Re: [time-nuts] EES RC 1454 100DB MSF/GPS clock
Hi Nigel, Connect did have some recently by this came from another? seller who is from the same town. WoodsGroup are also selling them (item 390489973647 ) but at excessive prices and without the antenna. The GPS mod seems to replace the PLL board and loops the LF signal through. The GPS antenna unit also has an LF antenna input. I traced the power (+5V +12V) connections and hooked it up to a bench supply without the antenna unit. The supply only has 500mA capability on the 12V and went into current limit. Tried a bigger supply and got smoke :-( A pot core inductor on the PLL board was cooking. A bit of tracing and it's in series with thr 12V supply and antenna connector. The was a short on the MCx to BNC lead. It disappaered when I moved it so I'll leave it be for now. I get a red power LED, green loop lock and 1PPS LEDs but no display. I've got the GPS ant on a windowsill so I'll let it seet and see if anything comes up. Robert G8RPI. From: gandal...@aol.com gandal...@aol.com To: time-nuts@febo.com Sent: Thursday, 29 November 2012, 19:45 Subject: Re: [time-nuts] EES RC 1454 100DB MSF/GPS clock Hi Robert For some reason I missed these until you mentioned them but have just taken a look and am reminded very much of the similarly modified and boxed EES 100s that Connect Distribution were selling around 5 years ago. Whilst this looks to be a much later unit both EES and Radiocode clocks do seem to have survived for an awful long time without too many significant revisions to their hardware, internal hardware anyway:-) I've seen a similar connector on one version of the RC060s but even that mainly used conventional D connectors. From what I remember of the antenna modules on the EES 100s I got the impression that the interface processor board extracted the timing information from the GPS signal and converted it into an MSF compatible signal to feed the EES 100. I'm sure they didn't frequency convert from L band to 60KHz but just took the GPS data and started from fresh to generate their own MSF compatible signal using that data. I never tried to use one of the modified units straight from MSF but will dig one out and try it, I don't think there was very much of a modification to the MSF receiver other than whatever was required to accept another 60KHz signal. I suspect all the hard work was done in the antenna module and the MSF unit was just used as decoder and display for the converted signal. I may have missed something, nothing unusual there then:-), but it always struck me as a rather odd way of accessing and displaying GPS timing data, unless initially there was some pressure to find a quick fix utilising existing approved equipment. Regards Nigel GM8PZR In a message dated 29/11/2012 18:58:47 GMT Standard Time, robert8...@yahoo.co.uk writes: Hi all, I recently gave in and bought one of the EES (european electronic systems) RC1454 Radio Clock units that have been on ebay.co.uk for a while. The one I snagged came with a GPS antenna unit. The main unit has a label saying GPS Modified The main box appears to be a MSF receiver but has no obvious power connector, just two rectangular multiway sockets, a 15W D plug and two BNC's. It is a 2U high card frame with 15 PCBS and a LED display on th front. Vintage is late 1990's and both units look like new. The GPS unit has an early Oncore (R1211A) receiver and a PCB with a CPU etc. Two BNC' marked MSF ANT and RX looks like a mod for either MSF or GPS time. Does anyone have any information on these beore I get into major reverse engineering? Robert G8RPI. ___ 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] Loran
Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.netwrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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. PTTI_12_abstract_paper27o.pdf Description: Adobe PDF document ___ 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] Loran
Maybe a patent search is in order. - Original Message - From: Mike Garvey r3m...@verizon.net To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Friday, November 30, 2012 3:24 PM Subject: Re: [time-nuts] Loran Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.netwrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] Loran
IF, and it's a big IF, it is compatible with existing LORAC-C receivers, it would be a most welcome development, and would mitigate to some extent the idiotic decision to shut down LORAN-C. If it's incompatible with the existing, installed receivers, because it uses some kind of proprietary, sole source, code or receiver technology, it's another waste of resources and bandwidth, IMO. -John = Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.netwrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] Loran
