Re: [time-nuts] Opera coordinator has resigned
Moin, On Sat, 31 Mar 2012 09:19:35 -0400 Chuck Harris cfhar...@erols.com wrote: I think that is why John said that you cannot inspect in quality. Every worker has to do his job right the first time, without relying on others to catch his mistakes. As to your questions about John Forster's competency at complicated tasks: You clearly don't know John! I didn't questions his competency on complicated tasks. But i questioned his finger pointing at the CERN guys. Yes, you have to teach everyone to do their job right at the first time, but mistakes happen, no matter how diligent you are. Especially if the system is as complex as modern nuclear physics expermients. And i do not like it, if people who are not involved in a complex project do finger pointing. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Moin, On Sun, 01 Apr 2012 16:54:09 -0700 Jim Lux jim...@earthlink.net wrote: Not a whole lot, but the whole paper goes into the various factors involved. Ultimately, it winds up that the mismatch from SMAs is a) a whole lot less than the usual worst case spec of 1.05:1 or 1.03:1 (which is basically a measurement limit) and b) doesn't change much with many mate/demate cycles He did look at things like coupling nut friction and what not. Do you have the name of the paper? It might be interesting to read. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 4/7/12 2:47 AM, Attila Kinali wrote: Moin, On Sun, 01 Apr 2012 16:54:09 -0700 Jim Luxjim...@earthlink.net wrote: Not a whole lot, but the whole paper goes into the various factors involved. Ultimately, it winds up that the mismatch from SMAs is a) a whole lot less than the usual worst case spec of 1.05:1 or 1.03:1 (which is basically a measurement limit) and b) doesn't change much with many mate/demate cycles He did look at things like coupling nut friction and what not. Do you have the name of the paper? It might be interesting to read. Attila Kinali I'll try to find it. I've got the pdf somewhere on my computer.. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Hi Attila, speaking about finger pointing, I would like to make clear, that the loose connector was on the italian (OPERA) side and not on the french-swiss side (CERN). The news articles all cited CERN got it wrong, but as a matter of fact it was OPERA. Achim I didn't questions his competency on complicated tasks. But i questioned his finger pointing at the CERN guys. Yes, you have to teach everyone to do their job right at the first time, but mistakes happen, no matter how diligent you are. Especially if the system is as complex as modern nuclear physics expermients. And i do not like it, if people who are not involved in a complex project do finger pointing. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 2 April 2012 00:54, Jim Lux jim...@earthlink.net wrote: On 4/1/12 2:25 PM, Dr. David Kirkby wrote: So it tells us nothing very much about the life of them in normal use, with a human mating and demating them. - or even the repeatability of the reflection coefficient with a human in the equation. Not a whole lot, but the whole paper goes into the various factors involved. Ultimately, it winds up that the mismatch from SMAs is a) a whole lot less than the usual worst case spec of 1.05:1 or 1.03:1 (which is basically a measurement limit) and b) doesn't change much with many mate/demate cycles He did look at things like coupling nut friction and what not. Without seeing the paper, it's difficult to comment much more. Clearly if he had shown the performance to be worst than the spec, then I think he would have a useful result, as he would have put a limit on what was achieveable even with perfect use. But I think the human element is quite critical with SMA connectors - or pretty much any connector for that matter. Anyway, SMAs are pretty good connectors overall for most RF things. It's a long time since I have used any LEMO connectors - the subject of orginal discussion. I've not been following the orignal thread in detail, or looked at the relevant papers, but I do feel it odd and unjust that someone should resign over what was a genuine mistake. We all make them from time to time, and sometimes the consequencies are quite serious - like someone dies. dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
If the FTL neutrino discovery had been kept quiet until fully vetted, he probably would not have had to resign. Compare with the discovery of Cold Fusion. The desire for PR got ahead of the science. In my view, somebody who is in responsible charge of any project that size morally ought to be held accountable as The buck stops here. Frankly, I'm entirely fed up with those in charge of projects who walk away scott free after a giant disaster. Those in responsible charge should be held liable, both professionally and personally, IMO. YMMV, -John [snip] I've not been following the orignal thread in detail, or looked at the relevant papers, but I do feel it odd and unjust that someone should resign over what was a genuine mistake. We all make them from time to time, and sometimes the consequencies are quite serious - like someone dies. dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 03/31/12 09:38 PM, Jim Lux wrote: On 3/31/12 1:15 PM, Brooke Clarke wrote: Hi Achim: SMA RF connectors have a very limited life (number of matings) until they are worn out. I don't think so. Yes, they're only rated for 500 cycles, but there's a paper by a guy at Maury Microwave that