BOUNCE rtl@rtlinux.org: Non-member submission from ["Srinivasa A.Shikaripura" <srinivasa.shikaripura@wipro.com>] (fwd)

[Der Herr Hofrat <der.herr@hofr.at>]

>From owner-rtl Sun Jul  1 21:49:25 2001
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Message-ID: <3B3FED87.858D127C@wipro.com>
Date: Mon, 02 Jul 2001 09:11:59 +0530
From: "Srinivasa A. Shikaripura" <srinivasa.shikaripura@wipro.com>
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To: rtl@fsmlabs.com
Subject: Re: [rtl] Time not so accurate ?
References: <3B3AE9CE.FB177725@b2i-toulouse.com> <3B3BF802.21EDE5B4@pacifier.com> <3B3C9316.CC35F010@b2i-toulouse.com>
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Have you accounted for the transmission delay in your calculations?
i.e. as the sender wakes-up after 1ms, how much time does it take 
for the data to travel to the other PC.

HTH,
-Sas

Sebastien GAUME wrote:
> 
> Hi Wayne,
> 
> > Do you mean here that the elapsed time as measured in the receiver is not one millisecond
> > and that the sum of the deviation from the expected 1 MS period accumulates to a positive
> > sum of errors when RTAI is the receiver and accumulates a negative sum of errors when rtl
> > is the receiver (respondent)? Or does the receiver initially have no error and after a
> > while start having a consistent error?
> 
> I never do any sum of errors. Initially there's no error. In fact, before starting measuring,
> I do some kind of synchronization between the two PCs, to make them start at the same time.
> That's why the receiver's first wakeup is quite similar to the sender's first sending
> (difference about 5 us). But after a while, the difference between the sending time and the
> receiving time increases.
> 
> Victor advised me to switch the two PCs, what I actually did. Unfortunately, the results
> remain the same. So what I have to do is to use CLOCK_GPOS.
> 
> Sebastien
> 
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