[time-nuts] PICTIC II ready-made?
I have wondered the same thing. Doc KX0O ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, 25 Apr 2012 02:01:36 + (UTC) Andrew Rodland and...@cleverdomain.org wrote: Would anyone be willing to sell (or loan for an extended period) one or two ready-to-go PICTIC IIs within the United States? I realize this may be rude to ask since it's a hobby project, but what can I say? All I want it for is to further my own hobby project. Why is it rude to ask? Not everyone can work with a soldering iron. And especially because it is a hobby project, it should be possible to ask whether someone would help out. Just my 0.05CHF Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] PICTIC II ready-made?
I agree, nevertheless let me add: because it is a hobby project it is good also starting to learn how to use the soldering iron. On Wed, Apr 25, 2012 at 2:59 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Apr 2012 02:01:36 + (UTC) Andrew Rodland and...@cleverdomain.org wrote: Would anyone be willing to sell (or loan for an extended period) one or two ready-to-go PICTIC IIs within the United States? I realize this may be rude to ask since it's a hobby project, but what can I say? All I want it for is to further my own hobby project. Why is it rude to ask? Not everyone can work with a soldering iron. And especially because it is a hobby project, it should be possible to ask whether someone would help out. Just my 0.05CHF Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, 25 Apr 2012 15:24:50 +0200 Azelio Boriani azelio.bori...@screen.it wrote: I agree, nevertheless let me add: because it is a hobby project it is good also starting to learn how to use the soldering iron. But for that, you need someone who shows you how to solder. You can learn it yourself, but it takes a lot more time and you waste a lot of electronics... and often you dont even know that the joints aren't good... Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to do it right. So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview; -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] PICTIC II ready-made?
Yes, better have someone who can help but nothing should prevent you from learning something. On Wed, Apr 25, 2012 at 4:44 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Apr 2012 15:24:50 +0200 Azelio Boriani azelio.bori...@screen.it wrote: I agree, nevertheless let me add: because it is a hobby project it is good also starting to learn how to use the soldering iron. But for that, you need someone who shows you how to solder. You can learn it yourself, but it takes a lot more time and you waste a lot of electronics... and often you dont even know that the joints aren't good... Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] Manuals for HP 570A clock?
On 4/25/2012 10:20 AM, Donald Henderickx wrote: On 4/23/2012 7:27 PM, Dan Veeneman wrote: Hello, I've got an HP 570A digital clock on the bench for which I am seeking both service and operator manuals. Are there PDF versions available somewhere? Thanks, Dan ___ time-nuts mailing list --time-nuts@febo.com To unsubscribe, go tohttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Dan I do not have a pdf version of this manual;however I do have have two copies of the original.I also have the clock which I am unable to make run consistently. Perhaps I could get you one of the manuals in exchange fo help in trouble shooting mine. Don wa9ylp ___ time-nuts mailing 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] Antique Rubidium Standard Questions
Ed, I downloaded that service manual - an interesting read. So much stuff was well-figured out even back then. You should look closely at section 4.4.7.1. regarding the presence of the 2f (310 Hz) signal. Ed Breya ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
You are not going to get anywhere near sub-mm levels without doing L1/L2 measurements with a geodetic grade receiver and thermally stabilized antenna (and receiver/cable). With a patch antenna (which is in a lot of timing antenas) on a geodetic L1/L2 receiver you can see 1 meter errors! ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 5:50 AM, Bill Dailey docdai...@gmail.com wrote: I have wondered the same thing. It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master -- 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] Sub mm measurements with gps timing antennas?
Hi Attila, On 04/25/2012 04:56 PM, Attila Kinali wrote: Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to do it right. So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview; You can get both L1 choke rings and pin-wheels on Ebay for fairly reasonable money. That should help on multipath. Another aspect is the temperature shielding of the receiver itself. If it can be kept at a fairly stable temperature would also help. Using a better reference oscillator could also be worthwhile. Consider what a FEI 5680 could do for you. Also, the way the antenna is mounted can be relevant. Up, up and away... such that any funny reflections is below the antenna. A simple temperature stabilisation might be to simply dig the GPS receiver down. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II ready-made?
