[time-nuts] Sub mm measurements with gps timing antennas?

[Azelio Boriani]

Was this the paper you are referring to?

tycho.usno.navy.mil/ptti/ptti99/PTTI_1999_405.PDF


On Fri, Apr 27, 2012 at 4:14 PM, Attila Kinali <attila at kinali.ch> wrote:

> Moin,
>
> On Wed, 25 Apr 2012 20:45:54 -0400 (EDT)
> SAIDJACK at aol.com wrote:
>
> > > But.. is the CSAC not on the ITAR list? I would expect it to  be,
> > > as even some precision OCXO and a lot of MCXO  are.
> >
> > This is the beauty, they are not ITAR or HAZMAT  restricted! They
> received
> > approvals.
>
> Now THAT is really cool!
>
> > We just published an article  about the CSAC GPSDO products we offer in
> the
> > Microwave Journal,  April issue, and this is listed there as one of the
> key
> > advantages of  CSAC's.
>
> Nice article, thanks!
>
> > > Oh.. the CSAC is  that low power? I thought they are in the 1W region.
> > > Good to  know...
> >
> > Yes, CSAC itself rated at 115mW typical. They have a power down mode
>  with
> > auto-correct of the TCXO that gets to less than 30mW on average. CSAC's
> are
> > game changers, and no one has anything even remotely  comparable.
>
> They indeed are!
>
> > > I'm not quite sure about this. It would work if we had only to  deal
> with
> > > one or two of devices, but with the numbers we need now, the work
>  would
> > > probably cost more than a reel (i actually don't know what a reel
>  costs,
> > > u-blox has not replied to my request for quotation i placed 3 weeks
>  ago).
> >
> > A reel will cost some real $$$ if you can get it, more than removing  the
> > shields from the units, even if you are doing say 100 units.. With a
> proper
> > heat gun, it takes only about 20 seconds to get the shield off, without
> any
> > damage to the unit itself.
>
> I just had a longer talk with a u-blox sales rep. Outcome is that they
> do not sell the chips in volumes lower than 50k/year. Which means we cannot
> use the chips to have easy access to the oscillator directly. Currently
> they are trying to figure out, whether we're allowed to get information
> about the LEA6-T module internas, so we can open the shield and replace
> the TCXO.
>
> >
> > The real question is, would a perfect 26MHz reference give you any GPS
> > position performance improvement or not, that is what would be
> interesting to
> > test..
>
> According to a paper which i currently cannot find, the use of a caesium
> as "oscillator" for a standard timing gps module improved the noise of the
> PPS quite a bit.
>
> Anyways.. i have to talk with the customer about this. I doubt that such
> a major redesign will be possible in this revision (the devices have to
> be ready by july), but it's definitly a good idea for the next version.
>
>                        Attila Kinali
>
> --
> The trouble with you, Shev, is you don't say anything until you've saved
> up a whole truckload of damned heavy brick arguments and then you dump
> them all out and never look at the bleeding body mangled beneath the heap
>                -- Tirin, The Dispossessed, U. Le Guin
>
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