Hello to the group. Its been working very fine all day long. I am using two austron 2100 series rcvrs. One is comparing the loran c sig to a hp3801 gps system and the other the house reference a RB. I expect the signal to go off the air most likely about 5pm. This is a 9-5 bunch after all. Some of the papers that ursanav released show a rcvr a un151 lf pnt. Sent an email to see what this credit card size system might cost and even if it were available. Its unclear to me that ursanav has any real long term approval or support. A pity actually. Regards Paul WB8TSL On Fri, Nov 30, 2012 at 4:05 PM, J. Forster j...@quikus.com wrote: IF, and it's a big IF, it is compatible with existing LORAC-C receivers, it would be a most welcome development, and would mitigate to some extent the idiotic decision to shut down LORAN-C. If it's incompatible with the existing, installed receivers, because it uses some kind of proprietary, sole source, code or receiver technology, it's another waste of resources and bandwidth, IMO. -John = Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.netwrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] Using a frequency synthesizer replacement for motherboard oscillator
Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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] Using a frequency synthesizer replacement for motherboard oscillator
Hi It's most commonly done with things like a Soekris 45xx series board. You don't need anything very exotic for the frequency conversion. The jitter in the PC is way worse than what the external chips will be creating. The real question is - what is the magic frequency on the particular mother board you are going to modify? Once upon a time they all were a pretty predictable 14.xxx MHz. These days, who knows what's going in where… Bob On Nov 30, 2012, at 4:55 PM, Sarah White kuze...@gmail.com wrote: Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
I am not sure that a precision clock will help if the cpu is busy and skips clock cycles. I believe this is one of the problems with general purpose OSes like Windows. I believe the better boards like the Soekis use hardware dividers to alleviate the cpu busy problem. Didier Sent from my Droid Razr 4G LTE wireless tracker. -Original Message- From: Sarah White kuze...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Fri, 30 Nov 2012 3:55 PM Subject: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
It all depends on what clock your talking about. Any given PC probably has more than one oscillator onboard. Generally there will be one for the CPU, one for the display circuitry, and probably one for the real time clock. Presuming you are talking about the CPU clock, it should be fairly straightforward to find the oscillator package on the motherboard find the pin with clock output and feed your clock input there. On Nov 30, 2012, at 16:59, Bob Camp li...@rtty.us wrote: Hi It's most commonly done with things like a Soekris 45xx series board. You don't need anything very exotic for the frequency conversion. The jitter in the PC is way worse than what the external chips will be creating. The real question is - what is the magic frequency on the particular mother board you are going to modify? Once upon a time they all were a pretty predictable 14.xxx MHz. These days, who knows what's going in where… Bob On Nov 30, 2012, at 4:55 PM, Sarah White kuze...@gmail.com wrote: Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. -Eric On Fri, Nov 30, 2012 at 3:04 PM, bownes bow...@gmail.com wrote: It all depends on what clock your talking about. Any given PC probably has more than one oscillator onboard. Generally there will be one for the CPU, one for the display circuitry, and probably one for the real time clock. Presuming you are talking about the CPU clock, it should be fairly straightforward to find the oscillator package on the motherboard find the pin with clock output and feed your clock input there. On Nov 30, 2012, at 16:59, Bob Camp li...@rtty.us wrote: Hi It's most commonly done with things like a Soekris 45xx series board. You don't need anything very exotic for the frequency conversion. The jitter in the PC is way worse than what the external chips will be creating. The real question is - what is the magic frequency on the particular mother board you are going to modify? Once upon a time they all were a pretty predictable 14.xxx MHz. These days, who knows what's going in where… Bob On Nov 30, 2012, at 4:55 PM, Sarah White kuze...@gmail.com wrote: Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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. ___ 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] Using a frequency synthesizer replacement for motherboard oscillator
On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Mostly I started this thread because there have been a few with people discussing implementing NTP on embedded microcontrollers, arduino, etc. and I was thinking of doing it from the other side (turning a nice-ish server into a rock-solid timekeeper) Thanks so far everyone. Really impressed that I already managed to get 4x replies so quickly :) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
