Re: [time-nuts] Can Lady Heather Keep Computer Clock On Time?
On 07/29/2010 03:57 PM, Mark Sims wrote: Yes, there is a time sync command that causes the program to set the system clock at periodic intervals or whenever it differs from GPS by a given amount. I'm still out on the Project From Hell Mark II and I don't remember all the gory details... I think /TSA on the command line says sync the time whenever the clocks differ by a millisecond. There is also /TSO /TSD /TSH /TSM /TSS to set it once, hourly, daily, every minute or second. There is also a /TSX command to specify the time offset from the Tbolt serial command to GPS (which is usually around 45 milliseconds). TS from the keyboard just syncs the clock once. ___ 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. I realize this request is for Windows, but I thought I'd mention this for the benefit of others. I'm using tboltd by Ralph Smith on Linux. It provides the time to ntpd and LH 3.00 beta can talk to tboltd via the TCP connection, so monitoring can happen at the same time as the ntpd. It works great on Linux, as well as BSD (for which it was designed): http://www.mail-archive.com/time-nuts@febo.com/msg26129.html It runs well under wine like this: wine heather.exe /IP=localhost:45000 /TW=250 The /etc/ntp.conf config file stanza looks like this. (I admit I've guessed at the 0.0275 delay.) # for attached GPS tos mindist 0.030 server 127.127.28.0 minpoll 4 maxpoll 4 prefer fudge 127.127.28.0 time1 0.0275 stratum 1 refid GPS Serious use would probably call for a Soekris box, but not so serious use lets me use the tbolt time signal for free, as I have it on for the 10MHz reference. Leigh/WA5ZNU ___ 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] Can Lady Heather Keep Computer Clock On Time?
Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather Keep Computer Clock On Time?
Hi My observation is that the displayed clock on LH can be off by 10 seconds. That's with the current beta code and Windows 7 on a quad processor machine or under XP on a dual core machine. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 29, 2010 2:04 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Can Lady Heather Keep Computer Clock On Time? Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Can Lady Heather Keep Computer Clock On Time?
with the assumption that he seems to be fine right after a sync, (seemingly supported in the OP) reconfiguring the windows time service to update frequently seems to me to be the easiest answer. under xp you can do so thus: http://support.microsoft.com/kb/314054 _eric On Thu, Jul 29, 2010 at 11:13 AM, Bob Camp li...@rtty.us wrote: Hi My observation is that the displayed clock on LH can be off by 10 seconds. That's with the current beta code and Windows 7 on a quad processor machine or under XP on a dual core machine. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 29, 2010 2:04 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Can Lady Heather Keep Computer Clock On Time? Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. -- --Eric _ Eric Garner ___ 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] Can Lady Heather Keep Computer Clock On Time?
Or even better download a real NTP for windows. http://www.meinberg.de/english/sw/ntp.htm#ntp_nt_stable -- Björn with the assumption that he seems to be fine right after a sync, (seemingly supported in the OP) reconfiguring the windows time service to update frequently seems to me to be the easiest answer. under xp you can do so thus: http://support.microsoft.com/kb/314054 _eric On Thu, Jul 29, 2010 at 11:13 AM, Bob Camp li...@rtty.us wrote: Hi My observation is that the displayed clock on LH can be off by 10 seconds. That's with the current beta code and Windows 7 on a quad processor machine or under XP on a dual core machine. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 29, 2010 2:04 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Can Lady Heather Keep Computer Clock On Time? Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. -- --Eric _ Eric Garner ___ 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] Can Lady Heather Keep Computer Clock On Time?
