Re: [time-nuts] 50:50 duty from a PRS10
Dave M wrote: Hello, I have a PRS10 rubidium which gives a 1pps output. The output is a 10 us positive pulse. I need to convert that to a 50:50 duty cycle pulse. Still 1pps. I'm hoping for a simple circuit rather than having to use a pic. I don't mind a bit of propagation delay, but I need to preserve the low jitter on the rising edge, and hopefully also the falling edge. Any ideas out there Regards Steve The simplest way that I can think of is to feed both inputs of an XOR gate with your 1pps signal to double it to 2pps, then feed the XOR output into a flipflop to get back to 1pps with 50% duty cycle. You might have to delay the 1pps into one of the XOR inputs with a small RC to reliably trigger the flipflop. Use 74HC or AC gates and the jitter should be tolerable. Cheers, David dgminala at mediacombb dot net All that will achieve is generating a pulse about 10us wide of indeterminate polarity. Bruce ___ time-nuts mailing 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] The future of UTC
Mr HeathKid, What is your reason for hating dst. The changeover is a pain - but after that, what is the problem? Jim On 22 July 2011 14:23, Heathkid heath...@heathkid.com wrote: I live at 39° 57' 46 N and I absolutely HATE DST! Yes, Indiana... we haven't had DST for too long. It's bad and I hope some day we go back to not having it. - Original Message - From: Rob Kimberley r...@timing-consultants.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Tuesday, July 19, 2011 1:57 PM Subject: Re: [time-nuts] The future of UTC My earlier reply about flexible working practices still holds. Why not just move with the seasons. Before clocks, I'm sure that's what we did - we got up when it was light, and went to bed when it was dark. The bit in between just happens to be elastic... I live at 53 degrees North in the UK by the way. Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-bounces@**febo.comtime-nuts-boun...@febo.com] On Behalf Of Jim Palfreyman Sent: 19 July 2011 1:58 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] The future of UTC Far out. I've just read so many logical fallacies and government conspiracies I'm embarrassed for this high quality list. Let's inject some facts here. I live at 43 degrees south. At the winter solstice (June 21) the sun rises at 7:41 and sets at 16:43. At the summer solstice (December 21) the sun rises (no DST) at 04:28 and sets at 19:49. Sunrise at 04:28 is ridiculous. Including twilight it starts getting light at 3:30. Switch to DST and sunrise moves to 05:28 and sets at 20:49. Much more reasonable. Nice summer evenings too. We have DST for 6 months of the year and wouldn't swap it for anything. I understand it's different the closer to the equator you are, but for mid latitudes it really works. Jim On Tuesday, 19 July 2011, Thomas A Frank ka2...@cox.net wrote: BLOCK: This may be kind of an urban legend, but I thought I had heard that one of the backers behind extending Daylight Saving Time into the beginning of November was the candy industry, and it all had to do with Halloween. Mr. DOWNING: This is no kind of legend. This is the truth. For 25 years, candy-makers have wanted to get trick-or-treat covered by Daylight Saving, figuring that if children have an extra hour of daylight, they'll collect more candy. In fact, they went so far during the 1985 hearings on Daylight Saving as to put candy pumpkins on the seat of every senator, hoping to win a little favor. I would say it backfired. At least here in Rhode Island, the extra daylight resulted in the compression of the trick or treating schedule, since all the little goblins and ghouls wanted to go out after dark (to better scare the homeowners and enjoy their glow in the dark costumes), but they also were expected home by 8pm (local). Net result is less candy given out. At least that has been my experience. Proving you shouldn't tamper with time. Measure yes, tamper, no. :-) Tom Frank, KA2CDK __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 50:50 duty from a PRS10
I was wondering how one would even use a PIC. You can make a 10MHz to 1PPS divider using a tiny 8-pin PIC. I have extras here. Send me email off-line if you want one. Cost is $2. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 50:50 duty from a PRS10
On 07/22/2011 05:38 AM, Dave M wrote: Hello, I have a PRS10 rubidium which gives a 1pps output. The output is a 10 us positive pulse. I need to convert that to a 50:50 duty cycle pulse. Still 1pps. I'm hoping for a simple circuit rather than having to use a pic. I don't mind a bit of propagation delay, but I need to preserve the low jitter on the rising edge, and hopefully also the falling edge. Any ideas out there Regards Steve The simplest way that I can think of is to feed both inputs of an XOR gate with your 1pps signal to double it to 2pps, then feed the XOR output into a flipflop to get back to 1pps with 50% duty cycle. You might have to delay the 1pps into one of the XOR inputs with a small RC to reliably trigger the flipflop. Use 74HC or AC gates and the jitter should be tolerable. The rise and fall transitions which trigger the XOR gate will cause the XOR output to occur at those times and not with a 500 ms spread as you wish them to be. You really need some form of memory that recalls that we have a high period for 500 ms rather than the 10 us. The method (and inherent precision) will vary, but there is no alternative to this memory. Dividers from the 10 MHz ensures it is a synchronous timed transition. If the fall transition isn't critical, the 555 solution or similar will do. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 50:50 duty from a PRS10