I've never done it using to the RTC crystal, but I do it quite frequently in my Day Job to Ethernet controllers on those same pc mother boards. -Eric On Fri, Nov 30, 2012 at 4:10 PM, Sarah White kuze...@gmail.com wrote: On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Mostly I started this thread because there have been a few with people discussing implementing NTP on embedded microcontrollers, arduino, etc. and I was thinking of doing it from the other side (turning a nice-ish server into a rock-solid timekeeper) Thanks so far everyone. Really impressed that I already managed to get 4x replies so quickly :) ___ 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] Loran
Nothing going on in Cape May for a while - I don't know if they are done testing. Bill WA2DVU Cape May, NJ -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Garvey Sent: Friday, November 30, 2012 3:25 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Loran Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.netwrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] Using a frequency synthesizer replacement for motherboard oscillator
Hi In the case of the Soekris, it was not the real time clock that we all played with. THe clock you fiddle is the CPU clock. The system is running FreeBSD or Lunix, so it's a cut above a typical embedded system. A RTOS (like Windows CE) will indeed do a bit better with a good CPU clock. Anything like conventional Windows will still have issues, even with a good clock. Bob On Nov 30, 2012, at 7:10 PM, Sarah White kuze...@gmail.com wrote: On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Mostly I started this thread because there have been a few with people discussing implementing NTP on embedded microcontrollers, arduino, etc. and I was thinking of doing it from the other side (turning a nice-ish server into a rock-solid timekeeper) Thanks so far everyone. Really impressed that I already managed to get 4x replies so quickly :) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
In this case, you're not looking for the RTC but rather the clock that drives the COU, which is what drives the system clock. On most systems, the RTC is read only at startup and is not used once the system is running. John On Nov 30, 2012, at 6:30 PM, Eric Garner garn...@gmail.com wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. -Eric On Fri, Nov 30, 2012 at 3:04 PM, bownes bow...@gmail.com wrote: It all depends on what clock your talking about. Any given PC probably has more than one oscillator onboard. Generally there will be one for the CPU, one for the display circuitry, and probably one for the real time clock. Presuming you are talking about the CPU clock, it should be fairly straightforward to find the oscillator package on the motherboard find the pin with clock output and feed your clock input there. On Nov 30, 2012, at 16:59, Bob Camp li...@rtty.us wrote: Hi It's most commonly done with things like a Soekris 45xx series board. You don't need anything very exotic for the frequency conversion. The jitter in the PC is way worse than what the external chips will be creating. The real question is - what is the magic frequency on the particular mother board you are going to modify? Once upon a time they all were a pretty predictable 14.xxx MHz. These days, who knows what's going in where… Bob On Nov 30, 2012, at 4:55 PM, Sarah White kuze...@gmail.com wrote: Has anyone ever used a TAPR clock block or other frequency synthesizer to sort the clock drift / timing problems on a regular computer? I'll probably end up with a used dell or IBM workstation for this purpose. Recently, I came across a low-cost frequency synthesizer capable of using a 10mhz frequency reference (planning on using the thunderbolt GPSDO I'm working with once I manage to sort out the temperature issues) http://www.tapr.org/~n8ur/Clock-Block_Manual.pdf ^ TAPR Clock Block has an installation example for how to do what I'm planning with a Soekris net4501 low-cost / low-power embedded device... What I'm hoping to figure out is how to do the same, except on a proper computer such as the local used ones I'm able to get for less than $200 with 2ghz with 30GB hard disk, 512mb or more ram, etc. So I figure this should be fine for what I'm planning. Example of what I'm trying to do, though based on the low-power embedded Soekris net4501 system from the TAPR manual's example section: http://www.febo.com/time-freq/ntp/soekris/index.html ^Aren't those the photos from clock block frequency synthesizer manual? Again, I'm wondering if anyone has opinions or experience about doing such things with NOT an embedded system (as I said, can get a nice 2ghz or so machine for less than $200 locally at a brick and mortar shop within walking distance) Thanks in advance, 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. ___ 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] Using a frequency synthesizer replacement for motherboard oscillator