Hi Eric: That seems to be for a time server. He is just using an ordinary PC and NTP to set it's time. Have Fun, Brooke Clarke http://www.PRC68.com Eric Garner wrote: with the assumption that he seems to be fine right after a sync, (seemingly supported in the OP) reconfiguring the windows time service to update frequently seems to me to be the easiest answer. under xp you can do so thus: http://support.microsoft.com/kb/314054 _eric On Thu, Jul 29, 2010 at 11:13 AM, Bob Campli...@rtty.us wrote: Hi My observation is that the displayed clock on LH can be off by 10 seconds. That's with the current beta code and Windows 7 on a quad processor machine or under XP on a dual core machine. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 29, 2010 2:04 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Can Lady Heather Keep Computer Clock On Time? Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Can Lady Heather Keep Computer Clock On Time?
see the section of the article Configuring the Windows Time service to use an external time source that details how to reconfigure the winXP time sync service so that it polls and external server for time at a specified interval. On Thu, Jul 29, 2010 at 12:10 PM, Brooke Clarke bro...@pacific.net wrote: Hi Eric: That seems to be for a time server. He is just using an ordinary PC and NTP to set it's time. Have Fun, Brooke Clarke http://www.PRC68.com Eric Garner wrote: with the assumption that he seems to be fine right after a sync, (seemingly supported in the OP) reconfiguring the windows time service to update frequently seems to me to be the easiest answer. under xp you can do so thus: http://support.microsoft.com/kb/314054 _eric On Thu, Jul 29, 2010 at 11:13 AM, Bob Campli...@rtty.us wrote: Hi My observation is that the displayed clock on LH can be off by 10 seconds. That's with the current beta code and Windows 7 on a quad processor machine or under XP on a dual core machine. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 29, 2010 2:04 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Can Lady Heather Keep Computer Clock On Time? Hi: I have a friend who's setting up an observatory and the PC that controls the telescope needs to have an accurate clock. The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. Running the observatory is like flying a 747, i.e. there's a lot to do and the time needs to be handled automatically, not by manual NTP updates. I know that TAC32 and a Motorola GPS will do this and you have a lot of options of how it does it. For example at a specified time interval or when the computer clock differs from GPS by a specified amount of time (50 ms in this case). What are the options in LH? I ask because it's a lower cost option then the Motorola GPS plus TAC32 option or building a NTP time server. -- Have Fun, Brooke Clarke http://www.PRC68.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. -- --Eric _ Eric Garner ___ 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] Can Lady Heather Keep Computer Clock On Time?
Yes, there is a time sync command that causes the program to set the system clock at periodic intervals or whenever it differs from GPS by a given amount. I'm still out on the Project From Hell Mark II and I don't remember all the gory details... I think /TSA on the command line says sync the time whenever the clocks differ by a millisecond. There is also /TSO /TSD /TSH /TSM /TSS to set it once, hourly, daily, every minute or second. There is also a /TSX command to specify the time offset from the Tbolt serial command to GPS (which is usually around 45 milliseconds). TS from the keyboard just syncs the clock once. ___ 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] Can Lady Heather Keep Computer Clock On Time?
The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. That looks like the classic time vs frequency problem. What is the primary goal? Pointing or tracking? Pointing requires time. Tracking requires frequency. If you are otherwise happy with Windows NTP sync, you may be able to solve your problem by doing a sync before pointing at another object if it's been more than N hours since the last sync. Long song and dance [Remember, I don't run Windows so I may screwup anything that's Windows specific.] The typical PC has 2 crystals. One runs at 32 KHz. The other is usually 14.xxx (from early PC days) that gets PLLed up to make clocks for the CPU and PCI and USB and ... The 32KHz crystal runs the battery backed RTC/TOY/CMOS clock. It's a watch crystal so it should be pretty good. But it's not very convenient for keeping time at the microsecond level. The 14 MHz crystal is stable, but typically not very accurate. (Remember low cost.) That's accurate at the PPM level, it will be fine if you just put a scope on it. It may be off by 50 PPM. Even if the hardware is good, the software can screw things up. (Linux is good at this. Current kernels don't get a consistent answer on the same hardware. Jumps by 200 PPM from boot to boot are not uncommon.) [Network and audio and ??? cards typically have a separate crystal. They are usually not convenient for timekeeping but if you do serious audio work you can measure it's actual frequency.] Let's see if I can do the math right... 3 hours is 10,000 seconds. 