Re: [time-nuts] GPS jumps of -13.7 us?

[NeT MonK]

Le 27 janv. 2016 18:04, "Martin Burnicki"  a
écrit :
>
> Magnus Danielson wrote:
> > Hi,
> >
> > On 01/26/2016 11:46 PM, Martin Burnicki wrote:
> >> Paul Boven wrote:
> >>> Hi everyone,
> >>>
> >>> Has anyone else seen GPS time jump by -13.7 usec today?

Good morning,

I have subscribed to this list following this incident as far as it was the
first of the few results of search in Google for three days ago.

On my linux platform of hundreds serveurs,  I had incident because of this,
on servers which only  use of ptp.
I have two sources grand master clock one I control (a meinberg appliance)
and act as passive and the second is just a Cisco relaying the ptp stream
from the market.

As a side effect of those glitch in the GPS matrix, the utc_valid_flag was
not anymore set in the stream of the primary master clock, just before my
secondary starts to become active (loss of primary stream) which leads to
linux server  ptp slave to readjust of +36 seconds and jump backward -36
seconds as far as the flags was coming back.

Am I the only one who suffered the loss of the utc_valid_flag in ptp stream
? And what appliance would behave like this ? As far I can tell my
secondary meinberg appliance aside a few oscillator recalibration message
in the console log behaved very nicely.

But I have no view of the primary master source and kind of hardware they
use.

Thank you in advance for your answer.

--
Netmonk
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Re: [time-nuts] Z3801 Newbie Question

[Artek Manuals]

Graham
Symmetricom 58532A antenna, just above the roof, with 8 feet of RG213.

Flat ( Florida) rural location with 360 degree view other than some trees. The 
GPS Antenna plot from Z38xx has filled in pretty much 360 degrees down to 20 
degrees solid and in most directions to down to 15 degrees elevation. The 
exception of course is the polar abyss to the north. I am going to lower the 
elevation angle for a while just to see if there is any difference

Looking at the link sent to me earlier
http://www.realhamradio.com/GPS_websites_list.htm . I am seeing the same phenomena 
on most all oft the plots for the Z3801 around the world, So I assume that my unit 
is :behaving normally" for a Z3801A ... Just cant explain why all of us see a 
sporadic jumps in PPS error for an hour or two once or twice a day

Dave
NR1DX
ArtekManuals.com

A man with a watch always knows what time it is
A man with two watches is never quite sure

. On 1/28/2016 6:23 PM, Graham / KE9H wrote:


Please describe your Antenna setup and location.
How much of the sky can it see, in which directions.
Which directions are blocked for direct line of sight, and must depend on
reflections from nearby buildings or objects?

--- Graham


And here is the question is the sudden jump in the pps deviation due to 
ionospheric and the satellite constellation change? IS there anything I can do 
to minimize it (or is it even necessary to worry/ wonder about)  This behavior 
has going on since the beginning so it is not likely related to events earlier 
in the week. But that set me to wondering could I minimize it by say raising 
the elevation mask? Are there satellites in the constellation that are 
notorious for noise etc  that could be excluded from the tracking list ...etc 
etc

Dave
NR1DX
ArtekManuals.com

A man with a watch always knows what time it is
A man with two watches is never quite sure




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[time-nuts] HP 5372A troubleshooting

[Morris Odell]

Hi all,

I have been on a steep learning curve on my new 5372A. It's a lovely
instrument but does seem to have a higher degree of trigger jitter than I
would expect. Going on previous experience with other unrelated instruments
I began by checking the power supplies. (in fact it's hard to go much deeper
without the unobtainium extenders :-(

Anyway the power supplies all check out OK voltage wise but the -15 does
have a higher amount of twice mains freq ripple than the others. It's about
0.5 V p-p at the test point on the triple regulator board and looks like a
sawtooth i.e. what you see from inadequate filtering. The service manual is
unhelpful as it doesn't give schematics, just says to replace the regulator
board! The -15 features on the schematics for many other parts of the 5372A
that would be expected to contribute to trigger stability. 

