Re: [time-nuts] Leap Second result on PST Model 1020
That's only about the third unit I've ever even heard of. They seem to be rarer than hen's teeth these days. All the more reason to kick myself for giving back the one I borrowed around Hallowe'en 1990 or so to compare it with my GC-1000 and watch Daylight Saving Time end for the year. It did so right at 2AM when it was supposed to. I was always impressed that that clock does as much as it can with what it's got so far (i.e. units of seconds start counting after the 2nd good 10-second marker, and so on.) I still want one. There have to be more than three out there. -- Jeff Woolsey j...@jlw.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebones, time, web services
jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. -- 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] GPS/UTC time
On 2015-07-04 15:01, Tom Van Baak wrote: (the Japan earthquake in 2011 sped the earth up by 1.8 microseconds/day. The Sumatra quake on 26 Dec 2004 had a bigger effect: 6.8 microseconds) Just in case you didn't know -- these are theoretical results only. There's a guy at JPL (Richard Gross) who does the calculations and any time there's a big seismic event he runs the simulations and out comes a number. That's pretty cool but the numbers so far are always smaller that what VLBI can actually measure. Still, it makes a nice press release and physics lesson. Buried in the articles is sometimes a clarification like the researchers concluded the Sumatra earthquake caused a length of day change too small to detect, but it can be calculated. Some recent calculations: NASA Details Earthquake Effects on the Earth http://www.jpl.nasa.gov/news/news.php?release=2005-009 Chilean Quake May Have Shortened Earth Days http://www.jpl.nasa.gov/news/news.php?release=2010-071 Japan Quake May Have Shortened Earth Days, Moved Axis http://www.jpl.nasa.gov/news/news.php?release=2011-080 All Days Are Not Created Equal http://www.jpl.nasa.gov/news/news.php?feature=15 See also: http://geodesy.unr.edu/hanspeterplag/library/projects/tsunami_loading/RotGravSigSumatraEqv4_pre.pdf While the modeled change in the Earth’s rotation that should have been caused by the 2004 Sumatran earthquake is less than the uncertainty in present-day measurements of the Earth’s rotation, it is still worth examining the measurements to see if an earthquake induced signal is present. http://www.obspm.fr/spip.php?page=imprimerid_article=2193lang=fr the effect in the movement of the pole should be of a few centimetres in the polhodie and of a few microseconds of time in the duration of the day, which is not very likely to be detected seen the current precision of the observations. The Sumatran earthquake impact on Earth Rotation from satellite gravimetric measurements https://hal-insu.archives-ouvertes.fr/hal-00117348/document For the length of the day Chao Gross (2006) modeled the increment of axial inertia moment and obtained a drop of 2-6 µs confirmed by our result (5 µs). This effect is undetectable in the LOD, because the precision on this parameter is of 20 µs. This last paper is really interesting because it compares space-based models with terrestrial models. And all this is of interest to time nuts because the earth is an oscillator and events like this affect the phase, frequency, and ADEV of the planet. Thanks for the good and interesting refs. One of the interesting points was that normal variations are multiples of those caused by earthquakes, and annual variations are up to 1ms and 1m. Another was that the jet streams produce large short term variations caused by temperature differences. Will this always turn up as an issue with all oscillators? ;^ -- Take care. Thanks, Brian Inglis ___ time-nuts mailing 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] leap second video from NICT Japan
Hi, This is leap second video from NICT Japan. https://www.youtube.com/watch?v=p_VV7d3GEhk everyone were gather together to see leap second moment. Best Regards, -- -dikshie- ___ time-nuts mailing 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] HP 5370a
