Re: [time-nuts] Low-long-term-drift clock for board level integration?
Le 20/02/2012 07:18, Bill Woodcock a écrit : Murphy says we won't. Bell curve, again. A very few will have good symmetric paths to Stratum-1 servers, most will have mediocre asymmetric paths, and some will have nothing usable at all. Are you targeting homes, offices, or machine rooms? The vast majority will be office buildings. A few datacenters. Probably only a handful of homes. With the exception of the mobile units, the units' position can be determined with google maps or local survey data prior to installation so if you are not relying on the GPS receiver for time sync, why not forget it, set the data prior to shipment and invest the saved cost on a better oscillator. ___ 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] Low-long-term-drift clock for board levelintegration?
I think a box that can't get some external source of time in three years is one that we can pretty well write off as lost. Thank you (several of you, actually) for the clear explanation of the math. http://www.msc-ge.com/en/news/pressroom/manu/1241-www/3567-www.html http://www.thinksrs.com/downloads/PDFs/Catalog/SC10c.pdf So if I'm reading those specs right, they both offer 2E-10, or 100 microseconds per 500,000,000,000, or 121 microseconds per week. So, if those are affordable (and I haven't yet called to check), that's telling me that in order to be useful in the long term, these boxes need to be getting some reference time from somewhere at least once a week. Hi Bill, Not quite. The 2E-10 isn't a time or frequency *accuracy* spec; it's a *frequency drift* spec. What this means is that the frequency may change by up to 2e-10 per day, day after day... Let's say the oscillator is keeping perfect time now. Then 24 hours from now it may be fast or slow in frequency by 2e-10. If the oscillator is fast by 2e-10 it will be gaining time at the rate of 0.2 nanoseconds per second. That doesn't sound like much but since there are 86400 seconds in a day, that's equivalent to gaining at a rate of 17 microseconds a day. But that's just the first day. The second day the oscillator may be fast by yet another 2e-10. By the end of the day it's now 4e-10 fast so it's now gaining at a rate of 35 microseconds a day, in addition to all the time error from yesterday. Think of frequency changing like an upward *ramp*. The time error accumulates like the *area* under that growing triangle. Hence the quadratic growth of time error (1/2 * drift * t^2). After a week the total time error is over 400 microseconds; you hit your 100 microsecond limit in about 3.5 days. The SC-10 starts at $250, presumably for a low-grade version, not the one you want. The DX-170 looks interesting. Let us know when you get a price quote. Note also the temperature spec; can you maintain the temperature of your device to +/- 1 C? /tvb ___ 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] Low-long-term-drift clock for board levelintegration?
Yes, the relation frequency_drift- time_error seems difficult to figure out. I see this misunderstanding daily here at work and haven't yet found a way to explain to my colleagues. I have already used: integral, area, count accumulation but none worked. On Mon, Feb 20, 2012 at 10:37 AM, Tom Van Baak t...@leapsecond.com wrote: I think a box that can't get some external source of time in three years is one that we can pretty well write off as lost. Thank you (several of you, actually) for the clear explanation of the math. http://www.msc-ge.com/en/news/**pressroom/manu/1241-www/3567-**www.htmlhttp://www.msc-ge.com/en/news/pressroom/manu/1241-www/3567-www.html http://www.thinksrs.com/**downloads/PDFs/Catalog/SC10c.**pdfhttp://www.thinksrs.com/downloads/PDFs/Catalog/SC10c.pdf So if I'm reading those specs right, they both offer 2E-10, or 100 microseconds per 500,000,000,000, or 121 microseconds per week. So, if those are affordable (and I haven't yet called to check), that's telling me that in order to be useful in the long term, these boxes need to be getting some reference time from somewhere at least once a week. Hi Bill, Not quite. The 2E-10 isn't a time or frequency *accuracy* spec; it's a *frequency drift* spec. What this means is that the frequency may change by up to 2e-10 per day, day after day... Let's say the oscillator is keeping perfect time now. Then 24 hours from now it may be fast or slow in frequency by 2e-10. If the oscillator is fast by 2e-10 it will be gaining time at the rate of 0.2 nanoseconds per second. That doesn't sound like much but since there are 86400 seconds in a day, that's equivalent to gaining at a rate of 17 microseconds a day. But that's just the first day. The second day the oscillator may be fast by yet another 2e-10. By the end of the day it's now 4e-10 fast so it's now gaining at a rate of 35 microseconds a day, in addition to all the time error from yesterday. Think of frequency changing like an upward *ramp*. The time error accumulates like the *area* under that growing triangle. Hence the quadratic growth of time error (1/2 * drift * t^2). After a week the total time error is over 400 microseconds; you hit your 100 microsecond limit in about 3.5 days. The SC-10 starts at $250, presumably for a low-grade version, not the one you want. The DX-170 looks interesting. Let us know when you get a price quote. Note also the temperature spec; can you maintain the temperature of your device to +/- 1 C? /tvb __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] Any spare switches for Racal-Dana 1992?
I'm wondering if anyone has any spare Racal-Dana 1992 switch mechanisms they would sell? The switches can be replaced from the front of the panel (as reported here) and what I really need is the small black rubber piece (circular pill shaped) with the little nipple which sits within the 4 legs of the white plastic piece with the stem (onto which the gray pushbutton fits). I need two of these black rubber pills. Many thanks. Please contact me off line at jsrobbins (at) earthlink.net. Thanks for the BW. Jim Robbins, N1JR ___ 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] Any spare switches for Racal-Dana 1992?
James wrote: I need two of these black rubber pills Speaking from extensive experience, if you need 2 now, plan on needing somewhere between 5 and 31 more over the next year or two. Best regards, Charles ___ 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] OP-Amps for 10MHz distribution...?
Hello, Time-Nutters-- Here is a link to a TI app note on using op-amps for RF. It occurred to me that this might work OK for distribution of the ref freq from a GPSDO... http://www.ti.com/lit/an/slyt102/slyt102.pdf Mike Baker --- ___ 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] Low-long-term-drift clock for board level integration?
Hi Bill, what about White Rabbit? http://www.ohwr.org/projects/white-rabbit/wiki/Description Successor of NTP.. PTP: precision time protocol. It delivers Gigabit Ethernet and precise (1nsec) timing over singlemode fiber. You would have to connect all devices into a fiber network instead of a copper based network and all switches in between would have to be WR compatible.. but this could solve your problem. Javier Serrano (one of the developers) is also on this list.. he might add/correct me. 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] OP-Amps for 10MHz distribution...?