My questions are:

1. Could anyone on the list with a functioning 5372A slip a scope probe onto
the -15V test point and check the ripple on a known good unit?

and

2. Has anyone had to deal with this this problem before?

Thanks,

Morris


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Re: [time-nuts] Z3801 misbehaving

[John Green]

Charles,
The place isn't out of the way. In fact, it wouldn't surprise me if it got
a power interruption sometime.  In addition, the temperature isn't stable
either. It will be at least a couple of weeks before I am ready to attempt
to use it for anything, and then it won't matter so much about absolute
accuracy. The thing that had me going about this was that even from the
very first time I ever fired it up, it always found satellites very
quickly. Next will be to get some kind of monitoring program running. I
will have to interrupt the GPS signal soon to insert the splitter so I can
hook up another receiver at the same time.

On Thu, Jan 28, 2016 at 10:58 PM, Charles Steinmetz 
wrote:

> John wrote:
>
> Tonight I got a GPS Lock light. Bravo!
>>
>
> Patience is a virtue.   ;-)
>
> Remember this when it comes to all the other metrics -- settling to good
> stability, in particular, which may take quite a while (weeks to months)
> since the OCXO has been off for so long.  My suggestion is to put it in an
> out-of-the-way place where the temperature is stable and there is little to
> no risk of it being physically jostled, and forget about it for a month.
> Then see where you are.  (I mean, really forget it -- don't monitor it,
> don't look at the lights -- because those will tempt you to play with it,
> which will make it take even longer to settle.)
>
> Charles
>
>
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Re: [time-nuts] GPS jumps of -13.7 us?

[Martin Burnicki]

Hello Net Monk,

NeT MonK wrote:
> I have subscribed to this list following this incident as far as it was the
> first of the few results of search in Google for three days ago.
> 
> On my linux platform of hundreds serveurs,  I had incident because of this,
> on servers which only  use of ptp.
> I have two sources grand master clock one I control (a meinberg appliance)
> and act as passive and the second is just a Cisco relaying the ptp stream
> from the market.
> 
> As a side effect of those glitch in the GPS matrix, the utc_valid_flag was
> not anymore set in the stream of the primary master clock, just before my
> secondary starts to become active (loss of primary stream) which leads to
> linux server  ptp slave to readjust of +36 seconds and jump backward -36
> seconds as far as the flags was coming back.
> 
> Am I the only one who suffered the loss of the utc_valid_flag in ptp stream
> ? And what appliance would behave like this ? As far I can tell my
> secondary meinberg appliance aside a few oscillator recalibration message
> in the console log behaved very nicely.
> 
> But I have no view of the primary master source and kind of hardware they
> use.

The time stamps sent in the PTP messages on the network are usually TAI,
not UTC. The PTP announce message contains a UTC offset field telling
the current time difference, and a flag indicating if the UTC parameter
is valid.

Currently the difference between TAI and UTC is 36 seconds, so if the
grandmaster sends no valid UTC offset, or utc_valid flag is not set,
then a client probably just evaluates the raw TAI time, and thus its
time steps by 36 seconds until it receives a PTP announcement message
with valid UTC parameters again.

I don't know the details of your PTP setup, but we (at Meinberg) have
already had another customer some time ago where a Cisco switch acting
as boundary clock didn't send UTC data reliably when the grandmaster was
switched.

So eventually you should contact Cisco and see if there is an update
available for the switch where this is fixed.

Martin

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[time-nuts] Looking for info on a Leica MX 9400R

[Pete Lancashire]

http://petelancashire.com/gallery/main.php?g2_itemId=5273

Unit was rebranded as a CMT GPS-L4 (local outfit long closed up)

An old web page

http://www.cmtinc.com/fieldcmp/gpsbase.html


-pete
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Re: [time-nuts] GPS jumps of -13.7 us?

[Chris Caudle]

On Fri, January 29, 2016 1:32 am, NeT MonK wrote:
> As a side effect of those glitch in the GPS matrix, the utc_valid_flag was
> not anymore set in the stream of the primary master clock, just before my
> secondary starts to become active (loss of primary stream) which leads to
> linux server  ptp slave to readjust of +36 seconds and jump backward -36
> seconds as far as the flags was coming back.

