[time-nuts] Time in a cave

[brent evers]

Look at the white rabbit project and you could also rebroadcast the GPS
signal into the cave.

brent

On Tue, May 12, 2015 at 7:00 PM, 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
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