[time-nuts] Accurate timestamping on computers (previously: For my whole life timezones have been weird)
On 11/3/2012 5:32 AM, Sarah White wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. Would be nice if windows 7 had an update to fix this issue: http://support.microsoft.com/kb/2687252 Article ID: 2687252 - Last Review: March 13, 2012 - Revision: 4.0 APPLIES TO Microsoft Windows XP Home Edition Microsoft Windows XP Professional Microsoft Windows XP Service Pack 3 Windows Vista Business Windows Vista Enterprise Windows Vista Home Premium Windows Vista Ultimate Windows Vista Service Pack 1 Windows Vista Service Pack 2 Windows 7 Enterprise Windows 7 Home Basic Windows 7 Home Premium Windows 7 Professional Windows 7 Ultimate Windows 7 Service Pack 1 Windows Server 2008 Datacenter Windows Server 2008 Enterprise Windows Server 2008 Standard Windows Server 2008 Service Pack 2 Windows Server 2008 R2 Datacenter Windows Server 2008 R2 Enterprise Windows Server 2008 R2 Standard Windows Server 2008 R2 Service Pack 1 Microsoft Windows Server 2003 Service Pack 2 ... Pretty sure that's 100% of all recent versions of windows. The whole thing started because windows 3.1 / 95 / 98 / 2000 / ME / etc. etc. etc. were all targeted with being backward compatible with the previous OS leading all the way back to DOS (first versions of DOS were coming out in 1981 the year I was born) For where I live, this weekend is the change your clocks for the fall... or don't, or do something else... petition microsoft maybe? I'd love for windows 7 to have a fix for this since I'm not upgrading to the horrible looking windows 8 --- windows 7 will be in extended support until 2020 (( reference: http://goo.gl/unxvj )) so I figure let's try to get them to fix it in the next few years. I'm serious about this. Let's fix this timezone problem!!! Pretty much every other operating system vendor out there (various POSIX platforms including more than one version of BSD, linux and even mac OSX since under the hood it is a POSIX based operating system) it is an option to leave the hardeware real-time-clock (bios clock) on UTC. Ok that's all I'm typing on this. Angry at several of my clocks today, Sarah White There are a number of reasons it can be problematic for an OS to change the hardware clock twice a year. Example being that sometimes is if you dual-boot more than one version of windows, both of them will try to adjust the clock. Historically, more than one machine I've run has had a glitch where the clock was set forward more than just a single hour adjustment due to dual-boot or just crash during reboots when summer time was being set/unset. Plenty can go wrong. It's just not anything I want to worry about / shouldn't be necessary (mac, linux, bsd, etc. don't have this flaw because they typically have the hardware clock set to UTC, and use software settings to display the local time by calculating offset) ...Someone contacted me offlist and pointed out that there is no reason I can't tell windows that I'm in a timezone that uses UTC (without summer time / daylight savings time adjustment) The workaround varies by windows version, but for me it looks basically like this: http://inkushi.freeshell.org/Saturday_November_03_2012_555_UTC_Protest.png http://inkushi.freeshell.org/Saturday_November_03_2012_637_UTC_Workaround.png Basically, a side effect is that windows is now reporting UTC as being local time even though that is NOT my desired local clock for display and other purposes. This was the only workaround I knew for certain would keep my hardware clock set to UTC. My emails are now being timestamped with UTC as a result. Shouldn't confuse me too badly, but this is the most optimal way I could come up with. I don't want to have to think about the behavior / performance of my NTP time synchronization twice a year. This is the main reason (for me) it is an issue. So maybe I really am a little bit nuts (about time too) Sarah White P.S. For windows 7, default tray / notification icon settings: All of the relevant settings are available by simply clicking the clock in the corner. Can even add additional clocks to display alternate timezones and name them whatever you like. Unfortunately, most software now reports the local clock wrong, and the only way I seem to be able to view local time is by using the windows clock / calendar applet in the corner of the taskbar (tray area) Whatever. For my purposes it was more important to have the hardware clock not be tampered with twice a year by the OS ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go
Re: [time-nuts] For my whole life timezones have been weird
Dear Sarah, Good morning. I just returned home from a long and difficult customer data center migration. I thought of sharing that I feel the same way as you do regarding your thread. Things should always behave like a Mac or Linux, in which if there is a glitch, the OS responsible party jumps into scene with a solution. Not the way it happens and builds your frustration with Windows. Food for thought, just an example of someone supporting their OS user base on a similar topic. To err is human, to fix the errors should also be: http://support.apple.com/kb/TA24568?viewlocale=en_US Cheers, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Nov 2, 2012, at 11:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. Would be nice if windows 7 had an update to fix this issue: http://support.microsoft.com/kb/2687252 Article ID: 2687252 - Last Review: March 13, 2012 - Revision: 4.0 APPLIES TO Microsoft Windows XP Home Edition Microsoft Windows XP Professional Microsoft Windows XP Service Pack 3 Windows Vista Business Windows Vista Enterprise Windows Vista Home Premium Windows Vista Ultimate Windows Vista Service Pack 1 Windows Vista Service Pack 2 Windows 7 Enterprise Windows 7 Home Basic Windows 7 Home Premium Windows 7 Professional Windows 7 Ultimate Windows 7 Service Pack 1 Windows Server 2008 Datacenter Windows Server 2008 Enterprise Windows Server 2008 Standard Windows Server 2008 Service Pack 2 Windows Server 2008 R2 Datacenter Windows Server 2008 R2 Enterprise Windows Server 2008 R2 Standard Windows Server 2008 R2 Service Pack 1 Microsoft Windows Server 2003 Service Pack 2 ... Pretty sure that's 100% of all recent versions of windows. The whole thing started because windows 3.1 / 95 / 98 / 2000 / ME / etc. etc. etc. were all targeted with being backward compatible with the previous OS leading all the way back to DOS (first versions of DOS were coming out in 1981 the year I was born) For where I live, this weekend is the change your clocks for the fall... or don't, or do something else... petition microsoft maybe? I'd love for windows 7 to have a fix for this since I'm not upgrading to the horrible looking windows 8 --- windows 7 will be in extended support until 2020 (( reference: http://goo.gl/unxvj )) so I figure let's try to get them to fix it in the next few years. I'm serious about this. Let's fix this timezone problem!!! Pretty much every other operating system vendor out there (various POSIX platforms including more than one version of BSD, linux and even mac OSX since under the hood it is a POSIX based operating system) it is an option to leave the hardeware real-time-clock (bios clock) on UTC. Ok that's all I'm typing on this. Angry at several of my clocks today, Sarah White ___ 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
Sarah, I am having a hard time understanding your problem. Or at least what you see as a problem. I am not sure what you are really complaining about here ? Is it the daylight change ? Or is it a dual boot problem which would suggest you do not have some settings in their rightful place ? The computer is merely displaying a form of time representation on the screen (human device). Internally, it seems to me, the computer's operating system is merely keeping a count of the passing seconds since reading the actual hardware, hardwired clock chip upon boot-up. After the initial boot it no longer reads the hardware clock chip to my understanding. If that is the case, it would suggest that a flag is recorded as to the daylight savings time change either in firmware or perhaps on the mass storage device that has the operating system. It is possible that the hardwired clock chip may keep track of the daylight savings function. If that is the case, perhaps the way to deal with it is to write a a small program that will make sure that hardwired chip stays in the NON daylight mode as part of a boot-up routine. As for the microsoft reference, it suggests not using a particular registry entry and if it is there to delete it. On my computer it is not present in the registry. While that only fixes some kind of system unresponsiveness issue, it does not seem to keep the daylight function from changing. With all the clock Synching available via the internet, it seems to me your clock should not be an issue in of itself. However, I am retired, as such, do not have a watch and pay little attention to the wall clock. BillWB6BNQ Sarah White wrote: On 11/3/2012 5:32 AM, Sarah White wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. Would be nice if windows 7 had an update to fix this issue: http://support.microsoft.com/kb/2687252 Article ID: 2687252 - Last Review: March 13, 2012 - Revision: 4.0 APPLIES TO Microsoft Windows XP Home Edition Microsoft Windows XP Professional Microsoft Windows XP Service Pack 3 Windows Vista Business Windows Vista Enterprise Windows Vista Home Premium Windows Vista Ultimate Windows Vista Service Pack 1 Windows Vista Service Pack 2 Windows 7 Enterprise Windows 7 Home Basic Windows 7 Home Premium Windows 7 Professional Windows 7 Ultimate Windows 7 Service Pack 1 Windows Server 2008 Datacenter Windows Server 2008 Enterprise Windows Server 2008 Standard Windows Server 2008 Service Pack 2 Windows Server 2008 R2 Datacenter Windows Server 2008 R2 Enterprise Windows Server 2008 R2 Standard Windows Server 2008 R2 Service Pack 1 Microsoft Windows Server 2003 Service Pack 2 ... Pretty sure that's 100% of all recent versions of windows. The whole thing started because windows 3.1 / 95 / 98 / 2000 / ME / etc. etc. etc. were all targeted