The difference between UTC and TAI is 36 seconds.

Are you running ptpd or linuxptp on your Linux servers?
It sounds like the ptp agent running on your servers interpreted the lack
of UTC valid flag to mean that the timestamps were now in TAI, so the
server kernel applied the TAI to UTC offset to the time received via PTP.

-- 
Chris Caudle



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Re: [time-nuts] Z3801 Newbie Question

[Graham / KE9H]

Dave:

Your antenna setup sounds reasonable.
You might want to try dropping your elevation mask down to 5 or 10 degrees,
as an experiment.

Things that cause the sporadic jumps could be certain satellites being
added to, or removed from the solution.
Also, if there are particular angles/directions where you receive the
satellite signal as a reflection, rather than a direct signal, you get
position errors that move into and out of your solution.  If the satellite
is behind one of your trees, and the received signal bouncing off the other
tree is temporarily stronger, you have a temporary path length/position
change.

--- Graham

==

On Fri, Jan 29, 2016 at 3:54 AM, Artek Manuals 
wrote:

> Graham
> Symmetricom 58532A antenna, just above the roof, with 8 feet of RG213.
>
> Flat ( Florida) rural location with 360 degree view other than some trees.
> The GPS Antenna plot from Z38xx has filled in pretty much 360 degrees down
> to 20 degrees solid and in most directions to down to 15 degrees elevation.
> The exception of course is the polar abyss to the north. I am going to
> lower the elevation angle for a while just to see if there is any difference
>
> Looking at the link sent to me earlier
> http://www.realhamradio.com/GPS_websites_list.htm . I am seeing the same
> phenomena on most all oft the plots for the Z3801 around the world, So I
> assume that my unit is :behaving normally" for a Z3801A ... Just cant
> explain why all of us see a sporadic jumps in PPS error for an hour or two
> once or twice a day
>
> Dave
> NR1DX
> ArtekManuals.com
>
> A man with a watch always knows what time it is
> A man with two watches is never quite sure
>
> . On 1/28/2016 6:23 PM, Graham / KE9H wrote:
>
> Please describe your Antenna setup and location.
>> How much of the sky can it see, in which directions.
>> Which directions are blocked for direct line of sight, and must depend on
>> reflections from nearby buildings or objects?
>>
>> --- Graham
>>
>>
>> And here is the question is the sudden jump in the pps deviation due to
>> ionospheric and the satellite constellation change? IS there anything I can
>> do to minimize it (or is it even necessary to worry/ wonder about)  This
>> behavior has going on since the beginning so it is not likely related to
>> events earlier in the week. But that set me to wondering could I minimize
>> it by say raising the elevation mask? Are there satellites in the
>> constellation that are notorious for noise etc  that could be excluded from
>> the tracking list ...etc etc
>>
>>> Dave
 NR1DX
 ArtekManuals.com

 A man with a watch always knows what time it is
 A man with two watches is never quite sure


>
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Re: [time-nuts] GPS jumps of -13.7 us?

[NeT MonK]

On Fri, Jan 29, 2016 at 2:45 PM, Martin Burnicki <
martin.burni...@burnicki.net> wrote:

> Hello Net Monk,
> ...
> I don't know the details of your PTP setup, but we (at Meinberg) have
> already had another customer some time ago where a Cisco switch acting
> as boundary clock didn't send UTC data reliably when the grandmaster was
> switched.
>
> So eventually you should contact Cisco and see if there is an update
> available for the switch where this is fixed.
>
> Martin
>
>
>
Hello Martin,

Thank you for your reply and details, this is also what i already stated on
my incident report.
My ptp client applied the utc offset when the flag disappeared which lead
to this jump forward and backward.

A call is already opened to Cisco and they are coming in coming weeks for
auditing the ptp infra.

Regards.
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Re: [time-nuts] HP 5372A troubleshooting

[Adrian]

Morris,

you might want to download the 5371A service manuals which contain
schematics.
The 5372A being an 'upgraded' version of the 5371A, most of its parts
are identical.
Look for 05371-90018 (Vol.1) and 05371-90034 (Vol.2).
They should be available at www.keysight.com
The scan quality is surprisingly good.