Hello, I have a PRS10 rubidium which gives a 1pps output. The output is a 10 us positive pulse. I need to convert that to a 50:50 duty cycle pulse. Still 1pps. I'm hoping for a simple circuit rather than having to use a pic. I don't mind a bit of propagation delay, but I need to preserve the low jitter on the rising edge, and hopefully also the falling edge. Any ideas out there Regards Steve Feed the PPS into both inputs of a 74HC164 clock with 10MHz to clock, ~CLR grounded. Take outputs C and H into J-K Flip-Flop (74HC112) also clocked with 10MHz - I think that will do it. See the schematic of my Frequency Divider http://perdrix.co.uk/FrequencyDivider/Frequency%20Divider%202%20Schematic.pdf where I take the RCO output from an AC163 and use this to derive 1MHz 50% duty cycle. The full write up is here: http://perdrix.co.uk/FrequencyDivider/index.html Regards, David Partridge -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: 22 July 2011 10:02 To: time-nuts@febo.com Subject: Re: [time-nuts] 50:50 duty from a PRS10 On 07/22/2011 05:38 AM, Dave M wrote: Hello, I have a PRS10 rubidium which gives a 1pps output. The output is a 10 us positive pulse. I need to convert that to a 50:50 duty cycle pulse. Still 1pps. I'm hoping for a simple circuit rather than having to use a pic. I don't mind a bit of propagation delay, but I need to preserve the low jitter on the rising edge, and hopefully also the falling edge. Any ideas out there Regards Steve The simplest way that I can think of is to feed both inputs of an XOR gate with your 1pps signal to double it to 2pps, then feed the XOR output into a flipflop to get back to 1pps with 50% duty cycle. You might have to delay the 1pps into one of the XOR inputs with a small RC to reliably trigger the flipflop. Use 74HC or AC gates and the jitter should be tolerable. The rise and fall transitions which trigger the XOR gate will cause the XOR output to occur at those times and not with a 500 ms spread as you wish them to be. You really need some form of memory that recalls that we have a high period for 500 ms rather than the 10 us. The method (and inherent precision) will vary, but there is no alternative to this memory. Dividers from the 10 MHz ensures it is a synchronous timed transition. If the fall transition isn't critical, the 555 solution or similar will do. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Spectrcom 8170 Reloaded
Hi Shaun I may have missed a email or something. I think. You are using the 8170s 1 MC out to drive a loran commercial simulator that then drives the austron. Do I understand this correctly? I designed and built a few simple chips loran c sim about 1.5 years ago and shared that information on Time-nuts before loran C shut down for good. It takes in 100kc -5 mc etc and provides a loran c master station output. Numbers of austrons I have lock to it very quickly and resolve down to the austron limits, as long as the reference is good. Several of us with the 8170s have noticed the significant 1 mc output phase jumps due to the depth of modulation of the wwvb signal. (Thats my theory at least). Believe all of these vintage rcvrs suffers the same issue this includes the tracor 599 and hp117s (To a far lesser extent). I have discussed with another time-nut Paul about adding a limiter or at least gain ahead of the I detector in the 8170 also will need to build at least an equivalent delay for the q detector to keep it at 90 degrees. Simply over the last few weeks have not had time to do so. My interest is in lowering the jitter of these units. What I am doing will have no effect on the propagation effects. Regards Paul WB8TSL On Fri, Jul 22, 2011 at 12:34 AM, Shaun Merrigan smerr...@compusmart.ab.cawrote: Last step is to let the Austrons (2100R and 2100F) lock to the new LORAN inputs thus: http://www.flickr.com/photos/acme-laboratories/5947818627/ and the 2100R: http://www.flickr.com/photos/acme-laboratories/5963265512/ Shaun M No Regret (Since 1996) ___ time-nuts mailing 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] Discipline an oscillator with NTP?
I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing 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] Discipline an oscillator with NTP?
On Fri, Jul 22, 2011 at 2:27 PM, Jason Rabel ja...@extremeoverclocking.com wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? I believe the Symmetricom NTP servers do this, whether or not they have external access to the oscillator or not I'm not sure. I know that even their most basic model has OCXO and/or Rubidium upgrade options. [1] The SyncServer S100 can be disciplined by either NTP via networking or GPS. I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator in a can [2] that the embedded processor uses. [1] http://www.symmetricom.com/products/ntp-servers/ntp-network-appliances/SyncServer-S100/ [2] such as http://www.foxonline.com/thru_hole_oscillators.htm ___ time-nuts mailing 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] Discipline an oscillator with NTP?