with being backward compatible with the previous OS leading all the way back to DOS (first versions of DOS were coming out in 1981 the year I was born) For where I live, this weekend is the change your clocks for the fall... or don't, or do something else... petition microsoft maybe? I'd love for windows 7 to have a fix for this since I'm not upgrading to the horrible looking windows 8 --- windows 7 will be in extended support until 2020 (( reference: http://goo.gl/unxvj )) so I figure let's try to get them to fix it in the next few years. I'm serious about this. Let's fix this timezone problem!!! Pretty much every other operating system vendor out there (various POSIX platforms including more than one version of BSD, linux and even mac OSX since under the hood it is a POSIX based operating system) it is an option to leave the hardeware real-time-clock (bios clock) on UTC. Ok that's all I'm typing on this. Angry at several of my clocks today, Sarah White There are a number of reasons it can be problematic for an OS to change the hardware clock twice a year. Example being that sometimes is if you dual-boot more than one version of windows, both of them will try to adjust the clock. Historically, more than one machine I've run has had a glitch where the clock was set forward more than just a single hour adjustment due to dual-boot or just crash during reboots when summer time was being set/unset. Plenty can go wrong. It's just not anything I want to worry about / shouldn't be necessary (mac, linux, bsd, etc. don't have this flaw because they typically have the hardware clock set to UTC, and use software settings to display the local time by
Re: [time-nuts] For my whole life timezones have been weird
On 11/3/2012 8:02 AM, Edgardo Molina wrote: Dear Sarah, Good morning. I just returned home from a long and difficult customer data center migration. I thought of sharing that I feel the same way as you do regarding your thread. Things should always behave like a Mac or Linux, in which if there is a glitch, the OS responsible party jumps into scene with a solution. Not the way it happens and builds your frustration with Windows. Food for thought, just an example of someone supporting their OS user base on a similar topic. To err is human, to fix the errors should also be: http://support.apple.com/kb/TA24568?viewlocale=en_US Cheers, Edgardo Molina Dirección IPTEL Microsoft puts out timezone updates too. The difference is, apple's version of the same doesn't adjust the hardware clock. https://wiki.archlinux.org/index.php/Time#Time_standard The localtime standard is what I'm wanting to get away from. Unfortunately, on windows there is no way to do this and still display the local time correctly. --Sarah ___ 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] For my whole life timezones have been weird
Microsoft also does updates regarding the day daylight savings time changes, similar to that Apple message. I suspect I'm not following this thread correctly. What I got from the orignal thread is Microsoft will thunk the RTC during the switchover. I'm going to make it a point to insure NTP is logging correctly, and then look for a time error at the switch over. (2AM I think.) -Original Message- From: Edgardo Molina xe1...@amsat.org Sender: time-nuts-boun...@febo.com Date: Sat, 3 Nov 2012 02:02:47 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: Re: [time-nuts] For my whole life timezones have been weird Dear Sarah, Good morning. I just returned home from a long and difficult customer data center migration. I thought of sharing that I feel the same way as you do regarding your thread. Things should always behave like a Mac or Linux, in which if there is a glitch, the OS responsible party jumps into scene with a solution. Not the way it happens and builds your frustration with Windows. Food for thought, just an example of someone supporting their OS user base on a similar topic. To err is human, to fix the errors should also be: http://support.apple.com/kb/TA24568?viewlocale=en_US Cheers, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Nov 2, 2012, at 11:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. Would be nice if windows 7 had an update to fix this issue: http://support.microsoft.com/kb/2687252 Article ID: 2687252 - Last Review: March 13, 2012 - Revision: 4.0 APPLIES TO Microsoft Windows XP Home Edition Microsoft Windows XP Professional Microsoft Windows XP Service Pack 3 Windows Vista Business Windows Vista Enterprise Windows Vista Home Premium Windows Vista Ultimate Windows Vista Service Pack 1 Windows Vista Service Pack 2 Windows 7 Enterprise Windows 7 Home Basic Windows 7 Home Premium Windows 7 Professional Windows 7 Ultimate Windows 7 Service Pack 1 Windows Server 2008 Datacenter Windows Server 2008 Enterprise Windows Server 2008 Standard Windows Server 2008 Service Pack 2 Windows Server 2008 R2 Datacenter Windows Server 2008 R2 Enterprise Windows Server 2008 R2 Standard Windows Server 2008 R2 Service Pack 1 Microsoft Windows Server 2003 Service Pack 2 ... Pretty sure that's 100% of all recent versions of windows. The whole thing started because windows 3.1 / 95 / 98 / 2000 / ME / etc. etc. etc. were all targeted with being backward compatible with the previous OS leading all the way back to DOS (first versions of DOS were coming out in 1981 the year I was born) For where I live, this weekend is the change your clocks for the fall... or don't, or do something else... petition microsoft maybe? I'd love for windows 7 to have a fix for this since I'm not upgrading to the horrible looking windows 8 --- windows 7 will be in extended support until 2020 (( reference: http://goo.gl/unxvj )) so I figure let's try to get them to fix it in the next few years. I'm serious about this. Let's fix this timezone problem!!! Pretty much every other operating system vendor out there (various POSIX platforms including more than one version of BSD, linux and even mac OSX since under the hood it is a POSIX based operating system) it is an option to leave the hardeware real-time-clock (bios clock) on UTC. Ok that's all I'm typing on this. Angry at several of my clocks today, Sarah White ___
Re: [time-nuts] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
On 11/3/2012 8:26 AM, WB6BNQ wrote: Sarah, I am having a hard time understanding your problem. Or at least what you see as a problem. I am not sure what you are really complaining about here ? Is it the daylight change ? Or is it a dual boot problem which would suggest you do not have some settings in their rightful place ? The computer is merely displaying a form of time representation on the screen (human device). Internally, it seems to me, the computer's operating system is merely keeping a count of the passing seconds since reading the actual hardware, hardwired clock chip upon boot-up. After the initial boot it no longer reads the hardware clock chip to my understanding. If that is the case, it would suggest that a flag is recorded as to the daylight savings time change either in firmware or perhaps on the mass storage device that has the operating system. It is possible that the hardwired clock chip may keep track of the daylight savings function. If that is the case, perhaps the way to deal with it is to write a a small program that will make sure that hardwired chip stays in the NON daylight mode as part of a boot-up routine. As for the microsoft reference, it suggests not using a particular registry entry and if it is there to delete it. On my computer it is not present in the registry. While that only fixes some kind of system unresponsiveness issue, it does not seem to keep the daylight function from changing. With all the clock Synching available via the internet, it seems to me your clock should not be an issue in of itself. However, I am retired, as such, do not have a watch and pay little attention to the wall clock. BillWB6BNQ begin reply 1 @ Bill / WB6BNQ wb6...@cox.net The hardware chip does not do any such tracking of the daylight savings time Here is a reference better explaining the problem: http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html begin reply 2 On 11/3/2012 8:38 AM, li...@lazygranch.com wrote: Microsoft also does updates regarding the day daylight savings time changes, similar to that Apple message. I suspect I'm not following this thread correctly. What I got from the orignal thread is Microsoft will thunk the RTC during the switchover. I'm going to make it a point to insure NTP is logging correctly, and then look for a time error at the switch over. (2AM I think.) @ li...@lazygranch.com Correct. This is the primary concern. Tweaking the clock twice a year to match up with local time is not desired. Seeing as I'm in the process of installing a hardware refclock (trimble thunderbolt connected via serial port) for my NTP, it is highly problematic and potentially error-prone for microsoft's OS to touch the bios hardware clock AT ALL. I'm entertaining the notion of writing a kernel-mode hardware timestamp / PPSAPI driver to pull the signal off the 1 PPS port on the tbolt one way or another. I plan to do this on windows. This is something I want to attempt even though the NT kernel doesn't have the best reputation for realtime hardware / interrupt handling. Plan is to put in a non-zero amount of work, up to and including steps where I go through the driver signing run-around with microsoft to actually have it fully recognized by the OS without modification. (unless budget issues are a limiting factor) ... Possibly, this project could even using a board which physically goes on in a PCI express bus slot in order to do hardware timestamping. ___ 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