The A10 regulator board is in Vol.2 on p. 7I-9.
The -15 are generated out of the unregulated +25V by a switch mode
regulator, so there should be much less (40kHz switch frequency) ripple
than described.
Otherwise the obvious electrolytics are to be suspected (in particular
C17, but also C7, C24).

Regards,
Adrian


Morris Odell schrieb:
> Hi all,
>
> I have been on a steep learning curve on my new 5372A. It's a lovely
> instrument but does seem to have a higher degree of trigger jitter than I
> would expect. Going on previous experience with other unrelated instruments
> I began by checking the power supplies. (in fact it's hard to go much deeper
> without the unobtainium extenders :-(
>
> Anyway the power supplies all check out OK voltage wise but the -15 does
> have a higher amount of twice mains freq ripple than the others. It's about
> 0.5 V p-p at the test point on the triple regulator board and looks like a
> sawtooth i.e. what you see from inadequate filtering. The service manual is
> unhelpful as it doesn't give schematics, just says to replace the regulator
> board! The -15 features on the schematics for many other parts of the 5372A
> that would be expected to contribute to trigger stability. 
>
> My questions are:
>
> 1. Could anyone on the list with a functioning 5372A slip a scope probe onto
> the -15V test point and check the ripple on a known good unit?
>
> and
>
> 2. Has anyone had to deal with this this problem before?
>
> Thanks,
>
> Morris
>
>
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Re: [time-nuts] TM500/TM5000/HP-5370 Extender cables and cards

[Robin Midgett]

Mark Sims  writes:

> 
> The TM500/5000 and HP5370 extender kits are now available (actually they 
were ready a few weeks ago, but I
> was going to be out of town and did not want to leave people hanging).Prices 
are:HP5370 extender card kit -
> has 2 x 36 pin extenders and 1 x 44 pin extender.  $30 setTektronix 
TM500/TM5000 module extender cable kit -
> $20Tektronix TM5000 GPIB extender cable (assembled) $20US shipping is $6 for 
any number of kits.
> International shipping is $15 for any number of kits.  If you need 
international tracking they must go
> registered mail which adds another $15 (and slows down the mail) or express 
mail which is stupid
> expensive.  
> All kits include everything you need to get going except solder and basic 
tools.Email me for my Paypal
> address.The HP5370 extenders are 5 inches long.The TM500 kits include a pair 
of 17" 40 pin IDE ribbon
> cables.  You may want to use your own, longer cables.  The TM5000 GPIB cable 
is around 28" long.Remember that
> some TM500/5000 modules require 2 or 3 extender cables...  I even have one 
that needs 4,  but it is a one-off
> custom design.  
> 

Hi Mark,
I found this post while trolling for these extender kits. If the kits are 
still available, I'm interested in acquiring at least one, perhaps two.




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Re: [time-nuts] Schlumberger FA2527 ocxo

[Luca Dal Passo]

Thank you Gianni. That unit looks quite different, but the informations can
be useful.
Bye
Luca

Il martedì 26 gennaio 2016, gianni  ha scritto:

> > Hi
> > I have a OCXO marked Schlumberger Adret 622 used in Adret 4101A
> Frequency standard receiver
> > I do not know if it is similar but performance seem OK
> > It is a cube of about 70 mm with DB9 output connector ; frequency is
> 5MHz with external pot adj.
> > The ADEV seem good: data here <
> https://drive.google.com/file/d/0B6ckpiy-AuMMV1RWaTg1UHc1NjA/view?usp=sharing
> >
> > schematics here:
> > <
> https://drive.google.com/file/d/0B6ckpiy-AuMMM1ZfalFWTTY5cnM/view?usp=sharing
> >
> > <
> https://drive.google.com/file/d/0B6ckpiy-AuMMZmdTdG5WZGxCcEU/view?usp=sharing
> >
> > <
> https://drive.google.com/file/d/0B6ckpiy-AuMMaEs4cHh6NFhyOU0/view?usp=sharing
> >
> >
>
> Gianni
> Il 25 gennaio 2016 12:32:29 +01:00, Luca Dal Passo  > ha scritto:
>
> > Hi group,
> > Does anyone know something about the Schlumberger type FA2527 5MHz
> > OCXO?
> > It seems to be a good unit, with mumetal shield, coarse and fine
> frequency
> > adj multiturn pots, fine temperature trimmer, good voltage regulator,
> good
> > assembly and internal cylindrical thermal chamber surronded by a wire
> > resistence (double oven?).
> > It was used in Schlumberger electronic counters in the seventies or
> > eighties as a high stability option.
> > I'm trying to understand pin out and supply voltage, but I wish to know
> > some more information about functions of pins, and specifications.
> > Nothing found on the net.
> > Thank you in advance!
> > Luca
> > iw2lje
> > Milano
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Re: [time-nuts] Z3801 misbehaving

