Slashdot Mirror
iOS App Acoustically Measures Distances Up To 25 Meters
n01 writes "A recently published app for the iOS platform uses the propagation of sound waves to measure distances of up to 25 meters in a dual device mode. The technique works through repeatedly sending a chirp signal from the master device to which the other (reflector) device synchronizes itself and then replies in a similar fashion. A novel combination of techniques has been engineered to enhance the robustness in noisy environments, such as using an optimum-autocorrelation-signal and semi-automatic frequency calibration together with an averaging over multiple cycles."
Now you to can be a space marine up until the point the aliens get to you and all you got for xmas was a stinking ipod...
But still an advertisement.
http://wiki.laptop.org/go/Distance
That's not very impressive. Anyone who has two devices that are syncronized to a common timing source (which most cell phones are) can accomplish this. You just say "I started transmitting at x and you received it at y. x-y/speed of sound at sea level = your result. Now if it could be done with one device, and use doppler effect,etc., to map out the room and roughly what's inside it (like in Batman) then we'd be getting somewhere.
#fuckbeta #iamslashdot #dicemustdie
I thought this was going to be a cool sonar thing- you'll need 2 iphones? get a tape measure...
Weapons Officer: "Captain I can't get a fix on the enemies position."
Science Officer: "We could try using an optimum-autocorrelation-signal and semi-automatic frequency calibration together with an averaging over multiple cycles."
Captain: "Good idea."
Me at home: "Who makes up this stuff."
Some humans can learn echo location[1], but just wondering if we could have an app that sends clicks and chirps and processes the echos and creates a picture or 3D model.
But it might need two or more "ears" to quickly build a 3D image of the environment.
[1] http://www.youtube.com/watch?v=qLziFMF4DHA
http://www.youtube.com/watch?v=GYWpxmcHTOc
Because such an app already existed for PocketPC (That'd be Windows Mobile):
http://nerdipedia.com/tiki-index.php?page=Sonar+CE
Oh, and desktop PC:
http://nerdipedia.com/tiki-index.php?page=Sonar&structure=index
I hear there's a flashlight app for iDevices, too - Slashdot should really look into that. It's magical.
Skynet: coming soon to an iPhone near you.
This didn't seem to do that good of a job, but was 2 years ago.
* Sonar Ruler, By Laan Labs: http://itunes.apple.com/app/sonar-ruler/id324621243?mt=8
* http://thenextweb.com/2009/08/20/amazing-iphone-app-lets-measure-distance-echoes-works/
Happy measuring!
http://stephan.sugarmotor.org
"Please note that while the resolution of the measurements may be as low as 1mm, the precision usually is not. While I have taken great care to make the app as reliable as possible, there are simply too many factors affecting the measurement process and the precision. That is why I want to be clear about one thing: there is absolutely no warranty that the measurements taken with Acoustic Ruler Pro are correct"
Another good example of incorrect usage of the word precision. In this case, the method is actually quite precious, as in measurements are very repeatable. What the author meant is that the accuracy is not very good. I tried out the app just now, at the range of 22 inch (width of my monitor), it under estimates the distance by 1 inch; and for something half an inch apart, it over estimates by over an inch. It is possible to measure the non-linearity using a control setup, but the result would be largely useless, as measurement of different items requires placing the item near the source and receiver, and this will likely change the acoustic behavior of the environment and affect measurement accuracy.
This Sig is removed due to factual inaccuracy
When I see the word 'novel' applied to techniques that have been used for decades, I smell 'patent lawyer'. And be extension: astroturf.
Signal processing techniques applied to sonar (whether active, passive or beaconed) including signal correlation, spectral adaptation/equalisation, and filtering are standard fare in this field.
Maybe by novel they mean "on an iPhone"?
That being said, there is nothing that says this won't work - as it worked extremely well 20 years ago on dedicated systems with far less processing power. (Those systems, however, used multiple arrayed transducers and tailored beam patterns to significantly reduce the effective noise floor.)
About 20 years ago, I had a hand-held device roughly the size of a smart phone but twice as thick that did distance measuring all by itself. It was infrared and as I recall, it was something like $25.00 from Rat Shack or Home Depot or some place like that. A 30 foot tape measure is about $8.00 and works a lot better.
Nothing worthwhile ever happens before noon
Or you can use a piece of string, as long as it's no shorter than 25m.
Please consider this account deleted, I just can't be bothered with the spam anymore.
Nobody in their right mind would buy two iOS devices just to use this app. But somebody who's got two of them already might consider buying this app for under a dollar. (Just one purchase required if you have both devices on the same iTunes account.)
