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Homemade 6 GHz pulse compression radar

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Re: Homemade 6 GHz pulse compression radar

#91

Post by KeplerBoy »

beeeeerp wrote: post #83
KeplerBoy wrote: post #67

Earlier quoted context omitted.

Isn't that Synthetic Aperture Radar though? You can get similar results (black and white aerial pictures) by strapping a pretty basic siso radar system on a drone.

I’m honestly not sure what the difference is. I kind of understand SISO, MIMO, and beam steering concepts, but just the basics from nerding out on my Starlink dish. This is what I’m talking about: https://www.twz.com/f-35-will-get-new-radar-under-massive-up... Specifically this image: https://www.twz.com/uploads/2023/01/03/20065813381381024.jpg I don’t know how targeting works, but with this level of resolution, I th…

Yes, that looks like regular SAR imagery. Checkout @umbraspace if you want to see some really nice SAR images captured by satellites launched along starlink satellites.

https://twitter.com/umbraspace

Re: Homemade 6 GHz pulse compression radar

#92

Post by Mo3 »

KeplerBoy wrote: post #70
a_random_canuck wrote: post #68

Earlier quoted context omitted.

There’s no risk of cancer from heating up tissue.

I did some reading and it seems you are right. No Idea why phones come with a SAR rating then and why there are safe limits defined, when no one found unsafe limits.

Because you tend to hold phones right to your brain.

Re: Homemade 6 GHz pulse compression radar

#93

Post by l33tman »

Regarding this "The suspiciously cheap $15 FPGA had equally suspiciously date and lot codes covered (white rectangles on the FPGA chip in the picture above). I have a development board of the same series chip with markings intact, so it definitely shouldn't look like this. It did end up working, but I wonder what the origin of these chips is."

I spoke with a GoPro operations guy once, and asked how you can get the chinese ripoffs at $40, that looked the same as their $400 "real" deal. He said that they literally get chips from scrapyards, like they get batches of memory chips that didn't pass the tests etc. They might work only in a very limited temperature range for example. Also many other components are picked and speced to work 6 months on avg not 6 years.. They know that most of those "gadget" products are bought and used for a weekend and then put in a cupboard anyway.

It would be fine for an R&D project like this but I would be very careful if I was going to make a commercial project (then you also have the politics side, probably fuelled by some paranoia - there are legislations coming up which prevents you from using chinese silicon components in products for certain markets)

Re: Homemade 6 GHz pulse compression radar

#94

Post by ctrw »

worewood wrote: post #80
Dylan16807 wrote: post #75

Earlier quoted context omitted.

> It's as awful as it sounds. Well to me it sounds like you'd get heat stroke and pass out before anything reaches particularly painful temperatures, because it's heating you pretty evenly and not via contact, but maybe that's not the right way to think about it? At higher frequencies I would guess it gets closer to normal burning?

> because it's heating you pretty evenly and not via contact My microwave oven disagrees

Without knowing anything about tissue interactions the reason why microwaves heat so unevenly is the sanding pattern that waves make.

Re: Homemade 6 GHz pulse compression radar

#95

Post by non-chalad »

rfrec0n wrote: post #77
wbl wrote: post #74

Earlier quoted context omitted.

I would prefer we not have homemade cruise missiles all over the place. The people who need them can make them after all.

To be fair, nobody actually neeeds cruise missles

I need some, for mail delivery. Those messages won't send themselves.

Re: Homemade 6 GHz pulse compression radar

#96

Post by ajb »

pythonguython wrote: post #36

Can someone explain why those differential pairs are routed with so many curves instead of straight paths? (E.g. see the photo under the “ADC and DAC rotting” section)

Path matching, as the other comments say, but also if you have a corner, at >Ghz frequencies it will emit RF.

Re: Homemade 6 GHz pulse compression radar

#97

Post by user_7832 »

itishappy wrote: post #26
user_7832 wrote: post #11

Earlier quoted context omitted.

So would this mean that with a few more transmitting and receiving antennas it could have comparable resolution to lidar?

In theory, though it sounds like to compete with LIDAR it will need about 1000x more antennas, with a related increase in electronics.

Any idea if these antennas can be made small/on a PCB, effectively miniaturizing them?

Re: Homemade 6 GHz pulse compression radar

#98

Post by andrelaszlo »

worewood wrote: post #80
Dylan16807 wrote: post #75

Earlier quoted context omitted.

> It's as awful as it sounds. Well to me it sounds like you'd get heat stroke and pass out before anything reaches particularly painful temperatures, because it's heating you pretty evenly and not via contact, but maybe that's not the right way to think about it? At higher frequencies I would guess it gets closer to normal burning?

> because it's heating you pretty evenly and not via contact My microwave oven disagrees

If you want to get heated evenly, don't remove the spinning glass plate before entering your microwave oven.

Re: Homemade 6 GHz pulse compression radar

#99

Post by TrackerFF »

auspiv wrote: post #15

Incredible work. Crazy that this could be done by a single person. Stick it on a rotating pedestal and you've got a planar radar detector. Add some tilt and then it's not much different than aircraft/weather radar I suppose. The cost (in $LOCAL_CURRENCY, or $570 according to another comment) isn't great but I can only imagine how many hours this took. Given a proper budget, the sky is the limit. Anyone know how .mil…

There are different ways

First and foremost, aircraft radars have receivers, which will also receive the transmitted pulse from the other radar. In fact, that is how radar jamming works - you deluge the other radar with power on the same band / wavelength, and it will fill the display with clutter.

With that said, radars have a bunch of characteristics that makes it somewhat easy to identify. Frequency, PRF (pulse-repetition frequency), waveform, etc.

The bands at which radars operates are regulated, and various agencies - military and otherwise - will pick up radar transmissions. These tiny DIY projects aren't a huge "threat" in that sense, but if you're active anywhere near a radar installation, and especially military ones, it could land you in hot water, real fast.

I'm not sure about Finland, but where I live, civilians for example are not allowed to fingerprint or build fingerprint databases of military radars. In fact, the military is the only ones allowed to do so.

The power-scaling makes these things go from DIY to non-DIY real quick.

Would be cool to see this guy build a phased-array (radar)

Source: Worked with radars

Re: Homemade 6 GHz pulse compression radar

#100

Post by fullspectrumdev »

CamperBob2 wrote: post #59
topynate wrote: post #41

Earlier quoted context omitted.

A similar ITAR restriction on controlled reception pattern antennas means that GPS jamming is still much more of a problem than it needs to be. Three antenna elements are all you get, according to this: https://www.gpsworld.com/toughen-gps-to-resist-jamming-and-s...

Interesting article. I wonder if any progress on the ITAR issue has been made since 2022? If Brad Parkinson can't steer ITAR in the direction of common sense, nobody can. (For those who don't know, he was the principal architect of the original Navstar GPS system.)

Nothing can steer ITAR into the direction of sense.

I’ve had to go to extremely ridiculous lengths to buy downlead cables for a headset recently because the cable was deemed ITAR.

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