yep, no luck. i have a good friend just finishing up his phd in a the field and working on applications for similar technology for european automakers.
I'd also love to try this, we're working on indoor positioning here and this is a solution we had been considering. Have you done any test with ultra sounds?
I used one of the codes on reddit. Though it looks like it's free now.
Nice work!
Couple of thoughts:
- I only have ear phones with a mic. It wasn't immediately clear how I should measure something. Perhaps a tutorial? If I hadn't watched the video first, it would have been difficult.
- It's loud, is there a different frequency that could be used?
- Without any other background info, it leads one to think that the temperature is the only additional variable in the equation. Wouldn't it then be possible to tell the temperature with a known distance?
- Unless I have multiple iOS devices, I can only measure just past a meter (from the video). Combining this with the fact that it's not very precise, it would be much more useful if I could measure longer distances (e.g., sonar).
In theory it would be possible to tell the temperature if you have a know distance. The only problem seems to be that the clock of the ADC/DAC is often not running exactly at its nominal frequency. So, if you have a known distance, slide the temperature slider until the result matches (this works even after the measurement is complete). I've thought about this problem but decided against having an additional slider for the clock calibration, because I think that would have been to difficult to understand.
If they use some specific waveform that is identified on the other side then it should be either perfectly accurate or fail to measure anything depending on background noice - not lose precision. Reflections from the walls is what I'd be more worried about.
The biggest source of error is actually the variation in the speed of sound. It increases around 2% when the temperature increases 10°C. Then there is a source of error because it seems the clock frequency of the ADC/DAC on the iPhone is not 100% accurate. If you recalibrate the app with a known distance (by moving the temp. slider until the displayed distance matches the actual distance) it should be pretty precise. No warranties, however. If the noise level is too high, it usually just doesn't show the measurement. There's one other source of error, that was actually the hardest to filter out: The sound doesn't only travel on the shortest path (line-of-sight) but on many paths. And often the sound from the longer paths arrive amplified, compared to the shortest path.
He seems to have a WP plugin allowing site.com/ac* to forward to /acoustic-ruler/. I'm not sure whether to consider that smart for allowing typos, or evil for allowing this type of behavior.
Not sure if I'm doing something wrong, but even after reading the instructions & watching the video I'm getting odd results which don't match what is in the video at all.
I realize there is a disclaimer that it may not necessarily be accurate, but it varies between 0 and some wildly innacurate value like 30 cm when I'm holding it 1 or 2cm away.
64 comments
[ 3.0 ms ] story [ 131 ms ] thread1) On your iPhone/iPod/iPad, tap the App Store icon from the Home Screen.
2) Navigate to the New section on the Featured tab.
3) Scroll to the bottom of the list to locate and tap the Redeem button.
4) Enter the promo code and tap the Redeem button in the upper right.
5) Tap done on the Thank You screen, then tap the home button to return to the home screen.
6) After a second, you should see the my app installing. (If the promo code was not used before...)
7) Please upvote if you took a code and leave a comment telling which was your code (so the next person doesn't have to try in vain).
8) If all codes are used up, please reply to this comment, I will then post more. This is more efficient than posting all codes at the start.
sigh Looks like nobody read your post seeing all of are used.
Enjoy some more:
Have some more:
Thank you HN for your tremendous interest!These codes are all taken.
The app is available for $0.99: http://itunes.apple.com/us/app/acoustic-ruler-pro/id47508196...
Thanks!
Nice work!
Couple of thoughts:
- I only have ear phones with a mic. It wasn't immediately clear how I should measure something. Perhaps a tutorial? If I hadn't watched the video first, it would have been difficult.
- It's loud, is there a different frequency that could be used?
- Without any other background info, it leads one to think that the temperature is the only additional variable in the equation. Wouldn't it then be possible to tell the temperature with a known distance?
- Unless I have multiple iOS devices, I can only measure just past a meter (from the video). Combining this with the fact that it's not very precise, it would be much more useful if I could measure longer distances (e.g., sonar).
http://www.reddit.com/r/iphone/comments/lz0i6/hello_riphone_...
In theory it would be possible to tell the temperature if you have a know distance. The only problem seems to be that the clock of the ADC/DAC is often not running exactly at its nominal frequency. So, if you have a known distance, slide the temperature slider until the result matches (this works even after the measurement is complete). I've thought about this problem but decided against having an additional slider for the clock calibration, because I think that would have been to difficult to understand.
How accurate is this in noisy environments?
It has the hardware to measure temperature, but we can't use it.
(See: http://www.iclarified.com/images/news/3832/14751/14751.png )
All codes are taken :-(
My app supports a dual-device mode where you can measure the distance between two iOS devices, and it works reliably up to 25 meters.
http://news.ycombinator.com/item?id=3227929 (by new user quadrix)
http://news.ycombinator.com/item?id=3221160 (by quadrix again)
http://news.ycombinator.com/item?id=3228256 (by new user greenale)
http://news.ycombinator.com/threads?id=makramer09 (new user or shill account makramer09)
http://news.ycombinator.com/threads?id=jgeorge (new user or shill account jgeorge)
http://news.ycombinator.com/threads?id=alexenko (new user or shill account alexenko)
I realize there is a disclaimer that it may not necessarily be accurate, but it varies between 0 and some wildly innacurate value like 30 cm when I'm holding it 1 or 2cm away.