On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: Matthias I am afraid I am not much help here. I did look at the a19/20 interpolators. A lot going on in that small space. I guess i would check the 200 MHz feeding into it. The VCO is fairly simple in using a gate and a delay line. I will guess the delay line is coax.. No its microstrip within the VCO package. Other coax delays are used in the oscillator turnoff and mixer logic. But there are all kinds of gates to control the system and Flip Flop used as a mixer. Not easy to deal with. Regards Paul. On Sat, Jul 4, 2015 at 1:44 PM, Matthias Jelen matthias.je...@gmx.de wrote: Dear Time-Nuts, I´m still struggling to get my 5370A to work reliable again. It keeps showing error 04. Sometimes it is working without any problems for hours, sometimes it ´s a matter of minutes until the error is displayed, and sometimes I doesn ´t come up without the error at all. I don´t think it´s related to temperarure, the usual procedures with a hairdryer and cooling spray didn´t show any effects. I dug into this a bit. It seems like the startable VCO on one of the interpolator boards isn´t working reliable anymore. The error stays with the board, no matter if I put it into the slot for the start channel or the stop channel. If the unit is in the non-working-state, there is no RF at the output of the VCO. As soon the VCO oscilates, the PLL locks and everything works fine, only the tuning voltage is a bit outside the range given in the service manual. If the VCO stops oscillating, the tuning voltage runs to it´s lower rail, just as expected. I opened the PLL loop and tuned the VCO with a external power supply, this works as expected - no regions in the tuning range in which the oscillator stops working or similiar. I checked the signals going to the board, and they all look OK. I fooled the logic that detects a tuning voltage outside the allowed area, and as expected, the error 04 isn´t displayed anymore, but also as expected the unit still stops working. I pulled the board, removed some components and supplied power to the VCO from an external power supply - same behaviour here. So I came to the conclusion that the VCO itself is defective, although I have no idea what could cause a VCO to behave that way. Now for the strange part: A noble member of this list sent me a spare interpolator board which was pulled from a working unit. This shows exactly the same behaviour! Also at this board the tuning voltage is outside the given window, and the oscillator doesn´t start from time to time. If a dead VCO module is a common problem, I´d expect that someone on this list also experienced this problem before. Otherwise, I think it´s unlikely that I found two defective interpolator boards in a row. I stil have the feeling that I´m overlooking something simple. So `d be happy to receive any comments on this. Also, if someone wants to get rid of a 5370 that needs repair I might be interested. I guess this is what you can expect if your´re using test equipment which was introduced before you were born, but it´s part of the fun... Thanks, Matthias ___ time-nuts mailing 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] Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO
re: Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO Hello to the Group, An admitted late arrival to the group here. My initial time system launch revolved around using a Trimble Thunderbolt. But used Trimble Thunderbolts for sale don't appear to be as plentiful as they once were and the current prices I see on Ebay seem a bit high. Another option is an auction listing for the Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO, aka Nortel NTBW50AA GPSTM GPS Timing Module offered for $159 US (plus shipping). Would anyone be able and willing to provide an opinion regarding the Nortel NTBW50AA modules compared to a Thunderbolt? Per an Ebay auction description, does the Nortel Module work well with Lady Heather? What I really need right now is the only 10MHz output. If I can get a comparable 10MHz output from the Nortel modules, fine. Else I continue on a quest to locate one or two more Thunderbolts. Or I'd appreciate any suggestions regarding other brands/modules comparable to a Trimble Thunderbolt. Thank you in advance for your replies. Regards, skipp skipp025 at yahoo dot com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5370a
No the oscillator frequency determining delay line is a microstrip line on a ceramic substrate. The coax delay lines are used for not critical delays in the delay line vco start and stop On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: Matthias I am afraid I am not much help here. inted I did look at the a19/20 interpolators. A lot going on in that small space. I guess i would check the 200 MHz feeding into it. The VCO is fairly simple in using a gate and a delay line. I will guess the delay line is coax.. But there are all kinds of gates to control the system and Flip Flop used as a mixer. Not easy to deal with. Regards Paul. On Sat, Jul 4, 2015 at 1:44 PM, Matthias Jelen matthias.je...