Acoustic camera . . .  wait a moment . . . what ??? - Page 1
Forum section: electronics / testgear

author: Fryguy
author_rank: Regular Contributor
timestamp: January 09, 2025, 10:00:14 pm
content: Did you know something like this exists ? I thought it was some new kind of shower head . . .https://www.flir.co.uk/instruments/condition-monitoring-solutions/choose-flir-si-series/

author: Simmed
author_rank: Frequent Contributor
timestamp: January 09, 2025, 10:07:05 pm
content: there is optic fiber that detect sound too

author: Fryguy
author_rank: Regular Contributor
timestamp: January 09, 2025, 10:13:53 pm
content: Not only sound - i did a repairjob a few month ago on optic fibers used to measure the temperature in a 2500sqmm 400KV cable . . .

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 10, 2025, 04:47:33 am
content: Brüel & Kjær was doing this for quite a while but I don't see much on their website now- they hide it well!https://www.hbkworld.com/en/solutions/applications/acoustics/noise-source-identification/noise-identification-acoustic-camera

author: lightman
author_rank: Contributor
timestamp: January 10, 2025, 05:10:16 am
content: Yup, Fluke has one, and it is amazing, I'm trying to convince them to let me borrow it, so i can do a reviewit costs a fortune, so it my take a while hehe, they can show you air/gas leaks with amazing precision.

author: Sorama
author_rank: Frequent Contributor
timestamp: January 10, 2025, 07:43:37 am
content: We bought an acoustic camera last year for our building physics department.But we went for an another branch as :The Fluke is (as most of the times) not developed by fluke (however the bought the company that did and recently produced a new version).Secondly, you cannot measure low frequencies like below 2kHz which you need if one one’s to measure vibration of a window or street traffic coming trough. The distance between their microphones is just too small to be able to measure those frequencies.Ours goes as low as 50Hz.We recently did a 3 days site survey for TotalEnergies for finding compressed air leaks using this camera.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 10, 2025, 01:36:52 pm
content: Yeah, one of my HVAC guys had an acoustic leak detector. "Listens" for ultrasonics. Apparently quite sensitive.

author: Sorama
author_rank: Frequent Contributor
timestamp: January 10, 2025, 02:02:07 pm
content: Quote from: Conrad Hoffman on January 10, 2025, 01:36:52 pmwhat you refer to is something completely different.you're talking about a single microphone on a stick that needs physical contact with the drains to pick up leak noise .It's not a camera.Acoustic camera's have dozens (mine has 64) of mics and displays remotely the source of the (air) pressure leak.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 10, 2025, 07:03:59 pm
content: Yes, I know that, but the pickup principle is the same. No contact is needed. What I find interesting is that a very small leak can produce enough acoustic output to even register.

author: bsdphk
author_rank: Regular Contributor
timestamp: January 10, 2025, 07:54:58 pm
content: Quote from: Conrad Hoffman on January 10, 2025, 07:03:59 pmUltrasonic detection of gas leaking through pinholes decades old.There's an article in HP Journal about it, from when HP entered that fray...

author: Sorama
author_rank: Frequent Contributor
timestamp: January 10, 2025, 07:55:25 pm
content: Quote from: Conrad Hoffman on January 10, 2025, 07:03:59 pmAgain, it is completely different.What you saw is a pin thatneeds fysical contactand will convertmechanicalvibration into an electrical signal. And it is not ultrasonic but verylowfrequency.Our building physics department has them too and even I use them on a weekly basis.It’s NOT a camera!The acoustical camera picks up the sound of a source at tens of meters of distance and due to delay of the sound that reaches 64 microphones, it can locate the direction and visualize it on a screen.It is quite the opposite of what you think you saw.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 10, 2025, 08:27:02 pm
content: Quote from: Conrad Hoffman on January 10, 2025, 01:36:52 pmYears ago I repaired an acoustic detector that was used by a pest control company to to detect the sound of termites chewing on wood. We tested it and it really worked!

author: Fryguy
author_rank: Regular Contributor
timestamp: January 10, 2025, 09:59:37 pm
content: I would like to take that detector apart - just to find out how it works . . . I bet it is different from the 124-microphone flir unit (which still looks to me like a high tech shower head) .Did that detector recognise the sound of the termites on its own ?

