[time-nuts] Looking for off-the-shelf device to timestampmultiple PPS inputs

[Bob Camp]

Hi

For milliseconds, route the signals into a hard wired parallel port (not
USB) and sample the data. Looking at it 1K times a second is pretty easy.
All software running on a tired old PC. Sync the thing up with NTP or what
ever to keep it stable long term.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Kevin Rosenberg
Sent: Wednesday, September 28, 2011 3:56 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Looking for off-the-shelf device to
timestampmultiple PPS inputs

On Sep 28, 2011, at 1:21 PM, Chris Albertson wrote:
> Milliseconds?  So why are we talking about HP counters and PicTic and
> so on.  A basic low end Linux system that is controlled by NTP and a
> GPS receiver is maybe about 100X better than your requirements.
> (I figure you are looking for about 1000 parts per million, NTP is way
> better then that if you have a local GPS)


Heh! I suppose milliseconds don't really belong on time nuts, they're in
the range of polling! But, for his needs, that's sufficient resolution. 
What would be nice is if the PPS times would just "show up" log file for
him. Hence, the request about off-the-shelf hardware.

But, as long as I'll be looking at buying some new hardware, I'd be glad to
get 
resolution of nanoseconds or better. Probably best sigma for the price will
be 
the XMega with 32 MHz input from Clockbox with a sigma of 31ns. I've written
more
than my share of microcontroller firmwares. But, I feel strongly that he
should do 
as much of the project as he can himself. So, I'll be teaching him some more
C, 
but I'd like that at around the level of GPIB programming and fprintf rather
than 
low-level XMega or other micro-controller programming.

So, if there was a way for the 53230A to do this, it sure would have a
pretty
display that he'd like (and a 20 ps single-shot resolution that I'd like).

Yes, I have some thunderbolts that I've used with some Soekris
net4501's+nonoBSD
and they're great. But, he's keen on using an the PRS-10 for his reference
clock. Something about the term "atomic", I'm sure. And, since we're just
talking 
milliseconds(!) over a month or so, then the PRS-10 will do well without any
GPS disciplining.

Kevin


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