Chris: I concur. Arduino base would allow simple extension to 'net control as well. Don Chris Albertson It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master -- 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. -- 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.
Re: [time-nuts] Sub mm measurements with gps timing antennas?
Hi Attila, I agree, keep the gps away from such fast and large temperature excursions. The internal tcxo is not as stable as one would expect.. Building a larger box and burying it could help slow the temp gradient.. Bye, Said Sent From iPhone On Apr 25, 2012, at 8:52, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Attila, On 04/25/2012 04:56 PM, Attila Kinali wrote: Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to do it right. So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview; You can get both L1 choke rings and pin-wheels on Ebay for fairly reasonable money. That should help on multipath. Another aspect is the temperature shielding of the receiver itself. If it can be kept at a fairly stable temperature would also help. Using a better reference oscillator could also be worthwhile. Consider what a FEI 5680 could do for you. Also, the way the antenna is mounted can be relevant. Up, up and away... such that any funny reflections is below the antenna. A simple temperature stabilisation might be to simply dig the GPS receiver down. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] PICTIC II ready-made?
I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Don It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master -- 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. -- 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.
Re: [time-nuts] Sub mm measurements with gps timing antennas?
Hi Both the receiver and the antenna have filters in them. The affordable ones (no need to say cheap) are made from ceramics that have significant temperature coefficients. If you are getting -40 to +30C jumps, they will definitely have an impact on the filters phase / delay. That's going to make sub mm work pretty tough. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: Wednesday, April 25, 2012 10:57 AM To: time-nuts@febo.com Subject: [time-nuts] Sub mm measurements with gps timing antennas? Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to do it right. So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview; -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
On 04/25/2012 06:37 PM, Said Jackson wrote: Hi Attila, I agree, keep the gps away from such fast and large temperature excursions. The internal tcxo is not as stable as one would expect.. Building a larger box and burying it could help slow the temp gradient.. Indeed. I forgot to say that such swings is not what make TCXOs to excel, and some of the frequency error will not be compensated in the same way as if it was kept stable at any of the these temperatures, the shift itself isn't really what makes the best of a crystal. 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] Antique Rubidium Standard Questions
Hi Ed, On 4/25/2012 9:41 AM, ed breya wrote: Ed, I downloaded that service manual - an interesting read. So much stuff was well-figured out even back then. Yes, the building blocks were all in place and are still used today. But when you look at some of the implementation details you see a few things that just have you scratching your head. My favorite is: How do you power TTL chips when you only have 15 or 20 volts available? Simple, just stack 3 or 4 chips in series and use capacitors to couple the inputs and outputs. I would never have thought it would work, but I guess it does. You should look closely at section 4.4.7.1. regarding the presence of the 2f (310 Hz) signal. Yes, that's the normal method of operation. The presence of the 2nd harmonic plus absense of fundamental equals a locked condition so stop the sweep, turn on the green light and connect the output of the Synchronous Detector (the Loop Error Signal) in series with the Oscillator Frequency Control to close the frequency control loop. But, as the OCXO drifts, it's the Loop Error Signal that nudges the OCXO back on frequency. The 2nd harmonic is only the indicator. Look at section 3.5.3. That's the only mention of the Sweep switch. But when I traced it out I found that it would allow locking without any 2nd harmonic because it bypasses the 2nd harmonic circuit, disables the sweep and connects the output of the Synchronous Detector in series with the Oscillator Frequency Control. This is the identical connection that normally happens when the 2nd harmonic is detected. The green light doesn't turn on because that function is controlled by the 2nd harmonic only. The result is a closed frequency control loop and, as long as there's enough Loop Error Signal to maintain it, a locked condition regardless of the presence or absence of the 2nd harmonic. Ed Ed Breya ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
