Range Report .22/BP/Shotgun Audio Chronograph (BETA TEST)

[Josh Smith]

Hello,

Here's something you might find fun to play with if you get bored:

http://www.mediafire.com/file/2q9lb62306dc80j/22RF%2050yd%20Audio%20Chronograph%20BETA.xlsx

You'll need a 50yd range, a sound editor/analyzer with graphical readout - Audacity ( http://audacity.sourceforge.net/ ) is totally free - and it helps if you have something that makes a lot of noise - like steel - at 50 yards. You need to hear the report and the impact (or, rather, the software needs to).

This particular chrono program is geared specifically to the .22lr at 50 yards. It opens with Microsoft Excel. Just plug the numbers in and you should get readings very close to those of a standard chronograph.

I've not tested it at ranges longer than 50yds, and so I just locked in 50 yards (unless you would like to manually change it).

Should work pretty well for muzzleloaders and slug guns - anything that might destroy the skyscreens of a standard chronograph - as well.

The average velocity should be about +/- 2% or so, but the MV is going to be off - and it'll be off even more so the further distance you move.

Have fun, and I hope to hear feedback, both positive and negative!

Thanks,

Josh

 

[gallonoffuel]

Re: .22/BP/Shotgun Audio Chronograph (BETA TEST)

I'm working on an acoustic chronograph written in Matlab that should work for all supersonic rounds. It will require 2 microphones and a laptop or desktop with a microphone input. I have some sample data and the basic gunshot detection algorithms working and giving relatively accurate readings, I need to work on the interface and making it run near real time, as well as testing for statistical accuracy against a real commercial optical chronograph.

The goal was to make a low-cost sanity check system that can export the data of your range day to a standard text file that you could print at home and keep with your cards for that day. It would also allow you to let the thing run during your entire session without playing with the buttons on a real Chrony and having that limited field of fire that optical systems need. Unfortunately, due to the relatively limited sampling rate of most mic inputs, it'll be limited to about plus or minus 15fps at 3600fps. To be clearer, if your actual velocity is 3685fps, it might be displayed as 3600 or 3570. The accuracy gets tighter the slower the bullet, down to plus or minus 2fps at just over Mach 1.

You'd be able to move the mics anywhere down range (provided you either leave the computer down there or have enough cord with low loss to run that far) to get velocity readings anywhere along the path.

I need some spare time to get to the range and test it fully, but once it is in a semi-working state I'll be releasing the source code for free.

 

[bohem]

Re: .22/BP/Shotgun Audio Chronograph (BETA TEST)

gallon, when you're ready to unleash it let me know. I'd like to try it out for sure. Finding a large number of people who can handle Matlab might be a problem, but I have a personal copy... what release are you writing it in?

Shoot me a PM if I can help. I write a lot of M-code...