Op amps have been used for quite a while. I have used buffer amps called lh003s preceded by a opamp (that I do not recal)to create a 2 X gain. They were power hungry. It looks like these have very wide bandwidth. You really do not need that wide of a bandwidth. Maybe 20 Mhz for a 10 Mhz ref. Good article. Regards Paul WB8TSL On Mon, Feb 20, 2012 at 11:28 AM, Michael Baker mp...@clanbaker.org wrote: Hello, Time-Nutters-- Here is a link to a TI app note on using op-amps for RF. It occurred to me that this might work OK for distribution of the ref freq from a GPSDO... http://www.ti.com/lit/an/**slyt102/slyt102.pdfhttp://www.ti.com/lit/an/slyt102/slyt102.pdf Mike Baker --- __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://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] OP-Amps for 10MHz distribution...?
On Mon, 20 Feb 2012 11:28:01 -0500 Michael Baker mp...@clanbaker.org wrote: Here is a link to a TI app note on using op-amps for RF. It occurred to me that this might work OK for distribution of the ref freq from a GPSDO... http://www.ti.com/lit/an/slyt102/slyt102.pdf Depends on what you want to do and what your specs are. If you just need a 10MHz signal that looks ok, then an Opamp is an obvious choice. It is by far simpler to design than a discrete solution (especially today, when nobody knows how a transistor works). Just plug it in, a few resistors around it and you're done. But there are two things that the article does not tell you: Noise and power. Opamps (used as amplifiers) generally have a higher noise than equivalent discrete transistor circuits and use more power. So if you care about jitter, noise and want to be in the nutty of the time-nutty region, then there is no way around designing your own distribution amplifier using discrete components. And just for reference: There are already Opamps around with a gain bandwidth product of 1GHz. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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] Low-long-term-drift clock for board level integration?
On 2/20/12 8:34 AM, Achim Vollhardt wrote: Hi Bill, what about White Rabbit? http://www.ohwr.org/projects/white-rabbit/wiki/Description Successor of NTP.. PTP: precision time protocol. It delivers Gigabit Ethernet and precise (1nsec) timing over singlemode fiber. You would have to connect all devices into a fiber network instead of a copper based network and all switches in between would have to be WR compatible.. but this could solve your problem. Javier Serrano (one of the developers) is also on this list.. he might add/correct me. I think the OP needs something over a large geographical area, and I don't know that PTP/1588 would work through a routed internet kind of connection. ___ 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] How best to exchange Large files?
Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Thanks ws *** ___ 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] How best to exchange Large files?
At 04:07 21-02-12, you wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Thanks ws Use a dropbox. Easy to use, and free. I just sent a 2.3 GB data file to a friend. Took half a day to upload, of course. Marco IK1ODO ___ 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] How best to exchange Large files?
On 2/20/12 9:52 AM, WarrenS wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? very big meaning megabytes.. 10s of MB? GB? What about something like dropbox? If the files are big enough, this is, of course, what bit-torrent was invented for. ___ 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] Low-long-term-drift clock for board level integration?
Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob On Feb 20, 2012, at 1:32 AM, Bill Woodcock wo...@pch.net wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On Feb 19, 2012, at 10:20 PM, Dennis Ferguson wrote: I think you may find that in many (most?) other countries the GSM BTS gear has no idea what time it is. Pretty wide range there… I've certainly seen some pretty crazy time-and-dates show up on my phone upon landing in some countries. But it's been a while since I've gotten a weird one in Europe or the more developed parts of Asia. Africa and South and Central Asia are pretty much all over the map, though. -Bill -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJPQejmAAoJEG+kcEsoi3+H1E4P/jYB0QRd5zUMBVUQdpc48xSX kwzZv/TmYUhTGkyBKifbeDrcTEmNmov9GscB+25oObEE6nfoSansDUJV0dxK6ux/ BPsMfYWZraTv3AJFJwGQ+R8ab9JTts/FgNoBUWCOaQwPkAN6lWE0LHU+8TW5o59R LFIeZ7tsD6BnIS+kiSLsLxrAQ6RzvxtzOwZXxCejGl04VwG6NcrfE/kJjzTn6WLk 0eanG6fvqZUdNQaD37uCZKf0SDneV9EKBIkoUMK+n3X1MS4N5gNQ3uFM/rli9JGz R7Cd2x1AgJzddNR+aOlPTTv//eWKR/nBiR2AHZRx8PjbzGrziQHVRakiJdeyqWa2 X09AKlSnaeG2+ZAFLUAxJbL2YJFSqMo/9RgTQKc65VQ7anA13OxxpioJ5W5vW+h5 E5uCMdQE7SKuChdkb+8dWJPvq4wYNwBT6MyDcvMqSQrEnDEcc/0NDsPPhHjcOKW5 ZR+1ASncyQYymI17aOHVYpLnW89bu2gUADzhfTviWLHzEgiDL9qSCVtIR5IiFVOj 8sAM+uTnd6He/96EWd6vIguY6IOGAVQX1RGBhXhOsm26Hhx11p3qAEhzuGHJLZZ2 N3bMQD8hJcFhKh0b6TkeC7a1QI2cr6cH0dKd74YnUFuJDK/NGixUUzZ1azP+iHkR kvdseSQTGWaRrpWWY+5f =H8L/ -END PGP SIGNATURE- ___ 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] How best to exchange Large files?
On Mon, 20 Feb 2012 09:52:39 -0800 WarrenS warrensjmail-...@yahoo.com wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. How about using bittorrent? There are multiple free trackers out there, which can handle the coordination between the nodes, if you don't want to run your own (e.g. [1]). Alternatively, i could host the files as long as the traffic stays below a couple 10GB/month. Attila Kinali [1] http://openbittorrent.com/ -- 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] How best to exchange Large files?
You can always upload them to my site as if it was a manual (follow the manual upload instructions). If you let me know in a comment, I will leave the file in the upload area where anyone can retrieve it via ftp. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: WarrenS warrensjmail-...@yahoo.com Sender: time-nuts-boun...@febo.com Date: Mon, 20 Feb 2012 09:52:39 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] How best to exchange Large files? Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Thanks ws *** ___ 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] How best to exchange Large files?