On Nov 30, 2012, at 7:10 PM, Sarah White kuze...@gmail.com wrote: On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Sarah, when I was designing and protoyping the ClockBlock, I did interface it with a standard mobo (don't recall the specifics). As someone else pointed out, the process is basically: 1. Find and remove the oscillator that drives the CPU, likely something between 33 and 100 Mhz in modern systems. It's *not* the 32.768 kHz crystal (if there still is one; I think it's actually built into thr RTC chip these days). 2. Figure out which pin is the output of the oscillator module. 3. Figure out the proper drive voltage (most easily based on the supply voltage of the oscillator). 4. Hook the ClockBlock output to the signal pad where the oscillator used to be via small-diameter coax cable such as RG-174, connecting the coax shield to ground on the board and using a series resistor if you need to drop the signal voltage below the 3.3V minimum that the ClockBlock can provide via its voltage-select jumper. Some math and/or experimentation may be involved; the goal is to get enough signal to drive the board, without exceeding the safe Vin rsting of whatever devices the clock is driving. 5. Set the ClockBlock jumpers for the proper clock frequency. Have fun! John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
On Nov 30, 2012, at 7:42 PM, John Ackermann N8UR j...@febo.com wrote: In this case, you're not looking for the RTC but rather the clock that drives the COU Read CPU. Stupid iPad keyboard. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
OK, I'll bite. Why? Jim I've never done it using to the RTC crystal, but I do it quite frequently in my Day Job to Ethernet controllers on those same pc mother boards. -Eric On Fri, Nov 30, 2012 at 4:10 PM, Sarah White kuze...@gmail.com wrote: On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Mostly I started this thread because there have been a few with people discussing implementing NTP on embedded microcontrollers, arduino, etc. and I was thinking of doing it from the other side (turning a nice-ish server into a rock-solid timekeeper) Thanks so far everyone. Really impressed that I already managed to get 4x replies so quickly :) ___ 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] Using a frequency synthesizer replacement for motherboard oscillator
On 11/30/12 4:58 PM, John Ackermann N8UR wrote: On Nov 30, 2012, at 7:42 PM, John Ackermann N8UR j...@febo.com wrote: In this case, you're not looking for the RTC but rather the clock that drives the COU Read CPU. Stupid iPad keyboard. I was wondering.. Clock Oscillator Unit? Cryptic Obfuscated Unknown? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
On 11/30/2012 7:54 PM, John Ackermann N8UR wrote: On Nov 30, 2012, at 7:10 PM, Sarah White kuze...@gmail.com wrote: On 11/30/2012 6:30 PM, Eric Garner wrote: the actual RTC on modern (Intel based) PC's is driven from a standard 32,768 Hz crystal attached to the PCH. some of them are in incredibly small packages now instead of the old tuning fork-in-a-can ones. peeling off the load caps and crystal from the board would allow you plenty of spaces to tack down a lead from an external synthesizer. Yeah, the one on the (Soekis) example was pretty small. So far none of of the replies have indicated that anyone on here has experience beyond an embedded system. Sarah, when I was designing and protoyping the ClockBlock, I did interface it with a standard mobo (don't recall the specifics). As someone else pointed out, the process is basically: 1. Find and remove the oscillator that drives the CPU, likely something between 33 and 100 Mhz in modern systems. It's *not* the 32.768 kHz crystal (if there still is one; I think it's actually built into thr RTC chip these days). 2. Figure out which pin is the output of the oscillator module. 3. Figure out the proper drive voltage (most easily based on the supply voltage of the oscillator). 4. Hook the ClockBlock output to the signal pad where the oscillator used to be via small-diameter coax cable such as RG-174, connecting the coax shield to ground on the board and using a series resistor if you need to drop the signal voltage below the 3.3V minimum that the ClockBlock can provide via its voltage-select jumper. Some math and/or experimentation may be involved; the goal is to get enough signal to drive the board, without exceeding the safe Vin rsting of whatever devices the clock is driving. 