I ran across when trying to get statistics on the reflection coefficient variation, and he set up a automated rig to mate/demate SMAs something like 10,000 times. I suspect that the jig he built does a better job of aligning them than what humans do. We put them on not quite square, move them around until the thread mates etc. I wonder if his jig tried to replicate a human or not? I suspect that there is a WIDE variation among mfrs in terms of life performance and manufacturing precision. Yes, I've worked in places where they use the cheapest they can get, and others where the more expensive, but much better quality Huber and Shuner connectors are used. I would expect the more expensive ones, which are machined more accurately, would last for more There is also a relationship between the torque you tighten them and their life. I happen to work somewhere where I can't get my boss to buy a torque wrench for them, despite we use a lot of SMA connectors. I don't know how common that practice is. Everywhere else I have worked does use a torque wrench. I one tried a quick experiment tightening them up by hand as tight as possible, then seeing how many extra turns it required to torque them to whatever the torque wrench was set to (not all SMA torque wrenches are set to the same figure). As far as I can tell, there is no way of even roughly estimating how tight they should be by saying hand tight + x turns. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 4/1/12 3:01 AM, Dr. David Kirkby wrote: On 03/31/12 09:38 PM, Jim Lux wrote: On 3/31/12 1:15 PM, Brooke Clarke wrote: Hi Achim: SMA RF connectors have a very limited life (number of matings) until they are worn out. I don't think so. Yes, they're only rated for 500 cycles, but there's a paper by a guy at Maury Microwave that I ran across when trying to get statistics on the reflection coefficient variation, and he set up a automated rig to mate/demate SMAs something like 10,000 times. I suspect that the jig he built does a better job of aligning them than what humans do. We put them on not quite square, move them around until the thread mates etc. I wonder if his jig tried to replicate a human or not? Nope.. back and forth in a straight line. He was measuring repeatability. I suspect that there is a WIDE variation among mfrs in terms of life performance and manufacturing precision. Yes, I've worked in places where they use the cheapest they can get, and others where the more expensive, but much better quality Huber and Shuner connectors are used. I would expect the more expensive ones, which are machined more accurately, would last for more There is also a relationship between the torque you tighten them and their life. I happen to work somewhere where I can't get my boss to buy a torque wrench for them, despite we use a lot of SMA connectors. I don't know how common that practice is. Everywhere else I have worked does use a torque wrench. I one tried a quick experiment tightening them up by hand as tight as possible, then seeing how many extra turns it required to torque them to whatever the torque wrench was set to (not all SMA torque wrenches are set to the same figure). As far as I can tell, there is no way of even roughly estimating how tight they should be by saying hand tight + x turns. Yes.. if you're talking about finger tight, there's a lot of variability. With an inexpensive open end wrench, though you can get pretty consistent.. perhaps it's the Calibrated thumb on the little wrench? Not anywhere as good as the click on the real torque wrench. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
If you think about it, tightening torque only relates very roughly to axial mating pressure. Torque is essentially the force requires to push an object up an inclined plane. That is the sum of two components, the normal component of the mating force plus the in plane component of (mating force)*(coefficient of friction). The latter is a guesstimate at best. -John === On 4/1/12 3:01 AM, Dr. David Kirkby wrote: I one tried a quick experiment tightening them up by hand as tight as possible, then seeing how many extra turns it required to torque them to whatever the torque wrench was set to (not all SMA torque wrenches are set to the same figure). As far as I can tell, there is no way of even roughly estimating how tight they should be by saying hand tight + x turns. Yes.. if you're talking about finger tight, there's a lot of variability. With an inexpensive open end wrench, though you can get pretty consistent.. perhaps it's the Calibrated thumb on the little wrench? Not anywhere as good as the click on the real torque wrench. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 04/ 1/12 03:33 PM, Jim Lux wrote: On 4/1/12 3:01 AM, Dr. David Kirkby wrote: On 03/31/12 09:38 PM, Jim Lux wrote: I don't think so. Yes, they're only rated for 500 cycles, but there's a paper by a guy at Maury Microwave that I ran across when trying to get statistics on the reflection coefficient variation, and he set up a automated rig to mate/demate SMAs something like 10,000 times. I suspect that the jig he built does a better job of aligning them than what humans do. We put them on not quite square, move them around until the thread mates etc. I wonder if his jig tried to replicate a human or not? Nope.. back and forth in a straight line. He was measuring repeatability. So it tells us nothing very much about the life of them in normal use, with a human mating and demating them. - or even the