I must say Jason, Yes, you are day dreaming, but hey, that is where ideas come from. I do not play with NTP, but isn't that the same thing ( or similar) as disciplining my local clock when I have it update against a reference like NIST over the Internet ? In other words, NTP is used to keep the local computer clock in sync and thus is basically keeping an oscillator disciplined so to speak. As to how you would directly make the hardware deal with the oscillator instead of just updating a register dealing with the time, I do not know. I am sure it can probably be done. BillWB6BNQ Jason Rabel wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing 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] Discipline an oscillator with NTP?
No exactly. A PPS generator syncrhonized with UTC time, using a GPS ntp server in the same LAN. Not too bad... but several microseconds jittery :) enough for my application then. Probably with long time constants it is doable, but if the ntp server is in the internet, and not in a LAN, I suspect that to get good results can be a bit difficult :) Regards, Javier El 22/07/2011 20:27, Jason Rabel escribió: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing 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] Discipline an oscillator with NTP?
El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator in a can [2] that the embedded processor uses. No, ntp algorithm does not adjust the oscillator itself. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Discipline an oscillator with NTP?
On 07/22/2011 11:48 AM, Javier Herrero wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator in a can [2] that the embedded processor uses. No, ntp algorithm does not adjust the oscillator itself. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Until LightSquared goes online we will have GPS available almost everywhere high speed internet is available. NTP disicipline is possible but the necessary time constants might approach the MTFB of associated systems. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing 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] Spectrcom 8170 Reloaded
Paul, Thanks for the reply. I have been out of the loop so to speak for a while, so I did not know about your simulator. I'll look in the archives and retrieve the information. The story behind the 8170 and 2042 is I purchased them well in advance of LORAN (in NA at least) going silent, but only just now had the time to start testing them. Thanks, Shaun M -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of paul swed Sent: July-22-11 8:39 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Spectrcom 8170 Reloaded Hi Shaun I may have missed a email or something. I think. You are using the 8170s 1 MC out to drive a loran commercial simulator that then drives the austron. Do I understand this correctly? I designed and built a few simple chips loran c sim about 1.5 years ago and shared that information on Time-nuts before loran C shut down for good. It takes in 100kc -5 mc etc and provides a loran c master station output. Numbers of austrons I have lock to it very quickly and resolve down to the austron limits, as long as the reference is good. Several of us with the 8170s have noticed the significant 1 mc output phase jumps due to the depth of modulation of the wwvb signal. (Thats my theory at least). Believe all of these vintage rcvrs suffers the same issue this includes the tracor 599 and hp117s (To a far lesser extent). I have discussed with another time-nut Paul about adding a limiter or at least gain ahead of the I detector in the 8170 also will need to build at least an equivalent delay for the q detector to keep it at 90 degrees. Simply over the last few weeks have not had time to do so. My interest is in lowering the jitter of these units. What I am doing will have no effect on the propagation effects. Regards Paul WB8TSL On Fri, Jul 22, 2011 at 12:34 AM, Shaun Merrigan smerr...@compusmart.ab.cawrote: Last step is to let the Austrons (2100R and 2100F) lock to the new LORAN inputs thus: http://www.flickr.com/photos/acme-laboratories/5947818627/ and the 2100R: http://www.flickr.com/photos/acme-laboratories/5963265512/ Shaun M No Regret (Since 1996) ___ time-nuts mailing 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] My Custom GPS clock
Hello Everyone, I thought some of you might be interested in the following. A few months ago, a few time-nuts discussed what they had done to convert existing equipment to a large GPS clock. I elected to design my own clock display instead. Mine is fed by a Garmin GPS-35 GPS and it uses a 64 x 8 LED array for the display. It is driven by a PIC18F1220 with custom firmware. I have posted a Youtube video that shows the unit in action: http://www.youtube.com/watch?v=RJE-PeUtxfU The unit is described in more detail on my website at: http://ve2zaz.net/GPS_Clock/GPS_Clock.htm Cheers, Bert, VE2ZAZ ___ time-nuts mailing 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] Discipline an oscillator with NTP?
On 7/22/11 11:59 AM, Chuck Forsberg WA7KGX N2469R wrote: On 07/22/2011 11:48 AM, Javier Herrero wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator in a can [2] that the embedded processor uses. No, ntp algorithm does not adjust the oscillator itself. Until LightSquared goes online we will have GPS available almost everywhere high speed internet is available. Except that GPS requires a view of the sky (or cabling to a place with a view of the sky).. There are a quite a lot of applications where you might have a network connection, but not view of the sky. The question is whether NTP is decent for disciplining. (PTP would almost certainly work) NTP disicipline is possible but the necessary time constants might approach the MTFB of associated systems. ___ time-nuts mailing 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] Discipline an oscillator with NTP?