5. Set the ClockBlock jumpers for the proper clock frequency. Have fun! John John :) Ok, wow, thanks! I couldn't have asked for a better answer to my specific question than one from the designer of the module itself (and more or less saying, and confirming yes, I've done this in testing) Slightly unrelated but... Any chance you could recommend a minimalist set of tools that would be helpful for poking around so I could make sure things are wired up right / signaling as desired, etc? Please don't say logic analyzer or oscilloscope because if that sort of thing is mandatory, I'll just give up now. I took a basic electrical engineering course nearly 20 years ago, and have worked on a few simple controllers and even modified a computer motherboard or two, so this won't be my first venture into such things. ... I'm just currently without ANY tools. (Not counting the dremmel rotory tool for doing acrylic fingernails, and/or various repair tooling, cutting, and sanding of things that would take too long by hand) ... Well mostly none. The only decent tool I have on hand is a soldering iron with a variable control / stand to adjust power and to have somewhere to sit it while it warms up (also, there's a position on the stand which is handy for holding the iron stationary so I can tin wires) Guess that's all for now. Thanks everyone :) P.S. Probably not doing anything like this for at least a month anyway. Still need to sock away enough budget for cheap computer to modify and the clock block itself (or some other appropriate frequency synthesizer) P.P.S This might be my last post of the night. Friend's birthday is today / have a party to finish getting things ready for. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] [off-list] Using a frequency synthesizer replacement for motherboard oscillator
On 11/30/2012 7:58 PM, John Ackermann N8UR wrote: On Nov 30, 2012, at 7:42 PM, John Ackermann N8UR j...@febo.com wrote: In this case, you're not looking for the RTC but rather the clock that drives the COU Read CPU. Stupid iPad keyboard. I use MessageEase on my android smartphone. The standard keyboard, the errors I frequently got, and some of the REALLY BAD / embarrasing auto-correct problems that resulted were causing me much grief. Works on: Android / iPhone / Windows / Pocket PC / Palm OS They even tested it with project glass typing in mid-air too. (google's wearable, headmounted mobile computer platform) Explanation video... http://youtu.be/26ayS-Ita6g Free (for android at least) and it supports multiple languages. I've only been using it for a few months (and I rarely text and almost never email from my phone) and I'm currently up to 30 words per minutes last I checked. ___ 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] [off-list] Using a frequency synthesizer replacement for motherboard oscillator
oops sorry that was supposed to be reply to sender not to list. Sorry sorry. ___ 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] Loran
Well as predicted they went home at 5pm. Signals off the air. On Fri, Nov 30, 2012 at 7:26 PM, Bill Riches bill.ric...@verizon.netwrote: Nothing going on in Cape May for a while - I don't know if they are done testing. Bill WA2DVU Cape May, NJ -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Garvey Sent: Friday, November 30, 2012 3:25 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Loran Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.net wrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] GPSDO recovery from holdover
Does anybody know what happens in a TBolt or Z3801? (or any other boxes?) Suppose your system goes into holdover for long enough to be interesting. Suppose for discussion that the clock drifts so that the PPS if off by a mircosecond. I can see two ways to recover. One is to jump the 10 MHz clock by 10 cycles. The other is to adjust the frequency so that the PPS slews back to on-time. The first approach gives you a second with the wrong number of cycles. The second approach has your clock frequency off for a while with a trade off between how far off and how long it's off. Are there any other approaches? -- These are my opinions. 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] Loran
There is some info here http://www.ursanav.com/ - click on the Latest LF News on the right side. There is a paper here http://www.nautelnav.com/wp-content/uploads/2011/09/Nautel-UrsaNav-NAV10-Research-Paper.pdfthat I think is relevant. It will take me some time to wade through it with no guarantee I'll understand it enough to be sure it is talking about the same thing so I thought I'd pass it along. Alan On Fri, Nov 30, 2012 at 6:46 PM, paul swed paulsw...@gmail.com wrote: Well as predicted they went home at 5pm. Signals off the air. On Fri, Nov 30, 2012 at 7:26 PM, Bill Riches bill.ric...@verizon.net wrote: Nothing going on in Cape May for a while - I don't know if they are done testing. Bill WA2DVU Cape May, NJ -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Garvey Sent: Friday, November 30, 2012 3:25 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Loran Might be these guys; this abstract is from the Precision Time and Time Interval (PTTI) Meeting which took place in Reston, VA during this past week. There will be a follow-up manuscript. Mike -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: Thursday, November 29, 2012 6:35 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran Rich Did not see anyone respond. Are you still hearing the signal? Paul WB8TSL On Mon, Nov 26, 2012 at 6:59 PM, Rich and Marcia Putz rp...@bnin.net wrote: Hi all; I 'm hearing Loran C signals here in northern Indiana this evening, I guessing from New Jersey. Anyone else hearing these? Rich __**_ 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/listin fo/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] Using a frequency synthesizer replacement for motherboard oscillator