On Mon, 20 Feb 2012 19:41:31 +0100, Attila Kinali att...@kinali.ch wrote: On Mon, 20 Feb 2012 09:52:39 -0800 WarrenS warrensjmail-...@yahoo.com wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. How about using bittorrent? There are multiple free trackers out there, which can handle the coordination between the nodes, if you don't want to run your own (e.g. [1]). Alternatively, i could host the files as long as the traffic stays below a couple 10GB/month. Attila Kinali [1] http://openbittorrent.com/ I have used uTorrent to distribute large data sets before using both the trackerless protocol and the OpenBitTorrent tracker. All I had to provide was either the torrent file or the magnet URL. The caveat of course is that you need to leave your bittorrent client running to seed the file or files and you will probably want to figure out your port forwarding so you can accept incoming connections. You would probably still want a simple web page though with the magnet links or torrent files. ___ 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] Low-long-term-drift clock for board level integration?
On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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] How best to exchange Large files?
On Mon, Feb 20, 2012 at 9:52 AM, WarrenS warrensjmail-...@yahoo.com wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Dropbox is easy to use and for moderate size files, like your 100MB files it works well. You can out grow it quickly if you try to transfer video files or DVD images.This link will get you going: http://db.tt/NNDLceror Google will find DropBox for you. Almost as easy is to run an FTP server on your home computer. Then there is no data transferred until someone comes to get it and there is no size limit. For moderate size files DropBox is easy but you do have limited space there before they ask for money. A server running at your house would not have such limits. And of course FTP servers are free and can be very secure. FTP servers come with most OSes and all to need to do is unable it with a few mouse clicks. (but maybe not MS Windows?) in any case it's easy to find and install. Chris Albertson Redondo Beach, California ___ 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] How best to exchange Large files?
WarrenS wrote: Recording high speed and/or long general purpose raw Osc data, the file can become very large. I'm looking for a simple, fast and easy (and cheap) way to transfer large compressed data files of up to say a 100 MB between time-nuts. I know there are all kinds places one can store large files that others can then have access to, so I do not want to use the OLD way of breaking it up into many small pieces. I do not need to do this very often, so I do not want to sign up for any long term thing or maintain a Friends or face book type thing, I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Time-nuts are welcome to use: http://www.c-c-i.com/exchange/ to exchange files. As the name says, the page is there to exchange files. The normal use would be to upload your file, tell people about it, let them download it, then delete it. Please note that the page is completely public. Anyone that knows about it (not many folks, actually) can see your files, download them, and delete them. Note the restriction on file types. Zip, gz, and tgz, among others, are supported. I would ask that after you have made a file available for a reasonable time that you go to the page and delete it. If you only want to make the file available to one person, ask them to delete it after they download it. If a file remains there more than a few weeks I may delete it. Best regards, -- Bob Smither, PhD Circuit Concepts, Inc. = If you want peace, work for justice. If you want justice, work for freedom. --Vote Libertarian-- = smit...@c-c-i.com http://www.C-C-I.Com 281-331-2744(office) -4616(fax) attachment: smither.vcf___ 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] Low-long-term-drift clock for board level integration?
I've looked at the posts on this topic, and from what I've seen so far I think is going to be a tough if not impossible call. 30 minutes to get GPS is OK, but what about the oscillator? It will need a lot longer than that to stabilise. You also then have the vagaries of the network. NTP won't hack the spec he is quoting and PTP won't hack the network. And, the budget is way too low. Food for a lot of thought methinks Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: 20 February 2012 19:07 To: time-nuts@febo.com Subject: Re: [time-nuts] Low-long-term-drift clock for board level integration? On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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] Low-long-term-drift clock for board level integration?
On Mon, Feb 20, 2012 at 12:15 AM, mike cook michael.c...@sfr.fr wrote: Le 20/02/2012 07:18, Bill Woodcock a écrit : Murphy says we won't. Bell curve, again. A very few will have good symmetric paths to Stratum-1 servers, most will have mediocre asymmetric paths, and some will have nothing usable at all. Are you targeting homes, offices, or machine rooms? The vast majority will be office buildings. A few datacenters. Probably only a handful of homes. With the exception of the mobile units, the units' position can be determined with google maps or local survey data prior to installation so if you are not relying on the GPS receiver for time sync, why not forget it, set the data prior to shipment and invest the saved cost on a better oscillator. I've been thinking that all along. The GPS receiver is not going to be useful at all for timing. Even for the first setup, even if GPS was able to get you perfect time as soon as you connect top NTP that perfect time will be wiped out with NTP's idea of the time. So it's pointless. Now that I've read you are building hundreds of these then I'd say there is ABSOLUTLY ZERO chance of ntp working at the uSec level. Yes it might work now and then but NOT all 100+ of your systems.For that to happen would would require a statistical miracle right up there with buying a dozen winning lottery tickets in one day. It might happen.But getting 100+ NTP installations to work that well is near impossible. You WILL need GPS and even then getting to 100% is hard. Some sites simply will not have a good view of the sky or if in a high rise building running antenna lead down 25 floors through conduit would cost to much. The ONLY way to get 100% success rate with hundreds of installations is to have multiple options. coockie cutter or turn-key just can't work. MOST places will not have a good enough network connection for uSec level times. Some data centers will. Small offices and homes will not.Most places will have a way to set up GPS. Then in the remaining places you can use cell phone based radio clocks. They cost more then GPS and have 100 times worse performance but they might be the only option in most cases. You said the person installing this will be rather clueless. The fix for that is good customer tech support. You can walk them through the decision process about what kind of clock is best for their site then help them set it up and test it. Testing is key. Have a few fall backs if the tests fail. Bottom line is that open loop timing at the level of 10 uSec per year costs well into 7 digit figures (Cesium clocks) so you need some connection to the outside world. So must choose a connection type. The available options are 1) NTP. Attractive because it is free but in most cases it will not meet your accuracy requirements, only in places with good networks like co-location facilities and some large data centers or if you are lucky and the customer already base GPS connected NTP servers on his local network (many places do have this. It is common with larger companies) 2) GPS. Works perfectly, not expensive but it does require an antenna that can see much of the sky. You may need a long antenna lead cable and running long wires in a commercial building can be expensive. 3) CDMA reference clocks. These can work at the uSecond level any place there is decent CDMA cell phone coverage. The clock and its antenna can be located indoors. Here is an example of one: http://www.endruntechnologies.com/pdf/UnisonCDMA.pdf 4) There may be other ways to connect to the outside, phone modems, WWB broadcasts. Loran is still running in some parts of the world. Your customer may already have a precision timing system of some kind and you can use that. (We use IRIG in our lab) But you do this case by case. If this were me. I'd have GPS as the default option but then tel the user he does not need it if a GPS connected NTP server is already installed at his facility, then he could just use NTP. Then use CDMA as a fall back if those fail. Chris Albertson Redondo Beach, California ___ 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] Low-long-term-drift clock for board level integration?
