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Thread: Breathalyzer for smartphone:

  1. #21
    Insider bronc's Avatar
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    Dang, things have got a lot smaller in the last few years. Now I feel old

  2. #22
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    It certainly looks possible, the problem is figuring out what part of the firing cycle to start measuring from.


    Indoors, 5 meters @ 280FPS. Phone about 0.5m underneath blowback marker.


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  3. #23
    Insider PBSteve's Avatar
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    What was your velo? Based on the obvious features, that looks like about 183fps/ 55 meters per second

  4. #24
    You'd want to tie it in with a laser range finder otherwise accurately measuring the distance would be a PITA... but I guess if you only had your phone it would be a great app for people at home without a chrono to get an idea of their velocity as they set up their guns.

  5. #25
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    ~ 280 FPS. Working backwards from the impact, I think I might see a little "pop" around when the ball stops accelerating and reaches the porting (or leaves the barrel), but it would be hard to pick that out accurately with software.

  6. #26
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    It certainly looks possible, the problem is figuring out what part of the firing cycle to start measuring from.
    Uhm... what app is that! I want!

    I would say the resolution would be near impossible - The two points are .205 or so till .290 - .085 difference, but with a margin of error of about .010 from just a quick look at the firing action, that makes for a larger then 10% accuracy - at 15ft. Having to set an accurate distance would be able to be done almost by paces, no laser pointer needed. Ha!

  7. #27
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    It's Audacity for PC (and the sound recorder app on my phone). Just a screenshot, it's more like 20khz resolution. Maybe have the option to select different marker sound signatures?

    You can do a simple rangefinder with the camera app, that's something I've been working on as an addendum my "other" project.

  8. #28
    Insider PBSteve's Avatar
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    Quote Originally Posted by neftaly View Post
    ~ 280 FPS. Working backwards from the impact, I think I might see a little "pop" around when the ball stops accelerating and reaches the porting (or leaves the barrel), but it would be hard to pick that out accurately with software.
    It would be great if you could mark it up with which features you believe are what, it's a bit tough to tell.
    Quote Originally Posted by pbjosh View Post
    I would say the resolution would be near impossible - The two points are .205 or so till .290 - .085 difference, but with a margin of error of about .010 from just a quick look at the firing action, that makes for a larger then 10% accuracy - at 15ft. Having to set an accurate distance would be able to be done almost by paces, no laser pointer needed. Ha!
    Using .09s and 5 meters you get my numbers above, which were wrong. And based on those graphs the resolution is clearly better than 0.01s.

  9. #29
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    Eh, I'd prefer to see calibrated tests & recordings before going any further than speculation. That was just for a rough proof of concept

  10. #30
    Insider PBSteve's Avatar
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    Could you at least point out which feature you think is the main valve opening?

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