@gmx.de wrote: Dear Time-Nuts, I´m still struggling to get my 5370A to work reliable again. It keeps showing error 04. Sometimes it is working without any problems for hours, sometimes it ´s a matter of minutes until the error is displayed, and sometimes I doesn ´t come up without the error at all. I don´t think it´s related to temperarure, the usual procedures with a hairdryer and cooling spray didn´t show any effects. I dug into this a bit. It seems like the startable VCO on one of the interpolator boards isn´t working reliable anymore. The error stays with the board, no matter if I put it into the slot for the start channel or the stop channel. If the unit is in the non-working-state, there is no RF at the output of the VCO. As soon the VCO oscilates, the PLL locks and everything works fine, only the tuning voltage is a bit outside the range given in the service manual. If the VCO stops oscillating, the tuning voltage runs to it´s lower rail, just as expected. I opened the PLL loop and tuned the VCO with a external power supply, this works as expected - no regions in the tuning range in which the oscillator stops working or similiar. I checked the signals going to the board, and they all look OK. I fooled the logic that detects a tuning voltage outside the allowed area, and as expected, the error 04 isn´t displayed anymore, but also as expected the unit still stops working. I pulled the board, removed some components and supplied power to the VCO from an external power supply - same behaviour here. So I came to the conclusion that the VCO itself is defective, although I have no idea what could cause a VCO to behave that way. Now for the strange part: A noble member of this list sent me a spare interpolator board which was pulled from a working unit. This shows exactly the same behaviour! Also at this board the tuning voltage is outside the given window, and the oscillator doesn´t start from time to time. If a dead VCO module is a common problem, I´d expect that someone on this list also experienced this problem before. Otherwise, I think it´s unlikely that I found two defective interpolator boards in a row. I stil have the feeling that I´m overlooking something simple. So `d be happy to receive any comments on this. Also, if someone wants to get rid of a 5370 that needs repair I might be interested. I guess this is what you can expect if your´re using test equipment which was introduced before you were born, but it´s part of the fun... Thanks, Matthias ___ time-nuts mailing 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] leap second video from NICT Japan
Hello Dikshie, Thanks for sharing this. Wow, not sure we had anything in the US that was comparable - crowd actually applauded. Best Regards, John W. On Sat, Jul 4, 2015 at 5:15 PM, dikshie diks...@gmail.com wrote: Hi, This is leap second video from NICT Japan. https://www.youtube.com/watch?v=p_VV7d3GEhk everyone were gather together to see leap second moment. Best Regards, -- -dikshie- ___ time-nuts mailing 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] Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO
On 07/05/2015 01:52 AM, skipp Isaham via time-nuts wrote: re: Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO Skipp, I have one of those. The supplied antenna is outside connected using RG59, high quality coax but presumably a 1.4 SWR, which is fine. Lady Heather is working showing the tracks of the satellites that she is following. ADEV of the 10 MHz oscillator is currently 1.98e-12 and the 1ppm ADEV is 8.86e-13. I don't use the multi connector: I fitted a standard coax power socket and soldered it to the supply rail inside. Ian, G4ICV, AB2GR -- ___ time-nuts mailing 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] HP 5370a
The problem is that the whole VCO is packaged. The connections from the VCO to the outside world are fairly simple: -5,2 Volt, a bias for the buffer amplifier, the tuning voltage and the start/stop line. The start/stop line is tied to gnd with 2.2 µH, so even if the start/stop circuit woud fail I can´t see how the oscillator could be kept from oscillating permanently. Anyone successfullly opened such a package (without damaging it permanently?) Regards, Matthias Am 05.07.2015 um 07:54 schrieb Bruce Griffiths: On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: Matthias I am afraid I am not much help here. I did look at the a19/20 interpolators. A lot going on in that small space. I guess i would check the 200 MHz feeding into it. The VCO is fairly simple in using a gate and a delay line. I will guess the delay line is coax.. No its microstrip within the VCO package. Other coax delays are used in the oscillator turnoff and mixer logic. But there are all kinds of gates to control the system and Flip Flop used as a mixer. Not easy to deal with. Regards Paul. On Sat, Jul 4, 2015 at 1:44 PM, Matthias Jelen matthias.je...