This is exactly what an NTP server does. It adjusts the rate of a local clock so that the local clock advances at the same rate is the set of Internet servers that have passed a clock selection test. NTP does this very well considering the uncertainly of the lag over the internet. There is a good argument the NTP is optimal but the best you can get using Internet time servers is about a milli second or 0.001 second. It would be nearly trivial to write software to produce a PPS output on one of the control line of a serial port. SO you NTP disciplined computer can produce PPS with about .001 second error Send this PPS to the normal GPSDXO in place of the GPS' PPS. The computer is only about 1000 times worse than a GPS and might work OK if you drastically increase the time constant on the GPSDXO's control loop. I think your NTPDXO might be as good as GPSDXO is measured over a long enough period, like months. Short term it might be about as good as the TTL can oscillator inside the PC. On Fri, Jul 22, 2011 at 11:27 AM, Jason Rabel ja...@extremeoverclocking.com wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] My Custom GPS clock
Hi Bert: Which Sure Electronics display board did you use (they make a bunch of different ones)? http://www.sureelectronics.net/category.php?id=60 Have Fun, Brooke Clarke http://www.PRC68.com http://www.End2PartyGovernment.com/ Bert, VE2ZAZ wrote: Hello Everyone, I thought some of you might be interested in the following. A few months ago, a few time-nuts discussed what they had done to convert existing equipment to a large GPS clock. I elected to design my own clock display instead. Mine is fed by a Garmin GPS-35 GPS and it uses a 64 x 8 LED array for the display. It is driven by a PIC18F1220 with custom firmware. I have posted a Youtube video that shows the unit in action: http://www.youtube.com/watch?v=RJE-PeUtxfU The unit is described in more detail on my website at: http://ve2zaz.net/GPS_Clock/GPS_Clock.htm Cheers, Bert, VE2ZAZ ___ time-nuts mailing 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] My Custom GPS clock
Hi Brooke, I go by memory here, but I believe it is a pair of DE-DP13112 (P4 32X8 3208 Red LED Dot Matrix Unit Board SPI Like), which are currently on sale for $11 ea. I bought mine on eBay. Cheers, Bert, VE2ZAZ From: Brooke Clarke bro...@pacific.net To: Bert, VE2ZAZ ve2...@yahoo.ca; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, July 22, 2011 4:36:33 PM Subject: Re: [time-nuts] My Custom GPS clock Hi Bert: Which Sure Electronics display board did you use (they make a bunch of different ones)? http://www.sureelectronics.net/category.php?id=60 Have Fun, Brooke Clarke http://www.PRC68.com http://www.End2PartyGovernment.com/ Bert, VE2ZAZ wrote: Hello Everyone, I thought some of you might be interested in the following. A few months ago, a few time-nuts discussed what they had done to convert existing equipment to a large GPS clock. I elected to design my own clock display instead. Mine is fed by a Garmin GPS-35 GPS and it uses a 64 x 8 LED array for the display. It is driven by a PIC18F1220 with custom firmware. I have posted a Youtube video that shows the unit in action: http://www.youtube.com/watch?v=RJE-PeUtxfU The unit is described in more detail on my website at: http://ve2zaz.net/GPS_Clock/GPS_Clock.htm Cheers, Bert, VE2ZAZ ___ time-nuts mailing 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] My Custom GPS clock
That's what I come up with from their web site. . . Great Clock!! 73's, Randy Hunt, KI6WAS -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bert, VE2ZAZ Sent: Friday, July 22, 2011 1:54 PM To: Brooke Clarke; time-nuts@febo.com Subject: Re: [time-nuts] My Custom GPS clock Hi Brooke, I go by memory here, but I believe it is a pair of DE-DP13112 (P4 32X8 3208 Red LED Dot Matrix Unit Board SPI Like), which are currently on sale for $11 ea. I bought mine on eBay. Cheers, Bert, VE2ZAZ From: Brooke Clarke bro...@pacific.net To: Bert, VE2ZAZ ve2...@yahoo.ca; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, July 22, 2011 4:36:33 PM Subject: Re: [time-nuts] My Custom GPS clock Hi Bert: Which Sure Electronics display board did you use (they make a bunch of different ones)? http://www.sureelectronics.net/category.php?id=60 Have Fun, Brooke Clarke http://www.PRC68.com http://www.End2PartyGovernment.com/ Bert, VE2ZAZ wrote: Hello Everyone, I thought some of you might be interested in the following. A few months ago, a few time-nuts discussed what they had done to convert existing equipment to a large GPS clock. I elected to design my own clock display instead. Mine is fed by a Garmin GPS-35 GPS and it uses a 64 x 8 LED array for the display. It is driven by a PIC18F1220 with custom firmware. I have posted a Youtube video that shows the unit in action: http://www.youtube.com/watch?v=RJE-PeUtxfU The unit is described in more detail on my website at: http://ve2zaz.net/GPS_Clock/GPS_Clock.htm Cheers, Bert, VE2ZAZ ___ time-nuts mailing 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] Discipline an oscillator with NTP?