On Fri, Nov 30, 2012 at 04:24:38PM -0600, shali...@gmail.com wrote: I am not sure that a precision clock will help if the cpu is busy and skips clock cycles. I believe this is one of the problems with general purpose OSes like Windows. I believe the better boards like the Soekis use hardware dividers to alleviate the cpu busy problem. Didier For what it is worth, for many generations now all major CPUs have had kernel software readable nanosecond level time of day time stamping counters that are clocked from the incoming clock to the CPU chip and run continuously and steadily without skipped or added ticks whatever the CPU is doing. And in addition to these time stamping counters, most all CPU chip sets also include real time clock interrupts which again are driven off of continuously counting counters referenced to the clock input to the CPU and can be programmed to interrupt ever n ticks of the master clock - regardless of CPU activity. Obviously while servicing the real time clock interrupts is usually a very high priority, depending on how the OS works and what privileges real time priority apps have occasionally a real time interrupt can be serviced so slowly that another one happens before it is cleared. Some OS real time clock handlers attempt to spot these cases and adjust their idea of time to compensate. Any OS based PLL driven by time stamping 1 PPS timing interrupts WILL see some jitter in its time stamps due to bus and internal CPU latencies and use of interrupt off intervals to protect against race conditions. This noise is unavoidable and does depend on CPU load and even how fast the CPU clocks are set to run at any instant (modern CPUS dynamically adjust clock rate in various areas of their logic to conserve power and reduce heat). So for a very fine control a hardware based 1PPS event time stamper will provide greater accuracy and less jitter, especially if it is driven by a high accuracy external clock source locked to some time reference. But of course it IS useful to clock the CPU with an accurate clock as that then means the internal CPU time stamp counter and real time tick interrupt is ticking at a known rate - starting from some epoch that can be eventually calibrated over time - and multiple 1 PPS ticks - within a few ns or so of 1 PPS GPS or other similar time. If the CPU clock is unstable and wanders around with time, temperature, power and fan activity it then becomes necessary - as the timing 1PPS PLLs built into many modern kernels do - to try to measure its frequency error and drift and estimate the error phase between it and true time. If the CPU clock is locked to a reference, this is not as hard a thing to do as the only relative unknown is when exactly the zero epoch on the counter occurred. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] GPSDO recovery from holdover
Hal, New JLT GPSDOs step back in 10 Steps over 10 seconds if more than 250ns off, then adjust the last ns slowly. If within 250ns, they just slowly slew back. Bye, Said Sent From iPhone On Nov 30, 2012, at 18:10, Hal Murray hmur...@megapathdsl.net wrote: Does anybody know what happens in a TBolt or Z3801? (or any other boxes?) Suppose your system goes into holdover for long enough to be interesting. Suppose for discussion that the clock drifts so that the PPS if off by a mircosecond. I can see two ways to recover. One is to jump the 10 MHz clock by 10 cycles. The other is to adjust the frequency so that the PPS slews back to on-time. The first approach gives you a second with the wrong number of cycles. The second approach has your clock frequency off for a while with a trade off between how far off and how long it's off. Are there any other approaches? -- These are my opinions. 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] GPSDO recovery from holdover
Hi A few more possibilities: 1) Slip the clock by one cycle per second rather than 10 at once. 2) Take the pps off of a 100 MHz source sync'd to the 10 MHz and slip by less than 100 ns per step 3) Take the pps off of a DDS and fine tune the slip however slowly you might wish. In practice, the approach is get back to +/- 100 ns as soon as you can. The system majority of specs care about being at the right time, and not so much how you get there. There are a few specs that prefer a frequency slew to bring the pps in from microseconds of error, but not many. Bob On Nov 30, 2012, at 9:10 PM, Hal Murray hmur...@megapathdsl.net wrote: Does anybody know what happens in a TBolt or Z3801? (or any other boxes?) Suppose your system goes into holdover for long enough to be interesting. Suppose for discussion that the clock drifts so that the PPS if off by a mircosecond. I can see two ways to recover. One is to jump the 10 MHz clock by 10 cycles. The other is to adjust the frequency so that the PPS slews back to on-time. The first approach gives you a second with the wrong number of cycles. The second approach has your clock frequency off for a while with a trade off between how far off and how long it's off. Are there any other approaches? -- These are my opinions. 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] Using a frequency synthesizer replacement for motherboard oscillator