Hi Bill: When the TRANSIT navigation satellites were put in orbit the receivers required Cesium clocks. The system worked but was very expensive. The GPS system was designed so that cheap clocks could be used in the receiver. This requires getting a lock on 4 satellites instead of the 3 that would be required for a 3D position fix. The forth satellite allows determining the the receivers clock offset and rate. You may be able to do a similar thing in your receivers. For example if the master node were to send a timing message at known times (say once at the top of every hour) the receivers could use that to determine their local clock offset and rate for those cases where the path was the same (or maybe even for a list of paths). The offset and rate numbers can be used to correct the measured time to actual time without changing the clock's rate using simple math. You can trade the receiver clock stability for the time between the timing messages. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Bill Woodcock wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Hi. This is my first posting to this list, and I'm not a timekeeping engineer, so my apologies in advance for my ignorance in this area. I'm building a small device to do one-way delay measurements through network. Once I'm done with prototyping, I'm planning a production run of several hundred of the devices. They'll have a GPS receiver, probably a Trimble Resolution SMT, and they have a bit of battery so they can initially go outdoors for ~30 minutes to get a good fix, but then they get taken indoors and plugged into the network, and probably never get a clear view of a GPS or GLONASS satellite again. - From that point forward (and we hope the devices will have an operational life of at least ten years) they'll be dependent on their internal clock and NTP, but we really need them to stay synchronized to within 100 microseconds. 10 microseconds would be ideal, but 100 would be acceptable. And in order to be useful, they need to stay synchronized at that level of precision essentially forever. My plan, such as it is, was just to get the best clock I could find within budget, integrate it onto the motherboard we're laying out as the system clock, and depend on NTPd to do the right thing with it. Anyone have any thoughts or advice on clocks I could use that would be, say, under USD 300 in quantity 500, and would be optimized for minimal long-term drift? Power-use is not particularly constrained. It needs to be integrated onto our board, but space isn't too constrained either. I'm also happy to pay for a few consulting hours if people want to give me detailed advice on a professional basis. Thanks, -Bill -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJPQYw8AAoJEG+kcEsoi3+HfuUP/3+VVQs+dyRL4ToEoCaAI0eQ 8TMEV1PD7r775P/rSA0M1wWzFsTxAegixUbBHmQDvgc2ouaEiN0ZJvQrbNwBxR8M +b7QIuxB4h84JYyvw+Add6l8HjWWWttDW52YiUEdNmv228Q+XO7z/CMBrZ79c9bB VeZ5CEJl3zLcEDthpBKxgtEKtHFqURUCQ0b3uqWC4dTYld3yTJ9NB7/mt5bLDlEF IoA02IKurWBgkmNf92FU2SeC458mPejw2EiYaQ/acSv8mK23q56XJoo0O1ogNhAk qajdSBj/z9hlLTKgRH5jBorwNeRwr0TN8AoyPjBBqIRAI14Q1QHbLJu5twhy5C92 oE78LzedFa93GBPg8+6mdxYgevG4Pm8v8qeB6CdlDBJVD8s91QF0m52Gce+l2H9V PUGO7ACWjhVdi7VIWSOeSYGlIlqsLV4C7UYLYS+4zy0+dnrgeLFeYf9A29i6Krhr BCrtPvE6XrC0JUr3oZ0gDzh/T9JPr0XFmWkA0w9JmOAK7D+YWfa7jTBS+vbSXemo 5XBpjK2Ioo9JBwKmUF1Gd8dOO7fSm7cclxfRYwmjjzvSGG+vXCihWhaLzJdwJz6Z PYf60+hk23Mhrfk4V2qjTi1hVg9FJtxxNA3oC0MRuuwU45tXGIFcUqpSw3F+FS6f IuLyIrTqwVzdakZL997f =PpgK -END PGP SIGNATURE- ___ 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] Low-long-term-drift clock for board level integration?
You may be able to do a similar thing in your receivers. For example if the master node were to send a timing message at known times (say once at the top of every hour) the receivers could use that to determine their local clock offset and rate for those cases where the path was the same (or maybe even for a list of paths). Nope. The problem is queuing delays in routers. Satellites don't have queues. I think those delays is what he is trying to measure. -- 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] Low-long-term-drift clock for board level integration?
Think trying to measure the distance between two distant moving spacecraft with no idea what the gravitational gradient is between them or the ability to measure the doppler. Unless, of course, Bill is doing much different things than he was when I last ran into him. :) On Mon, Feb 20, 2012 at 3:32 PM, Hal Murray hmur...@megapathdsl.net wrote: You may be able to do a similar thing in your receivers. For example if the master node were to send a timing message at known times (say once at the top of every hour) the receivers could use that to determine their local clock offset and rate for those cases where the path was the same (or maybe even for a list of paths). Nope. The problem is queuing delays in routers. Satellites don't have queues. I think those delays is what he is trying to measure. -- 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] How best to exchange Large files?
Time-nuts are welcome to use: http://www.c-c-i.com/exchange/ to exchange files. As the name says, the page is there to exchange files. The normal use would be to upload your file, tell people about it, let them download it, then delete it. Please note that the page is completely public. Anyone that knows about it (not many folks, actually) can see your files, download them, and delete them. Note the restriction on file types. Zip, gz, and tgz, among others, are supported. I would ask that after you have made a file available for a reasonable time that you go to the page and delete it. If you only want to make the file available to one person, ask them to delete it after they download it. If a file remains there more than a few weeks I may delete it. Best regards, -- Bob Smither, PhDCircuit Concepts, Inc. Bob, Thanks for the upload space, but when I go there, I don't see a box to enter the name of the file that I want to download, not a button to push that lets me download it. All I see on the page is a button to delete a file, a Browse box and button to upload a file. What am I doing wrong? Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ 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] How best to exchange Large files?