On Fri, Jul 22, 2011 at 2:48 PM, Javier Herrero jherr...@hvsistemas.es wrote: El 22/07/2011 20:39, michael taylor escribió: I think all NTP server appliances have this functionality by their nature, whether or not the oscillator is of particular high quality (low noise) or not. Many of the low-end ones likely just use a standard oscillator in a can [2] that the embedded processor uses. No, ntp algorithm does not adjust the oscillator itself. Yes, while the NTP algorithm or protocol does not adjust the oscillator (or RTC) hardware directly, it does pass trimming or de-skewing recommendations via software (ntp_adjtime, adjustime, or hardpps) to OS, allowing the OS to adjust its system's clock. But in the case of a NTP appliance (or embedded device), having intimate knowledge of a single design means that the appliance's Operating System could implement ntp_adjustime or hardpps to a VCO (voltage controlled oscillator) via a DAC, a DDS or similar, to actually fine time the device's master oscillator. Which becomes worthwhile if there is an high quality oscillator driving (or steering) the computer hardware's system clock, such as an OCXO or Rubidium oscillator. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Discipline an oscillator with NTP?
Hi The easy way is to take a pps off of your external oscillator and feed that into a port on your NTP server. Let NTP tell you where that pps is. Don't let NTP lock to the pps, just let it report it's position. After that all you need to do is write some code to read the location of the pulse and implement a *long* time constant loop. Taking the 1 ms number and a 1x10^-10 goal, the time constant would need to be around 4 months. There are a few minor details about drift of the local reference and how valid 1 ms is over long time periods. A reasonable GPSDO will likely be much more stable and much more accurate. To get it into the range of being practical, you have to get the NTP setup into single digit microseconds. In the us range you still would not beat the GPSDO, but at least you would have a useful device. 1 us can be done on a LAN with NTP. It's tough to do better than 1 ms over the net. Since PTP suffers the same issues over the net that NTP does, it's not a lot of help in this situation. Bob On Jul 22, 2011, at 5:30 PM, Javier Herrero wrote: I've found a plot of the ntp-synthesized GPS output compared with the UTC-aligned GPS from a Thunderbolt. The generated PPS output was 1us wide, and it is represented in infinite persistence to get an idea of the jitter. The offset was around 50us, and the jitter around 8us, so not very bad (it was at least one order of magnitude better than my requirements, so I did not bother to optimize it further). The ntp source was a M12-based ntp server (a blackfin running uClinux, not a Soekris :) ). Driving the PPS output to a serial port from the ntp is not as trivial as you think. This PPS output is from an oscillator disciplined to the system clock - really a stearable divider from the system clock (it is an embedded system using uClinux). If you try to drive a digital output directly from the timer interrupt to get the PPS, you would get far more jitter and error. Best regards, Javier P.S. not sure if the attachment will show up... El 22/07/2011 22:19, Chris Albertson escribió: This is exactly what an NTP server does. It adjusts the rate of a local clock so that the local clock advances at the same rate is the set of Internet servers that have passed a clock selection test. NTP does this very well considering the uncertainly of the lag over the internet. There is a good argument the NTP is optimal but the best you can get using Internet time servers is about a milli second or 0.001 second. It would be nearly trivial to write software to produce a PPS output on one of the control line of a serial port. SO you NTP disciplined computer can produce PPS with about .001 second error Send this PPS to the normal GPSDXO in place of the GPS' PPS. The computer is only about 1000 times worse than a GPS and might work OK if you drastically increase the time constant on the GPSDXO's control loop. I think your NTPDXO might be as good as GPSDXO is measured over a long enough period, like months. Short term it might be about as good as the TTL can oscillator inside the PC. On Fri, Jul 22, 2011 at 11:27 AM, Jason Rabel ja...@extremeoverclocking.com wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. PPSAGPS.pdf___ time-nuts mailing 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] Discipline an oscillator with NTP?