repeatability of the reflection coefficient with a human in the equation. dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 4/1/12 2:25 PM, Dr. David Kirkby wrote: On 04/ 1/12 03:33 PM, Jim Lux wrote: On 4/1/12 3:01 AM, Dr. David Kirkby wrote: On 03/31/12 09:38 PM, Jim Lux wrote: I don't think so. Yes, they're only rated for 500 cycles, but there's a paper by a guy at Maury Microwave that I ran across when trying to get statistics on the reflection coefficient variation, and he set up a automated rig to mate/demate SMAs something like 10,000 times. I suspect that the jig he built does a better job of aligning them than what humans do. We put them on not quite square, move them around until the thread mates etc. I wonder if his jig tried to replicate a human or not? Nope.. back and forth in a straight line. He was measuring repeatability. So it tells us nothing very much about the life of them in normal use, with a human mating and demating them. - or even the repeatability of the reflection coefficient with a human in the equation. Not a whole lot, but the whole paper goes into the various factors involved. Ultimately, it winds up that the mismatch from SMAs is a) a whole lot less than the usual worst case spec of 1.05:1 or 1.03:1 (which is basically a measurement limit) and b) doesn't change much with many mate/demate cycles He did look at things like coupling nut friction and what not. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 03/31/2012 05:52 AM, Sanjeev Gupta wrote: . On Mar 30, 2012 10:45 PM, paul swedpaulsw...@gmail.com wrote: I have to say that in general I have been staying clear of this thread. But its really a surprise that they are that sloppy and basing the results on a Vectron OCXO. Not that I have ever had a complaint about those. It just seems like the stunt I would do in the basement on my surplus accelerator. Their accelerator _was_ in their basement ;) Still is as I gather. Seems like facilities like that should regularly have a connector tightening party. What I reacted on was the slope of the signal. Steeper slopes would not had allowed for such a large effect. Also, the receiving end should have a signal level detector and possibly some additional quality of the signal being monitored to ensure that it is correct. Continuous or flickering detection would then give a hint that there is a problem, and is in fact what we use to indicate that we need to send out a tech on the field to polish fibre and tighten connectors. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On Fri, 30 Mar 2012 10:42:55 -0700 (PDT) J. Forster j...@quikus.com wrote: When doing a complex experiment, you have to be an absolute SOB about everything. You cannot inspect in quality. Uhm.. Have you ever visited a site of modern nuclear high energy physics? Have you ever seen what kind of constructions they have to just being able to measure something? I guess not, otherwise you wouldn't talk like this. I guess, Fermilab has also tours like CERN does, go and visit them. Have a look on how complex the aparatus is. Then think again whether it's possible to catch all and every error that might occur. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
I think that is why John said that you cannot inspect in quality. Every worker has to do his job right the first time, without relying on others to catch his mistakes. As to your questions about John Forster's competency at complicated tasks: You clearly don't know John! -Chuck Harris Attila Kinali wrote: On Fri, 30 Mar 2012 10:42:55 -0700 (PDT) J. Forsterj...@quikus.com wrote: When doing a complex experiment, you have to be an absolute SOB about everything. You cannot inspect in quality. Uhm.. Have you ever visited a site of modern nuclear high energy physics? Have you ever seen what kind of constructions they have to just being able to measure something? I guess not, otherwise you wouldn't talk like this. I guess, Fermilab has also tours like CERN does, go and visit them. Have a look on how complex the aparatus is. Then think again whether it's possible to catch all and every error that might occur. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On Fri, 30 Mar 2012 10:42:55 -0700 (PDT) J. Forster j...@quikus.com wrote: When doing a complex experiment, you have to be an absolute SOB about everything. You cannot inspect in quality. Uhm.. Have you ever visited a site of modern nuclear high energy physics? Yes. Have you ever seen what kind of constructions they have to just being able to measure something? I guess not, otherwise you wouldn't talk like this. I guess, Fermilab has also tours like CERN does, go and visit them. Have a look on how complex the aparatus is. Then think again whether it's possible to catch all and every error that might occur. I've been in responsible charge of a couple of spacecraft payloads. You have to instill in everybody to double check everything they do or the thing will likely fail. They have to understand that in all likelihood no human will ever revisit what they are doing at every step. -John Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Yes, I am aware of that. Bayonet and threaded connectors can be mated, or partially mated as I said. This applies to BNC, C, N, HN, TNC, SMA, APC-7, and MS at least, but not to LEMO and some families of military and commercial multipin connectors. Improper mating can easily be seen on a VNA, and can sometimes destroy a TWTA if it is not protected with an internal isolator. Normally FO connectors have their faces lapped very flat and exactly normal to the fiber axis. If they are not lapped properly or mated properly, the insertion loss increases dramatically. It was happenstance that the OPERA connector was mated enough to work, but not enough to work properly. -John On Sat, Mar 31, 2012 at 6:23 PM, J. Forster j...