[time-nuts] A real-world precision timing need....
Javier Herrero
jherrero at hvsistemas.es
Sun Oct 31 13:14:55 UTC 2010
Hello,
Long ago I was involved in a project that has something to do with test
cannons. They used a doppler radar (a commercially available equipment,
but I don't remember the manufacturer) for measuring the speed of the
bullet (a rather big one... if I was right, it was a 155mm caliper :) )
during its travel from the cannon aperture to the end point (about 500m
distance or so).
Regards,
Javier
El 31/10/2010 13:56, Michael Baker escribió:
> Hello, Time-Nutters--
> A real-world precision timing need:
> As a dedicated long-range rifle shooter and
> ballistics enthusiast, I am in the early stages
> of a project I am getting started on...
> The object is to measure the velocity of a
> rifle bullet both at the muzzle and downrange at
> various distances up to 800 yards/meters or so.
> Conventional optical sky-screens will will be
> used for measuring the velocity at both ends.
> However, I also need time-of-flight and this
> requires knowing the timing relationship between
> the time the bullet crosses the muzzle sky-screen
> and the downrange sky-screen. Bullet muzzle velocities
> will be between 1900 to 3200 feet-per-second.
> Additionally, I will be using the output from an
> array of 4 ultrasonic sensors located on the
> corners of a 4-foot PVC pipe square to determine
> the size of the shot group at the far end and
> telemeter this info back to a laptop at the
> shooting bench.
> I can use a 10-MHz crystal for the sky-screen clocks
> and the for the 4 ultrasonic bullet shot location
> sensors. However, determining the time-of-flight is
> a more difficult task as this requires syncing clocks
> together at both ends to a moderate degree of accuracy.
> Out to 100 yards I can send the time-of-flight
> far-end pulse back by wire and compare it to the
> muzzle-end sky-screen pulse but this is not practical
> to do by wire out at 800 yards.
> This project is on a tight budget-- namely, MY
> wallet, so cost is a major concern. Suggestions
> will be most welcome!!
> Thanks!!
> Mike Baker
> Gainesville, Florida, USA
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--
------------------------------------------------------------------------
Javier Herrero EMAIL: jherrero at hvsistemas.com
Chief Technology Officer
HV Sistemas S.L. PHONE: +34 949 336 806
Los Charcones, 17 FAX: +34 949 336 792
19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com
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