@gmx.de wrote: Dear Time-Nuts, I´m still struggling to get my 5370A to work reliable again. It keeps showing error 04. Sometimes it is working without any problems for hours, sometimes it ´s a matter of minutes until the error is displayed, and sometimes I doesn ´t come up without the error at all. I don´t think it´s related to temperarure, the usual procedures with a hairdryer and cooling spray didn´t show any effects. I dug into this a bit. It seems like the startable VCO on one of the interpolator boards isn´t working reliable anymore. The error stays with the board, no matter if I put it into the slot for the start channel or the stop channel. If the unit is in the non-working-state, there is no RF at the output of the VCO. As soon the VCO oscilates, the PLL locks and everything works fine, only the tuning voltage is a bit outside the range given in the service manual. If the VCO stops oscillating, the tuning voltage runs to it´s lower rail, just as expected. I opened the PLL loop and tuned the VCO with a external power supply, this works as expected - no regions in the tuning range in which the oscillator stops working or similiar. I checked the signals going to the board, and they all look OK. I fooled the logic that detects a tuning voltage outside the allowed area, and as expected, the error 04 isn´t displayed anymore, but also as expected the unit still stops working. I pulled the board, removed some components and supplied power to the VCO from an external power supply - same behaviour here. So I came to the conclusion that the VCO itself is defective, although I have no idea what could cause a VCO to behave that way. Now for the strange part: A noble member of this list sent me a spare interpolator board which was pulled from a working unit. This shows exactly the same behaviour! Also at this board the tuning voltage is outside the given window, and the oscillator doesn´t start from time to time. If a dead VCO module is a common problem, I´d expect that someone on this list also experienced this problem before. Otherwise, I think it´s unlikely that I found two defective interpolator boards in a row. I stil have the feeling that I´m overlooking something simple. So `d be happy to receive any comments on this. Also, if someone wants to get rid of a 5370 that needs repair I might be interested. I guess this is what you can expect if your´re using test equipment which was introduced before you were born, but it´s part of the fun... Thanks, Matthias ___ time-nuts mailing 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] GPS/UTC time
On 7/4/15 10:25 PM, Brian Inglis wrote: Thanks for the good and interesting refs. One of the interesting points was that normal variations are multiples of those caused by earthquakes, and annual variations are up to 1ms and 1m. Another was that the jet streams produce large short term variations caused by temperature differences. Will this always turn up as an issue with all oscillators? ;^ There's a fair amount of noise (some looks periodic) in that plot from USNO of day length So, what *is* the ADEV of the earth's rotation? ___ time-nuts mailing 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] leap second video from NICT Japan
On Sun, Jul 5, 2015 at 7:52 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Hello Dikshie, Thanks for sharing this. Wow, not sure we had anything in the US that was comparable - crowd actually applauded. sorry for wrong url. the previous one was 2012. the 2015 leap second video is here: https://www.youtube.com/watch?v=mQvwMgwTMNs sorry for the inconvenience. Best Regards, -Dikshie- ___ time-nuts mailing 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] beaglebones, time, web services
On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. Prototype is 6 pixels to demonstrate concept and work out the bugs. Long term, probably several dozen. Time Accuracy? better than a second Turns out, having done some experimenting, the real issue is angular accuracy. RC servos aren't all that great, and have significant jitter (probably not an issue in their design application which tends to have good mechanical low pass filtering). They're cheap and easy to use (as in, I had a bunch in the garage I could cannibalize out of another project). But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a picture on the wall that's, say, 10 meters away, you really need angular pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly 270 degree rotation corresponding to 256 steps of PWM (in the Arduino implementation). ___ time-nuts mailing 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] HP 5370a