After that all you need to do is write some code to... Oh - if I had a nickel for every time I've heard that! Brent On Fri, Jul 22, 2011 at 6:07 PM, Bob Camp li...@rtty.us wrote: Hi The easy way is to take a pps off of your external oscillator and feed that into a port on your NTP server. Let NTP tell you where that pps is. Don't let NTP lock to the pps, just let it report it's position. After that all you need to do is write some code to read the location of the pulse and implement a *long* time constant loop. Taking the 1 ms number and a 1x10^-10 goal, the time constant would need to be around 4 months. There are a few minor details about drift of the local reference and how valid 1 ms is over long time periods. A reasonable GPSDO will likely be much more stable and much more accurate. To get it into the range of being practical, you have to get the NTP setup into single digit microseconds. In the us range you still would not beat the GPSDO, but at least you would have a useful device. 1 us can be done on a LAN with NTP. It's tough to do better than 1 ms over the net. Since PTP suffers the same issues over the net that NTP does, it's not a lot of help in this situation. Bob On Jul 22, 2011, at 5:30 PM, Javier Herrero wrote: I've found a plot of the ntp-synthesized GPS output compared with the UTC-aligned GPS from a Thunderbolt. The generated PPS output was 1us wide, and it is represented in infinite persistence to get an idea of the jitter. The offset was around 50us, and the jitter around 8us, so not very bad (it was at least one order of magnitude better than my requirements, so I did not bother to optimize it further). The ntp source was a M12-based ntp server (a blackfin running uClinux, not a Soekris :) ). Driving the PPS output to a serial port from the ntp is not as trivial as you think. This PPS output is from an oscillator disciplined to the system clock - really a stearable divider from the system clock (it is an embedded system using uClinux). If you try to drive a digital output directly from the timer interrupt to get the PPS, you would get far more jitter and error. Best regards, Javier P.S. not sure if the attachment will show up... El 22/07/2011 22:19, Chris Albertson escribió: This is exactly what an NTP server does. It adjusts the rate of a local clock so that the local clock advances at the same rate is the set of Internet servers that have passed a clock selection test. NTP does this very well considering the uncertainly of the lag over the internet. There is a good argument the NTP is optimal but the best you can get using Internet time servers is about a milli second or 0.001 second. It would be nearly trivial to write software to produce a PPS output on one of the control line of a serial port. SO you NTP disciplined computer can produce PPS with about .001 second error Send this PPS to the normal GPSDXO in place of the GPS' PPS. The computer is only about 1000 times worse than a GPS and might work OK if you drastically increase the time constant on the GPSDXO's control loop. I think your NTPDXO might be as good as GPSDXO is measured over a long enough period, like months. Short term it might be about as good as the TTL can oscillator inside the PC. On Fri, Jul 22, 2011 at 11:27 AM, Jason Rabel ja...@extremeoverclocking.com wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. PPSAGPS.pdf___ time-nuts mailing 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] Rubidium stability
List, Someone asked about surplus rubidium stability. Here are my results. I had five Lucent Rubidium’s. Three were from RDR in centennial, CO and two were from the Huntsville hamfest. Before measuring stability, I ran them for a week on the bench. Using A Lucent GPS and a HP 5370B counter I found all of mine between 200 to 800 pico-seconds above or below 10 Mhz. BTW one can still get the Lucent units (Rubidium and GPS) for $79 and shipping from RDR. I’m not knocking any other supplier but I feel that the Lucent units have more space for hacking so one could discipline the rubidium first and then apply it to the crystal Osc for better phase noise if needed. One pays their money and makes their choices. Regards, Perrier ___ time-nuts mailing 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] Discipline an oscillator with NTP?
On Fri, 22 Jul 2011 13:27:34 -0500 Jason Rabel ja...@extremeoverclocking.com wrote: I was just thinking (dangerous I know)... Has anyone attempted to build a stand-alone oscillator that is disciplined via NTP? i.e. NTP keeps it on-frequency... And I'm not talking about NTP that is locked to a local GPS, I'm curious about purely syncing to other NTP servers over a network. (The presumption is that you have no access to GPS, WWVB, Cellular, or similar.) Is it even possible or am I just day dreaming? There is something similar. Somewhere on the net, a guy described how he build a frequency counter using ntp. Unfortunately i'm unable to find it. AFAIK it worked pretty well with decent results, if the integration time was in the hours (iirc less than a day). Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] My Custom GPS clock