@quikus.com wrote: Frankly, I'm a bit surprised at the connector problem. Much of High Energy instrumentation uses LEMO connectors, which have a definite click when mated. They are not like BNCs which can be mated, without locking. It was an optical bayonet-type connector, not an electrical one. Changes in optical power induced by the loose connection resulted in big changes in delay through the mechanism of charging and discharging the capacitance associated with the photodiode. At least that is my crude understanding of the matter, I rest my case. You simply cannot inspect in quality. It's hard to disagree with this statement. Who doesn't like quality? I was trying to go a bit more concrete and suggest that redundant systems, especially based on alternative technologies, can help catch errors which may have gone undetected using other means, like inspection and other sanity checks. In fact, if you have experience with space electronics I think I don't have to convince you of the benefits of redundancy, as well as of the fact that the probability of making mistakes is never 0. If you think about it, this whole issue was solved thanks to redundancy: there was another experiment in the same lab which detected cosmic muons, and it was through the correlation of the muon detections between the two experiments that the slip between time bases was discovered. I think redundancy is a good complement, not necessarily a substitute, to other quality assurance methods. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
I agree that you can't inspect quality into a system, but it is far to easy to 'not inspect' quality right out of the system. Some of the new 'buzz-word' systems (TQM,6 sigma, etc.) seem to want everyone to be their own QA inspector to lessen the involvement of independent QA. I find that no matter how careful I inspect my own work, just knowing someone else will be looking over it makes me do a better job. Mike On 3/31/2012 11:23 AM, J. Forster wrote: Frankly, I'm a bit surprised at the connector problem. Much of High Energy instrumentation uses LEMO connectors, which have a definite click when mated. They are not like BNCs which can be mated, without locking. --- As to my point about inspecting in quality, look at the (crummy) attached picture: The leads to CR5 (a photocell) just to the left of the ceramic IC have NEVER been soldered or clipped. Yet, this 5519A Laser Interferometer head was built by HP, inspected by HP, tested by HP, and sold to a ciustomer by HP as part of a$60,000 system. I rest my case. You simply cannot inspect in quality. -John Jim Lux wrote: And we do things like stake connectors with epoxy, just in case. Serves two purposes: 1) a second independent look at the connector (after the first guy went through and tightened it with the torque wrench with the QA guy watching) 2) if, for some reason, there was a problem with #1 (maybe the torque wrench had an issue, or the QA guy sneezed and looked away, or...), at least the connector won't back off with vibration. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Dear John and all, I do work in high energy physics and we use LEMO and other standards. For some years now, I have started to advertise against LEMO (in particular the LEMO 00 size), as it is VERY sensitive to mechanical defects and partial connection (yes, you can ..). We have found very often defective LEMO connections, which could only be detected via time domain reflectometry. Or LEMO interfaces, which changed impedance significantly when rotating them in the fully mated position.. this list could be extended a lot more. And this famous click when mating is inaudible in typical high energy physics electronics barracks.. too much fan noise. In addition, for the very fast signals of modern DAQ systems, LEMO 00 is just not up to speed (literally) anymore. If size is not of ultimate importance, we switched to SMA, or SMC if size matters. About this dreadful OPERA fiber connector: It very much looks like a FC connector. It has a polarisation nut and I have to confess having misconnected them more than once myself. It might have been beneficial to shorten in this standard the thread length so there is no possibility to engage the thread (not even partially) when not properly aligned. As the thread is indeed fairly long, you can do what seemed to have happened in OPERA. I acknowledge the importance of QA, but also some design-inherent features like low power indications should be in place to prevent these things from happening. Regards, Achim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Sorry. click is a bad choice of words. It's more a feel as you mate them than an audible click. -John = Dear John and all, I do work in high energy physics and we use LEMO and other standards. For some years now, I have started to advertise against LEMO (in particular the LEMO 00 size), as it is VERY sensitive to mechanical defects and partial connection (yes, you can ..). We have found very often defective LEMO connections, which could only be detected via time domain reflectometry. Or LEMO interfaces, which changed impedance significantly when rotating them in the fully mated position.. this