Brooke Clarke wrote: Hi: I've used: https://www.yousendit.com/ with no problems. Have Fun, Looks useful, but it appears to be mailing to a destination e-mail address. I know that some e-mail servers will not pass large files. Am I missing something? Thanks, -- = Bob Smither, PhD Circuit Concepts, Inc. America - born free, taxed to death ... smit...@c-c-i.com http://www.C-C-I.Com 281-331-2744(office) = attachment: smither.vcf___ 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] How best to exchange Large files?
I've used this http://free.mailbigfile.com/ for years. You upload the file and they send an email to the recipient who then downloads the file. Brent On 2/20/2012 10:52 AM, WarrenS wrote: I'm just looking for an easy, temporary way (say lasting up to a week each) to transfer a few big files that are too large to email. Suggestions anyone? Thanks ws ___ 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] How best to exchange Large files?
Bob Worked great for my long zip file, and a large. jpg Thanks very easy to use, this will be very helpful to me. still a little problem, It would NOT take my short .gif file unless I falsely renamed it with a .jpg extension ws Bob Smither smither at c-c-i.com Bob Smither wrote: After some changes, I was able to upload a 30 MB file with no problem. I will try a larger one later today. I just uploaded a 119 MB file - so the exchange page http://www.c-c-i.com/exchange/ seems to be working. -- Bob Smither, Ph.D. smither at c-c-i.com = ___ 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] How best to exchange Large files?
WarrenS wrote: Bob Worked great for my long zip file, and a large. jpg Thanks very easy to use, this will be very helpful to me. still a little problem, It would NOT take my short .gif file unless I falsely renamed it with a .jpg extension Thanks Warren! Should be fixed now. -- Bob Smither, Ph.D. smit...@c-c-i.com == I'm sorry I ever invented the Electoral College. - Al Gore 11/08/00 == attachment: smither.vcf___ 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] Low-long-term-drift clock for board level integration?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On Feb 20, 2012, at 8:34 AM, Achim Vollhardt wrote: what about White Rabbit? It delivers Gigabit Ethernet and precise (1nsec) timing over singlemode fiber. Ahah, but if I had singlemode fiber between locations all over the world, I wouldn't use it to measure the Internet, I'd use it to REPLACE THE INTERNET! :-) Seriously, though, thank you for the suggestion, but I'm guessing it'll be easier to start with NTP than with IEEE 1588, since the former assumes the Internet as its operational environment (which is what we actually have) rather than assuming a more predictable network with controlled latencies. -Bill -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJPQtNzAAoJEG+kcEsoi3+HpRIQAM4TK1s+gbXHORxSiXad6If3 FEC8x6GSayf52iRLrvqYcVk+w0oGeTg32eYN+7Zvb8lp75pnaoRP9nQu3Qn6GWZ8 p9LpNKNXR98dXqnH3/25P0xqnq/KPZXiEqOgEYIu8kU36DdlBcjnTEv5esyj1ogV 3uBGvvUMnqzCnrwnL24MJ/oWCEIR4DU6hd8i1gU/KPOA27KBLOFyyzMkRc+UydLo U5jimmzd7yJUotMY+4UrW0OYlny8xvJ5bh3PHa2ba9omohYMZsGEG2+NCJGy63K9 N2sBbyr0t3ylv0xO51S1bq76OkMnxhILrAyB2NrlFNUgTzDa4FnD4niKQ1BCY8em DBzJjX1Cf1zgwBUj7OE00RJ9UpZT7ylyfaKZwX4AkeBBxXQiJrS60nzFeJtU+Qx5 iEsXD49Z+VWxSshEvxLplvZlfa1iCka1sg1ictnD90gFYjyWgIExEUQ9BuF5VhdT 7UYB6tDJRuRUZWAXOP3k9YDhtP6q0xizDLOmfBziMfO/orm2l0PWj0v7LMTmVVmR FudQdAIAOznxstg87+L0wpgLUOU/wkoHZSmoU/oLgWV//75jQkqCm6a6B28giBUO W/xbusfA4UQQHtgOY6GOuIXBHCSRUE5Euub1usFff3H4G9TjvIYJs/EzuCXACZys HIgkSJuaTYB1n+N0Zl3S =IPHP -END PGP SIGNATURE- ___ 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] How best to exchange Large files?
Bob The gif files upload OK now but the ones with funny non standard names will not download for me. can you tell me which character it does not like? ws * [time-nuts] How best to exchange Large files? WarrenS wrote: Bob Worked great for my long zip file, and a large. jpg Thanks very easy to use, this will be very helpful to me. still a little problem, It would NOT take my short .gif file unless I falsely renamed it with a .jpg extension Thanks Warren! Should be fixed now. -- Bob Smither, Ph.D. Smither at c-c-i.com ___ 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] Low-long-term-drift clock for board level integration?
Hi Since the network is being measured, I suspect that using it as the time reference would present a basic problem. Bob On Feb 20, 2012, at 2:07 PM, Jim Lux jim...@earthlink.net wrote: On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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] Using digital broadcast TV for timing?