Matthias OK my diagrams show traditional parts like ecl gates. To Bruces comment that the delay line is not coax. Makes sense. But I have never had to get to the level you will need. It is odd that two do not work. But interpolators are funny things and its possible both are on some edge. Not to mis-lead you. By the way at this point if I have a piece of test gear thats basically Dead I dive in and open cans etc. The nothing to loose mode. Best of luck Paul WB8TSL On Sun, Jul 5, 2015 at 5:13 AM, Matthias Jelen matthias.je...@gmx.de wrote: The problem is that the whole VCO is packaged. The connections from the VCO to the outside world are fairly simple: -5,2 Volt, a bias for the buffer amplifier, the tuning voltage and the start/stop line. The start/stop line is tied to gnd with 2.2 µH, so even if the start/stop circuit woud fail I can´t see how the oscillator could be kept from oscillating permanently. Anyone successfullly opened such a package (without damaging it permanently?) Regards, Matthias Am 05.07.2015 um 07:54 schrieb Bruce Griffiths: On Saturday, July 04, 2015 05:20:45 PM paul swed wrote: Matthias I am afraid I am not much help here. I did look at the a19/20 interpolators. A lot going on in that small space. I guess i would check the 200 MHz feeding into it. The VCO is fairly simple in using a gate and a delay line. I will guess the delay line is coax.. No its microstrip within the VCO package. Other coax delays are used in the oscillator turnoff and mixer logic. But there are all kinds of gates to control the system and Flip Flop used as a mixer. Not easy to deal with. Regards Paul. On Sat, Jul 4, 2015 at 1:44 PM, Matthias Jelen matthias.je...@gmx.de wrote: Dear Time-Nuts, I´m still struggling to get my 5370A to work reliable again. It keeps showing error 04. Sometimes it is working without any problems for hours, sometimes it ´s a matter of minutes until the error is displayed, and sometimes I doesn ´t come up without the error at all. I don´t think it´s related to temperarure, the usual procedures with a hairdryer and cooling spray didn´t show any effects. I dug into this a bit. It seems like the startable VCO on one of the interpolator boards isn´t working reliable anymore. The error stays with the board, no matter if I put it into the slot for the start channel or the stop channel. If the unit is in the non-working-state, there is no RF at the output of the VCO. As soon the VCO oscilates, the PLL locks and everything works fine, only the tuning voltage is a bit outside the range given in the service manual. If the VCO stops oscillating, the tuning voltage runs to it´s lower rail, just as expected. I opened the PLL loop and tuned the VCO with a external power supply, this works as expected - no regions in the tuning range in which the oscillator stops working or similiar. I checked the signals going to the board, and they all look OK. I fooled the logic that detects a tuning voltage outside the allowed area, and as expected, the error 04 isn´t displayed anymore, but also as expected the unit still stops working. I pulled the board, removed some components and supplied power to the VCO from an external power supply - same behaviour here. So I came to the conclusion that the VCO itself is defective, although I have no idea what could cause a VCO to behave that way. Now for the strange part: A noble member of this list sent me a spare interpolator board which was pulled from a working unit. This shows exactly the same behaviour! Also at this board the tuning voltage is outside the given window, and the oscillator doesn´t start from time to time. If a dead VCO module is a common problem, I´d expect that someone on this list also experienced this problem before. Otherwise, I think it´s unlikely that I found two defective interpolator boards in a row. I stil have the feeling that I´m overlooking something simple. So `d be happy to receive any comments on this. Also, if someone wants to get rid of a 5370 that needs repair I might be interested. I guess this is what you can expect if your´re using test equipment which was introduced before you were born, but it´s part of the fun... Thanks, Matthias ___ time-nuts mailing 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] Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO
Hi On Jul 5, 2015, at 1:52 AM, skipp Isaham via time-nuts time-nuts@febo.com wrote: re: Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO Hello to the Group, An admitted late arrival to the group here. My initial time system launch revolved around using a Trimble Thunderbolt. But used Trimble Thunderbolts for sale don't appear to be as plentiful as they once were and the current prices I see on Ebay seem a bit high. Another option is an auction listing for the Nortel Trimble NTBW50AA GPSTM 10MHz Oscillator GPSDO, aka Nortel NTBW50AA GPSTM GPS Timing Module offered for $159 US (plus shipping). Would anyone be able and willing to provide an opinion regarding the Nortel NTBW50AA modules compared to a Thunderbolt? Per an Ebay auction description, does the Nortel Module work well with Lady Heather? The GPSTM will work to a limited degree with Lady Heather. The TBolt will let you modify and save the control loop parameters. The GPSTM will not let you modify them. The GPSTM comes with any of a wide variety of OCXO’s. Some are better than others. Tom has plots on his site of four of them. None of the GPSTM