Hi Attila, Are you sure the customer said sub-mm and not sub-meter? I know post-processing is really helpful, but the LEA-6 is a single frequency receiver so all the advantage of L2 is lost for this customer. The bullet antenna's don't even have an arrow for North ;-) One thought -- seeing how this is a research project. It might be possible to cross-correlate the post-processed data against the Az-El of each SV along with ambient temperature over days or weeks and thus actually measure the phase center profile as well as tempco of the system. This would be no small effort, depending on the math and programming skills of the researcher(s), but the advantage for them is that is costs time instead of money. Then armed with this calibration data (possibly unique to each unit), it would be possible to reduce these effects, improving precision. I have no idea how much. Still, an interesting project. A simple test that could be done locally (refrigerator, sauna, etc.) would be to measure the tempco of the entire system (antenna, cables, LEA-6T) before they deploy it to a mountain. It may also be the case that the system has both a temperature coefficient and a temperature change coefficient so it's not a simple 2-point test. You can probably ignore humidity and barometric pressure. Another test would be to rotate the antenna at 1 RPH (revolution per hour) and then look for modulation in the post-processed solution. This would give a hint of the quality of the antenna. As a baseline, try the same test using a precision gps antenna. I have spare pin-wheel, choke-ring, and ground-plane antennas that I could loan, but surely these are available where you are, and probably cheaper than postage from here. It seems that everyone else that does sub-ns precision timing or mm positioning uses a large combination of tricks: dual-frequency antenna and receiver, geodetic-quality antenna, passive or active temperature control, phase-stabilized cables, GPS and Glonass, external frequency reference, and post-processing. Your customer is only using one from this long, expensive list. So there may be a lesson there. Can you share any data they have collected already? I would be interested to know how far one could push a LEA-6T. Thanks, /tvb - Original Message - From: Attila Kinali att...@kinali.ch To: time-nuts@febo.com Sent: Wednesday, April 25, 2012 7:56 AM Subject: [time-nuts] Sub mm measurements with gps timing antennas? Moin, We've a customer who does sub mm measurements using GPS in alpine enviroment. This is done using LEA-6T modules, logging of raw phase data and offline post processing using long averaging windows. Now, the customer had some problems reaching the precision requirements and i'm wondering whether one of the causes might be the use of a Trimble Bullet antenna [1] (3V type) and not a geodetic antenna. Can it be that the phase center of the Trimble Bullet antenna isn't as well defined as it should be for this application? Would the addional gain of the 5V version help (35dB instead of 30dB)? Or should we evaluate a different antenna all together. A major restriction in this application is that there is a very harsh enviroment, temperature wise. We have measured -40°C to +30°C jumps in just 2h. Most of the time the devices are below freezing temperature, but can go up to 50°C when in direct sunlight. The next big restriction is, that this is a research project. So there isn't as much money available as there should be to do it right. So, if someone could give a few tips how to improve things, this would be much appreciated. Attila Kinali [1] http://www.trimble.com/timing/bullet-gps-antenna.aspx?dtID=overview; -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] PICTIC II ready-made?
