[time-nuts] Time in a cave

Jason Ball jason at ball.net
Tue May 12 21:32:08 EDT 2015


If you don't require an accurate external sync (GPS), one options is to use
solarflare 10GB NIC's with the high resolution clock on board, using this
clock to govern the PC clock.    Running PTP through this can yield +-250ns
synchronisation between the nodes due to the hardware implementation for
the PTP stack and does support external sync to a GPS PTP signal if
available.

I have no association with the company, but I like the product.

http://www.solarflare.com/Precision-Time-Synchronization-PTP

J.

On Wed, May 13, 2015 at 9:00 AM, Tucek, Joseph <joseph.tucek at hp.com> wrote:

> I'm looking for information on non-GPS time sources.
>
> For background, I need to provide PTP to a cluster where we don't have
> line of sight to the sky, and are unlikely to get roof-rights without a
> fight.  There are CDMA solutions that would work (e.g. Endrun
> Technologies), but I was wondering if there were any other options.  I
> either need an indoor capable PTP, or an indoor capable PPS.  Microsemi
> claims to have an indoor capable "GNSS" system, but I've yet to find a
> sales rep to talk about it; if anyone has a link to one who can, I'd love
> to find out the problems^W^W^W^W talk to them about it.
>
> For an example of something that almost but doesn't quite work, Beagle
> Software has a CDMA NTP server, but they do neither PTP nor PPS in the CDMA
> version.  Similarly, Meinberg will sell a PTP unit that freeruns (if you
> override the config), but they have no solution to discipline via CDMA.
>
> I'm also curious if anyone has any idea about non-GPS time sync after CDMA
> gets turned off (can I get time from 4G?).
>
> My endgame worst case is to just do PPS from a stratum 2 NTP (or even a
> freerunning oscillator) and lie to my PTP server; hard sync to UTC is a
> secondary concern so long as the cluster agrees with itself.  Endrun is
> looking pretty good, but I'd really like to have a second option to compare
> against.
>
> -Joe
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
--
Teach your kids Science, or somebody else will :/

jason at ball.net
vk2vjb at google.com <vk2flnx at google.com>
callsign: vk2vjb


More information about the time-nuts mailing list