OCXO’s are as good as the TBolt OCXO for phase noise. Some of them are a bit better on temperature stability. The phase noise is masked by the noise of the digital stuff. The stability has little effect in normal operation. ADEV of an un-tuned GPSTM is similar to an un-tuned TBolt. With careful tuning (possibly involving board mods) the TBolt ADEV can be quite a bit better. The GPSTM will run off of a single supply and is insensitive to supply stability. The TBolt works best with a linear regulated supply on the +12V line. Lots of differences, none of them may matter much in your application …... Bob What I really need right now is the only 10MHz output. If I can get a comparable 10MHz output from the Nortel modules, fine. Else I continue on a quest to locate one or two more Thunderbolts. Or I'd appreciate any suggestions regarding other brands/modules comparable to a Trimble Thunderbolt. Thank you in advance for your replies. Regards, skipp skipp025 at yahoo dot com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebones, time, web services
Hi On Jul 5, 2015, at 8:46 AM, Jim Lux jim...@earthlink.net wrote: On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. Prototype is 6 pixels to demonstrate concept and work out the bugs. Long term, probably several dozen. Time Accuracy? better than a second Turns out, having done some experimenting, the real issue is angular accuracy. RC servos aren't all that great, and have significant jitter (probably not an issue in their design application which tends to have good mechanical low pass filtering). They're cheap and easy to use (as in, I had a bunch in the garage I could cannibalize out of another project). But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a picture on the wall that's, say, 10 meters away, you really need angular pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly 270 degree rotation corresponding to 256 steps of PWM (in the Arduino implementation). Probably a good place to use the “drive a stepper as a selsyn trick. Steppers are dirt cheap these days and you can either program the drive yourself or get chips that will do it for you. You have essentially zero load and zero acceleration. There is no need for anything big. Bob ___ time-nuts mailing 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] beaglebones, time, web services
These are pricey but offer 5900 steps over 120 degrees. 0.02 degree per step. At least you could try a couple. If you have many of them it would get expensive quickly. http://www.horizonhobby.com/ds8231-ultra-precision-servo-jrps8231 Sent from mobile On Jul 5, 2015, at 7:46 AM, Jim Lux jim...@earthlink.net wrote: On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. Prototype is 6 pixels to demonstrate concept and work out the bugs. Long term, probably several dozen. Time Accuracy? better than a second Turns out, having done some experimenting, the real issue is angular accuracy. RC servos aren't all that great, and have significant jitter (probably not an issue in their design application which tends to have good mechanical low pass filtering). They're cheap and easy to use (as in, I had a bunch in the garage I could cannibalize out of another project). But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a picture on the wall that's, say, 10 meters away, you really need angular pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly 270 degree rotation corresponding to 256 steps of PWM (in the Arduino implementation). ___ time-nuts mailing 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] beaglebones, time, web services
I have been working on and off on that kind of project for a while. One type of issue you have when trying to control hardware from a web page is that any hardware access from a web server poses many issues, such as permissions and the fact that web servers are basically stateless and many are multitasking. What happens if your web page (or the python script behind it) tries to send data on a serial port (for instance) and another request for the same thing comes along? The current approach I am using is to have a separate process that maintains the device status in files that be easily accessed by the web server, so that simple status requests can be serviced immediately without needing to query the device each time, and use a fifo to pipe commands between the web page script and the process. The process is the only one that talks to the hardware, so there is no contention. On the client side, you can use Ajax to keep the web page updated with fresh data without reloading everything each time. It is JavaScript, but there is not too much of it. That part is relatively easy, unless you want to make it really pretty. In that case, it takes a different set of skills (art major with CSS experience...) Here is a demo: http://www.ko4bb.com/AjaxDemo/x-web.html The back end of that runs on php, but it could be python just the same. Obviously failing the pretty test :) Didier KO4BB On July 4, 2015 8:13:06 AM CDT, Jim Lux jim...