A few years ago, I did a similar clock for use in the car, but using a 4 line lcd. I never thought about correcting it for the software delays- an excellent idea Bert, thanks. I guess I am going to have to do a bit of a re-write sometime soon. Thinking about it, I could just feed the 1pps into the pic and use that to trigger the display update but with one second added. If anyone is interested, the clock is here www.vk7krj.com/ham_stuff.htm and if anyone wants the source code (it's in crownhill pic basic) I'm happy to supply it. On 2011-07-23 05:41, Bert, VE2ZAZ wrote: Hello Everyone, I thought some of you might be interested in the following. A few months ago, a few time-nuts discussed what they had done to convert existing equipment to a large GPS clock. I elected to design my own clock display instead. Mine is fed by a Garmin GPS-35 GPS and it uses a 64 x 8 LED array for the display. It is driven by a PIC18F1220 with custom firmware. Cheers, Bert, VE2ZAZ -- Cheers, Ken vk7...@users.tasmanet.com.au www.vk7krj.com 'It seems hard to sneak a look at God's cards. But that He plays dice and uses telepathic methods is something that I cannot believe for a single moment.' (Einstein's famous quote on Quantum theory) No virus found in this outgoing message. Checked by AVG - www.avg.com Version: 9.0.901 / Virus Database: 271.1.1/3782 - Release Date: 07/23/11 04:34:00 ___ time-nuts mailing 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] Rubidium stability
Perrier: Can you clarify your results? What do you mean by 200 to 800ps above or below 10MHz? Is that how much they gained or lost in a one second period (meaning 2 to 8E-10 error)? Or was it error in period measurement (hopefully not, 8E-3 error). Jose -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry Sandeen Sent: Friday, July 22, 2011 3:49 PM To: time-nuts@febo.com Subject: [time-nuts] Rubidium stability List, Someone asked about surplus rubidium stability. Here are my results. I had five Lucent Rubidium’s. Three were from RDR in centennial, CO and two were from the Huntsville hamfest. Before measuring stability, I ran them for a week on the bench. Using A Lucent GPS and a HP 5370B counter I found all of mine between 200 to 800 pico-seconds above or below 10 Mhz. BTW one can still get the Lucent units (Rubidium and GPS) for $79 and shipping from RDR. I’m not knocking any other supplier but I feel that the Lucent units have more space for hacking so one could discipline the rubidium first and then apply it to the crystal Osc for better phase noise if needed. One pays their money and makes their choices. Regards, Perrier ___ time-nuts mailing 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] The future of UTC
Ha, you may well ask. The reason to hate DST is given to us in the southern parts of Australia, by our Queensland cousins: The problems with DST is : 1. The Cows get very confused and the farmers have problems milking them. 2. The chickens don't know anymore when to lay the eggs. it is rumoured, that the shape of the eggs may suffer. However, this has not been proven, since Queensland never had DST. and 3. most importantly, The extra daylight fades the curtains more, and as every housewife will tell you: That will never do On 22/07/2011 17:19, Jim Palfreyman wrote: Mr HeathKid, What is your reason for hating dst. The changeover is a pain - but after that, what is the problem? Jim On 22 July 2011 14:23, Heathkidheath...@heathkid.com wrote: I live at 39° 57' 46 N and I absolutely HATE DST! Yes, Indiana... we haven't had DST for too long. It's bad and I hope some day we go back to not having it. - Original Message - From: Rob Kimberley r...@timing-consultants.com To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Tuesday, July 19, 2011 1:57 PM Subject: Re: [time-nuts] The future of UTC My earlier reply about flexible working practices still holds. Why not just move with the seasons. Before clocks, I'm sure that's what we did - we got up when it was light, and went to bed when it was dark. The bit in between just happens to be elastic... I live at 53 degrees North in the UK by the way. Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-bounces@**febo.comtime-nuts-boun...@febo.com] On Behalf Of Jim Palfreyman Sent: 19 July 2011 1:58 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] The future of UTC Far out. I've just read so many logical fallacies and government conspiracies I'm embarrassed for this high quality list. Let's inject some facts here. I live at 43 degrees south. At the winter solstice (June 21) the sun rises at 7:41 and sets at 16:43. At the summer solstice (December 21) the sun rises (no DST) at 04:28 and sets at 19:49. Sunrise at 04:28 is ridiculous. Including twilight it starts getting light at 3:30. Switch to DST and sunrise moves to 05:28 and sets at 20:49. Much more reasonable. Nice summer evenings too. We have DST for 6 months of the year and wouldn't swap it for anything. I understand it's different the closer to the equator you are, but for mid latitudes it really works. Jim On Tuesday, 19 July 2011, Thomas A Frankka2...@cox.net wrote: BLOCK: This may be kind of an urban legend, but I thought I had heard that one of the backers behind extending Daylight Saving Time into the beginning of November was the candy industry, and it all had to do with Halloween. Mr. DOWNING: This is no kind of legend. This is the truth. For 25 years, candy-makers have wanted to get trick-or-treat covered by Daylight Saving, figuring that if children have an extra hour of daylight, they'll collect more candy. In fact, they went so far during the 1985 hearings on Daylight Saving as to put candy pumpkins on the seat of every senator, hoping to win a little favor. I would say it backfired. At least here in Rhode Island, the extra daylight resulted in the compression of the trick or treating schedule, since all the little goblins and ghouls wanted to go out after dark (to better scare the homeowners and enjoy their glow in the dark costumes), but they also were expected home by 8pm (local). Net result is less candy given out. At least that has been my experience. Proving you shouldn't tamper with time. Measure yes, tamper, no. :-) Tom Frank, KA2CDK __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Discipline an oscillator with NTP?