I still have a supply of boards and most parts including the 74ac175 but no interest in assembly or the kitting process. If someone would like to take this on then I could provide the boards etc ... in bulk. Because of my limited space the kitting process takes several hours to do them one at time :-( Stanley - Original Message - From: Don Latham d...@montana.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, April 25, 2012 11:37 AM Subject: Re: [time-nuts] PICTIC II ready-made? I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Don It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master -- 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. -- 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. ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
From a friend: Yes, emphatically! It was established more than twenty years ago, by theory and experiment, that simple GPS receiving antennas yield position determinations with errors of many millimeters, and time-synchronization errors of equivalent magnitude (i.e., many millimeters multiplied by the speed of light), for two reasons: (1) The locus of constant phase of the antenna's received-signal output is not spherical, even when the antenna is in an anechoic environment. In other words, the antenna has no well-defined phase-center. The apparent phase center is typically a strong function of the elevation angle, and also varies substantially with the azimuth, from which a signal is received. (2) In the real world, an antenna's received-signal output is a superposition of the desired signal (received directly from a satellite via free-space TEM propagation) and one or more undesired signals, received via reflection and/or scattering from surfaces/objects near the antenna. The strongest of these undesired signals has usually been reflected from the ground. The phase of the composite signal, i.e., the superposition of desired and undesired signal components, differs from the phase of the desired signal. The magnitude of the difference can be greater than a radian, and can vary so slowly, or so _systematically_, that time-averaging fails to eliminate its effects. An ideal GPS receiving antenna would respond to signals received directly from satellites without introducing direction-dependent phase variation; and would NOT respond to reflected or scattered signals. A highly directive antenna such as a well-designed parabolic dish reflector with very low sidelobes could do this for just one satellite at a time, but simultaneous observations of multiple satellites are required to cancel receiver-related errors; so the antenna that's usually regarded as ideal has a upper-hemispheric gain pattern. That is, its gain (both magnitude and phase) is uniform for the whole sky, but its gain is zero below the horizon. The gain must be nil below the horizon because it is practically impossible to prevent reflection from the surface of the ground, and because ground-reflection effects cannot be modeled and accounted for theoretically unless the electromagnetic properties of the ground material(s) can be characterized and the topography determined at the millimeter level. In some GPS geodetic measurements, sub-millimater accuracy has been achieved by covering the actual ground with a usefully large sheet of metal that was planar and horizontal within a small fraction of one millimeter. However, a sufficiently large and precise artificial ground plane is expensive and cumbersome, so it is seldom used. Artificial ground-planes having diameters less than a meter are not uncommon, but careful experiments have shown that they are not satisfactory for submillimeter work. In antenna theory there is a well-known Fourier-transform relation between an antenna's gain as a function of direction, and the spatial distribution of RF current on the surface of the antenna. It follows from Fourier-transform properties that, for the gain of an antenna to cut off very sharply at the horizon, the antenna must be spatially large. Sharp horizon-cutoff is most efficiently achieved by extending the antenna vertically (perpendicular to the horizon plane). Sharp horizon-cutoff can also be achieved by extending the antenna horizontally for all azimuths, in other words, by making the antenna in the form of a very large, circular, disk. One-dimensional, vertical extension requires less material (mass, weight, and cost) than two-dimensional, horizontal extension. The referenced bullet antenna you mention has small extent both vertically and horizontally; so it is effectively useless for millimeter-level work. Best, -John === You are not going to get anywhere near sub-mm levels without doing L1/L2 measurements with a geodetic grade receiver and thermally stabilized antenna (and receiver/cable). With a patch antenna (which is in a lot of timing antenas) on a geodetic L1/L2 receiver you can see 1 meter errors! ___ time-nuts mailing 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] PICTIC II ready-made?
On 4/25/2012 7:44 AM, Attila Kinali wrote: On Wed, 25 Apr 2012 15:24:50 +0200 Azelio Borianiazelio.bori...@screen.it wrote: I agree, nevertheless let me add: because it is a hobby project it is good also starting to learn how to use the soldering iron. But for that, you need someone who shows you how to solder. You can learn it yourself, but it takes a lot more time and you waste a lot of electronics... and often you dont even know that the joints aren't good... Attila Kinali Then there is also the matter of surface mount components. Some people my not physically be able to work with them, learning to solder or not. I am rapidly joining that group be cause of my vision. Just my 2 cents worth. . . Randy, KI6WAS ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 9:37 AM, Don Latham d...@montana.com wrote: I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Yes, MOST of the design could be re-used. As an Arduino shield there is no need for a PIC or RS-232 interface becusethe Arduino does that function. You'd need to replace the 74ACT175 part but that is not hard. About changing the cap values without soldering. I guess you could push the leads into a 0.1 inch header strip or install several and use a DIP switch to select which are in. But I don't know if the extra inductance al that wiring adds is enough to worry about. -- 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 11:09 AM, Randy D. Hunt randy_hunt...@yahoo.comwrote: Then there is also the matter of surface mount components. Some people my not physically be able to work with them, learning to solder or not. I am rapidly joining that group be cause of my vision. Get yourself a web-cam or an used DV video camera with a firewire cable (Sony had a difference name or it xxxlink maybe?) You may need to add some dioptors to the camera lens (an ordinary magnifying glass works too) and certainly aim a desk lamp at the work. Then you aim the camera straight down and watch the work on a large computer monitor. I can make the smaller chips look 2 inches wide on my screen. It is more comfortable to use the big LCD monitor than a microscope. -- 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] PICTIC II ready-made?
