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Ask HN: Any tools to do generic WiFi imaging?

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Re: Ask HN: Any tools to do generic WiFi imaging?

#61

Post by hyperific »

mjlee wrote: post #20
hyperific wrote: post #12

For anyone trying to find and map electrical wires in their walls I recommend an inductive electromagnetic listening device like the FarField on Tindie. Plug a device into an outlet and you'll be able to hear the electromagnetic field of the wire in your wall via the FarField's stereo inductors. Soma Ether is also a good one but pricey.

Do you think you could trace copper pipes with the same technique?

If there's current running through them then yes. There needs to be a EM field for the device's inductor to detect.

Re: Ask HN: Any tools to do generic WiFi imaging?

#63

Post by jiveturkey »

You're most likely overthinking it.

For your use case, you are primarily concerned with fireblocks. They are unlikely to exist in an older home. They can be detected with a simple stud finder, which range from $30 for the simple (good enough) kind, to $1000 for the radar kind. Simply knocking on the wall is also good for this purpose.

You likely have pretty fixed locations where you want the wires to exit into the room, so you can run a borescope through those places. These are also pretty inexpensive.

Re: Ask HN: Any tools to do generic WiFi imaging?

#64

Post by yorick »

yayr wrote: post #32
yorick wrote: post #23

2.4ghz isn't great at detecting small obstacles like wires. There's a smartphone mounted device that can do this with 60ghz: https://walabot.com/

it seems to be optimized for dry walls. not sure how it would perform on concrete or other stone walls. Also I could not find a technical description how it works.

It uses the 60ghz radar from https://vayyar.com/ . I'm not sure how or if it works, I haven't tried it myself. They also sell dev kits: https://walabot.com/products/walabot-developer-pack-new

Re: Ask HN: Any tools to do generic WiFi imaging?

#65

Post by jhester6 »

You would likely have an exceedingly hard time getting that sort of output using WiFi. The real issue is resolution (your ability to isolate your target from nearby reflectors) which, in range, is determined by your usable bandwidth. In the best case, with the 1.2 GHz (ish) supplied by WiFI-6, your resolution would be c/(2B) = 12.5 cm (with c being the celerity of light). Then, you would have to measure from at least three different locations to get a 3D image with sufficient resolution.

An alternative approach would be to use holographic principles, but these require you to measure very accurately the position of your transmitters, whether you use a multiplicity of them placed in different locations or employ Synthetic Aperture Radar methods with a single one (by moving your transmitter).

That is why using 60 Ghz radars (with 4 GHz of bandwidth and Angle of Arrival capabilities) at short ranges would probably be the most promising direction. You can get a dev kit for one of these from Texas Instruments or some other supplier for not too much money.

Re: Ask HN: Any tools to do generic WiFi imaging?

#67

Post by brudgers »

_Microft wrote: post #13
brudgers wrote: post #4

To me, WiFi is the X in an XY problem. An endoscope can be had for https://www.google.com/search?q=endoscope Good luck.

I think you meant borescopes[0]. Endoscopes are for medical use. [0] https://en.wikipedia.org/wiki/Borescope

Tell Google, Amazon, and Ali Express. I was surprised to TIL myself.

Re: Ask HN: Any tools to do generic WiFi imaging?

#68

Post by greggsy »

sleepybrett wrote: post #53
greggsy wrote: post #25

Get an infrared thermometer camera. I have a FLIR add-on for iPhone that lets me see studs, gaps in insulation, leaks... it's amazing what shows up. It won't show cables, unless they're hot. You can use an AC stud finder for that. You can flip the photo between the actual and IR image, and it overlays an outline over the image. I make a video in and out of the house on the hottest and coldest days.

get a cheap 30$ endoscope from amazon. You can go in through power outlets/lightswitches etc. (probably want to cut the breaker first though). Handy tool to have around for all kinds of tasks.

I do have a cheap one, and hate it with an absolute passion. The problem is that it’s 30ft long making it an unwieldy thing to manoeuvre, and the wifi connection means I have to hold the phone at the same time.

I’ll definitely just get a trigger style one that’s only 3-6ft max next time.

Re: Ask HN: Any tools to do generic WiFi imaging?

#69

Post by pizzafeelsright »

mrgoldenbrown wrote: post #59
pizzafeelsright wrote: post #56

I have remodeled a dozen houses of and haven't hit anything of importance. How: Study the building code to determine with >95% accuracy what is behind the wall based upon surrounding fixtures.

How do you know the building code from 100+ years ago? And whether they actually followed it back then?

100 years ago there wasn't really code, or electricity or extensive plumbing and everything is pretty obvious.

As for following - after the 50's everything was, in theory, built to code with exceptions.

Worse case really is hitting a water pipe.

Re: Ask HN: Any tools to do generic WiFi imaging?

#70

Post by fignews »

kukkeliskuu wrote: post #39
fignews wrote: post #34

Earlier quoted context omitted.

Used my Infriray while house hunting. Possibly saved me big time €. Great also for spotting leaks any water in/on surfaces shows up quite clearly. In the same vein I use it to spot pet accidents. The infriray is the Chinese knockoff brand which is actually better than flir because they don’t have to follow the US weapons law. So with it I get 30(?) fps instead of the ~5 with flir. Resolution is better too. It’s very…

How did it save you money when house hunting? What kind of things did you detect?

I saved money by not buying a badly insulated house. There were some walls that shocked me in how little they were insulated. Also found a roof leak in another house
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