author: DaJMasta
author_rank: Super Contributor
timestamp: January 10, 2025, 10:54:53 pm
content: Neat. I had been thinking about using some old PXI modules to do mic array for a visual representation of sound but didn't realize it was already a product.While it's probably not exotic, I wonder what their DSP looks like - I assume they're not especially narrow field mic elements so they use them together as a phased array to decipher position information, but can they also do an FFT on a hotspot (or on every array element) to give you the frequency components too? Maybe that's already part of their noise reduction algorithm.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 10, 2025, 11:20:29 pm
content: I've seen a couple of homebrew versions of this - not too hard nowadays - a bunch of cheap digital output MEMs microphones and an FPGA.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: January 11, 2025, 09:59:24 pm
content: I would say that ultrasound imaging cameras are commercially available since about 10 years. I heard about that topic 5 or 6 years ago.It seems that this storystarted in Switzerland.Today, several manufacturers other than Fluke also sell such kind of TE that are quite a game changer in gas leak detection and electrical discharge analysis. Most of the available products feature a sensor that looks more or less like a shower head. Behind each hole sits a small microphone. All of the devices feature at least a visible cam et perform image fusion.Some other brands:-Distran-SDTin Belgium in collaboration with Crysound from Hangzhou, China. It seem that their products are only sold in Europe an Africa.-Sonotechin GermanyAs I found such kind of TE really interesting and also a nice enhancement to thermal imaging which I already use. I even had a quick look on how such a gear could be built, electronically speaking.Actually there are probably 1 or 2 man/years of work to devise such a TE, so it was not reasonable to dive into that just as a hobby activity.Speaking about funny toys,this onereally amazes me.

author: Fryguy
author_rank: Regular Contributor
timestamp: January 11, 2025, 10:43:39 pm
content: Now there is a really funny toy - especially when you notice the 3D version of it . . . a 3D see through wall radar imagerNow we definitely need to shield entire buildings if we want to keep our privacy . . .I wonder - can a local police force even afford such a toy ? This looks really expensive . Thanks for posting , timeandfrequency .BTW , i know the reason for all the holes in the shower head - i said that just for fun . If it had a gardenhose connector right underneath the grip - then things would really get strange

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: January 12, 2025, 12:54:56 am
content: Hello Sorama,Quote from: Sorama on January 10, 2025, 02:02:07 pmQuote from: Sorama on January 10, 2025, 07:55:25 pmIMO, Conrad Hoffman's point is probably correct.Refrigerant ultrasonic leak detectorsused by HVAC guys do not need any physical contact.Check out the video (dated 2018) whereCraig finds the leak.Once the fins removed, the sensor still detects the leak at a distance of at least 10 cm.

author: hanakp
author_rank: Regular Contributor
timestamp: January 12, 2025, 09:36:22 am
content: Quote from: Conrad Hoffman on January 10, 2025, 04:47:33 amA few years ago, I posted about repair of B&K acquisition module that's used with their "acoustic camera":https://www.eevblog.com/forum/repair/bruel-and-kjaer-type-3053-audio-daq-module-repair/msg3134926/#msg3134926

author: Sorama
author_rank: Frequent Contributor
timestamp: January 12, 2025, 09:51:00 am
content: Quote from: timeandfrequency on January 12, 2025, 12:54:56 amNo, he is not.You’re referring to devices that search for gas leaks, as any leaking gas produces a freq. spectrum that can be measured.That link you gave needs you to follow the tube for leaks, it has no camera nor can it show from several meters away the position of the leak.I’m referring to detecting either a leak of a liquid like water leaking in a (underground) drain or pressure tube which needs physical contact with the floor (as it is converting mechanical vibration into an electrical signal) and is what we call ‘acoustic leak detection’, either finding a leak of a gas and specifically its location by using an acoustic camera.Those cameras have dozens of microphones and are able to show you the leak from dozens of meters of distance.Leaking gasses, like pressurized air, has a spectrum between 6 and 100kHz, while vibrating walls or windows are very low frequency around 80 till 500 Hz.Very few , certain not the flir, can go that low.But again, it all depends on what you want to measure.

author: Sorama
author_rank: Frequent Contributor
timestamp: January 12, 2025, 09:59:00 am
content: Quote from: hanakp on January 12, 2025, 09:36:22 amWe have B&K stuff too, but they lost the battle of acoustic a cameras.They stopped development of modern acoustic cameras, they only tried to make their lab module portable which just doesn’t work in practice/in the field.But at least they focussed on low frequency measurements as that is what we need when evaluating building physics like air gaps.However, now there is also some development going on for finding air leaks in a building by using ultrasonics.For that, the market always uses smoke test in combination with a blower door test and thermography.we are making that move also. (From smoke and Co to ultrasonics)