[time-nuts] Best location for a GPS antenna...?

[Bob Bownes]

Don't forget to tighten the fiber connectors and correct for the length of
the fiber or you'll be off by 60ns! ;)


On Wed, Apr 11, 2012 at 1:17 PM, Chris Albertson
<albertson.chris at gmail.com>wrote:

> On Wed, Apr 11, 2012 at 7:19 AM, Bob Bownes <bownes at gmail.com> wrote:
>
> > The issue is that this treats the t'bolt as a sacrificial item. I would
> > contend that, at a cost of $80-90, you could spend far more time and
> effort
> > trying to isolate, amplify, correct, and bias the antenna than that is
> > worth. Effort and gear that would need to be replaced every time
>
> I thought of that right after I suggested using fiber data lines.
> You'd loose a few expensive t-bolts.    But I think there is a better
> and cheaper way to go:   Buy a cheap Motorola Oncore receiver.   The
> Oncore UT costs all of about $18 on eBay, buy four of them.    The
> only signal you need to bring into the workroom from an Oncore is PPS
> and that is "way easy" to do using fiber.   The other signals (rs232)
> can be connected as needed and that is not often.  Then you build a
> "standard" GSPDO in the workshop.    The initial cost is lower and the
> engineering is simple (because only the PPS has to go over fiber)
>
> The Oncore and GPSDO can give as good of result as the t-bolt.  It
> mostly depends on how good the OCXO is, maybe even you build two
> GPSDOs running off the same PPS the second one being  Rubinium based.
> My $35 Rb can holdover for many weeks (at the level I need) if GPS is
> down.
>
> Then you can install the t-bolt with an antenna you can disconnect and
> only use the t-bolt now and then during good wearer to double check
> the GPSDO that you can leave running 24x7
>
>
> Chris Albertson
> Redondo Beach, California
>
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