[time-nuts] A few questions about Tboltmon

Pete Stephenson pete at heypete.com
Thu Aug 6 04:58:11 EDT 2015

The GPS satellites are not geosynchronous; they move with an orbital period
of 12 hours, so their position in the sky is constantly changing. However,
they return to the same position in the sky (modulo repositioning) twice
per day.

It sounds like your Thunderbolt has a saved location that differs from your
own location, so its calculations regarding timing are erroneous. Based on
its (incorrect) location it thinks there are certain satellites overhead
and will only look for those. Since it is not at that location that choice
of satellites is not a good one and won't match well with what is overhead
at your location.

You should do a factory reset to clear the saved location and reset
everything to defaults. This should cause the Thunderbolt to do a
self-survey (this takes a bit less than an hour) to accurately determine
its location. Once that's done everything should "just work".

On Aug 6, 2015 6:15 AM, "Chris Waldrup" <kd4pbj at gmail.com> wrote:

> Hi,
> I got my new Thunderbolt up and running this past weekend but I have a few
> questions. I understand Lady Heather is a better program, and I have
> downloaded it. However right now I am trying to get things right with
> Tboltmon first. I had used it with my previous GPSDO, a Starloc II. I hate
> to say but the Starlic just worked, so I didn't pay much attention to
> Tboltmon other than to see that I was seeing satellites. Please forgive me
> if some of the questions may sound simplistic, but I'm sort of new to being
> a time nut.
> The Thunderbolt is brand new in package. I purchased a Power One open
> frame supply from EBay that was also new old stock. Before connecting it to
> the Thunderbolt, I went ahead and ordered new electrolytic caps from Mouser
> and spent last Friday night recapping the Power One box. I measured the
> outputs with a DMM to make sure I had 5 V, -12 V and 12 V.
> Noticing that in my old antenna location I could now only see 1-2
> satellites (trees have grown a bit) I moved the antenna to the roof of my
> house, attached to a plumbing vent pipe, with a completely open view of the
> sky here on top of a mountain in Tennessee.
> Here's what I am noticing:
> To start with I simply turned on the Thunderbolt on Saturday morning
> without doing a warm or cold reset. Within a few minutes, I was seeing six
> or seven satellites, with the SV boxes lit up green with various numbers
> which I assume are satellite ID numbers. When I woke up Sunday I was down
> to seeing only two satellites. The numbers listed were different than the
> ones I saw before I went to bed Saturday.  But when I unplugged the AC
> power from the Thunderbolt and plugged it back in, I was back to six
> satellites.
>  I had thought that the GPS satellites I am able to see from my location
> are fixed 24/7. Do they move and different satellites come into view with
> rotation of the earth?
> I did a warm reset when I got up at 4:45 this morning and when I got home,
> four satellites were still green on Tboltmon. About an hour ago I went
> ahead and did a cold reset.
> I now have 6 satellites where the SV is green, and one with a yellow SV
> with a value of 7.0.
> All critical alarms are green, and all minor alarms are green except
> position questionable which is yellow. That has been yellow since Saturday.
> Under the Disciplining status, Mode is (0) Normal and Activity is (0)
> Phase Locking.
> The Timing Outputs are all over the place and have been since Saturday.
> Twenty minutes ago I got:
> PPS  -106588.28 ns GPS
> 10 MHz  166.08 ppb
> So far today I have gotten the following ppb readings:
> -41.48
> 374.30
> 0.48
> 0.70
> Should the Timing output variance concern me?
> Thanks in advance for any help or advice.
> Chris
> Monteagle, TN
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