[ntp:questions] Re: Generating a PPS output.

Richard B. Gilbert rgilbert88 at comcast.net
Sat May 27 14:41:51 UTC 2006


Alexander Fisher wrote:

> Hello
> 
> I have an application where I'll have 2 PCs on an ethernet LAN.  One
> of these will be fed a GPS PPS input and act as a level-1 NTP server.
> The other PC will be an NTP client.  I need to get the client PC to
> output a PPS signal.  The new PPS signal needs to match the original
> to within 1 ms.   The LAN will be 100Mb/sec or better, won't contain
> many switches and will hopefully not be highly loaded.
> 
> The intention is that both systems run Linux.
> 
> Has anybody here attempted this before?  I'm guessing that in a
> controlled environment NTP can be accurate enough for this?
> 
> What about generating the PPS output?  I'm thinking about using
> something like RTAI.
> This article ...
> http://linuxgazette.net/issue97/pramode.html
> describes how to control the parallel port pins in a deterministic way.
> 
> Does this look like a good way forward?  Any advice?
> 
> Many thanks,
> Alex
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I think it might be considerably simpler and easier to feed the original 
PPS signal to a buffer or line driver and feed the output of that to 
everything that needs a PPS signal




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