Hi The problem just the clock it's also the operating system. If it's not designed with timing in mind (= it's an RTOS at some level) then you will have sloppy timing. Counters can help, but they are not the entire solution. If your email (or anti-virus or ...) program can pop up and monopolize the cpu for a chunk of a second (as in 10's or 100's of ms), precision timing isn't going to work very well. There's only so much you can do after the fact. If the pps edge was supposed to go out 27 ms ago, and you only got control back now, you are out of luck. Bob On Nov 30, 2012, at 9:19 PM, David I. Emery d...@dieconsulting.com wrote: On Fri, Nov 30, 2012 at 04:24:38PM -0600, shali...@gmail.com wrote: I am not sure that a precision clock will help if the cpu is busy and skips clock cycles. I believe this is one of the problems with general purpose OSes like Windows. I believe the better boards like the Soekis use hardware dividers to alleviate the cpu busy problem. Didier For what it is worth, for many generations now all major CPUs have had kernel software readable nanosecond level time of day time stamping counters that are clocked from the incoming clock to the CPU chip and run continuously and steadily without skipped or added ticks whatever the CPU is doing. And in addition to these time stamping counters, most all CPU chip sets also include real time clock interrupts which again are driven off of continuously counting counters referenced to the clock input to the CPU and can be programmed to interrupt ever n ticks of the master clock - regardless of CPU activity. Obviously while servicing the real time clock interrupts is usually a very high priority, depending on how the OS works and what privileges real time priority apps have occasionally a real time interrupt can be serviced so slowly that another one happens before it is cleared. Some OS real time clock handlers attempt to spot these cases and adjust their idea of time to compensate. Any OS based PLL driven by time stamping 1 PPS timing interrupts WILL see some jitter in its time stamps due to bus and internal CPU latencies and use of interrupt off intervals to protect against race conditions. This noise is unavoidable and does depend on CPU load and even how fast the CPU clocks are set to run at any instant (modern CPUS dynamically adjust clock rate in various areas of their logic to conserve power and reduce heat). So for a very fine control a hardware based 1PPS event time stamper will provide greater accuracy and less jitter, especially if it is driven by a high accuracy external clock source locked to some time reference. But of course it IS useful to clock the CPU with an accurate clock as that then means the internal CPU time stamp counter and real time tick interrupt is ticking at a known rate - starting from some epoch that can be eventually calibrated over time - and multiple 1 PPS ticks - within a few ns or so of 1 PPS GPS or other similar time. If the CPU clock is unstable and wanders around with time, temperature, power and fan activity it then becomes necessary - as the timing 1PPS PLLs built into many modern kernels do - to try to measure its frequency error and drift and estimate the error phase between it and true time. If the CPU clock is locked to a reference, this is not as hard a thing to do as the only relative unknown is when exactly the zero epoch on the counter occurred. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ 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] GPSDO recovery from holdover
Hi Typo… Sorry Bob On Nov 30, 2012, at 9:49 PM, Bob Camp li...@rtty.us wrote: Hi A few more possibilities: 1) Slip the clock by one cycle per second rather than 10 at once. 2) Take the pps off of a 100 MHz source sync'd to the 10 MHz and slip by less than 100 ns per step 3) Take the pps off of a DDS and fine tune the slip however slowly you might wish. In practice, the approach is get back to +/- 100 ns as soon as you can. The system majority of specs care about being at the right time, and not so much how you get there. There are a few specs that prefer a frequency slew to bring the pps in from microseconds of error, but not many. That should have been milliseconds of error. A microsecond is a ppm off for a second, that you commonly see corrected with a frequency slew. Bob On Nov 30, 2012, at 9:10 PM, Hal Murray hmur...@megapathdsl.net wrote: Does anybody know what happens in a TBolt or Z3801? (or any other boxes?) Suppose your system goes into holdover for long enough to be interesting. Suppose for discussion that the clock drifts so that the PPS if off by a mircosecond. I can see two ways to recover. One is to jump the 10 MHz clock by 10 cycles. The other is to adjust the frequency so that the PPS slews back to on-time. The first approach gives you a second with the wrong number of cycles. The second approach has your clock frequency off for a while with a trade off between how far off and how long it's off. Are there any other approaches? -- These are my opinions. 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. ___ 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] 3120A Phase Noise Test Probe