-Original Message- From: Sarah White [] Seeing as I'm in the process of installing a hardware refclock (trimble thunderbolt connected via serial port) for my NTP, it is highly problematic and potentially error-prone for microsoft's OS to touch the bios hardware clock AT ALL. I'm entertaining the notion of writing a kernel-mode hardware timestamp / PPSAPI driver to pull the signal off the 1 PPS port on the tbolt one way or another. I plan to do this on windows. This is something I want to attempt even though the NT kernel doesn't have the best reputation for realtime hardware / interrupt handling. Plan is to put in a non-zero amount of work, up to and including steps where I go through the driver signing run-around with microsoft to actually have it fully recognized by the OS without modification. (unless budget issues are a limiting factor) [] Sarah, I don't know which version of Windows you are proposing to use, but I have NTP stratum-1 servers based on GPS devices with a PPS signal on the DCD line of the COM port, and Windows altering, or not altering, the hardware clock has /no effect/ at all. I'm using Dave Hart's serialPPS.sys device driver on Windows-2000 up to Windows-7/64 (including telling Win-7/64 to ignore the signed 64-bit driver requirement). GPS hardware: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Sure-GPS.htm Windows stratum-1 notes: http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html I would note that for the best performance on a stratum-1 server you may want to try FreeBSD or even Linux on a Raspberry Pi. http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html If Dave Hart's driver suits your needs, I'm sure he would be interested in getting it signed for Microsoft use (if he hasn't already done so). 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
On 11/3/2012 9:18 AM, David J Taylor wrote: -Original Message- From: Sarah White [] Seeing as I'm in the process of installing a hardware refclock (trimble thunderbolt connected via serial port) for my NTP, it is highly problematic and potentially error-prone for microsoft's OS to touch the bios hardware clock AT ALL. I'm entertaining the notion of writing a kernel-mode hardware timestamp / PPSAPI driver to pull the signal off the 1 PPS port on the tbolt one way or another. I plan to do this on windows. This is something I want to attempt even though the NT kernel doesn't have the best reputation for realtime hardware / interrupt handling. Plan is to put in a non-zero amount of work, up to and including steps where I go through the driver signing run-around with microsoft to actually have it fully recognized by the OS without modification. (unless budget issues are a limiting factor) [] Sarah, I don't know which version of Windows you are proposing to use, but I have NTP stratum-1 servers based on GPS devices with a PPS signal on the DCD line of the COM port, and Windows altering, or not altering, the hardware clock has /no effect/ at all. I'm using Dave Hart's serialPPS.sys device driver on Windows-2000 up to Windows-7/64 (including telling Win-7/64 to ignore the signed 64-bit driver requirement). GPS hardware: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Sure-GPS.htm Windows stratum-1 notes: http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html I would note that for the best performance on a stratum-1 server you may want to try FreeBSD or even Linux on a Raspberry Pi. http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html If Dave Hart's driver suits your needs, I'm sure he would be interested in getting it signed for Microsoft use (if he hasn't already done so). Cheers, David Thanks so much David... Really. Thanks. I feel alot better now. Regardless of documented issues on: http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html (quote) The numerous past malfunctions of Microsoft operating systems caused by keeping local time in the RTC and trying to cleverly perform the RTC adjustment semi-automatically have been repeatedly the subject of concerned public discussion: RISKS 16.54.1 RISKS 18.96.3 RISKS 19.11.16, RISKS 19.12.14 RISKS 19.43.13, RISKS 19.43.14, RISKS 22.34.3... (multiple links) Not sure what timezone you're in... ... So I don't know which day your summer time ends this year. I'd love to see the your loopstats file for as many of your windows boxes as possible (with refclock, or without. Either is fine.) for the day of the DST update this fall (and maybe any other loopstats data from when the realtime clock got updated due to summer time / DST updates) According to: http://www.satsignal.eu/mrtg/daily_ntp.html (section: Hardware and OS configuration) I'm assuming the relevant list is: feenix, stamsund, bacchus, narvik, alta, molde, ystad, puffin, and any other NT-5.x / NT 6.x based kernel (windows machines) I missed. Wow that's a wonderfully diverse list :) I actually thought about it a bit, and in hindsight I'm realizing that internally, NTP uses a synthetic timebase anyway. Perhaps I was being paranoid after all. Thanks for the reply, Sarah White P.S. Your site has always had great documentation about NTP configurations with a GPS-type reflock since I first saw it a couple years ago. I've found it very useful. ___ 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] For my whole life timezones have been weird
Windows actually CHANGES the RTC at DST changover, rather than let it tick montinically, and adjust the offset. This is what is bad ... Dave Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of li...@lazygranch.com Sent: 03 November 2012 08:38 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] For my whole life timezones have been weird Microsoft also does updates regarding the day daylight savings time changes, similar to that Apple message. I suspect I'm not following this thread correctly. What I got from the orignal thread is Microsoft will thunk the RTC during the switchover. I'm going to make it a point to insure NTP is logging correctly, and then look for a time error at the switch over. (2AM I think.) ___ 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
-Original Message- From: Sarah White Sent: Saturday, November 03, 2012 9:49 AM Thanks so much David... Really. Thanks. I feel alot better now. Regardless of documented issues on: http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html (quote) The numerous past malfunctions of Microsoft operating systems caused by keeping local time in the RTC and trying to cleverly perform the RTC adjustment semi-automatically have been repeatedly the subject of concerned public discussion: RISKS 16.54.1 RISKS 18.96.3 RISKS 19.11.16, RISKS 19.12.14 RISKS 19.43.13, RISKS 19.43.14, RISKS 22.34.3... (multiple links) Not sure what timezone you're in... ... So I don't know which day your summer time ends this year. I'd love to see the your loopstats file for as many of your windows boxes as possible (with refclock, or without. Either is fine.) for the day of the DST update this fall (and maybe any other loopstats data from when the realtime clock got updated due to summer time / DST updates) According to: http://www.satsignal.eu/mrtg/daily_ntp.html (section: Hardware and OS configuration) I'm assuming the relevant list is: feenix, stamsund, bacchus, narvik, alta, molde, ystad, puffin, and any other NT-5.x / NT 6.x based kernel (windows machines) I missed. Wow that's a wonderfully diverse list :) I actually thought about it a bit, and in hindsight I'm realizing that internally, NTP uses a synthetic timebase anyway. Perhaps I was being paranoid after all. Thanks for the reply, Sarah White P.S. Your site has always had great documentation about NTP configurations with a GPS-type reflock since I first saw it a couple years ago. I've found it very useful. Sarah, There's really no issue over the hour change as NTP and Windows work in UTC internally, nevertheless, for your interest some loopstats are here: http://www.satsignal.eu/ntp/2012-10-28-loopstats.zip I'm in UTC here, colloquially GMT/BST and we swap on the last Sunday of October. My PCs all run with wall clock time displayed, and UTC internally (just the normal Windows default). The RTC is only consulted at system boot time, so with systems running 24 x 7 there's no issue. None of my systems multi-boot normally, just possibly the odd test PC may have Win-7 and Win-8 installed. I'm delighted that you find the site useful! 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
On 11/3/2012 11:31 AM, David J Taylor wrote: -Original Message- From: Sarah White Sent: Saturday, November 03, 2012 9:49 AM Thanks so much David... Really. Thanks. I feel alot better now. Regardless of documented issues on: http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html (quote) The numerous past malfunctions of Microsoft operating systems caused by keeping local time in the RTC and trying to cleverly perform the RTC adjustment semi-automatically have been repeatedly the subject of concerned public discussion: RISKS 16.54.1 RISKS 18.96.3 RISKS 19.11.16, RISKS 19.12.14 RISKS 19.43.13, RISKS 19.43.14, RISKS 22.34.3... (multiple links) Not sure what timezone you're in... ... So I don't know which day your summer time ends this year. I'd love to see the your loopstats file for as many of your windows boxes as possible (with refclock, or without. Either is fine.) for the day of the DST update this fall (and maybe any other loopstats data from when the realtime clock got updated due to summer time / DST updates) According to: http://www.satsignal.eu/mrtg/daily_ntp.html (section: Hardware and OS configuration) I'm assuming the relevant list is: feenix, stamsund, bacchus, narvik, alta, molde, ystad, puffin, and any other NT-5.x / NT 6.x based kernel (windows machines) I missed. Wow that's a wonderfully diverse list :) I actually thought about it a bit, and in hindsight I'm realizing that internally, NTP uses a synthetic timebase anyway. Perhaps I was being paranoid after all. Thanks for the reply, Sarah White P.S. Your site has always had great documentation about NTP configurations with a GPS-type reflock since I first saw it a couple years ago. I've found it very useful. Sarah, There's really no issue over the hour change as NTP and Windows work in UTC internally, nevertheless, for your interest some loopstats are here: http://www.satsignal.eu/ntp/2012-10-28-loopstats.zip I'm in UTC here, colloquially GMT/BST and we swap on the last Sunday of October. My PCs all run with wall clock time displayed, and UTC internally (just the normal Windows default). The RTC is only consulted at system boot time, so with systems running 24 x 7 there's no issue. None of my systems multi-boot normally, just possibly the odd test PC may have Win-7 and Win-8 installed. I'm delighted that you find the site useful! Cheers, David Great, thanks for the loopstats. For the included loopstats, I believe Alta was among the ones on which you were running windows 7 + NTP... Would you mind confirming which setting you have for your timezone? (since I'm reasonably certain I know what the timezone menus would look like) http://inkushi.freeshell.org/bst.png http://inkushi.freeshell.org/utc.png Windows has more than one entry for most UTC offsets (DST schedule varies by hemisphere, country, some don't have summer time at all, etc.) ... so the timezone I personally have selected is the UTC option without a summer time adjustment (never set to UTC+01 / BST) ... Also, curious what you mean when you say you have wall clock time displayed (UTC internally) ... ? --Sarah ___ 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] A counter for phase measures
Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? Thanks Volker - DF9PL Am 02.11.2012 16:32, schrieb Volker Esper: Dear fellows, I'm searching for a counter that allows me to make automated measure series. Of course, Allan Deviation is an important thing to determine when experimenting with or developing GPSDOs (what I intend). So it seemed to be a nice thing to measure phase deviation with a counter (HP 53132A or SR-620 or so). When experimenting with that stuff I discovered, that all my equipment would not be adequate to determine Allan Deviations beyond 10e-11 (or so). The question is, can any counter deliver that precision / low noise to make such measurements possible? Or does it have to be a more sophisticated technique, such as cross spectrum analysis? Thanks a lot in advance Volker (I guess you recognize, that I am just a newbie to that all) ___ 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
-Original Message- From: Sarah White Great, thanks for the loopstats. For the included loopstats, I believe Alta was among the ones on which you were running windows 7 + NTP... Would you mind confirming which setting you have for your timezone? (since I'm reasonably certain I know what the timezone menus would look like) http://inkushi.freeshell.org/bst.png http://inkushi.freeshell.org/utc.png Windows has more than one entry for most UTC offsets (DST schedule varies by hemisphere, country, some don't have summer time at all, etc.) ... so the timezone I personally have selected is the UTC option without a summer time adjustment (never set to UTC+01 / BST) ... Also, curious what you mean when you say you have wall clock time displayed (UTC internally) ... ? --Sarah = Sarah, PC Alta is Win-7/64, with a GPS/PPS ref-clock using Dave Hart's serialPPS.sys device driver. The time-zone on all my PCs is London, Edinburgh, Dublin, which implies GMT (i.e. UTC) in the Winter and BST - British Summer Time - (UTC+1) in the Summer. I.e. http://inkushi.freeshell.org/bst.png What I mean by wall-clock time is that I have the standard settings in the control panel, i.e. telling Windows that I am located in Edinburgh so that the time displayed by normal applications alters with the season, and that the time agrees with normal wall-clock time. This is nothing special, and how almost all PCs in the UK would be set. I mean that I have /not/ set Casablanca where there both Summer and Winter are UTC. I did have one PC set to UTC only and NTP ran equally well on it. As I mentioned, internally Windows runs on UTC, and a program can interrogate that time. Windows also provides offsets so that UTC can be converted to local (wall-clock) time for display within applications. NTP uses the internal UTC time and is unaffected by time-zone or seasonal changes. 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] A counter for phase measures
On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
On 11/03/2012 05:05 AM, Sarah White wrote: Seeing as I'm in the process of installing a hardware refclock (trimble thunderbolt connected via serial port) for my NTP, it is highly problematic and potentially error-prone for microsoft's OS to touch the bios hardware clock AT ALL. Just in case it isn't perfectly clear from the other replies, the hardware RTC is not used for timekeeping while the system is running. There are a number of other timers in your typical PC which are used for actual operational purposes, e.g. HPET and TSC. These tick fast enough (10MHz) that the OS kernel can discipline them in software by altering the number of ticks considered to comprise a second. As far as I know none have a voltage-controlled oscillator but that would certainly be interesting :-) The RTC's current purpose is to keep time while the system is off, as it can run for many years from a lithium coin cell, and to wake the system at a scheduled time if desired. Adjusting the RTC will have no impact whatsoever on the running system clock(s) and, as pointed out elsewhere, internally even Windows keeps time in UTC. That said, I'm all for storing UTC in the RTC for more practical reasons, e.g. dual-boot compatibility and avoiding shenanigans if the power is cut during the changeover window. Maybe someday they will be sufficiently motivated to cut their ties to the past. -- m. tharp ___ 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] For my whole life timezones have been weird
On Fri, Nov 2, 2012 at 10:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. I always wonder why people continue to use MS Windows. Perhaps thheir employers force them to. But other than that why? I went to a meetig once where Bill Gate talked about the new OS called MS-DOS At that time I already had a reasonable education in computer science and was working the systems software for multi-user systems and networking.What absolutly amazzed me was the Gates said his plan was to make DOS more and more nix-like over the years. Then he went on to say what thatment and it was clear he did NOT know the difference between an operating system and a shell. He absolutely didn't. That is the root cause of all Window's problems. The company was run be a chief software architect who technically very ignorant and lacked any formal education in the subject. Windows still suffers because it tries to maintain backwards compatabilty You have to remember that in 1980 we have computers that would allow 100 people to simultainiously log in and do work from 100 different termmiansl. We have the Internet (called arpanet back then. We had email and UNIX was alive and well. We even had mice and track balls This was not the dark ages the only real difference was the price of hardware. And in this age gates did NOT know the difference between an OS and a command shell and he was running Microsoft. 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] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
On 11/3/2012 3:12 PM, David J Taylor wrote: -Original Message- From: Sarah White Great, thanks for the loopstats. For the included loopstats, I believe Alta was among the ones on which you were running windows 7 + NTP... Would you mind confirming which setting you have for your timezone? (since I'm reasonably certain I know what the timezone menus would look like) http://inkushi.freeshell.org/bst.png http://inkushi.freeshell.org/utc.png Windows has more than one entry for most UTC offsets (DST schedule varies by hemisphere, country, some don't have summer time at all, etc.) ... so the timezone I personally have selected is the UTC option without a summer time adjustment (never set to UTC+01 / BST) ... Also, curious what you mean when you say you have wall clock time displayed (UTC internally) ... ? --Sarah = Sarah, PC Alta is Win-7/64, with a GPS/PPS ref-clock using Dave Hart's serialPPS.sys device driver. The time-zone on all my PCs is London, Edinburgh, Dublin, which implies GMT (i.e. UTC) in the Winter and BST - British Summer Time - (UTC+1) in the Summer. I.e. http://inkushi.freeshell.org/bst.png What I mean by wall-clock time is that I have the standard settings in the control panel, i.e. telling Windows that I am located in Edinburgh so that the time displayed by normal applications alters with the season, and that the time agrees with normal wall-clock time. This is nothing special, and how almost all PCs in the UK would be set. I mean that I have /not/ set Casablanca where there both Summer and Winter are UTC. I did have one PC set to UTC only and NTP ran equally well on it. As I mentioned, internally Windows runs on UTC, and a program can interrogate that time. Windows also provides offsets so that UTC can be converted to local (wall-clock) time for display within applications. NTP uses the internal UTC time and is unaffected by time-zone or seasonal changes. Cheers, David Ah. Ok, cool. I guess the synthetic timebase used by NTP is probably doing what it was meant to do (ignore inconsistency in the RTC under various circumstances) By the way, I suspect that you didn't know that morocco (casablanca) has observed a summer time adjustment since the year 2008. I sure didn't. http://www.timeanddate.com/news/time/morocco-dst-2012.html Apparently there is now even a special case during the muslim month of ramadan: -(quote: timeanddate.com)- According to the new law, the DST period will be interrupted during the Muslim month of Ramadan (July 20 – August 20, 2012 in the Gregorian calendar) -(end quote)- Earlier I was looking for a UTC timezone to use on my android phone, and nearly set it to casablaca without fact-checking first... Oops! For now I suppose that can be one of my clocks set to local time (NY) since it's a well-known timezone I shouldn't have to worry about too much. --Sarah P.S. Seems strange that the only two options for a UTC+0 timezone are London, Dublin or Casablanca (neither of which are year-round UTC) ... I'll try to remember to point this out to the cyanogenmod team (running an aftermarket version of android, cyanogenmod on my phone) so it can be fixed in the next release. ___ 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] For my whole life timezones have been weird
