[time-nuts] Entering Altitude for Thunderbolt
John Ackermann N8UR
jra at febo.com
Sun Feb 12 19:08:55 UTC 2012
Hi Warren --
Thanks for the hint about looking for phase jumps.
I just changed the altitude from my initial entry based on MSL altitude to GPS altitude and that made about an 80 - 90 nanosecond change in PPS compared to the other units, and in the right direction (brought the Tbolt closer to the others).
So a very tentative guess is that it should be entered as GPS, which in the US is always lower than the MSL version.
What I'm trying to do today is get all the devices using the same coordinates and then compare their offsets to one another. My goal is to reduce the uncertainty in my realization of GPS time down to less than 50 nanoseconds. Don't want to be late to work, you know. :-)
On Feb 12, 2012, at 1:44 PM, "WarrenS" <warrensjmail-one at yahoo.com> wrote:
> I have Not seen any reliable consistent way to predict what the Tbolt will use for it's altitude, It seems to just do it's own thing.
> It is certainly NOT the same as the Oncore's answers.
> To get close and see if the different is 30 meters etc, take the Tbolt out of fixed location and watch it's reported location for a while and then you add whatever correction that seems closest to your others altitude.
> For self check, If you get any of the Tbolt's locations wrong, It will do large Phase jumps as the sat switch.
> If its is happy with it's location settings, and there is a good antenna signal there will be almost no sudden phase jumps as sat change.
> [time-nuts] Entering Altitude for Thunderbolt
> John Ackermann N8UR jra at febo.com
> That's an experiment I should run, but the current experiment requires setting the Tbolt to the same coordinates as the other units, so I'm just looking to do that. :-)
> On Feb 12, 2012, at 12:42 PM, "David C. Partridge" <david.partridge at perdrix.co.uk> wrote:
>> Or even better get Lady Heather to do the 48 hour survey.
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Azelio Boriani
>> Sent: 12 February 2012 16:31
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Entering Altitude for Thunderbolt
>> Let the TBolt do its autosurvey
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