I just found an interesting new Symmetricom product http://www.symmetricom.com/products/test-and-measurement/phase-noise-allan-deviation-test-sets/3120A-Phase-Noise-Test-Probe/ It looks familiar, doesn't it? Adrian ___ 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] GPSDO recovery from holdover
saidj...@aol.com said: New JLT GPSDOs step back in 10 Steps over 10 seconds if more than 250ns off, then adjust the last ns slowly. Thanks/interesting. How/why did you pick 10? If within 250ns, they just slowly slew back. How fast is slowly? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
On Fri, Nov 30, 2012 at 09:58:29PM -0500, Bob Camp wrote: Hi The problem just the clock it's also the operating system. If it's not designed with timing in mind (= it's an RTOS at some level) then you will have sloppy timing. Counters can help, but they are not the entire solution. If your email (or anti-virus or ...) program can pop up and monopolize the cpu for a chunk of a second (as in 10's or 100's of ms), precision timing isn't going to work very well. There's only so much you can do after the fact. If the pps edge was supposed to go out 27 ms ago, and you only got control back now, you are out of luck. No doubt that you get into a sort of philosophic meaning of what-really-is-now relativity here... if parts of the kernel know what time it is quite precisely but other parts and most user programs are only loosely aware of and only able to react to it post facto by large and jittery intervals, what is the meaning of microsecond or even ns level OS time sync ? Most modern kernels *internally* have at least some degree of fairly serious real time high priority tight deadline stuff going on - and API hooks for accessing it available - the degree to which this is exposed and visible to or usable by user space threads varies a lot, and correctly using this stuff always requires pretty deep skill and thought. Not for the faint of heart or inexperienced. Very easy to make subtle errors that cause bugs that happen only once every few hundred or even many thousands of hours. And pretty obviously the more control and access the user (eg applications programmers) get and use the less likely it is that some combination of separately developed and architected applications and a particular kernel running on particular hardware will handle all of this right ALL the time. Emphasis here on ALL, it usually works most of the time but making it essentially never fail is really really hard. And many of those failures result in things like deadly embrace lockups which can cause everything to stop or rare conditions in which apparent causality and temporal coherence completely inverts and things which cannot happen happen exposing all kinds of reasonable but not quite bulletproof assumptions. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Using a frequency synthesizer replacement for motherboard oscillator
On Fri, Nov 30, 2012 at 8:39 PM, David I. Emery d...@dieconsulting.comwrote: On Fri, Nov 30, 2012 at 09:58:29PM -0500, Bob Camp wrote: Hi The problem just the clock it's also the operating system. If it's not designed with timing in mind (= it's an RTOS at some level) then you will have sloppy timing. What is sloppy timing? If about 10 microseconds of error is sloppy then you are right. None of the effects you describe need to cause a problem. Even on a non-RTOS the limiting factor is the uncertainty in the interrupt latency. The way it works is that the PPS interrupts the CPU and then inside the handler a hardware counter is sampled and stored and that is it. Nothing else needs to occur in real time. Quite a few people are able to run NTP serversand keep there system clocks for small (uSecs) error from UTC.But now the question is if an application program can us the clock .without some error I think it can. A simple example is a program that time stamps data. It waits for data then when it comes in reads the system clock then tags the data with the sampled clock. The problem is if the CPU is taken away. One way to detect a problem is to read the clock twice and check for a deta time of more than a few nanoseconds. Then if you read the data between those to clock samples you will know the clock was acuratly sampled. 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.