Does anyone know if ABC used Cesium or just Rubidium standards? I have the Tracor 304SC shown in this URL: http://www.bdairfield.com/stan/time-nuts/Tracor-304SC/IMG_4216.JPG I assume the SC in the model number stands for the color subcarrier frequency for NTSC: 3.579545 MHz. The boards seem to be mostly hand wired on turret pins, so I don't think they made very many. I usually try and clean up front panels and remove non-manufacturer stickers, but I thought the ABC New York, Rubidium 1 and ADJ May 21 84 were cool, so the stickers stayed. Under the top cover is a tag that says: Model 304-SC S/N 127 Frequency relative to USFS -300 X 10 ** -10 DATE 10-11-68 The front panel has a 5 MHz output, while the back has a 3.58 MC output. I'm told this unit no longer works. KO4BB does not have the manual on his site, if you know where one is, send me a link off list. If some folks know more about the history of network broadcast color subcarrier frequency standards, I think it's an interesting subject that would be worth hearing more about. Stan On Wed, Feb 8, 2012 at 7:07 PM, paul swed paulsw...@gmail.com wrote: All gone these days in the US. Indeed I can speak to the CBS network it was driven by CS references in the 80s and 90s. I used CBS for aligning my references Xtal oven oscillators that were never ever turned off in a large facility that uplinked all 8 CBS regions and 22 other cable networks. Unfortunately few could get to that color burst signal as devices called frame synchronizers came into play from the 80s to the 90s. They would strip off that burst and insert the local reference of generally much lower quality. As far as todays digital TV signals they can contain significant jitter. But its actually trickier then that and I honestly have to say I am not sure that you might not be able to get something useful. Several interesting points. Many of the television transmitters do use GPS referenced sources. Its an interesting exploration. I simply don't have the time though. Regards Paul WB8TSL On Wed, Feb 8, 2012 at 7:38 PM, jerryfi jerryfi...@yahoo.com wrote: A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time code in the signal and I'm pretty sure the bits are clocked at a very accurate rate. Also TV receivers are very easy to find and put hooks into. I'd bet the broadcast TV signal could be almost as good as GPS. The plan is to try and phase lock a local oscillator and use a very long time constant on the loop filter. I bet the TV transmitters are locked to GPS and over a long enough time are as good as GPS. Also in many cities there are many TV transmitters, should be able to take advantage of that. Before I try some experiments anyone want to tell me why I'm wrong? -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Low-long-term-drift clock for board level integration?
Hi Bob: It was my understanding that the receiving station knows the path taken, is that the case? Or are you saying even when it's the same path the time delay has large variations? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Bob Camp wrote: Hi Since the network is being measured, I suspect that using it as the time reference would present a basic problem. Bob On Feb 20, 2012, at 2:07 PM, Jim Luxjim...@earthlink.net wrote: On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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] Low-long-term-drift clock for board level integration?
The path is variable. Internet routing is constantly in flux as routes are injected and retracted. On Feb 20, 2012, at 19:56, Brooke Clarke bro...@pacific.net wrote: Hi Bob: It was my understanding that the receiving station knows the path taken, is that the case? Or are you saying even when it's the same path the time delay has large variations? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Bob Camp wrote: Hi Since the network is being measured, I suspect that using it as the time reference would present a basic problem. Bob On Feb 20, 2012, at 2:07 PM, Jim Luxjim...@earthlink.net wrote: On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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. ___ 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] Low-long-term-drift clock for board level integration?
bro...@pacific.net said: It was my understanding that the receiving station knows the path taken, is that the case? Or are you saying even when it's the same path the time delay has large variations? Even if the path is stable, the delays vary due to queuing delays in routers. The simple example is a router with 3 cables. Call them A, B, and C. Assume they are all the same speed. If B is idle, packets that come in on A can go out C right away. But suppose A and B are both sending traffic out C. If packets arrive at close to the same time, the second one will have to wait on a queue until the first one is finished. If a clump of packets arrives the queue can get longer. There is another source of queuing. That's when the link speed changes. Suppose the server has a 100 megabit connection, the backbone has gigabit links, and the last hop is 1 megabit. (just to pick some round numbers) If the server sends a clump of packets, they go out at 100 megabits, probably won't hit much queuing delay in the backbone, but then they pile up on the last hop. -- 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] Using digital broadcast TV for timing?
Stan By gosh that really is an old one. ABC very well could have been driven by a Rb ref. Though as I mentioned CBS was CS. So a bit hard to believe ABC and NBC were not. But I really simply do not remember. There had been a time when the networks were used for freq dissemination and thats why at least CBS had the CS. An alternate thought could be that it came from a local owned an operated station. And it was adjusted to the network. Some inside pixs would be pretty neat top see. Like you I chose to leave the USNO sticker on my sad but semi operational CS reference. Regards Paul WB8TSL On Mon, Feb 20, 2012 at 7:48 PM, Stan Searing timenuts...@gmail.com wrote: Does anyone know if ABC used Cesium or just Rubidium standards? I have the Tracor 304SC shown in this URL: http://www.bdairfield.com/stan/time-nuts/Tracor-304SC/IMG_4216.JPG I assume the SC in the model number stands for the color subcarrier frequency for NTSC: 3.579545 MHz. The boards seem to be mostly hand wired on turret pins, so I don't think they made very many. I usually try and clean up front panels and remove non-manufacturer stickers, but I thought the ABC New York, Rubidium 1 and ADJ May 21 84 were cool, so the stickers stayed. Under the top cover is a tag that says: Model 304-SC S/N 127 Frequency relative to USFS -300 X 10 ** -10 DATE 10-11-68 The front panel has a 5 MHz output, while the back has a 3.58 MC output. I'm told this unit no longer works. KO4BB does not have the manual on his site, if you know where one is, send me a link off list. If some folks know more about the history of network broadcast color subcarrier frequency standards, I think it's an interesting subject that would be worth hearing more about. Stan On Wed, Feb 8, 2012 at 7:07 PM, paul swed paulsw...@gmail.com wrote: All gone these days in the US. Indeed I can speak to the CBS network it was driven by CS references in the 80s and 90s. I used CBS for aligning my references Xtal oven oscillators that were never ever turned off in a large facility that uplinked all 8 CBS regions and 22 other cable networks. Unfortunately few could get to that color burst signal as devices called frame synchronizers came into play from the 80s to the 90s. They would strip off that burst and insert the local reference of generally much lower quality. As far as todays digital TV signals they can contain significant jitter. But its actually trickier then that and I honestly have to say I am not sure that you might not be able to get something useful. Several interesting points. Many of the television transmitters do use GPS referenced sources. Its an interesting exploration. I simply don't have the time though. Regards Paul WB8TSL On Wed, Feb 8, 2012 at 7:38 PM, jerryfi jerryfi...@yahoo.com wrote: A bit off topic, but historically related back in the 70's, I tapped off the color burst oscillator in my TV (a Heathkit) to get a 3.579545 MHz (315/88 MHz) source to calibrate my homebrew frequency counter. The TV's color burst oscillator was phase locked to the color burst signal on the broadcast signal (which was on the back porch of the hori sync signals). Supposedly, the networks were locked to Cesium standards traceable to NBS for LIVE broadcasts, such as news and sports. Taped programs, of course, were not usable as an accurate source. In any case, that signal served my purposes at the time (providing a reference for calibrating my counter that was more accurate than anything else available to me). I'm not sure if, what, or where analog TV is still broadcast, but I think there are still a few stations (low power) around. You might still be able to use that signal, IF you can dig it out of your old analog TV. ;-) I do have analog tv's hooked up to my cable box - I suspect that live broadcasts would still have an accurate color burst, so maybe I think the other methods discussed here (ie, GPS) would provide easier and more reliable timing sources. ;-) Trying to locate the appropriate signal(s) in a digital TV today would be interesting. Just as a historical aside. Jerry Finn Santa Maria, CA Date: Tue, 7 Feb 2012 18:01:26 -0800 From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Using digital broadcast TV for timing? Message-ID: cabbxvhvb3skzumx+bdykttesgzuf2k5hsjwypdkk+rqoarx...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 GPS requires a good view of the sky, Hard to do in say the 7th floor of a 40 story building if you have no windows. I'm wondering about using the new digital TV signals for timing. I'm pretty sure there is time
Re: [time-nuts] Low-long-term-drift clock for board level integration?
