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Groups > comp.arch.embedded > #12917 > unrolled thread
| Started by | Don Y <this@isnotme.com> |
|---|---|
| First post | 2013-08-03 00:45 -0700 |
| Last post | 2013-08-20 14:49 -0700 |
| Articles | 3 on this page of 103 — 16 participants |
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Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 00:45 -0700
Re: Comparing phase of physically distant signals Jan Panteltje <pNaonStpealmtje@yahoo.com> - 2013-08-03 07:51 +0000
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 09:58 +0100
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-03 13:21 +0300
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 12:16 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 11:56 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 20:17 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 13:41 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 22:46 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 14:57 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 23:09 +0100
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-03 13:58 +0300
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 12:30 +0100
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-03 16:08 +0300
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 14:22 +0100
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-03 16:38 +0300
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 10:46 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 10:40 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 20:04 +0100
Re: Comparing phase of physically distant signals Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-08-04 15:55 +0200
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-04 19:42 +0300
Re: Comparing phase of physically distant signals Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-08-04 21:08 +0200
Re: Comparing phase of physically distant signals upsidedown@downunder.com - 2013-08-05 15:28 +0300
Re: Comparing phase of physically distant signals Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-08-05 22:17 +0200
Re: Comparing phase of physically distant signals Richard Damon <Richard@Damon-Family.org> - 2013-08-05 23:20 -0400
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 14:26 +0100
Re: Comparing phase of physically distant signals George Neuner <gneuner2@comcast.net> - 2013-08-03 14:47 -0400
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 08:17 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 12:08 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 20:37 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 12:57 -0700
Re: Comparing phase of physically distant signals Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2013-08-04 15:58 +0200
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 12:44 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 18:36 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-04 09:56 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-05 14:53 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-05 15:38 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-07 01:25 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-07 08:06 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-07 09:21 -0700
Re: Comparing phase of physically distant signals josephkk <joseph_barrett@sbcglobal.net> - 2013-08-03 15:40 +0000
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 10:05 -0700
Re: Comparing phase of physically distant signals John S <Sophi.2@invalid.org> - 2013-08-03 12:13 -0500
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 10:26 -0700
Re: Comparing phase of physically distant signals John S <Sophi.2@invalid.org> - 2013-08-03 12:51 -0500
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 11:54 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-03 20:27 +0100
Re: Comparing phase of physically distant signals George Neuner <gneuner2@comcast.net> - 2013-08-05 03:26 -0400
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-05 10:34 +0100
Re: Comparing phase of physically distant signals Richard Damon <Richard@Damon-Family.org> - 2013-08-05 23:29 -0400
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 08:53 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 12:49 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 12:34 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 12:18 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 12:52 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 13:21 -0700
Re: Comparing phase of physically distant signals Jeff Liebermann <jeffl@cruzio.com> - 2013-08-03 13:31 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-03 14:46 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 15:03 -0700
Re: Comparing phase of physically distant signals Jeff Liebermann <jeffl@cruzio.com> - 2013-08-03 17:25 -0700
Re: Comparing phase of physically distant signals Joerg <invalid@invalid.invalid> - 2013-08-03 14:50 -0700
Re: Comparing phase of physically distant signals "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2013-08-04 11:06 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-04 12:19 -0700
Re: Comparing phase of physically distant signals John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> - 2013-08-03 11:47 -0700
Re: Comparing phase of physically distant signals Richard Damon <Richard@Damon-Family.org> - 2013-08-03 18:23 -0400
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-05 16:53 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-05 13:19 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 00:27 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-05 20:09 -0700