50 PPM times 10,000 seconds is 500,000 microseconds. So if the clock is off by 50 PPM, it will drift 1/2 second in 3 hours. Even 5 PPM will drift 50 ms in 3 hours. The main reason for running real ntpd rather than just setting the time occasionally is that ntpd will figure out how far off the frequency is and correct for it. ntpd calls that fudge factor drift and prints it out in PPM with 3 digits to the right of the decimal point. If all you need is 50 ms, you should be able to get that most of the time by just running ntpd over the net. It's sure worth a try. It may not be good enough if you have a crappy net connection or change from no-load to uploading tons of data from observations earlier in the evening. (Contact me off list if you want help in monitoring a ntp server and/or setting up and interpreting its log files.) Odds and ends to keep in mind... Modern PCs use spread spectrum clocking. That fudges things by 1 or 1/2 % or so which is huge in terms of PPM. The point is that you have to measure it. Just doing the math from the nominal CPU frequency isn't good enough. The actual frequency is temperature dependent, so things will change if you open the roof and let the cold air in or the CPU changes from idle (or off) to working hard. The ballpark is 1 PPM per 10 F. One of the classic ways to screwup timekeeping is to miss interrupts, typically because some other interrupt routine is running too long. This was easy to tickle on (very) old Linux systems that used PIO rather than DMA for disk transfers. I only mention it because you might have some strange hardware with buggy interrupt routines. Normal Windows clocks tick every 10 ms. Windows has a multimedia mode that does much better. There is a switch in the Registry or something. It may help to use that mode. I think you want to leave it on. (The Meinberg ntpd-installer package turns it on.) ntpd is both a client and server. A system will act as a client to get time from lower stratum servers and act as a server to provide time to higher stratum servers. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather Keep Computer Clock On Time?
Hi There is a standard NTP driver that talks Thunderbolt. The full blown NTP package is pretty easy to set up. It will hold ms accuracy slaved to a GPS. Bob On Jul 29, 2010, at 7:29 PM, Hal Murray hmur...@megapathdsl.net wrote: The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. That looks like the classic time vs frequency problem. What is the primary goal? Pointing or tracking? Pointing requires time. Tracking requires frequency. If you are otherwise happy with Windows NTP sync, you may be able to solve your problem by doing a sync before pointing at another object if it's been more than N hours since the last sync. Long song and dance [Remember, I don't run Windows so I may screwup anything that's Windows specific.] The typical PC has 2 crystals. One runs at 32 KHz. The other is usually 14.xxx (from early PC days) that gets PLLed up to make clocks for the CPU and PCI and USB and ... The 32KHz crystal runs the battery backed RTC/TOY/CMOS clock. It's a watch crystal so it should be pretty good. But it's not very convenient for keeping time at the microsecond level. The 14 MHz crystal is stable, but typically not very accurate. (Remember low cost.) That's accurate at the PPM level, it will be fine if you just put a scope on it. It may be off by 50 PPM. Even if the hardware is good, the software can screw things up. (Linux is good at this. Current kernels don't get a consistent answer on the same hardware. Jumps by 200 PPM from boot to boot are not uncommon.) [Network and audio and ??? cards typically have a separate crystal. They are usually not convenient for timekeeping but if you do serious audio work you can measure it's actual frequency.] Let's see if I can do the math right... 3 hours is 10,000 seconds. 50 PPM times 10,000 seconds is 500,000 microseconds. So if the clock is off by 50 PPM, it will drift 1/2 second in 3 hours. Even 5 PPM will drift 50 ms in 3 hours. The main reason for running real ntpd rather than just setting the time occasionally is that ntpd will figure out how far off the frequency is and correct for it. ntpd calls that fudge factor drift and prints it out in PPM with 3 digits to the right of the decimal point. If all you need is 50 ms, you should be able to get that most of the time by just running ntpd over the net. It's sure worth a try. It may not be good enough if you have a crappy net connection or change from no-load to uploading tons of data from observations earlier in the evening. (Contact me off list if you want help in monitoring a ntp server and/or setting up and interpreting its log files.) Odds and ends to keep in mind... Modern PCs use spread spectrum clocking. That fudges things by 1 or 1/2 % or so which is huge in terms of PPM. The point is that you have to measure it. Just doing the math from the nominal CPU frequency isn't good enough. The actual frequency is temperature dependent, so things will change if you open the roof and let the cold air in or the CPU changes from idle (or off) to working hard. The ballpark is 1 PPM per 10 F. One of the classic ways to screwup timekeeping is to miss interrupts, typically because some other interrupt routine is running too long. This was easy to tickle on (very) old Linux systems that used PIO rather than DMA for disk transfers. I only mention it because you might have some strange hardware with buggy interrupt routines. Normal Windows clocks tick every 10 ms. Windows has a multimedia mode that does much better. There is a switch in the Registry or something. It may help to use that mode. I think you want to leave it on. (The Meinberg ntpd-installer package turns it on.) ntpd is both a client and server. A system will act as a client to get time from lower stratum servers and act as a server to provide time to higher stratum servers. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Can Lady Heather Keep Computer Clock On Time?
