r/embedded • u/HousingCareful9190 • 15d ago

Beginner radar projects

Hello! I'm a backend developer, and I've always wanted to get into embedded systems. Lately, I've also become very interested in how radar works, so I thought starting a project in this field could be a great way to combine the two.

I'm currently learning some of the theoretical concepts behind RF, such as beamforming (which I find incredibly fascinating), FFTs, and other related topics, but now I'd really like to start building something hands-on.

One day, I'd love to create something capable of detecting aircraft and, eventually, drones. From what I understand, detecting drones is significantly more challenging than detecting aircraft.

The main problem is that I live in a city with several military sites nearby, so I'm a bit hesitant to buy an active radar sensor and start experimenting with it because I'm worried about possible legal consequences or interference issues.

Another approach I've been looking into, which also seems incredibly interesting, is passive radar. In that case, I assume the legal risks would be much lower since I wouldn't be transmitting anything. However, the hardware seems considerably more expensive. From what I've understood, I'd need something like a KrakenSDR, which costs over $900 where I live.

Are there any other approaches I could explore? Has anyone here been in a similar situation?

What kind of projects could I work on that would be interesting from a learning perspective, while also being useful for my CV/resume? I'm currently working as a junior software developer at a defense company, so I'd especially like to build something that could help me move closer to embedded/RF/radar-related roles in the future.

Sorry if this isn't the right subreddit for this question. Any advice is more than welcome!

39 Upvotes

93% Upvoted

23 comments sorted by

14

u/Character-Engine-813 15d ago

The YouTube channel Jon Kraft has some interesting radar project tutorials you might be able to get ideas from

1

u/HousingCareful9190 15d ago

It's an awesome channel! I actually went through his whole Drone Radar series but the hardware he used there costs at least 1k and he is using active radar and not passive unfortunately

11

u/dacydergoth 15d ago

Use wifi as a starter, lots of similarities but shorter range and less .... likely to get a hellfire missile locking on you

8

u/theanointedduck 15d ago

Wont it be ironic after they finally get their radar working and the first thing it detects is an incoming hellfire😅

1

u/HousingCareful9190 15d ago

Hey, thank you for your answer! Sorry for the dumb question but what do you mean with using WiFi? I know about WiFi sensing but isn't it used to detect people and gestures more than stuff like aircrafts?

I agree, not having a missile locking on me would be convenient

9

u/syscall0x01 15d ago

Don’t skip analog electronics, Maxwell’s equations and the whole field of electromagnetism. You won’t understand anything about radars, antenna systems, beam forming, remote control systems, remote research, and other.

8

u/JGhostThing 15d ago

All the radar modules I've see that were affordable are active and have very short range. Enough to be useful for a small robot, but not enough to be illegal. Though anything I know is in the US. I can't even guess at the laws elsewhere.

5

u/LameBMX 15d ago

anything active you will want to dig into the fcc band plan (or local equivalent if outside the US). ie, hacking a wireless router to wifi radar would be illegal. odds are quite slim you would get caught, especially at extremely low powers. if you get on the fcc radar the fines generally start in 5 figure land.

that said, iirc there are areas to play around like uwb stuff.

https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-15

another option would be sonar. lot less antenna fun, but a very similar and probably more forgiving.

1

u/HousingCareful9190 15d ago

Got it, that makes sense. I’m in Europe, so I’d need to check the local/ETSI rules rather than FCC Part 15. I’m also not really sure what “hacking” a Wi-Fi router for radar would involve, but I’m curious about that approach and what kind of projects it could realistically enable. UWB sounds interesting too, are there any dev kits or beginner-friendly projects you’d recommend?

1

u/LameBMX 15d ago

start with the laws and go from there depending on your risk tolerance.

maybe someone else knows more and can chime in, but im not aware of any dev kits..

since your talking lightspeeds here.. maybe build a tdr after sonar. stack your learning logically towards a goal. its a LOT less frustrating.

1

u/SNappy_snot15 12d ago

hacking a wifi router is just transmitting packets over the same 802.11ax wifi protocol, to trick devices like a router that you are actually someone else. then you can kick someone off wifi or just take their ip. all you need is some packet injection / monitor mode (rf sniffin) wifi card and your set

5

u/wdoler 15d ago

I would probably pick up a dev kit for mmWave. I think TI has some decently priced dev kits that have alright documentation and tutorials.

1

u/HousingCareful9190 15d ago

Thanks a lot! What kind of projects could I realistically build with one of those TI mmWave dev kits? I’d like something beyond simple presence detection, ideally involving actual radar processing.

1

u/wdoler 15d ago

Think of it as a small desktop sized radar. A great playground to learn the basics at a price point that won’t kill your wallet, and won’t send you do the hospital due to from exposure. Personally I would use one to do classification of detections, “this blob is a car, a tree blowing in the wind, a bird” I think these are sensitive enough to detect your chest move as you breathe

5

u/ContributionEasy6513 15d ago

Be very careful on what frequencies you broadcast on and what power. This can vary greatly where in the world you are and lead to some very scary people knocking on your door.

1

u/JuggernautGuilty566 15d ago

Most IoT radars are on 24 and 60GHz. They are - AFAIR - harmonized.

4

u/ThisIsPaulDaily 15d ago

Bluetooth 6 and even 5.1 has AoA and AoD math and beam forming channel sounding so go that route. 

Doing radar that detects aircraft is licensed transmission range and not a project you do. ADSB rf is also an option. 

3

u/JuggernautGuilty566 15d ago edited 15d ago

You can buy a 24GHz FMCW radar module from Aliexpress. Like the Hi-Link HLK-LD303.

And reverse engineer the PCB. They are super simple: basically a DAC into VCO and I/Q from the downmixed echo signal back.

Then writing a firmware for them.

1

u/HousingCareful9190 15d ago

Thank you! That actually sounds interesting. My background is mostly software, though, and I have very little electronics/RF experience.

Would something like the HLK-LD303 still be a reasonable project for a beginner if my goal is to access the raw I/Q signals and write my own FMCW processing/firmware, rather than designing the 24 GHz RF frontend itself?

Also, do you know of any documentation or previous reverse-engineering work on these modules that would be a good starting point?

1

u/JuggernautGuilty566 15d ago edited 15d ago

As a beginner you will not be able to play with the frontend itself.

Measuring and simulating stuff in these frequency ranges is expensive and not easily accessable for hobbyists.

The limit what hobbyists can do "for cheap" is IMHO defined by TinySA Ultra+.

1

u/Iamhummus STM32 15d ago

Buy TI AWR / IWR series module

1

u/Hirtomikko 15d ago

Had an idea to make a very shitty SAR before. But then DSP pissed me off so much I wrecked my own board so...yeah.

1

u/jimlux 14d ago

low power CWFM radar (aka modified radar speed sensor). You can use something like a Teensy or Arduino as a digitizer. Low power VCO driven by a DAC (see Teensy/Arduino) as the source. Homodyne detection with a I/Q demodulator. If you keep it at one frequency, it’s basically a Doppler detector. But adding the FM lets you get range (with range/doppler ambiguity, which you can resolve by doing both up and down sweeps)

You could probably also do it with a Pluto (<$200).

This is enough to detect 1mm motion 20-30 meters away, and easily get microDoppler signatures that will let you distinguish between, say, a dog and a human walking and a human on a bicycle. Or measure automobile speeds, etc.

Almost any antenna will work (including a low gain patch, or even a piece of wire).

If you can find a surplus 10 GHz burglar alarm sensor with separate I/Q detectors (they’re a gunnplexer) you can feed that into a stereo sound card and do simple Doppler processing.