171–180 of 249 posts
QuadRF creator here. Happy to answer questions! We have a quick demo video as well: https://m.youtube.com/watch?v=QvniJk3uNyA Along with a deeper dive video: https://m.youtube.com/watch?v=zdJ9Tbm8ALg We didn't give Jeff great direction on camera alignment calibration or setting the radio gain but he seemed to mostly figure it out. We're improving the UI based on his suggestions (it's open source so you can customize…
Earlier quoted context omitted.
Moisture camera. Now there is an idea.
Initially I scoffed, but then I recalled that certain RF bands are disproportionately absorbed by water and this is used for certain sorts of atmospheric imaging by satellites. So you'd need a moisture "light" and an RF camera. Other than being cost prohibitive it sounds like an awesome toy.
A leak only turns invisible if the water has the exact same temperature as the wall and there is no meaningful evaporation happening (as that cools the affected area).
Of course don't let me stop you from actively probing your all using RF. Though also there you might have good chances with IR, since wet $stuff should behave differently than dry $stuff ;-)
QuadRF creator here. Happy to answer questions! We have a quick demo video as well: https://m.youtube.com/watch?v=QvniJk3uNyA Along with a deeper dive video: https://m.youtube.com/watch?v=zdJ9Tbm8ALg We didn't give Jeff great direction on camera alignment calibration or setting the radio gain but he seemed to mostly figure it out. We're improving the UI based on his suggestions (it's open source so you can customize…
Product looks cool, not sure what I’ll use it for but did just purchase it on crowdsupply :) How did you settle on that frequency range btw? It’s 4.9 - 6ghz, so it will visualize the higher freq WiFi, but I guess it will not work for the 2.4ghz WiFi, or Bluetooth which is also around that frequency? And I don’t know tooo much about RF, but would including support for that range also, have necessitated much more compl…
I don't understand what this is trying to say. Everyone who has ever used wi-fi knows that it works through walls. You try to connect to a wi-fi in an apartment, and there are dozens of other networks showing up.
So this headline just seems...meaningless?
One day I want to build something like this, except for sound. It would be great to get a heading and distance for where a sound is coming from. This could be both for small scale things (e.g. which part of this is squeaking?) or large scale (e.g. is that booming noise coming from the construction a few blocks away?)
>It can see WiFi through walls I don't understand what this is trying to say. Everyone who has ever used wi-fi knows that it works through walls. You try to connect to a wi-fi in an apartment, and there are dozens of other networks showing up. So this headline just seems...meaningless?
The visualizer reminds me of my thermal camera. I have heard claims of devices (mostly TVs) supposedly coming with secret 5G cell uplinks built in [never heard a specific model mentioned though]. If there were more variants covering more commonly-used RF bands, people could walk around and literally check for once. (incidentally i'm sure three letter agencies have had this sort of tech in their bug-detecting toolkit…
> I have heard claims of devices (mostly TVs) supposedly coming with secret 5G cell uplinks built This is occasionally mentioned on HN, but I have not yet seen a specific instance of this. Please share if you know something about secret 5G cell modems used to spy on people.
Earlier quoted context omitted.
Moisture camera. Now there is an idea.
Initially I scoffed, but then I recalled that certain RF bands are disproportionately absorbed by water and this is used for certain sorts of atmospheric imaging by satellites. So you'd need a moisture "light" and an RF camera. Other than being cost prohibitive it sounds like an awesome toy.
>It can see WiFi through walls I don't understand what this is trying to say. Everyone who has ever used wi-fi knows that it works through walls. You try to connect to a wi-fi in an apartment, and there are dozens of other networks showing up. So this headline just seems...meaningless?
Earlier quoted context omitted.
The really intriguing part is the "Custom ADC" here, seems like some kind of 1-bit ΣΔ oversampling ADC (704 MSPS?). Single differential transistor, and captured by FPGAs LVDS RX. Neat way to reduce cost and pin-count? But I think the typical FPGA clock tree has poor jitter performance. Not using the internal PLL(s) might help with spurs but the clock buffers are unavoidable. The documentation mentions it's likely fur…
We've got the switching noise nailed down. Fortunately the LVDS jitter doesn't affect the sigma delta too badly because that impacts proportional to baseband frequency which is largely filtered out by the decimation filters beyond 40 MHz.. With a total of eight ADCs per QuadRF, you can see we are getting huge savings by being custom! While the per-ADC ENOB is 7-8 bits, another nice thing about phased arrays is that t…
Reading these comments first, I assumed you were using a variant of Spartan 6 LVDS TDC trick which allows up to 200 Msps rates. (https://sps.ewi.tudelft.nl/pubs/Homulle15fpga.pdf)
But this is a really interesting use case as well, and something that could be used for a 16 channel logic analyzer with analog recording support like the Saleae Logic 16 Pro, but without expensive ADC from Analog Devices.