list could be extended a lot more. And this famous click when mating is inaudible in typical high energy physics electronics barracks.. too much fan noise. In addition, for the very fast signals of modern DAQ systems, LEMO 00 is just not up to speed (literally) anymore. If size is not of ultimate importance, we switched to SMA, or SMC if size matters. About this dreadful OPERA fiber connector: It very much looks like a FC connector. It has a polarisation nut and I have to confess having misconnected them more than once myself. It might have been beneficial to shorten in this standard the thread length so there is no possibility to engage the thread (not even partially) when not properly aligned. As the thread is indeed fairly long, you can do what seemed to have happened in OPERA. I acknowledge the importance of QA, but also some design-inherent features like low power indications should be in place to prevent these things from happening. Regards, Achim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
j...@quikus.com said: It was happenstance that the OPERA connector was mated enough to work, but not enough to work properly. A while ago, I was thinking that half the problem was a design error. But then I couldn't figure out how to do it right. Maybe monitoring the pulse height would have caught this error. Maybe a different encoding scheme would be easier to monitor. I've worked with fibers for communications, but that was many years ago. The receivers have AGCs. If you monitor the AGC control voltage you should be able to catch things like loose connections. I don't think we ever did that. We did monitor the error rate. It was always 0. But that adds another level of complexity. Checking/monitoring is good. Complexity is evil. How do you decide? -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
If you use a good design on the receivers, AGC output is virtually free. It doesn't take much more to run that signal to a go/no go comparator. -John j...@quikus.com said: It was happenstance that the OPERA connector was mated enough to work, but not enough to work properly. A while ago, I was thinking that half the problem was a design error. But then I couldn't figure out how to do it right. Maybe monitoring the pulse height would have caught this error. Maybe a different encoding scheme would be easier to monitor. I've worked with fibers for communications, but that was many years ago. The receivers have AGCs. If you monitor the AGC control voltage you should be able to catch things like loose connections. I don't think we ever did that. We did monitor the error rate. It was always 0. But that adds another level of complexity. Checking/monitoring is good. Complexity is evil. How do you decide? -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Remember, there are two varieties of SMA: Those with a gold plated center pin soldered onto the center conductor and those with a sharpened center conductor of 0.141 hard line. The latter are near junk, IMO. -John == On 3/31/12 1:15 PM, Brooke Clarke wrote: Hi Achim: SMA RF connectors have a very limited life (number of matings) until they are worn out. I don't think so. Yes, they're only rated for 500 cycles, but there's a paper by a guy at Maury Microwave that I ran across when trying to get statistics on the reflection coefficient variation, and he set up a automated rig to mate/demate SMAs something like 10,000 times. I suspect that there is a WIDE variation among mfrs in terms of life performance and manufacturing precision. the 3.5mm connector (sort of a precision, super SMA), is rated for 3000 cycles. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 3/31/12 1:46 PM, J. Forster wrote: Remember, there are two varieties of SMA: Those with a gold plated center pin soldered onto the center conductor and those with a sharpened center conductor of 0.141 hard line. The latter are near junk, IMO. Only if you're planning on multiple mates/demates. The crimp on 0.141 style works fine for the first couple mates. Good inspection and gaging is needed to make sure you don't get little shreds of copper from when you sharpen the point, and that your tooling got the length of the pin correct. It's sort of a works once scheme (like those head bolts or piston rod bolts that you can only torque once. Once stretched, they can't be used again.) They're pretty handy when building prototypes. You get your big length of 141 and your little bending tool, the die set and crimper from Kings, and you can cable up stuff (once) pretty quickly and neatly. If you take a cable off, you just throw it away (or cut the connectors off and use the remaining cable for something new) But if you're going to take it apart and reassemble it.. yep.. you want the real captured gold plated machined center pin. I use a lot of the semi-flexible or formable stuff from Tensolite and RF-Coax these days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