[paul swed]

I added 2 X AA batteries external to the 3801 to the GPS receiver. Will run
several years and very easy to replace. Now that doesn't make it instant
start but certainly sub hour or less maybe 20 minutes.
Good luck.
Paul
WB8TSL

On Fri, Jan 29, 2016 at 8:43 AM, John Green  wrote:

> Charles,
> The place isn't out of the way. In fact, it wouldn't surprise me if it got
> a power interruption sometime.  In addition, the temperature isn't stable
> either. It will be at least a couple of weeks before I am ready to attempt
> to use it for anything, and then it won't matter so much about absolute
> accuracy. The thing that had me going about this was that even from the
> very first time I ever fired it up, it always found satellites very
> quickly. Next will be to get some kind of monitoring program running. I
> will have to interrupt the GPS signal soon to insert the splitter so I can
> hook up another receiver at the same time.
>
> On Thu, Jan 28, 2016 at 10:58 PM, Charles Steinmetz  >
> wrote:
>
> > John wrote:
> >
> > Tonight I got a GPS Lock light. Bravo!
> >>
> >
> > Patience is a virtue.   ;-)
> >
> > Remember this when it comes to all the other metrics -- settling to good
> > stability, in particular, which may take quite a while (weeks to months)
> > since the OCXO has been off for so long.  My suggestion is to put it in
> an
> > out-of-the-way place where the temperature is stable and there is little
> to
> > no risk of it being physically jostled, and forget about it for a month.
> > Then see where you are.  (I mean, really forget it -- don't monitor it,
> > don't look at the lights -- because those will tempt you to play with it,
> > which will make it take even longer to settle.)
> >
> > Charles
> >
> >
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Re: [time-nuts] GPS jumps of -13.7 us?

[Tom Van Baak]

A nice summary:

http://www.insidegnss.com/node/4831

/tvb
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Re: [time-nuts] GPS jumps of -13.7 us?

[NeT MonK]

On Fri, Jan 29, 2016 at 3:29 PM, Chris Caudle  wrote:

> On Fri, January 29, 2016 1:32 am, NeT MonK wrote:
> > As a side effect of those glitch in the GPS matrix, the utc_valid_flag
> was
> > not anymore set in the stream of the primary master clock, just before my
> > secondary starts to become active (loss of primary stream) which leads to
> > linux server  ptp slave to readjust of +36 seconds and jump backward -36
> > seconds as far as the flags was coming back.
>
> The difference between UTC and TAI is 36 seconds.
>
> Are you running ptpd or linuxptp on your Linux servers?
> It sounds like the ptp agent running on your servers interpreted the lack
> of UTC valid flag to mean that the timestamps were now in TAI, so the
> server kernel applied the TAI to UTC offset to the time received via PTP.


Dear Chris,

I run sfptpd  which is a fork of linux ptpd daemon adapted to solarflare
network adapter.
I will have to fine tune it in order to be more resilient in such scenario.

But i guess it's not very often the gps system as such incident.

Regards
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Re: [time-nuts] GPS jumps of -13.7 us?

[Eric Scace]

   I have an idle curiosity as to whether the erroneous UTC correction 
propagated into any high-speed trading platforms in the financial markets in a 
what that caused a disruption.


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