On 11/3/12 8:50 AM, Chris Albertson wrote: On Fri, Nov 2, 2012 at 10:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. I always wonder why people continue to use MS Windows. Perhaps thheir employers force them to. But other than that why? I don't know that it's force... At JPL we have an enormous variety of desktop OSes, and for the most part, nobody much cares which one you use as long as you can get your job done. Perhaps because you have a (expensive to replace) tool that requires IE for access? Perhaps because the large installed base means that design tools are written for Windows first and others later? Perhaps because of the large installed base it's easier to find folks to write software for Windows than for other products. Perhaps because for all its ills, Windows isn't that bad a desktop environment. The kind of timekeeping thing we're discussing here is, when it gets right down to it, not going to affect the vast majority (99.99%?) of users. That is the root cause of all Window's problems. The company was run be a chief software architect who technically very ignorant and lacked any formal education in the subject. Windows still suffers because it tries to maintain backwards compatabilty Hardly the root of all problems.. Yes, the conflation of kernel and UI (most of Windows is really all about UI capabilities: heck it's the very name of the product). The kernel of NT was based on the architecture of VAX/VMS, which was fairly nice. Real multitasking, real pre-emption, real process isolation, real dynamic run time binding. (none of which DOS had) You can say it suffers from needing backward compatibility.. overall, they've done a half way decent implementation of this these days (there were some real clunkers along the way). But it's also important to allow people to use their significant investment in old software. You may have the best idea in the world and a very cool OS that implements it, but who's going to pay for recoding all those billions of lines of software for your new OS? And assuming that money falls from the sky to pay for it, where are you going to find all those software people to do the work, at any price? Sure, I've seen lots of people just dying for the opportunity to decipher some 20 year old enterprise application and convert it to a new OS. You have to remember that in 1980 we have computers that would allow 100 people to simultainiously log in and do work from 100 different termmiansl. Well before that actually. More like late 60s. TymShare corp, for instance. Dartmouth BASIC for another. ANd note that those timesharing systems provided an environment that essentially hid the OS (kernel wise) from the user. You fired up your ASR33 and were in the BASIC environment from the get go. This also is the environment that BillG started doing computing work in. He didn't start sitting at a keypunch cranking out JCL cards to compile his COBOL or FORTRAN jobs and allocating DASD for the temporary files. We have the Internet (called arpanet back then. We had email and UNIX was alive and well. We even had mice and track balls This was not the dark ages the only real difference was the price of hardware. And in this age gates did NOT know the difference between an OS and a command shell and he was running Microsoft. Don't make the mistake of confusing public statements with background and knowledge. For all you know, Gates wanted to deliberately confuse the two for marketing reasons. 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.
[time-nuts] Option 14 on EIP 545A frequency counter
I've acquired an EIP 545A counter which seems to be in decent shape. In reading through the service manual there is a reference to option 14, a high resolution mode that increases gate time to 10 seconds. As far as I can tell, this doesn't appear to be an add-on board. Anyone know the details? Is it a jumper setting? An entry in the EEPROM? Different firmware set? Or something else? Any pointers would be appreciated. Scott ___ 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] Option 14 on EIP 545A frequency counter
Try asking on the EIP_Microwave Yahoo Group. Best, -John === I've acquired an EIP 545A counter which seems to be in decent shape. In reading through the service manual there is a reference to option 14, a high resolution mode that increases gate time to 10 seconds. As far as I can tell, this doesn't appear to be an add-on board. Anyone know the details? Is it a jumper setting? An entry in the EEPROM? Different firmware set? Or something else? Any pointers would be appreciated. Scott ___ 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] A counter for phase measures
Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. Thanks; Thomas Knox Date: Sat, 3 Nov 2012 16:28:42 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] A counter for phase measures On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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] A counter for phase measures
Hi Both counters have their weak points long term. On the balance I think the 620 should last longer. The 620 is the higher resolution of the two. The 620 normally comes with a bit better reference. Both are supported by various Time Nut software packages. Both do GPIB and serial i/o. The 620 is a bit more controllable over serial. The 53132 takes up less space on your bench. For the same price - go for the 620. For the usual 53132 is $1300 and the 620 is $2400, not so clear. Bob On Nov 3, 2012, at 10:10 AM, Volker Esper ail...@t-online.de wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? Thanks Volker - DF9PL Am 02.11.2012 16:32, schrieb Volker Esper: Dear fellows, I'm searching for a counter that allows me to make automated measure series. Of course, Allan Deviation is an important thing to determine when experimenting with or developing GPSDOs (what I intend). So it seemed to be a nice thing to measure phase deviation with a counter (HP 53132A or SR-620 or so). When experimenting with that stuff I discovered, that all my equipment would not be adequate to determine Allan Deviations beyond 10e-11 (or so). The question is, can any counter deliver that precision / low noise to make such measurements possible? Or does it have to be a more sophisticated technique, such as cross spectrum analysis? Thanks a lot in advance Volker (I guess you recognize, that I am just a newbie to that all) ___ 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] A counter for phase measures
Hi The 620 is still pretty good (when tuned up). It certainly beats the Pendulum's on a single shot basis. The 53230 is spec'd to be as good as the 620. I suspect it meets or exceeds it's stated specs. Bob On Nov 3, 2012, at 12:58 PM, Tom Knox act...@hotmail.com wrote: Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. Thanks; Thomas Knox Date: Sat, 3 Nov 2012 16:28:42 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] A counter for phase measures On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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. ___ 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] For my whole life timezones have been weird
On 11/3/2012 6:32 AM, Sarah White wrote: /Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. Would be nice if windows 7 had an update to fix this issue: //http://support.microsoft.com/kb/2687252/ The knowledge base article you report suggests a fix which consists in eliminating one entry of the Windows registry. I checked, and my Windows XP Professional + SP3 does not have that entry. So probably Microsoft did already issue a fix for that, in one of the many updates released. I keep my Windows always up-to-date, applying each and every fixes issued by Microsoft. Doing this, I have never had problems. 73 Alberto I2PHD ___ 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] For my whole life timezones have been weird
Hi Possibly because they run multiple very large / very expensive software packages that are Windows only items. Bob On Nov 3, 2012, at 11:50 AM, Chris Albertson albertson.ch...@gmail.com wrote: On Fri, Nov 2, 2012 at 10:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. I always wonder why people continue to use MS Windows. Perhaps thheir employers force them to. But other than that why? I went to a meetig once where Bill Gate talked about the new OS called MS-DOS At that time I already had a reasonable education in computer science and was working the systems software for multi-user systems and networking.What absolutly amazzed me was the Gates said his plan was to make DOS more and more nix-like over the years. Then he went on to say what thatment and it was clear he did NOT know the difference between an operating system and a shell. He absolutely didn't. That is the root cause of all Window's problems. The company was run be a chief software architect who technically very ignorant and lacked any formal education in the subject. Windows still suffers because it tries to maintain backwards compatabilty You have to remember that in 1980 we have computers that would allow 100 people to simultainiously log in and do work from 100 different termmiansl. We have the Internet (called arpanet back then. We had email and UNIX was alive and well. We even had mice and track balls This was not the dark ages the only real difference was the price of hardware. And in this age gates did NOT know the difference between an OS and a command shell and he was running Microsoft. 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] For my whole life timezones have been weird
