module worked just as a CW doppler. Any thoughts?
Maybe a silly question: what are the pros and cons of using a spectrum analyzer for measuring PN instead of a real signal source analyzer?
The con is: Reasonably priced spectrum analyzers aren't good enough to measure PN. You have to have one in the nosebleed price range.
thanks
I don't understand how those diodes work without bias. How much voltage could there be?
What is the maximum speed detected by the sensor?
Did you mean to say butterfly inductor instead of butterfly resistor?
How would you use this $6 module without the many multiples of that spectrum analyzer? Can we measure that fan speed from a breadboard? ;)
Yes, you'll get an audio output on the IF pin. The frequency will be related to the speed of the fan.
You have your receive and transmit antennae mixed up.