On 07/23/2011 12:07 AM, Bob Camp wrote: Hi The easy way is to take a pps off of your external oscillator and feed that into a port on your NTP server. Let NTP tell you where that pps is. Don't let NTP lock to the pps, just let it report it's position. After that all you need to do is write some code to read the location of the pulse and implement a *long* time constant loop. Taking the 1 ms number and a 1x10^-10 goal, the time constant would need to be around 4 months. There are a few minor details about drift of the local reference and how valid 1 ms is over long time periods. A reasonable GPSDO will likely be much more stable and much more accurate. To get it into the range of being practical, you have to get the NTP setup into single digit microseconds. In the us range you still would not beat the GPSDO, but at least you would have a useful device. 1 us can be done on a LAN with NTP. It's tough to do better than 1 ms over the net. Since PTP suffers the same issues over the net that NTP does, it's not a lot of help in this situation. There are people already hacking an OCXO into the system clock of their NTP server. Now, look at the correction log (frequency and phase) of the system, low-pass filter that and use it to steer a secondary loop steering the oscillator. It should be fairly easy and not require much of hacking to achieve. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Discipline an oscillator with NTP?
On Fri, Jul 22, 2011 at 2:30 PM, Javier Herrero jherr...@hvsistemas.es wrote: I've found a plot of the ntp-synthesized GPS output compared with the UTC-aligned GPS from a Thunderbolt. The generated PPS output was 1us wide, and it is represented in infinite persistence to get an idea of the jitter. The offset was around 50us, and the jitter around 8us, so not very bad (it was at least one order of magnitude better than my requirements, so I did not bother to optimize it further). The ntp source was a M12-based ntp server (a blackfin running uClinux, not a Soekris :) ). Driving the PPS output to a serial port from the ntp is not as trivial as you think. This PPS output is from an oscillator disciplined to the system clock - really a stearable divider from the system clock (it is an embedded The software PPS on the serial port that i suggested would be an intermediate step. What you measured was the output of what I called a NTPDXO decided down. I think we are talking about the same kind of design. I guessed that the jitter on the final PPS would be 1000x worse than from a GPS and your 8uS measurement is spot on that. The M12 has a handful of nS error Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Discipline an oscillator with NTP?
On 7/22/11 3:46 PM, brent evers wrote: After that all you need to do is write some code to... Oh - if I had a nickel for every time I've heard that! Brent When I worked in the physical effects business, we'd get a set of storyboards from a director, and we'd have to figure out how we were going to build a rig or arrange the effect as required. The catch phrase was always then, all you gotta do is... representing some sort of incredibly difficult, tedious, or impractical activity. Sure, install 10,000 lightbulb sockets into a frame and wire them up before tomorrow morning's call time at 6AM.. *all you gotta do* is get 50 people to each wire 200 sockets, screw in the bulbs and test them. ___ time-nuts mailing 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] Discipline an oscillator with NTP?
Yes but in this case it really is easy; Below is an outline (don't
try to compile it.). It has a slight problem because just using
sleep is kind of simplistic. One should wait on the new second and
add some error chacking Point here is just to show that this is not
weeks and weeks worth of work. The below pulse a bit every second
and if the system is running NTP then the length of a second is
controlled by NTP.
Main()
{
int status;
int fd;
int pw = 1000 /* pulse width in uS */
fd=open(dev/tty,O_RDWR);
while(1) {
status = 1;
ioctl(fd, TIOCMSET, status);
ussleep(pw);
status = 0;
ioctl(fd, TIOCMSET, status);
ussleep(100-pw);
}
}
On Fri, Jul 22, 2011 at 6:08 PM, Jim Lux jim...@earthlink.net wrote:
On 7/22/11 3:46 PM, brent evers wrote:
After that all you need to do is write some code to...
Oh - if I had a nickel for every time I've heard that!
Brent
When I worked in the physical effects business, we'd get a set of
storyboards from a director, and we'd have to figure out how we were going
to build a rig or arrange the effect as required. The catch phrase was
always then, all you gotta do is...
representing some sort of incredibly difficult, tedious, or impractical
activity. Sure, install 10,000 lightbulb sockets into a frame and wire them
up before tomorrow morning's call time at 6AM.. *all you gotta do* is get 50
people to each wire 200 sockets, screw in the bulbs and test them.
___
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--
Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Discipline an oscillator with NTP?
First, catch your rabbit... Jim Lux On 7/22/11 3:46 PM, brent evers wrote: After that all you need to do is write some code to... Oh - if I had a nickel for every time I've heard that! Brent When I worked in the physical effects business, we'd get a set of storyboards from a director, and we'd have to figure out how we were going to build a rig or arrange the effect as required. The catch phrase was always then, all you gotta do is... representing some sort of incredibly difficult, tedious, or impractical activity. Sure, install 10,000 lightbulb sockets into a frame and wire them up before tomorrow morning's call time at 6AM.. *all you gotta do* is get 50 people to each wire 200 sockets, screw in the bulbs and test them. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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.