And remember how late they were to network support? I had a computer store at that time and sold a lot of Artisoft LANtastic kits because Win3.1 did not have network support. I believe it was slipstreamed in 3.11. Most of my installations were so several machines in an office could share a common printer. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Saturday, November 03, 2012 08:50 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] For my whole life timezones have been weird On Fri, Nov 2, 2012 at 10:32 PM, Sarah White kuze...@gmail.com wrote: So, at or around 1981 (the year I was born) there was a cool concept. IBM was selling personal computers (IBM-PC compatible later became a thing) and by the time I was old enough to operate a modem, I had one myself. Life was good. Wonder if there is any sensible way to petition microsoft to fix this stupid mistake dating back to the DOS era. Windows 8 / metro is out now, and I can't bloody stand the changes. I always wonder why people continue to use MS Windows. Perhaps thheir employers force them to. But other than that why? I went to a meetig once where Bill Gate talked about the new OS called MS-DOS At that time I already had a reasonable education in computer science and was working the systems software for multi-user systems and networking.What absolutly amazzed me was the Gates said his plan was to make DOS more and more nix-like over the years. Then he went on to say what thatment and it was clear he did NOT know the difference between an operating system and a shell. He absolutely didn't. That is the root cause of all Window's problems. The company was run be a chief software architect who technically very ignorant and lacked any formal education in the subject. Windows still suffers because it tries to maintain backwards compatabilty You have to remember that in 1980 we have computers that would allow 100 people to simultainiously log in and do work from 100 different termmiansl. We have the Internet (called arpanet back then. We had email and UNIX was alive and well. We even had mice and track balls This was not the dark ages the only real difference was the price of hardware. And in this age gates did NOT know the difference between an OS and a command shell and he was running Microsoft. 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] A counter for phase measures
Hi Tom, On 11/03/2012 05:58 PM, Tom Knox wrote: Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. I haven't tested the new 53230 counter, and not the CNT-91/PM-6691 counter either, but much of the others. It should not be too hard to test this. I have made some tests with the aggregate of single-shot and trigger noise on a sine signal, i.e. 5 MHz out of a BVA. It gave the expected separation as a linear slope on the ADEV. On the other hand just tossing a sine into counters isn't necessary the most fair comparison, so in that sense it just gave a rough image. This thread have again had me consider reviving the testing aspect, and I decided to get a 53132A counter finally, now that prices have gone down. 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] For my whole life timezones have been weird
On Sat, Nov 3, 2012 at 9:24 AM, Jim Lux jim...@earthlink.net wrote: On 11/3/12 8:50 AM, Chris Albertson wrote: That is the root cause of all Window's problems. The company was run be a chief software architect who technically very ignorant and lacked any formal education in the subject. Windows still suffers because it tries to maintain backwards compatabilty Hardly the root of all problems.. Yes, the conflation of kernel and UI (most of Windows is really all about UI capabilities: heck it's the very name of the product). The kernel of NT was based on the architecture of VAX/VMS, which was fairly nice. Real multitasking, real pre-emption, real process isolation, real dynamic run time binding. (none of which DOS had) There was also OS/2... We have the Internet (called arpanet back then. We had email and UNIX was alive and well. We even had mice and track balls This was not the dark ages the only real difference was the price of hardware. And in this age gates did NOT know the difference between an OS and a command shell and he was running Microsoft. Don't make the mistake of confusing public statements with background and knowledge. For all you know, Gates wanted to deliberately confuse the two for marketing reasons. Not to mention that in the early 80s, Microsoft was a leading supplier of Unix, er, Xenix! Here is an interesting history: http://www.softpanorama.org/People/Torvalds/Finland_period/xenix_microsoft_shortlived_love_affair_with_unix.shtml and note the comment by John Wilson* here: https://plus.google.com/112975947891556571931/posts/Vpmx4EBMCR3 Yes, Unix was alive and well back then and Microsoft were actively using and selling it. The PC market was a different animal. Orin, Worked in Europe in the early 80s with Xenix. *Managed the group at Logica in London that sold Xenix in Europe. He had the misfortune that Microsoft kept poaching his staff to work in Redmond on Windows! ___ 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] For my whole life timezones have been weird
On 11/3/2012 6:31 PM, Orin Eman wrote: There was also OS/2... The best OpSys ever killed by IBM itself, as an internal, confidential, report indicated that developing middleware for Windows NT could produce much more revenues than continuing to develop OS/2... So they decided to let it slowly die, by moving developers from Boca Raton, FL, to the West coast where that middleware had its developing labs... 73 Alberto I2PHD ___ 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] A counter for phase measures
Hi Bob I didn't expect something to be tunable in the counter (except for the oscillator) - what is it that has to be calibrated? Thanks Volker Am 03.11.2012 18:04, schrieb Bob Camp: Hi The 620 is still pretty good (when tuned up). It certainly beats the Pendulum's on a single shot basis. The 53230 is spec'd to be as good as the 620. I suspect it meets or exceeds it's stated specs. Bob On Nov 3, 2012, at 12:58 PM, Tom Knoxact...@hotmail.com wrote: Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. Thanks; Thomas Knox Date: Sat, 3 Nov 2012 16:28:42 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] A counter for phase measures On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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. ___ 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. smime.p7s Description: S/MIME Cryptographic 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] A counter for phase measures
Hi There is a fairly elaborate alignment procedure for the 620. It's been reported in great detail here on the list. The counter definitely does better after you go through the full process. Bob On Nov 3, 2012, at 3:42 PM, Volker Esper ail...@t-online.de wrote: Hi Bob I didn't expect something to be tunable in the counter (except for the oscillator) - what is it that has to be calibrated? Thanks Volker Am 03.11.2012 18:04, schrieb Bob Camp: Hi The 620 is still pretty good (when tuned up). It certainly beats the Pendulum's on a single shot basis. The 53230 is spec'd to be as good as the 620. I suspect it meets or exceeds it's stated specs. Bob On Nov 3, 2012, at 12:58 PM, Tom Knoxact...@hotmail.com wrote: Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. Thanks; Thomas Knox Date: Sat, 3 Nov 2012 16:28:42 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] A counter for phase measures On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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. ___ 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] A counter for phase measures
Hi Bob What is it, that limits a counters life, are you speaking of typical counter specific failures or do you just mean the common wearout? Sorry, I know those are no smart questions - but my heart is thumping when I think of the price and the long way it has to go over the sea... Thanks Volker Am 03.11.2012 17:59, schrieb Bob Camp: Hi Both counters have their weak points long term. On the balance I think the 620 should last longer. The 620 is the higher resolution of the two. The 620 normally comes with a bit better reference. Both are supported by various Time Nut software packages. Both do GPIB and serial i/o. The 620 is a bit more controllable over serial. The 53132 takes up less space on your bench. For the same price - go for the 620. For the usual 53132 is $1300 and the 620 is $2400, not so clear. Bob On Nov 3, 2012, at 10:10 AM, Volker Esperail...@t-online.de wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? Thanks Volker - DF9PL Am 02.11.2012 16:32, schrieb Volker Esper: Dear fellows, I'm searching for a counter that allows me to make automated measure series. Of course, Allan Deviation is an important thing to determine when experimenting with or developing GPSDOs (what I intend). So it seemed to be a nice thing to measure phase deviation with a counter (HP 53132A or SR-620 or so). When experimenting with that stuff I discovered, that all my equipment would not be adequate to determine Allan Deviations beyond 10e-11 (or so). The question is, can any counter deliver that precision / low noise to make such measurements possible? Or does it have to be a more sophisticated technique, such as cross spectrum analysis? Thanks a lot in advance Volker (I guess you recognize, that I am just a newbie to that all) ___ 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] A counter for phase measures
Hi In the case of the 53132, the power supply seems to be the weak link. Out of maybe a hundred or so in the fleet, we see maybe one or two die each month. On the SR620 the power supply also seems to go from time to time. Both have the normal keyboard and display issues, but those can be fixed. If you go back to things like the 5335, the weak point is the input amp, it blows if you get +5 on it. Like power transformers - not a replaceable item... Bob On Nov 3, 2012, at 4:10 PM, Volker Esper ail...@t-online.de wrote: Hi Bob What is it, that limits a counters life, are you speaking of typical counter specific failures or do you just mean the common wearout? Sorry, I know those are no smart questions - but my heart is thumping when I think of the price and the long way it has to go over the sea... Thanks Volker Am 03.11.2012 17:59, schrieb Bob Camp: Hi Both counters have their weak points long term. On the balance I think the 620 should last longer. The 620 is the higher resolution of the two. The 620 normally comes with a bit better reference. Both are supported by various Time Nut software packages. Both do GPIB and serial i/o. The 620 is a bit more controllable over serial. The 53132 takes up less space on your bench. For the same price - go for the 620. For the usual 53132 is $1300 and the 620 is $2400, not so clear. Bob On Nov 3, 2012, at 10:10 AM, Volker Esperail...@t-online.de wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? Thanks Volker - DF9PL Am 02.11.2012 16:32, schrieb Volker Esper: Dear fellows, I'm searching for a counter that allows me to make automated measure series. Of course, Allan Deviation is an important thing to determine when experimenting with or developing GPSDOs (what I intend). So it seemed to be a nice thing to measure phase deviation with a counter (HP 53132A or SR-620 or so). When experimenting with that stuff I discovered, that all my equipment would not be adequate to determine Allan Deviations beyond 10e-11 (or so). The question is, can any counter deliver that precision / low noise to make such measurements possible? Or does it have to be a more sophisticated technique, such as cross spectrum analysis? Thanks a lot in advance Volker (I guess you recognize, that I am just a newbie to that all) ___ 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. ___ 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] UTC + 0 (was Accurate timestamping on computers )