Re: Comparing phase of physically distant signals Paul Rubin <no.email@nospam.invalid> - 2013-08-05 22:12 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 09:12 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 01:47 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 10:08 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 02:25 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 02:48 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 10:49 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 03:06 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 11:57 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 10:28 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 21:52 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-07 01:34 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-07 09:46 +0100
Re: Comparing phase of physically distant signals Les Cargill <lcargill99@comcast.com> - 2013-08-06 07:22 -0500
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 10:42 -0700
Re: Comparing phase of physically distant signals Les Cargill <lcargill99@comcast.com> - 2013-08-06 23:04 -0500
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 23:50 -0700
Re: Comparing phase of physically distant signals Les Cargill <lcargill99@comcast.com> - 2013-08-07 13:05 -0500
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-07 18:22 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-08 09:35 +0100
Re: Comparing phase of physically distant signals Paul Rubin <no.email@nospam.invalid> - 2013-08-06 22:18 -0700
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-07 03:09 -0700
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-07 12:39 +0100
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-07 13:18 +0100
Re: Comparing phase of physically distant signals Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-08-06 09:23 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 02:02 -0700
Re: Comparing phase of physically distant signals "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2013-08-06 09:49 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-06 02:17 -0700
Re: Comparing phase of physically distant signals Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-08-16 21:07 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-16 14:50 -0700
Re: Comparing phase of physically distant signals Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-08-18 19:55 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-19 11:43 -0700
Re: Comparing phase of physically distant signals Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-08-20 21:43 +0100
Re: Comparing phase of physically distant signals Don Y <this@isnotme.com> - 2013-08-20 14:49 -0700
Page 6 of 6 — ← Prev page 1 2 3 4 5 [6]
| From | Don Y <this@isnotme.com> |
|---|---|
| Date | 2013-08-19 11:43 -0700 |
| Message-ID | <kutp1a$vc9$1@speranza.aioe.org> |
| In reply to | #13133 |
Hi Paul,
On 8/18/2013 11:55 AM, Paul E Bennett wrote:
>>> You might find this of interest and useful if you had a couple of fibres
>>> in your installed bundle. I was chatting to one of the guys visiting JET
>>> from CERN today and he stated that the timing accuracy is 1ps on phase
>>> and 1ns on time synchronicity.
>>>
>>> <http://www.ohwr.org/projects/white-rabbit/documents>
>>
>> Yeah, amazing what deep pockets can do, eh? :>
>> Did you, perhaps, manage to ask how they *verify* this performance
>> while the nodes are deployed? (i.e., physically not collocated)
>> Or, do they just rely on the system to report its own level
>> of performance? ("Trust me...")
>>
>> I'm guessing (?) their physical layout (and budget) would make it
>> relatively easy for them to deploy a long "wire" (of known length)
>> just to make in situ measurements easier.
>>
>> What has their experience been like with the whole notion
>> of distributed SCADA? Any surprises that they didn't expect?
>> (pleasant or otherwise)
> If I get to chat to the person most involved in that I'll make a point of
> asking him that question. One of his work colleagues pointed me to the
> project but didn't know enough about the testing regime for verification.
> Knowing them they certainly made sure of the timing.
As I've said, I can see how to "prove" proper functionality "on
a bench" (with a coil of cable -- in their case, fibre -- under
the bench). And, that "stretching out" (uncoiling) that cable
should not, in itself, alter the operation of the system -- i.e.,
unless you physically damaged something as you moved it from
point A to point B, any followup "testing" should simply be
a confidence building exercise.
What I'm trying to figure out is how to design a "troubleshooting
plan" (avoiding the word "test") that would prescribe how a
"technician/troubleshooter" would approach such a *deployed*
system in its physically distributed state to figure out what
might have "gone wrong" with a system that is *apparently* not
working properly.
E.g., the analogy to troubleshooting something electronic
on the bench: verify all connections are intact; verify the
availability of suitably conditioned power at each input;
apply prescribed inputs; observe specified outputs; etc.
and, based on these actions, come to the following conclusions...
I suspect they (CERN) will have a process that does NOT immediately
suspect the timing system. Or, that quickly performs some cursory
tests of the device (node) in situ RELYING ON IT'S EXPECTED PROPER
OPERATION. E.g., inspecting performance statistics that the node
itself collects/generates to see if things "look right" (from the
node's perspective). Implicitly counting on whatever may be "wrong"
with the system to manifest itself there, first.
For example, if the node claims that it can't obtain a frequency
lock on the reference timebase, then *assume* that it really can't
and go looking at those inputs to see if they are, perhaps,
missing or corrupt.
Only when everything *looks* right -- yet still *isn't* -- do you
(they) resort to dragging out a mile of cable...
