If I may disagree without being disagreeable, it is entirely possible to use a scope with sufficient resolving power to see target holes at 800m. I didn't promise it would be cheap. [?]
You're right about the atmospheric instability, of course. And that instability, in addition to a number of other indeterminate variables is what will put pay to attempts at exceedingly precise measurements. On Mon, Nov 1, 2010 at 10:08 PM, Bob Camp <[email protected]> wrote: > Hi > > Two gotchas, one minor, the other a bit bigger. > > At 800 yards, even a *very* good optical setup can't / won't see holes in a > target. The atmosphere is just to unstable. You would have to mount the > camera down range (minor issue). > > The larger one is that you really don't want to truck down a half mile of > path to put up a new piece of paper. After a while the "target" gets pretty > ragged. There's not much for the optics to pick up, especially if you have > good groups. > > Cool idea though .... > > Bob > > > On Nov 1, 2010, at 10:04 PM, Predrag Dukic wrote: > > > > > Why not using optical methods for shot grouping? > > > > A cheap web camera with equally cheap telescopic lense can resolve 1mm. > > Some image processing software can find shot positions within the 1kx1k > pixel bitmap.... etc.. > > > > > > > > > > At 01:03 2.11.2010, you wrote: > >> Timenutters-- > >> I appreciate the feedback for implementing my > >> ballistic field measurement project but I think > >> there is some misunderstanding of what the goal is. > >> For instance, it is not practical to find 800 meters > >> of coax and trench it in out to the downrange target. > >> This system needs to be relatively portable so it > >> can be set up at any given shooting range. > >> I need to determine: A) down-range velocity of the > >> still super-sonic projectile, B) time of flight and > >> C) shot-group size. > >> Measuring down-range shot-group size with an array of > >> ultrasonic sensors is pretty straightforward. I can > >> do all the computation with a $6 microprocessor and > >> send the X/Y coordinates back to the laptop at the > >> shooting bench with a simple RF link. Down-range > >> velocity is easily determined with a set of sky-screens > >> and the results also sent back via an RF link. > >> Time-of-flight is much more problematic to determine > >> but the plan is to determine the elapsed time between > >> the moment the projectile passes over the muzzle skyscreen > >> and the moment of passing over the downrange skyscreen. > >> This means syncing the 10 MHz clocks at both ends together. > >> I guess the crux of my question to the time-nuts gang > >> is what is the easiest (cheapest!!) way to do this. > >> For a number of years I have been using an ultrasonic > >> shot-group size measurement system made by Oehler > >> Research. It can resolve individual shot placement > >> to within 1 cm. Some less expensive systems that > >> use fewer sensors can only resolve to +/- 2 cm. The > >> Oehler Research system also determines time of flight. > >> The problem is that these systems all use a cable > >> to connect back to the equipment at the shooting bench. > >> I am trying to find a way to synchronize/coordinate > >> a downrange 10 MHz clock to the "master" 10 MHz system > >> clock at the shooting bench without spending hundreds > >> of $$ doing it. It is not too big a problem to process > >> all of the signals from the downrange skyscreens and the > >> ultrasonic shot-group sensors and telemeter the results > >> back to the shooting bench. > >> However, time-of-flight info (via an RF link requires > >> that I sync the 10MHz clocks at both ends together. > >> Use of GPS receivers seems to be the most likely way > >> to do this but how do I keep the cost and complexity > >> down? > >> Thanks in advance for any feedback on the matter! > >> Mike Baker > >> --------------------- > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >
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