[time-nuts] Need usb time interval time for portable bullet chrongraph

Bob Camp lists at rtty.us
Mon Aug 27 12:11:06 EDT 2012


Hi

All of the "good stuff" in a chrono is in the trigger part of it. Even with
very well designed triggers, there is a lot of ambiguity (by Time Nut
standards) in the measured time of flight. A simple time base and counter is
way more than adequate for the digital end of the device.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Don Latham
Sent: Monday, August 27, 2012 1:52 AM
To: Paul Cianciolo; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Need usb time interval time for portable bullet
chrongraph

Hi Paul:
I'm presently adapting a chrony chronograph because I want to use the
triggers for timing and other purposes. They've spent a LOT of
engineering time to get proper triggering, and the triggers can easily
be pulled off without disturbing the basic unit. The triggers are robust
and will drive a piece of coax with a nice pulse at a 5 v level. The
cheapest chrony is under $100 and using their triggers will save you
HOURS and HOURS of fiddling around, trust me!
You can use something like an arduino which has two interrupt inputs to
do the time measurement, or as Tom suggests.
Don

Paul Cianciolo
> Hello Folks
>
> I have been looking at bullet chrographs and wondering if I could get
> the a usb module to do a interval measurement and display on my laptop.
> on a yet to be discovered module to calculate the time interval between
> the pulses?
>
> The bullet travels at approx 1050 feet per second.
> By spacing my gates providing the start stop pulses precisely 1 foot
> apart I think a direct read out except for the decibal point being in
> the wrong place .
>
> Does this seem fesable?
>  
> Here is one module I found http://www.weedtech.com/index_eventcount.html
>  
> Any thoughts on this?
> The reason for the USB would be for display on my laptop at the firing
> range
>
> Thank you for any help I would really appreciate it
>
> PaulC
> W1VLF
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-- 
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com



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