You can save some bucks by buying a Little IMP tubing bender that takes 1/8 OD tubing for about $10 at Home Depot. 1/8 = 0.125 which is very close to 0.141. Two minutes with a rattail file and Voila. -John On 3/31/12 1:46 PM, J. Forster wrote: Remember, there are two varieties of SMA: Those with a gold plated center pin soldered onto the center conductor and those with a sharpened center conductor of 0.141 hard line. The latter are near junk, IMO. Only if you're planning on multiple mates/demates. The crimp on 0.141 style works fine for the first couple mates. Good inspection and gaging is needed to make sure you don't get little shreds of copper from when you sharpen the point, and that your tooling got the length of the pin correct. It's sort of a works once scheme (like those head bolts or piston rod bolts that you can only torque once. Once stretched, they can't be used again.) They're pretty handy when building prototypes. You get your big length of 141 and your little bending tool, the die set and crimper from Kings, and you can cable up stuff (once) pretty quickly and neatly. If you take a cable off, you just throw it away (or cut the connectors off and use the remaining cable for something new) But if you're going to take it apart and reassemble it.. yep.. you want the real captured gold plated machined center pin. I use a lot of the semi-flexible or formable stuff from Tensolite and RF-Coax these days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 03/31/2012 10:29 PM, Jim Lux wrote: On 3/31/12 12:24 PM, Achim Vollhardt wrote: Dear John and all, I do work in high energy physics and we use LEMO and other standards. For some years now, I have started to advertise against LEMO (in particular the LEMO 00 size), as it is VERY sensitive to mechanical defects and partial connection (yes, you can ..). We have found very often defective LEMO connections, which could only be detected via time domain reflectometry. Or LEMO interfaces, which changed impedance significantly when rotating them in the fully mated position.. this list could be extended a lot more. And this famous click when mating is inaudible in typical high energy physics electronics barracks.. too much fan noise. In addition, for the very fast signals of modern DAQ systems, LEMO 00 is just not up to speed (literally) anymore. If size is not of ultimate importance, we switched to SMA, or SMC if size matters. On bad connectors.. K connectors are horrible.. they can intermate with SMA, but they don't tolerate the range of SMA mechanical variation, so it's possible to damage a K jack by mating an SMA plug with it. Not all SMA plugs, but some percentage of them. And it's not obvious that the jack has been damaged unless you measure it. You can mate a K or SMA (properly) with it, it will work, mostly, but now, there's a tiny gap in the center conductor, sometimes, depending on the connector flex, etc. We have a dreadful connector at JPL which is a mini twinax (used for balanced pairs, like MIL-STD-1553). The key is a stamped metal bump so small that it's easy to mismate in the 180 degree reversed position. There's a much better version which is hermaphroditic (each side has one male and one female pin) and it can only mate one way. But that other connector hangs on, and on, because you get the device A uses connector type X, so you build test equipment with mating Connector Type X, then the next device B has that connector, so we can re-use the test harnesses. The next batch of test equipment is made to be compatible with device B, and so it goes. The last people I know (not at JPL) who bought those connectors called up the mfr and was quoted a spectacularly long lead time (6 months or a year), so they asked who else had bought them, maybe they could buy the half dozen they needed. Naturally, JPL had bought the last batch, something like 15 or 20 years ago, and of course, we had dozens of them sitting in bonded stores. I was at an IEEE conference a few years ago on high speed interconnects (10 Gbps is slow for those guys), and a bunch of the folks were talking about how too much time is being spent on trying to get impedance controlled connectors, instead of reliable connectors. Their point was that in any real high speed (which would, for time nuts be high timing precision) system, you already have multiple transitions: die to IC package pin to PWB trace to connector pin to connector, before you worry about the connector's potential mismatch. These other ones are even harder to control the impedance on, and trying to do so makes the boards hard to route, etc, so why not bite the bullet and just implement a good adaptive equalizer in your high speed interface. Then you can use a mechanically robust connector that has a positive mating, can't be mismated or partially mated, and in fact, the equalizer can tell you if the cabling is screwed up. From a cost standpoint, it might actually be cheaper. Implementing the equalizers in a standard high speed SERDES doesn't cost much more in silicon (yes, the IP development costs money, so the selling price is higher), and you save a lot in the rest of the system. We have equalizers as well as pre/post emphesis to shape the eye of the signal. It's really required. We adjust the sampling point on our bits. That's standard business today. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Opera coordinator has resigned
http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On Fri, Mar 30, 2012 at 3:07 PM, iov...@inwind.it iov...@inwind.it wrote: http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
El 30/03/2012 16:55, Javier Serrano escribió: On Fri, Mar 30, 2012 at 3:07 PM, iov...@inwind.itiov...@inwind.it wrote: http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 Thanks for sharing them I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. The devil is ever in the small things :) It is truly very interesting I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. This is true. And also perhaps the use of neutrinos for time transfer purposes :) Nowadays nort their generation in a controlled way either the detection is easy, but who knows in the future... Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