@earthlink.net wrote: I've got a project I'm working on to make a sophisticated sundial with moving mirrors. I've got a batch of Arduinos that move the mirrors to the appropriate places, given the current sun angle, etc. I've got a beaglebone that runs some python code to calculate sun angle based on time The beaglebone will have a GPS feeding it to get time. BUT now, I'd like to add a web interface, so that it can be manipulated by a mobile device using a browser. One way I can think of is to run some sort of limited web server. there are a couple that come with the beaglebone, including the python simplehttpserver. But I'm sort of stuck on the interface between the webserver and the other code running. I've done this kind of thing where the one task goes out and updates files in the tree that's being served by the web server, and that works fine for status display kinds of things that don't update very quickly. It's also nicely partitioned. but I want to be able to change the behavior of the system (e.g. by having the server respond to a PUT or something) Is the best scheme to go in and modify the webserver code to look for specific URLs requested, and then fire off some custom code to do what I want? I'm not particularly interested in javascript, and would prefer python. Or are there libraries that make this more cookbook? (the little getting started with beaglebone book talks about flask) There's quite a few websites out there where someone has done some sort of home automation, but they tend to be a bit light on the analysis of pros and cons of implementation architectures: I built X using Y and Z and it sort of works. Actually, along a similar line.. my solar position code isn't very pretty (it's sort of replicating some code I wrote in Basic a long time ago, with some changes from stuff I cribbed from ccmatlab). If someone knows of a python package that just does this, I'd love to hear about it. Either Az El, or X,Y,Z in ECI or ECF would do. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things. ___ time-nuts mailing 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] beaglebones, time, web services
On 7/5/15 8:43 AM, Bob Camp wrote: Hi On Jul 5, 2015, at 8:46 AM, Jim Lux jim...@earthlink.net wrote: On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. Prototype is 6 pixels to demonstrate concept and work out the bugs. Long term, probably several dozen. Time Accuracy? better than a second Turns out, having done some experimenting, the real issue is angular accuracy. RC servos aren't all that great, and have significant jitter (probably not an issue in their design application which tends to have good mechanical low pass filtering). They're cheap and easy to use (as in, I had a bunch in the garage I could cannibalize out of another project). But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a picture on the wall that's, say, 10 meters away, you really need angular pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly 270 degree rotation corresponding to 256 steps of PWM (in the Arduino implementation). Probably a good place to use the “drive a stepper as a selsyn trick. Steppers are dirt cheap these days and you can either program the drive yourself or get chips that will do it for you. You have essentially zero load and zero acceleration. There is no need for anything big. Indeed, microstepping might be the way to go in a production system. But steppers don't have convenient mechanical mounting stuff like RC servos do. I could assemble my prototype with zip ties, double sided foam tape and a few screws. For a stepper scheme I'd need to design and build (e.g. fabricate) bracketry. It's also more complex than just plugging a servo into a pin on the Arduino; that's pretty easy. And then you also get into the do you really want to use an arduino, why not program a X microcontroller on a custom board you've designed for the purpose with all the driver components, etc. If I were building up a full scale system, that's probably what I'd do. BUT, in the mean time, my 6 RC servo az/el thingys are good to fool with and get a feel for various configurations and what the design issues on a larger system would be. The virtue of the BBB and Arduino scheme is mostly that it can be cobbled together without much work. And you can leverage large consumer equipment volumes for the actuators, servos are $10 each in any sort of quantity; it would be hard to find a packaged motor/gear train with a feedback pot for that much (leaving aside surplus). I used to have a box of small 200 step/rev motors (floppy drive positioners), but they had a weird sized shaft, so we're back to the fabrication of mounts: the servo has a nice splined nylon shaft that mates with cheap other injection molded stuff. ___ time-nuts mailing 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] GPS/UTC time