On Mon, Feb 20, 2012 at 12:13 PM, Brooke Clarke bro...@pacific.net wrote: You may be able to do a similar thing in your receivers. For example if the master node were to send a timing message at known times (say once at the top of every hour) the receivers could use that to determine their local clock offset and rate for those cases where the path was the same (or maybe even for a list of paths). The offset and rate numbers can be used to correct the measured time to actual time without changing the clock's rate using simple math. You can trade the receiver clock stability for the time between the timing messages. So you are suggesting a very simplified version of NTP. I doubt you'd do better than using real-NTP. It turns out the method works at the millisecond level but not at the uSec level unless everyone is on the same local Ethernet There is one way to improve timing but it only works if you have control of all the network equipment. This means it can't work on the Internet but it can work on some large networks. Use PTP. This is a little like NTP in that it uses a network for time distribution but has a slightly different method. Unlike NTP, for PTP you need special routers and switches built to support PTP but then PTP can support uSecond level timing over a wide area and NTP mostly can't http://en.wikipedia.org/wiki/Precision_Time_Protocol Chris Albertson Redondo Beach, California ___ 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] Low-long-term-drift clock for board level integration?
Even if the path is mapped the ques in the switches can change. Say your packet is first and the next trip its the 50th. Just depends on the overall network loading. This has been tried many times and there is the ability to get a feel on the timing. But not like GPS. Regards Paul. WB8TSL On Mon, Feb 20, 2012 at 8:40 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Mon, Feb 20, 2012 at 12:13 PM, Brooke Clarke bro...@pacific.net wrote: You may be able to do a similar thing in your receivers. For example if the master node were to send a timing message at known times (say once at the top of every hour) the receivers could use that to determine their local clock offset and rate for those cases where the path was the same (or maybe even for a list of paths). The offset and rate numbers can be used to correct the measured time to actual time without changing the clock's rate using simple math. You can trade the receiver clock stability for the time between the timing messages. So you are suggesting a very simplified version of NTP. I doubt you'd do better than using real-NTP. It turns out the method works at the millisecond level but not at the uSec level unless everyone is on the same local Ethernet There is one way to improve timing but it only works if you have control of all the network equipment. This means it can't work on the Internet but it can work on some large networks. Use PTP. This is a little like NTP in that it uses a network for time distribution but has a slightly different method. Unlike NTP, for PTP you need special routers and switches built to support PTP but then PTP can support uSecond level timing over a wide area and NTP mostly can't http://en.wikipedia.org/wiki/Precision_Time_Protocol Chris Albertson Redondo Beach, California ___ 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] How best to exchange Large files?
Time-nuts are welcome to use: http://www.c-c-i.com/exchange/ to exchange files. As the name says, the page is there to exchange files. The normal use would be to upload your file, tell people about it, let them download it, then delete it. Please note that the page is completely public. Anyone that knows about it (not many folks, actually) can see your files, download them, and delete them. Note the restriction on file types. Zip, gz, and tgz, among others, are supported. I would ask that after you have made a file available for a reasonable time that you go to the page and delete it. If you only want to make the file available to one person, ask them to delete it after they download it. If a file remains there more than a few weeks I may delete it. Best regards, -- Bob Smither, PhDCircuit Concepts, Inc. Bob, Thanks for the upload space, but when I go there, I don't see a box to enter the name of the file that I want to download, not a button to push that lets me download it. All I see on the page is a button to delete a file, a Browse box and button to upload a file. What am I doing wrong? Thanks for the fix, Bob. All I was seeing earlier were the column headings and a delete button, not a list of files available to download (perhaps because there weren't any files yet posted and available for download?). I understood how to upload a file.. .just wasn't clear how to specify and download a file. Cheers, Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ 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] Low-long-term-drift clock for board level integration?
