[time-nuts] Sources for Mission Time Clock

Chris Albertson albertson.chris at gmail.com
Sun Jan 11 19:53:43 EST 2015

I worked at a place where we actually did launch rockets, big ones.
We did have a few LED displays that were driven by IRIG but really the
"clocks" were mostly computer displays with time in the corner some
place. The display is ether on a monotor of it is projected on a
screen.  Projectors have gotten cheap.  Most of those special purpose
displays were stored in closets under boxes IBM punch cards or the

For a display time-nut level accuracy is not really even needed
because the refresh rate on the display is on the order of 1/100
second soi.  NTP over Ethernet is more than enough for a visual
display.   The screen refresh is the weak link,  (well really the
human eye/brain is.)

Now for real time keeping (vs. the display) you probably want
something that runs off GPS.

On Sun, Jan 11, 2015 at 9:12 AM, Bill Hawkins <bill at iaxs.net> wrote:
> Martin,
> It seems like the only cost-effective way to get that display is to
> find a surplus source. If that's not possible, how about mounting a
> flat panel computer monitor on the wall and driving it with some
> custom software in a commercial computer with a standard operating
> system. There are standard ways to handle NTP, IRIG-B, and 1 PPS.
> Do you need to hold the countdown the way NASA does? Does the clock
> provide the electrical signal to launch or deploy?
> Bill Hawkins
> -----Original Message-----
> From: Martin A Flynn
> Sent: Sunday, January 11, 2015 9:31 AM
> I am looking for a GMT/GET mission time clock  that has the following
> characteristics:
>   * Reads T minus prior to launch or deployment,  T plus after.
>   * Second display for GMT.
>   * Simulating it on a PC display would be OK, would prefer an LED/LCD
>     version for wall mounting
> There is a example of what I am looking for in the background of this
> photo: https://www.hq.nasa.gov/alsj/a16/A16_116_13_15.jpg   .   We have
> NTP, IRIG-B, and a 1 PPS source to work with.
> Any suggestions on a cost-effective way to accomplish this?
> Cheers
> Martin Flynn
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Chris Albertson
Redondo Beach, California

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