Reykjavík, Iceland is UTC+0 without summer time changes. Brent On 11/3/2012 9:55 AM, Sarah White wrote: P.S. Seems strange that the only two options for a UTC+0 timezone are London, Dublin or Casablanca (neither of which are year-round UTC) ... I'll try to remember to point this out to the cyanogenmod team (running an aftermarket version of android, cyanogenmod on my phone) so it can be fixed in the next release. ___ 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] A counter for phase measures
Ah, ok, that helps. Meanwhile, I've found the manual and the schematics, and it seems to be possible, to get a died power supply back running. Thanks a lot! Volker Am 03.11.2012 21:36, schrieb Bob Camp: Hi In the case of the 53132, the power supply seems to be the weak link. Out of maybe a hundred or so in the fleet, we see maybe one or two die each month. On the SR620 the power supply also seems to go from time to time. Both have the normal keyboard and display issues, but those can be fixed. If you go back to things like the 5335, the weak point is the input amp, it blows if you get +5 on it. Like power transformers - not a replaceable item... Bob On Nov 3, 2012, at 4:10 PM, Volker Esperail...@t-online.de wrote: Hi Bob What is it, that limits a counters life, are you speaking of typical counter specific failures or do you just mean the common wearout? Sorry, I know those are no smart questions - but my heart is thumping when I think of the price and the long way it has to go over the sea... Thanks Volker Am 03.11.2012 17:59, schrieb Bob Camp: Hi Both counters have their weak points long term. On the balance I think the 620 should last longer. The 620 is the higher resolution of the two. The 620 normally comes with a bit better reference. Both are supported by various Time Nut software packages. Both do GPIB and serial i/o. The 620 is a bit more controllable over serial. The 53132 takes up less space on your bench. For the same price - go for the 620. For the usual 53132 is $1300 and the 620 is $2400, not so clear. Bob On Nov 3, 2012, at 10:10 AM, Volker Esperail...@t-online.de wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? Thanks Volker - DF9PL Am 02.11.2012 16:32, schrieb Volker Esper: Dear fellows, I'm searching for a counter that allows me to make automated measure series. Of course, Allan Deviation is an important thing to determine when experimenting with or developing GPSDOs (what I intend). So it seemed to be a nice thing to measure phase deviation with a counter (HP 53132A or SR-620 or so). When experimenting with that stuff I discovered, that all my equipment would not be adequate to determine Allan Deviations beyond 10e-11 (or so). The question is, can any counter deliver that precision / low noise to make such measurements possible? Or does it have to be a more sophisticated technique, such as cross spectrum analysis? Thanks a lot in advance Volker (I guess you recognize, that I am just a newbie to that all) ___ 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. ___ 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] A counter for phase measures
Great, your answere gives me hope, that the calibration procedure can be done at my home :-) Thank you! Volker Am 03.11.2012 21:08, schrieb Bob Camp: Hi There is a fairly elaborate alignment procedure for the 620. It's been reported in great detail here on the list. The counter definitely does better after you go through the full process. Bob On Nov 3, 2012, at 3:42 PM, Volker Esperail...@t-online.de wrote: Hi Bob I didn't expect something to be tunable in the counter (except for the oscillator) - what is it that has to be calibrated? Thanks Volker Am 03.11.2012 18:04, schrieb Bob Camp: Hi The 620 is still pretty good (when tuned up). It certainly beats the Pendulum's on a single shot basis. The 53230 is spec'd to be as good as the 620. I suspect it meets or exceeds it's stated specs. Bob On Nov 3, 2012, at 12:58 PM, Tom Knoxact...@hotmail.com wrote: Hi Magnus; I hope this is not to far off thread. Has anyone in the group done real world measurements of single shot res, and jitter on the new Agilent and Tektronix/Pendulum counters compared to the SR620 and Agilent 53132A. I would imagine that counter designs would be an area that really benefits from ongoing advances in digital technology. I have also found that it is much easier to claim specs then meet specs. Thanks; Thomas Knox Date: Sat, 3 Nov 2012 16:28:42 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: Re: [time-nuts] A counter for phase measures On 11/03/2012 03:10 PM, Volker Esper wrote: Thank you for the interesting information. Now, the time has come to look for an adequate counter - anyone who has experience with the HP 53132A and the SR620? If they both where at - say 1000 USD - what would you prefer for the job of phase measurement? I've read about that massive single shot capability of the SR, but - as being a newbie - is there anything I overlook at this moment? For short time-scales, single shot resolution and trigger jitter dominates your measurement floor. Single-shot resolution is the time resolution by which you make a single measurement. Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. So, it may not be the single-shot resolution which limits you, but a combination of things. I would recommend you to pick up a SR620. It has 4 ps single shot resolution and about 25 ps jitter (but you can get less). That is significantly better than the 53152A provides. SR620 manual (one of many links): http://ilrs.gsfc.nasa.gov/docs/timing/sr620_manual.pdf 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. ___ 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. smime.p7s Description: S/MIME Cryptographic 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] Distribution amps and slew rate
Folks, Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? david Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. ___ 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] A counter for phase measures
On 11/03/2012 09:36 PM, Bob Camp wrote: Hi In the case of the 53132, the power supply seems to be the weak link. Out of maybe a hundred or so in the fleet, we see maybe one or two die each month. On the SR620 the power supply also seems to go from time to time. Both have the normal keyboard and display issues, but those can be fixed. If you go back to things like the 5335, the weak point is the input amp, it blows if you get +5 on it. Like power transformers - not a replaceable item... Another weak point on the 5335 is the relay. We had to replace it and the relay-holder, but once that was done, it was back up operational. The 5335 ticks in as the most human-friendly of the counters at work, while the 53132 is competing with the 5372 as being the most human-unfriendly, where the 5372 has more capabilities to present, so it gets used more. 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] Distribution amps and slew rate
David, On 11/03/2012 10:44 PM, David Hooke wrote: Folks, Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? ... or rather, why do we design our input stages so they are so slew-rate sensitive? Sine isn't necessary a bad choice, the benefit of a sine is that you would not have to be as wide-band as to handle a whole number of overtones. That translates into lower amount of noise. There isn't really one right way of doing it, you can go about it in several ways, but you need to do it consistently. I've modified my TADD-2:s such that I use the input treatment to drive one of the outputs, so that they will square up sines for me. For some signals this have lowered my trigger jitter and hence improved my ability to see more of the actual signal I want to see. Just as much as you can get a counter with very high single shot resolution, it doesn't help if you do not treat your signals properly to get the most of that counter. When doing DMTD tricks, the mixer is the easy part, squaring the signal up to get good trigger jitter for the total is what takes a lot of effort. 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] A counter for phase measures
Usually you don't need a BVA to test the single-shot capability of a counter: a length (say 50nS) of good RF coaxial cable and your preferred OCXO/Rb/GPSDO should be enough. On Sat, Nov 3, 2012 at 11:14 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 11/03/2012 09:36 PM, Bob Camp wrote: Hi In the case of the 53132, the power supply seems to be the weak link. Out of maybe a hundred or so in the fleet, we see maybe one or two die each month. On the SR620 the power supply also seems to go from time to time. Both have the normal keyboard and display issues, but those can be fixed. If you go back to things like the 5335, the weak point is the input amp, it blows if you get +5 on it. Like power transformers - not a replaceable item... Another weak point on the 5335 is the relay. We had to replace it and the relay-holder, but once that was done, it was back up operational. The 5335 ticks in as the most human-friendly of the counters at work, while the 53132 is competing with the 5372 as being the most human-unfriendly, where the 5372 has more capabilities to present, so it gets used more. 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] Distribution amps and slew rate