Hi Hal: The key thing is pointing, not tracking (where a guide star is commonly used). A TPoint model is made by pointing to known stars and the quality of the model depends on good computer time. Have Fun, Brooke Clarke http://www.PRC68.com Hal Murray wrote: The telescope can point to within arc seconds of a star and that implies that the computer clock needs to be within 50 ms. If he does a Windows NTP sync first thing in the evening after a few hours there's too big an error. That looks like the classic time vs frequency problem. What is the primary goal? Pointing or tracking? Pointing requires time. Tracking requires frequency. If you are otherwise happy with Windows NTP sync, you may be able to solve your problem by doing a sync before pointing at another object if it's been more than N hours since the last sync. Long song and dance [Remember, I don't run Windows so I may screwup anything that's Windows specific.] The typical PC has 2 crystals. One runs at 32 KHz. The other is usually 14.xxx (from early PC days) that gets PLLed up to make clocks for the CPU and PCI and USB and ... The 32KHz crystal runs the battery backed RTC/TOY/CMOS clock. It's a watch crystal so it should be pretty good. But it's not very convenient for keeping time at the microsecond level. The 14 MHz crystal is stable, but typically not very accurate. (Remember low cost.) That's accurate at the PPM level, it will be fine if you just put a scope on it. It may be off by 50 PPM. Even if the hardware is good, the software can screw things up. (Linux is good at this. Current kernels don't get a consistent answer on the same hardware. Jumps by 200 PPM from boot to boot are not uncommon.) [Network and audio and ??? cards typically have a separate crystal. They are usually not convenient for timekeeping but if you do serious audio work you can measure it's actual frequency.] Let's see if I can do the math right... 3 hours is 10,000 seconds. 50 PPM times 10,000 seconds is 500,000 microseconds. So if the clock is off by 50 PPM, it will drift 1/2 second in 3 hours. Even 5 PPM will drift 50 ms in 3 hours. The main reason for running real ntpd rather than just setting the time occasionally is that ntpd will figure out how far off the frequency is and correct for it. ntpd calls that fudge factor drift and prints it out in PPM with 3 digits to the right of the decimal point. If all you need is 50 ms, you should be able to get that most of the time by just running ntpd over the net. It's sure worth a try. It may not be good enough if you have a crappy net connection or change from no-load to uploading tons of data from observations earlier in the evening. (Contact me off list if you want help in monitoring a ntp server and/or setting up and interpreting its log files.) Odds and ends to keep in mind... Modern PCs use spread spectrum clocking. That fudges things by 1 or 1/2 % or so which is huge in terms of PPM. The point is that you have to measure it. Just doing the math from the nominal CPU frequency isn't good enough. The actual frequency is temperature dependent, so things will change if you open the roof and let the cold air in or the CPU changes from idle (or off) to working hard. The ballpark is 1 PPM per 10 F. One of the classic ways to screwup timekeeping is to miss interrupts, typically because some other interrupt routine is running too long. This was easy to tickle on (very) old Linux systems that used PIO rather than DMA for disk transfers. I only mention it because you might have some strange hardware with buggy interrupt routines. Normal Windows clocks tick every 10 ms. Windows has a multimedia mode that does much better. There is a switch in the Registry or something. It may help to use that mode. I think you want to leave it on. (The Meinberg ntpd-installer package turns it on.) ntpd is both a client and server. A system will act as a client to get time from lower stratum servers and act as a server to provide time to higher stratum servers. ___ 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.