I have to say that in general I have been staying clear of this thread. But its really a surprise that they are that sloppy and basing the results on a Vectron OCXO. Not that I have ever had a complaint about those. It just seems like the stunt I would do in the basement on my surplus accelerator. Regards Paul. On Fri, Mar 30, 2012 at 12:57 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Javier, Thanks very much for posting the link to the presentations. For those of you who just want a summary of the resolution of the neutrino faster than light problem, here's what happened: 1) For several years an optical cable connector was loose. I have attached photos from pages 7 and 8 of the G._Sirri.pptx where you can see the actual connector and waveforms, before/after. 2) They used a Vectron OCXO to generate timestamps within each 0.6 second measurement cycle. This oscillator was found to be high in frequency by 0.124 ppm. Thus, depending on where within this 0.6 s interval the timestamp was made a timing bias of 0 to 74 ns would occur. Javier -- if you have contacts there, it looks to me like they forgot to include OCXO frequency drift effects into their analysis. What they did was compensate for linear time drift (which assumes a fixed frequency offset). They call the 124.1 ns/s time drift stable since 2008. What evidence do they have for this? We know that OCXO will drift in *frequency* over time; the time drift is quadratic. The time drift rate may be 124e-9 today, but it probably wasn't last month or last year, etc. /tvb There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/**materialDisplay.py?materialId=** slidesconfId=4896http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
There are failures and there are failures. A negative result is a failure that is worth reporting. A failure due to an improperly mated connector... not so much. When doing a complex experiment, you have to be an absolute SOB about everything. You cannot inspect in quality. YMMV, -John On 03/30/2012 04:55 PM, Javier Serrano wrote: On Fri, Mar 30, 2012 at 3:07 PM, iov...@inwind.itiov...@inwind.it wrote: http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. As in any research, even a failure is worth reporting, as people can learn from it. Many forget this and tend to select their results which can be a danger as you can go into bad science that way. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. Will be quite interesting to follow. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On Fri, Mar 30, 2012 at 7:42 PM, J. Forster j...@quikus.com wrote: There are failures and there are failures. A negative result is a failure that is worth reporting. A failure due to an improperly mated connector... not so much. That is saying to anyone who wants to do a similar experiment in the future that they need at least two redundant systems. I believe that is quite a valuable lesson. Concerning the OCXO, one has to bear in mind that this experiment was not meant to measure time of flight, but rather neutrino oscillations. The message for me here is that it's good to publish all your designs, including gateware sources, as soon as possible, but I don't know how compatible that is with today's highly competitive scientific world. So I think there is an important lesson behind each one of the two issues. Of course this is easy to see from outside and after the fact. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On Fri, Mar 30, 2012 at 7:42 PM, J. Forster j...@quikus.com wrote: There are failures and there are failures. A negative result is a failure that is worth reporting. A failure due to an improperly mated connector... not so much. That is saying to anyone who wants to do a similar experiment in the future that they need at least two redundant systems. I believe that is quite a valuable lesson. Not quite, IMO. You need to do sanity checks. When you are doing science in unknown territory, you need to eliminate everything you can, as a source of error. Remember the problems Perkin Elmer had with the Hubble mirror? Concerning the OCXO, one has to bear in mind that this experiment was not meant to measure time of flight, but rather neutrino oscillations. The message for me here is that it's good to publish all your designs, including gateware sources, as soon as possible, but I don't know how compatible that is with today's highly competitive scientific world. Was there any real competition to this experiment? Seems like they have a lot of very, very big, expensive, unique hardware that can't exactly be bought at Radio Shack. Which is more important? Getting it fast, or getting it right? -John = So I think there is an important lesson behind each one of the two issues. Of course this is easy to see from outside and after the fact. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
May anybody out there explain why the connector was simply photographed, and not put in place, on October 13, that is one month before the updated version (Nov 17) of the Opera paper? Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
I suppose that when it was photographed, nobody noticed it. After noticed that it was no correctly plugged-in, the past pictures were reviewed and found that in fact it was not fully plugged in :) El 31/03/2012 01:04, iov...@inwind.it escribió: May anybody out there explain why the connector was simply photographed, and not put in place, on October 13, that is one month before the updated version (Nov 17) of the Opera paper? Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