Sort of like relying on the automation on a DSRV to tell you what
*it* thinks it's problems are -- instead of pulling it back to
the surface just so you can take "it's opinion" out of the loop.
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| From | Paul E Bennett <Paul_E.Bennett@topmail.co.uk> |
|---|---|
| Date | 2013-08-20 21:43 +0100 |
| Message-ID | <b7i2n3F2p51U1@mid.individual.net> |
| In reply to | #13135 |
Don Y wrote: > Hi Paul, [%X] > Sort of like relying on the automation on a DSRV to tell you what > *it* thinks it's problems are -- instead of pulling it back to > the surface just so you can take "it's opinion" out of the loop. The chap from CERN I needed to interrogate was, unfortunately, back at CERN before you asked your question here. I only heard about the White Rabbit from one of the people he was working with who introduced me to the Open Hardware web-site (which is hosted by CERN). I haven't looked too closely at the website yet but I do know there is some mention of White Rabbit on there. These links might help a bit more. <http://www.google.co.uk/url?sa=t&rct=j&q=white%20rabbit%20timing%20verification&source=web&cd=1&ved=0CC0QFjAA&url=http%3A%2F%2Findico.scc.kit.edu%2Findico%2FmaterialDisplay.py%3FcontribId%3D23%26sessionId%3D0%26materialId%3Dslides%26confId%3D22&ei=p9ETUrr4NMqO7QajsoGoBw&usg=AFQjCNEuQdabA3AzElyL9aERxEor60bZZw&bvm=bv.50952593,d.d2k&cad=rja> <http://en.wikipedia.org/wiki/The_White_Rabbit_Project> <http://www.google.co.uk/url?sa=t&rct=j&q=white%20rabbit%20timing%20verification&source=web&cd=3&ved=0CDkQFjAC&url=http%3A%2F%2Findico.cern.ch%2FmaterialDisplay.py%3FcontribId%3D195%26sessionId%3D17%26materialId%3Dslides%26confId%3D186337&ei=p9ETUrr4NMqO7QajsoGoBw&usg=AFQjCNGbQWqXgctLHXywkd8D_HwdqO2oNg&cad=rja> When I have some more time I am going to be just as interested in this material. -- ******************************************************************** Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett@topmail.co.uk> Forth based HIDECS Consultancy.............<http://www.hidecs.co.uk> Mob: +44 (0)7811-639972 Tel: +44 (0)1235-510979 Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
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| From | Don Y <this@isnotme.com> |
|---|---|
| Date | 2013-08-20 14:49 -0700 |
| Message-ID | <kv0oa3$jpd$2@speranza.aioe.org> |
| In reply to | #13139 |
Hi Paul, [Check your mail] On 8/20/2013 1:43 PM, Paul E Bennett wrote: >> Sort of like relying on the automation on a DSRV to tell you what >> *it* thinks it's problems are -- instead of pulling it back to >> the surface just so you can take "it's opinion" out of the loop. > > The chap from CERN I needed to interrogate was, unfortunately, back at CERN > before you asked your question here. Shame on him! With all that technology at his fingertips, wasn't he able to *anticipate* my questions??? :> > I only heard about the White Rabbit > from one of the people he was working with who introduced me to the Open > Hardware web-site (which is hosted by CERN). I haven't looked too closely at > the website yet but I do know there is some mention of White Rabbit on > there. It (or, similar technology) is also discussed on various manufacturers' websites (IIRC, TI had something similar -- same sorts of performance claims) > These links might help a bit more. [URL's snipped] Thanks, I will chase them down and add to my bookmarks. > When I have some more time I am going to be just as interested in this > material. I'm not interested in pushing the envelope as far as these folks are attempting (though one can imagine everything sliding down the cost/performance curve given enough time!). But, at "modest" levels (e.g., O(1us)... *certainly* sub-millisecond!) it seems like this is the direction things will be taking. Esp as SoC's become "popcorn parts" -- easier to add a separate processor *in* the "field" than drag the field *to* a single processor! It will be interesting to hear of "real-world experiences" as this sort of approach becomes more commonplace, less "exotic". --don
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