Hi If you have a sine wave, it gets into everything. You can identify it and take it out of your data. If you have a broad band uber-fast high level pules, it gets into everything. Identifying it's impact and taking it out of the data - not so easy. That may sound a bit crazy. I've actually worked in a place that went over to a square wave based system. It lasted for about a day. Got into all sorts of things, total nightmare. Bob On Nov 3, 2012, at 5:44 PM, David Hooke dho...@gmail.com wrote: Folks, Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? david Trigger jitter is the noise at the trigger point. it's a combination of thermal noise and the slew-rate at the trigger points. It is often that trigger jitter is dominated by slew-rate, but there is also internal sources of trigger jitter. The slope dependent trigger jitter follows the formula: t_jitter = v_noise / s_slew t_jitter is the trigger jitter (s) v_noise is the noise power (V) s_slew is the slew rate (V/s) When the time-span of a measurement is long, long-term stability comes in as well as systematic drifts. Also, systematic noise such as hum also becomes important. To see how much you depend on slew-rate limitation, you can reduce the amplitude, and as this reduces the slew-rate you can separate the slew-rate dependent jitter from the intrinsic jitter of the input. It also helps you to identify if you need to work on the slew-rate limit rather than anything else. ___ 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] A counter for phase measures
Hi The relay *can* be replaced. Not so much with the input amp. If it goes, you lost the counter. The displays also die from time to time. Like the relay, they can be replaced. Bob On Nov 3, 2012, at 6:14 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 11/03/2012 09:36 PM, Bob Camp wrote: Hi In the case of the 53132, the power supply seems to be the weak link. Out of maybe a hundred or so in the fleet, we see maybe one or two die each month. On the SR620 the power supply also seems to go from time to time. Both have the normal keyboard and display issues, but those can be fixed. If you go back to things like the 5335, the weak point is the input amp, it blows if you get +5 on it. Like power transformers - not a replaceable item... Another weak point on the 5335 is the relay. We had to replace it and the relay-holder, but once that was done, it was back up operational. The 5335 ticks in as the most human-friendly of the counters at work, while the 53132 is competing with the 5372 as being the most human-unfriendly, where the 5372 has more capabilities to present, so it gets used more. 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.
[time-nuts] WWVB new modulation scheme monograph
This has probably already been posted more than once, but if anyone is still looking for a description of the new WWVB modulation scheme: http://tf.boulder.nist.gov/general/pdf/2651.pdf (Sept. 2012) 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.
Re: [time-nuts] Distribution amps and slew rate
david wrote: Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? Magnus made some good points in response to your question. To elaborate a bit: it is much easier to provide a friendly transmission environment for a sine wave (single frequency), and sine waves are less sensitive to imperfections in the transmission environment (impedance discontinuities and mismatches, noise ingress, etc.). Reflections in the transmission environment will put funny steps in what started life as clean square waves or pulses, and differential phase shifts will also mis-shape square waves or pulses. This can even be a problem with sine waves -- see, for example, the NIST paper on the timing effects of distortion in sine wave sources for an example of the sensitivity of sine wave systems to harmonics (Walls and Ascarrunz, The Effect of Harmonic Distortion on Phase Errors in Frequency Distribution and Synthesis) -- but it is much worse with square waves or pulses. Sine wave systems are also much less prone to radiating noise. Anyone who operates one or more frequency standards as well as sensitive RF receivers can testify that sine waves are much less of a hassle. 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.
Re: [time-nuts] Distribution amps and slew rate
The below is correct but a simpler way to say it is this: A square wave contains the fundamental frequency plus every odd harmonic up to infinity. A sine wave contains only the fundamental frequency. It is the up to infinity part that causes all the trouble. And yes it really does go to infinity, at least in theory. but in real life you can't have frequencies so high so without them you can't and don't have a perfect square wave. In other words perfect square wave can't esist in the real world but perfect sine wave, at least in theory could On Sat, Nov 3, 2012 at 4:39 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: david wrote: Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? Magnus made some good points in response to your question. To elaborate a bit: it is much easier to provide a friendly transmission environment for a sine wave (single frequency), and sine waves are less sensitive to imperfections in the transmission environment (impedance discontinuities and mismatches, noise ingress, etc.). Reflections in the transmission environment will put funny steps in what started life as clean square waves or pulses, and differential phase shifts will also mis-shape square waves or pulses. This can even be a problem with sine waves -- see, for example, the NIST paper on the timing effects of distortion in sine wave sources for an example of the sensitivity of sine wave systems to harmonics (Walls and Ascarrunz, The Effect of Harmonic Distortion on Phase Errors in Frequency Distribution and Synthesis) -- but it is much worse with square waves or pulses. Sine wave systems are also much less prone to radiating noise. Anyone who operates one or more frequency standards as well as sensitive RF receivers can testify that sine waves are much less of a hassle. Best regards, Charles __**_ 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. -- 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] Distribution amps and slew rate
Of course you can't have a perfect square wave! That would imply zero transition time and since frequency is inverse to time that implies infinitely high frequency bandwidth is required to achieve that perfect square wave. Getting a square wave with a fast enough slew rate between high and low levels is certainly achievable and better than that perfect square wave. Be careful what you ask for, because with a perfect square wave you would have such high frequency content that you would get induced noise everywhere. Peter On 11/3/2012 8:05 PM, Chris Albertson wrote: The below is correct but a simpler way to say it is this: A square wave contains the fundamental frequency plus every odd harmonic up to infinity. A sine wave contains only the fundamental frequency. It is the up to infinity part that causes all the trouble. And yes it really does go to infinity, at least in theory. but in real life you can't have frequencies so high so without them you can't and don't have a perfect square wave. In other words perfect square wave can't esist in the real world but perfect sine wave, at least in theory could On Sat, Nov 3, 2012 at 4:39 PM, Charles P. Steinmetz charles_steinm...@lavabit.com wrote: david wrote: Given that slew rate is so critical, why do we distribute sine waves and perform the zero-crossing detection at every target instrument? Magnus made some good points in response to your question. To elaborate a bit: it is much easier to provide a friendly transmission environment for a sine wave (single frequency), and sine waves are less sensitive to imperfections in the transmission environment (impedance discontinuities and mismatches, noise ingress, etc.). Reflections in the transmission environment will put funny steps in what started life as clean square waves or pulses, and differential phase shifts will also mis-shape square waves or pulses. This can even be a problem with sine waves -- see, for example, the NIST paper on the timing effects of distortion in sine wave sources for an example of the sensitivity of sine wave systems to harmonics (Walls and Ascarrunz, The Effect of Harmonic Distortion on Phase Errors in Frequency Distribution and Synthesis) -- but it is much worse with square waves or pulses. Sine wave systems are also much less prone to radiating noise. Anyone who operates one or more frequency standards as well as sensitive RF receivers can testify that sine waves are much less of a hassle. Best regards, Charles __**_ 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] Distribution amps and slew rate
On 11/04/2012 01:13 AM, Peter Gottlieb wrote: Of course you can't have a perfect square wave! That would imply zero transition time ... oh, THAT would be useful! :D No trigger point jitter! ... and it would be a hell to contain within the cables and connectors we have, as they leak a lot as you get up into frequency. and since frequency is inverse to time that implies infinitely high frequency bandwidth is required to achieve that perfect square wave. Getting a square wave with a fast enough slew rate between high and low levels is certainly achievable and better than that perfect square wave. Be careful what you ask for, because with a perfect square wave you would have such high frequency content that you would get induced noise everywhere. Indeed. Bob has shown this. Another aspect of it is that phase-shifts at higher frequencies may eat into the phase shift of the zero transition, so it may for some systems give a worse environmental/temperature dependence than a sine would. Then again, if you check your signal properly, a square-wave may be exactly what you want and need. It's just that again, your milage may vary. 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.