Le 5 juil. 2015 à 14:38, Jim Lux jim...@earthlink.net a écrit : On 7/4/15 10:25 PM, Brian Inglis wrote: Thanks for the good and interesting refs. One of the interesting points was that normal variations are multiples of those caused by earthquakes, and annual variations are up to 1ms and 1m. Another was that the jet streams produce large short term variations caused by temperature differences. Will this always turn up as an issue with all oscillators? ;^ There's a fair amount of noise (some looks periodic) in that plot from USNO of day length So, what *is* the ADEV of the earth's rotation? Check out tvb’s great presentation at FOSDEM15 and elsewhere. http://leapsecond.com/FOSDEM15/tvb-2015-Precise-Time-Hacking.pdf He has it at 10^-8-10^-9. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité. Benjimin Franklin ___ time-nuts mailing 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] beaglebones, time, web services
Hi On Jul 5, 2015, at 3:17 PM, Jim Lux jim...@earthlink.net wrote: On 7/5/15 8:43 AM, Bob Camp wrote: Hi On Jul 5, 2015, at 8:46 AM, Jim Lux jim...@earthlink.net wrote: On 7/4/15 7:53 PM, Hal Murray wrote: jim...@earthlink.net said: Exactly... I've got an array of mirrors on az/el mounts (two servos stacked) and the reflection from the mirrors on the wall forms the display. How many pixels in that display? Or what is the unit of quality measurement? What sort of ADEV are you aiming for? If your goal is solar time rather than TAI or UTC, you should be able to get pretty good. Prototype is 6 pixels to demonstrate concept and work out the bugs. Long term, probably several dozen. Time Accuracy? better than a second Turns out, having done some experimenting, the real issue is angular accuracy. RC servos aren't all that great, and have significant jitter (probably not an issue in their design application which tends to have good mechanical low pass filtering). They're cheap and easy to use (as in, I had a bunch in the garage I could cannibalize out of another project). But if you have 3x3 inch mirrors (call it 7.5 cm), and want to create a picture on the wall that's, say, 10 meters away, you really need angular pointing of 0.007 radians.. that's about 1/2 degree. An RC servo has roughly 270 degree rotation corresponding to 256 steps of PWM (in the Arduino implementation). Probably a good place to use the “drive a stepper as a selsyn trick. Steppers are dirt cheap these days and you can either program the drive yourself or get chips that will do it for you. You have essentially zero load and zero acceleration. There is no need for anything big. Indeed, microstepping might be the way to go in a production system. But steppers don't have convenient mechanical mounting stuff like RC servos do. I could assemble my prototype with zip ties, double sided foam tape and a few screws. For a stepper scheme I'd need to design and build (e.g. fabricate) bracketry. It's also more complex than just plugging a servo into a pin on the Arduino; that's pretty easy. *Small*steppers (which is all you need) don’t take much in the way of mounts. More or less that’s why they invented 3D printing. A printed mount is plenty good enough in this case. And then you also get into the do you really want to use an arduino, why not program a X microcontroller on a custom board you've designed for the purpose with all the driver components, etc.” Feature creep - that’s my middle name …... If I were building up a full scale system, that's probably what I'd do. BUT, in the mean time, my 6 RC servo az/el thingys are good to fool with and get a feel for various configurations and what the design issues on a larger system would be. A *lot* of home built milling machines are lashed together out of steppers with various drivers. It is a bit of a step up from R/C servos, but not *that* bit a step. The virtue of the BBB and Arduino scheme is mostly that it can be cobbled together without much work. And you can leverage large consumer equipment volumes for the actuators, servos are $10 each in any sort of quantity; it would be hard to find a packaged motor/gear train with a feedback pot for that much (leaving aside surplus). That’s not all that different than the way home made mills are built. I used to have a box of small 200 step/rev motors (floppy drive positioners), but they had a weird sized shaft, so we're back to the fabrication of mounts: the servo has a nice splined nylon shaft that mates with cheap other injection molded stuff. 3D printing ….You *must* have a friend with a printer …. Bob ___ time-nuts mailing 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.
