[time-nuts] Low-long-term-drift clock for board levelintegration?

Mark Spencer mspencer12345 at yahoo.ca
Tue Feb 21 19:12:43 UTC 2012

Perhaps another way to approach this problem would be to see if there are entities and or individuals who already have precision time keeping equipment (or at least access to GPS antennas) who might be able to participate in collecting this data.

--- On Tue, 2/21/12, Attila Kinali <attila at kinali.ch> wrote:

> From: Attila Kinali <attila at kinali.ch>
> Subject: Re: [time-nuts] Low-long-term-drift clock for board levelintegration?
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Received: Tuesday, February 21, 2012, 1:47 PM
> On Tue, 21 Feb 2012 10:05:04 -0800
> Chris Albertson <albertson.chris at gmail.com>
> wrote:
> > Perhaps he has now given up on that approach and has
> > gone to using relative time and round trip timing which
> would work
> > even using a $2   TTL "can oscillator"
> If you read carefully what the OP wrote, you'll see that he
> wants to measure one way trips. 
> RTT is easy and well understood. You can use a standard PC
> and
> get to ~100us resolution with no special components. If you
> take
> a NIC with time stamping, you get well below that. 
> But the problem is, in order to understand how networks
> behave
> exactly and how this behaviour is changing over time, you
> need
> to know the one way delays (mostly due to asymetric routing
> which leads to asymetric load etc pp). And to do this, you
> need
> a global time scale for time stamping. There is no way
> around it.
> Attila Kinali
> -- 
> Why does it take years to find the answers to
> the questions one should have asked long ago?
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