Re: [time-nuts] Trimble Thunderbolt no longer determines thecorrect date

[Nick Sayer via time-nuts]

FWIW, the SkyTraq receivers have the notion of a “UTC reference date” which 
allows the 1024 week window to roll forward indefinitely as long as you update 
that value once in a while. I’ve written code in my GPS Clock to update the 
reference date once a year as well as update the default GPS-UTC delta whenever 
it’s wrong (this fixes the “off by 2 seconds for a minute or two” problem). 
This latter issue is an interesting one - If you supply SkyTraq modules with 
backup power, then on *power up* it will copy the GPS-UTC delta to flash, as 
long as the memory of what it was at shut down remains preserved.

The UTC reference date also allows the clock to workaround the Y2K issue in the 
NMEA sentences - you can query the reference date and use a 100 year rolling 
window similarly for that. As long as you power the clock up and give it 
reception at least once every 19 years or so, it should calculate the correct 
date as long as GPS remains available (this only really matters for the clock 
because it’s how DST decisions are made - it doesn’t actually display the date).

I haven’t done this for my GPSDOs because the controller isn’t wired to speak 
to the GPS receiver. But you can use the diagnostic port and SkyTraq’s GNSS 
viewer software to do this if you care to. The only use the GPSDO makes of the 
time/date is time-stamping the logs.

> On Jul 27, 2017, at 7:01 PM, Tom Van Baak  wrote:
> 
>> Well quite an unpleasant surprise. So after the 30th do the TBolts stop
> 
> Paul,
> 
> This topic has been covered a number of times over the years. Some time-nuts 
> have even run TBolt's under GPS simulators to verify that the 10 MHz and 1PPS 
> outputs will be fine. So apparently the only effect is that the date & time 
> (in binary TSIP messages) are off by 1024 weeks. This rollover-related effect 
> is by now a "common" issue with many GPS receivers.
> 
> The current version of Mark's Lady Heather program has code to detect this 
> and fix it so you're good to go for the next 19.6 years.
> 
> /tvb
> 
> - Original Message - 
> From: "paul swed" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Sent: Thursday, July 27, 2017 5:36 PM
> Subject: Re: [time-nuts] Trimble Thunderbolt no longer determines thecorrect 
> date
> 
> 
>> Well quite an unpleasant surprise. So after the 30th do the TBolts stop
>> working or is it a case of just the wrong date? I know my Hp3801s been
>> working just fine and its old. Is the TBolt the same issue. Wrong date but
>> still locks thats all I care about actually.
>> With to respect of some sort of a hack I can see that being fairly
>> difficult.
>> Regards
>> Paul
>> WB8TSL
> 
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[time-nuts] Trimble Thunderbolt no longer determines thecorrect date

[ed briggs]

The current model Thunderbolt E #60333-50, v1.04 firmware has a 
last valid date on the 22nd December 2029.

It is probably  a good idea to specify what firmware you  have in these 
discussions as different versions will have different properties, and some of 
the used Thunderbolts are quite old.



On Jul 28, 2017, at 9:05 AM, 
"time-nuts-requ...@febo.com<mailto:time-nuts-requ...@febo.com>" 
mailto:time-nuts-requ...@febo.com>> wrote:

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Today's Topics:

  1. Trimble Thunderbolt no longer determines thecorrectdate
 (Mark Sims)
  2. Symmetricom X72 and Lady Heather results (Mark Sims)


--

Message: 1
Date: Fri, 28 Jul 2017 02:32:44 +
From: Mark Sims mailto:hol...@hotmail.com>>
To: "time-nuts@febo.com<mailto:time-nuts@febo.com>" 
mailto:time-nuts@febo.com>>
Subject: [time-nuts] Trimble Thunderbolt no longer determines
   thecorrectdate
Message-ID:
   
mailto:sn1pr11mb1024404ed519704b9a2aff4bce...@sn1pr11mb1024.namprd11.prod.outlook.com>>

Content-Type: text/plain; charset="iso-8859-1"

Actually,  Lady Heather's rollover compensation code has no limit on the 
correction.  It can compensate for any number of rollovers.   In fact you can 
use it to adjust the receiver time by any number of seconds (including 
fractional seconds).

The default behavior is to trigger after 10 seconds of consecutive time 
messages where the time is before year 2016.  The 10 second filter is to avoid 
false triggers from corrupted packets.   This means that for the first 10 
seconds after starting Heather on a Tbolt,  the date will be wrong.  When 
rollover compensation is in effect, the date is shown in yellow and a "ro" flag 
appears next to it.   It would nice if somebody could come up with a patched 
firmware...

You can get a false rollover detection if you start monitoring a receiver 
before it has acquired the almanac since most receivers output time based upon 
the GPS epoch if they don't have an almanac.



The current version of Mark's Lady Heather program has code to detect this and 
fix it so you're good to go for the next 19.6 years.

--

Message: 2
Date: Fri, 28 Jul 2017 01:27:07 +
From: Mark Sims mailto:hol...@hotmail.com>>
To: "time-nuts@febo.com<mailto:time-nuts@febo.com>" 
mailto:time-nuts@febo.com>>
Subject: [time-nuts] Symmetricom X72 and Lady Heather results
Message-ID:
   
mailto:sn1pr11mb102437f0ff83a8dadb9baf99ce...@sn1pr11mb1024.namprd11.prod.outlook.com>>

Content-Type: text/plain; charset="iso-8859-1"

I'm in the process of adding support to Lady Heather for the Symmetricom X72 
(and SA22) rubidium oscillators.  I have a most of the functionality working.  
The X72 has a "health" message that dumps a couple dozen values.  The values 
are labeled with some rather cryptic names that give some hint about what they 
are,  but no where in their (miserable) documentation do they elaborate on what 
the values mean.   Does anybody have any info on them.

The X72 is user interface is a very frustrating an infuriating thing to work 
with.   The device has several glaring omissions in what it does...  like no 
way to read back any settings that you have made and no way to save most of 
them in EEPROM and no command to restore the unit to its factory default state.

Attached is a plot showing most of the non-static health values... it looks 
like most of them are highly correlated with temperature.  Without heavily 
average-filtering the display,  the values look a lot like noise.
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