Hi My understanding is that the path delay is what is being monitored. Bob On Feb 20, 2012, at 7:56 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: It was my understanding that the receiving station knows the path taken, is that the case? Or are you saying even when it's the same path the time delay has large variations? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Bob Camp wrote: Hi Since the network is being measured, I suspect that using it as the time reference would present a basic problem. Bob On Feb 20, 2012, at 2:07 PM, Jim Luxjim...@earthlink.net wrote: On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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. ___ 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] Low-long-term-drift clock for board level integration?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On Feb 20, 2012, at 11:07 AM, Jim Lux wrote: One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) Well, it's not a hard limit, it's a target at which our system would be performing at a level we'd be happy with. Obviously some measurements will be less accurate, others more so, and we get what we get. One of the primary reasons for doing link-by-link unidirectional delay measurement is to estimate the length or routing of cables. Each microsecond of inaccuracy is 650 feet of inaccuracy in the estimate. 650 feet isn't of any interest. But twelve miles (100 microseconds of inaccuracy) is starting to get up into the range where you might not be able to distinguish one city from another, for instance. One millisecond is 123 miles, and we might well be into another country or something at that point. Measuring queue depths and estimating degrees of resource contention or processing inside routers is a more complex topic, but similar in that it tends to still be interesting in the 100 microsecond range, but less so at another order of magnitude less precision. -Bill -BEGIN PGP SIGNATURE- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJPQvtsAAoJEG+kcEsoi3+HafsQAJQJAkux30PcrGkzcw2oZQNx 7xKXvGYA/V4Lnr11NpB/7x8JewiXvKC83iSLlJGRpmNC3Sy1egbbP13YMkfew83l YcOn5O5g+d336//EA/hj4lrQAslr3HGG7nayt7sIZPbLnkBuiWf4mv8YMUSi+f/B RMSeSCtGPbEwa7aqs6MmTZ4QKZIzE587v5nsoZFnN056NbE+kS2MrlF2Y5ll0apC cfE/RBAoYp3X8ev+Gh+C0jxHX4nfutDaS/vAcJub5o/WDW3rmn5yj7wztiDst2T/ 36ACCxAfll0EqbcmYQF97/rOiteLJOyJOjzOEXBrV/at2v66bYwENKRSwZYMRgVT tG/7+fgZ/DOFCPCjE/y/Ywgmfn5vAn+iNHaW3hUxi0xVgCidQwEZtVyqwrj8LC4Z XFKWG+eUwNLWAnCI2KZAJJFYHtaZooXlSQXuh4IwfCZPeD1by49u4aH6LRLbP1at eXghWWjhOL4WzGzGQFn/WnPLB+cYADzarNuQf3uk2e2DvgJh4/JJH3H/+IX2m7UF 4Vc6Cm3ojlhnMMbmdA5IUrpqawfGgd61y+7LEK3vjwK6x8XMWjNV/RL6JfSrrs/i JoxF1svN+HVYIykn2fSPjnaODbzw+BgtAweCZ22YtkECWQA7m0kFGqSDYe/s2xwG ddesTvAo4pZ+O7j6Lpl2 =149M -END PGP SIGNATURE- ___ 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] Low-long-term-drift clock for board level integration?
Even with a very minimal local Ethernet where the path is the same for every packet you still have variable timing. There are queues and buffers. Also it is not so easy to measure the time a network packet arrives at a computer. The serial port is the best hardware for timing. The DCD pin is directly tied to a hardware interrupt that has as low a latency as you will find on the PC. These is nothing like this hardware interrupt in the Ethernet controller. There is a way around this, some Ethernet controllers can time stamp the data packets in hardware. This can be used by PTP for timing that is almost as good as the serial port. So you add the uncertain timing because of queues to the un-abilty to accurately determine when the data pack arrives and you are stuck in the millisecond level On Mon, Feb 20, 2012 at 6:02 PM, Bob Camp li...@rtty.us wrote: Hi My understanding is that the path delay is what is being monitored. Bob On Feb 20, 2012, at 7:56 PM, Brooke Clarke bro...@pacific.net wrote: Hi Bob: It was my understanding that the receiving station knows the path taken, is that the case? Or are you saying even when it's the same path the time delay has large variations? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/Brooke4Congress.html Bob Camp wrote: Hi Since the network is being measured, I suspect that using it as the time reference would present a basic problem. Bob On Feb 20, 2012, at 2:07 PM, Jim Luxjim...@earthlink.net wrote: On 2/20/12 10:31 AM, Bob Camp wrote: Hi Simple answer: A rack mount cesium standard is as good as you can get. Figure on 15 ns per day of drift. That gets you to 15 us in 1000 days. You may or may not get one that drifts that little, a lot depends on little details. For 3 years, consider an ensemble of cesiums. At $50K each cost can go up pretty fast. There is nothing out there that will do better stand alone for less money. Either you get a sky view or you change the budget Bob But he *does* have the ability to have an external network connection.. So the real question is whether one could come up with a better-than-NTP scheme to get the 100 (or 10) microseconds. I suspect that with sufficiently controlled network paths (which might be doable in a widescale deployment) and a tweaking of the NTP stuff, you might be able to get it to work. 100 microseconds out of a day is 1E-10, which is actually a fairly liberal drift spec for an OCXO or even a TCXO. (which are things like ppb/day) Maybe there's a particular time of day (or day of week) when network uncertainties are minimal, or can be bounded. So what you really need is a onboard oscillator that is good at carry over between periodic calibration checks. One question about the 100 microsecond spec.. is that a worst case at any instant, or is it an average spec over a day (so a consistent diurnal variation would cancel out) ___ 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. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] How best to exchange Large files?
Hi: I've used: https://www.yousendit.com/ with no problems. Have Fun, Brooke Clarke .. but the limit on that service has changed from 100 MB down to 50 MB, making it rather less useful to me. Cheers, David -- SatSignal software - quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ 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] OP-Amps for 10MHz distribution...?
On Mon, Feb 20, 2012 at 7:32 PM, Steve iteratio...@gmail.com wrote: Decent frame? Plenty of internal room for tweaking? What make and model? You've got me interested! You have to keep watching, every day or two. thinks like this come up. Craigs list also it you live in a place with lots of video production Look up eBay item 250977591548. The description is still on the seller's page. I figured it was worth the cost to ship even if All I got as the metal case. The case cleaned up ok. the stickers and velcro came off. It is powered by a pair of LM7805 and LM7905. I can double the voltage with minor hardware hacking. parts are rated for more than triple voltage but that requires major hardware hacking. Steve ___ 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. -- Chris Albertson Redondo Beach, California ___ 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] OP-Amps for 10MHz distribution...?
Mike, op amps for that purpose should be available from a lot of companies. They are not created all equal. My latest own design of a distribution amp involves one AD8007 input stage with variable gain and 8 AD8007 output stages. This design is good for a channel to channel isolation of 90 dB and an output to input isolation of 113 dB. The AD8007 has VERY small distortion and I needed to build a lowpass/bandpass filter to measure it because NONE of my sources (HP3325/HP8660) was clean enough that it could match the AD8007. The -125 dBm noise floor of my sprectrum analyser were just enough to see any amplifier produced noise. The power supply design may be as important as the choice of amplifier. Best regards Ulrich Banget -Ursprungliche Nachricht- Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Michael Baker Gesendet: Montag, 20. Februar 2012 17:28 An: time-nuts@febo.com Betreff: [time-nuts] OP-Amps for 10MHz distribution...? Hello, Time-Nutters-- Here is a link to a TI app note on using op-amps for RF. It occurred to me that this might work OK for distribution of the ref freq from a GPSDO... http://www.ti.com/lit/an/slyt102/slyt102.pdf Mike Baker --- ___ 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.