Hi: I take a lot of photos for my web pages and every now and then I go back and find something that was in a photo that I missed when it was taken. It's quite possible that the displayed photos were cropped from larger images showing more of the system. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Javier Herrero wrote: I suppose that when it was photographed, nobody noticed it. After noticed that it was no correctly plugged-in, the past pictures were reviewed and found that in fact it was not fully plugged in :) El 31/03/2012 01:04, iov...@inwind.it escribió: May anybody out there explain why the connector was simply photographed, and not put in place, on October 13, that is one month before the updated version (Nov 17) of the Opera paper? Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
On 3/30/12 4:16 PM, Javier Herrero wrote: I suppose that when it was photographed, nobody noticed it. After noticed that it was no correctly plugged-in, the past pictures were reviewed and found that in fact it was not fully plugged in :) We do this all the time at JPL. You have someone come in and take lots of pictures, sort of en masse. If something goes wrong, then you go back and look at the pictures. Sometimes it's a tiny detail that wasn't noticeable until you knew what to look for. (and we've also had loose connector problems.. thankfully not in space that I'm aware of, but I've had more than one SMA that wasn't fully torqued. You can't tell the difference by looking whether it was finger tight or torqued. But after rolling the rack of gear around and shipping it across country a couple times.) El 31/03/2012 01:04, iov...@inwind.it escribió: May anybody out there explain why the connector was simply photographed, and not put in place, on October 13, that is one month before the updated version (Nov 17) of the Opera paper? Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opera coordinator has resigned
. On Mar 30, 2012 10:45 PM, paul swed paulsw...@gmail.com wrote: I have to say that in general I have been staying clear of this thread. But its really a surprise that they are that sloppy and basing the results on a Vectron OCXO. Not that I have ever had a complaint about those. It just seems like the stunt I would do in the basement on my surplus accelerator. Their accelerator _was_ in their basement ;) Regards Paul. On Fri, Mar 30, 2012 at 12:57 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Javier, Thanks very much for posting the link to the presentations. For those of you who just want a summary of the resolution of the neutrino faster than light problem, here's what happened: 1) For several years an optical cable connector was loose. I have attached photos from pages 7 and 8 of the G._Sirri.pptx where you can see the actual connector and waveforms, before/after. 2) They used a Vectron OCXO to generate timestamps within each 0.6 second measurement cycle. This oscillator was found to be high in frequency by 0.124 ppm. Thus, depending on where within this 0.6 s interval the timestamp was made a timing bias of 0 to 74 ns would occur. Javier -- if you have contacts there, it looks to me like they forgot to include OCXO frequency drift effects into their analysis. What they did was compensate for linear time drift (which assumes a fixed frequency offset). They call the 124.1 ns/s time drift stable since 2008. What evidence do they have for this? We know that OCXO will drift in *frequency* over time; the time drift is quadratic. The time drift rate may be 124e-9 today, but it probably wasn't last month or last year, etc. /tvb There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/**materialDisplay.py?materialId=** slidesconfId=4896 http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. On Mar 30, 2012 10:45 PM, paul swed paulsw...@gmail.com wrote: I have to say that in general I have been staying clear of this thread. But its really a surprise that they are that sloppy and basing the results on a Vectron OCXO. Not that I have ever had a complaint about those. It just seems like the stunt I would do in the basement on my surplus accelerator. Regards Paul. On Fri, Mar 30, 2012 at 12:57 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Javier, Thanks very much for posting the link to the presentations. For those of you who just want a summary of the resolution of the neutrino faster than light problem, here's what happened: 1) For several years an optical cable connector was loose. I have attached photos from pages 7 and 8 of the G._Sirri.pptx where you can see the actual connector and waveforms, before/after. 2) They used a Vectron OCXO to generate timestamps within each 0.6 second measurement cycle. This oscillator was found to be high in frequency by 0.124 ppm. Thus, depending on where within this 0.6 s interval the timestamp was made a timing bias of 0 to 74 ns would occur. Javier -- if you have contacts there, it looks to me like they forgot to include OCXO frequency drift effects into their analysis. What they did was compensate for linear time drift (which assumes a fixed frequency offset). They call the 124.1 ns/s time drift stable since 2008. What evidence do they have for this? We know that OCXO will drift in *frequency* over time; the time drift is quadratic. The time drift rate may be 124e-9 today, but it probably wasn't last