Thanks for clearing this up! I will use the word accuracy in the next update!
One suspects that the primary use case for this application is not, "Hey, we need to measure this, let's go get two iPhones!" It's "Hey we need to measure this and happen to have two iPhones, but no tape measure." Most people carry their phones around with them all the time, but unless they're contractors don't carry tape measures. The point of near ubiquitous mobile computers is that you can use them for lots of things. This is a cute and clever thing that you can now use them for.
I don't need a million points of light, just two points of multi-mode fiber and a 10 Gig-E router.
...seems a little expensive for a tape measure.
Is there any benefit to moving to ultrasonic frequencies? Other than making it inaudible (so you don't bother people but maybe dogs!), would this improve the resolution? Does the range decrease? Do consumer level devices cover such a broad spectrum?
By the way, has anyone made an iOS or Android App that can record in the ultrasound (or infrasonic) ranges and change it so that we can listen in audible ranges? Might be neat to see/hear what the bats are doing!
Also, how DO bats build up a good 3D map of their surroundings using just one "speaker" and two "microphones"? Do they send out beams or are their ears swiveling? And, with the limited amount of computing power on a smartphone, would it be able to duplicate it? A bat's brain doesn't seem particularly large and they are doing this FAST (on the fly, ha ha).
No, the primary use case is "oh, this is nifty, let me play with it". The accuracy is nowhere near good enough for any measurement that actually matters.
Except for all those MB Airs I saw up at Google the other day. Yep, those Google programmers sure don't like numbers. Right?
Can't a laser do this kind of job instead of sound?
Why OpalCalc is the best Windows calc
Tape measure? Where do I get that app?
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
You could measure room wall lengths close enough for basic estimates on how much paint to buy or fence length estimates and such where you don't need cut to fit accuracy.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
At least say "I recently published an app for the iOS platform that" instead of "A recently published app for the iOS platform".
Pretending it's something interesting you just stumbled across is being deceptive.
No, the tricorder app is cute and clever, and measures a lot more things. Useful? That's debatable.
but unless they're contractors don't carry tape measures
And unless they are contractors they don't need to measure anything. Do you recall an event in your life when you, completely out of the blue, needed to measure something like that? I can only think of the hardware store like Home Depot, but measuring tape is readily available there.
You can buy devices that do it standalone, with only one device. Home Depot sells them. They shine a laser for aiming and generate repeated clicks. They then listen for the reflection and give you a distance measurement using that. Works reasonably well. Have to use it in a somewhat quiet indoor space, and if you aim it at something that absorbs sound it doesn't work, but for all that it lets you get a quick and pretty accurate distance measurement for cheap.
There are more expensive ones that use laser pulses to do it all optically and are more accurate and work in more environments, however they do cost like 10x as much since it requires much more precision timing equipment to deal with things moving at light speed instead of the speed of sound.
Nothing special about this kind of technology.
I tried out the app just now, at the range of 22 inch (width of my monitor)
I'm 99.6% sure you got it right, considering this is slashdot and all, but you're sure your monitor is 22" wide, aren't you?
(Just checking in case you're thinking you have a 22" monitor, so it must be 22" wide. Unlikely all things considered, but I still have to ask.) :)
Or two iOS devices...
I (tried to) learn a lot from these postings (some of it was at the limit of my understanding though). I appreciate the information!
It's good enough for photography. It's good enough for buying carpet, tiles, or paint.
"... and more and more now there are all kinds of electronic goodies available" -- Pink Floyd 1972
Fuck, it's even easier just to use a damn tape measure. You don't have to synchronize them or any of this bullshit. Not only is a tape measure easier, but it's a fuck of a lot cheaper, too. Now you don't have to drop at least $1000 on some Apple devices.
That would be a valid comment if anyone actually bought an iPhone for use exclusively as a tape measure.
To have a right to do a thing is not at all the same as to be right in doing it
You can get enough accuracy for buying paint and fence length by counting your steps.
You have to walk from one end of the measurement to the other whether you're counting steps or just putting the phones in place, but you don't have to walk back to the starting point to pick up a phone, however, so the entire process is easier and faster if you just count steps.
The prostitute that laughed at you and said "that's not even four inches" doesn't count.
Is there an Android app (or, preferably, library) that can use the sonar to sense the size and rough shape of a whole room, making a 3D model? Maybe by correlating distance pings with the accelerometer (and GPS for added position context) while waving the device around..
--
make install -not war