On 25 April 2012 19:09, Randy D. Hunt randy_hunt...@yahoo.com wrote: Then there is also the matter of surface mount components. Some people my not physically be able to work with them, learning to solder or not. I am rapidly joining that group be cause of my vision. Since Arduino has been mentioned I feel obliged to provide a link for Nanode, an Arduino-compatible that integrates Ethernet and low power wireless (e.g. 868MHz) for around the same price of an Arduino. It's supplied as a kit of through-hole components... http://wiki.london.hackspace.org.uk/view/Project:Nanode Or a nice alternative might be a daughterboard for a Raspberry Pi, which would give you an ARM/Linux base for not much more money, and you could use it to create a standalone system that drives an old monitor for a display. http://en.wikipedia.org/wiki/Raspberry_Pi Regards, Andrew -- Andrew Back http://carrierdetect.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] Sub mm measurements with gps timing antennas?
Moin, On Wed, 25 Apr 2012 10:05:00 -0700 Tom Van Baak t...@leapsecond.com wrote: Are you sure the customer said sub-mm and not sub-meter? I know post-processing is really helpful, but the LEA-6 is a single frequency receiver so all the advantage of L2 is lost for this customer. The bullet antenna's don't even have an arrow for North ;-) Yes, it is sub-mm. They are already doing sub-cm with the current setup, but it isn't precise enough yet. IIRC during the first tests last year they got 4mm precision. And yes, using a LEA6-T with a Trimble Bullet antenna. I don't know what they actually do with the raw phase data, beside that they average over several hours and use a 100m baseline reference consisting of two stations mounted at a fixed position. One thought -- seeing how this is a research project. It might be possible to cross-correlate the post-processed data against the Az-El of each SV along with ambient temperature over days or weeks and thus actually measure the phase center profile as well as tempco of the system. This would be no small effort, depending on the math and programming skills of the researcher(s), but the advantage for them is that is costs time instead of money. Then armed with this calibration data (possibly unique to each unit), it would be possible to reduce these effects, improving precision. I have no idea how much. Still, an interesting project. Hmm.. That would be an idea, but i don't know whether it is feasible. Maybe i should here expand a little bit what the project actually is. The effort is part of the Permasense[1] Project, which does measurements of different parameters of permafrost soil/rock in high alpine regions. The idea of this sub-project is to measure the exact movement of rocks and other solid and unmovable things with regard to weather conditions. Beside the harsh environment, this also means that the devices cannot be reached for most of the year (there is usually a 3 months window when the devices can be accessed)..and some years they cannot access them at all (adverse weather conditions preventing ascend). For installation, a helicopter has to fly everything up into the mountains, which means that pre-assembled stuff cannot be transported, because it's too bulky (prevents whole system calibration in a climate chamber). After installation the system runs on solar power with a backup battery. But this doesn't guarrantee power at all. The solar panel could be below a meter or two of snow. Hence the whole system has to cope with periodic power los and has to be as low power as possible (ie no OCXO, no Rb, no temperature stabilization). The snow also prevents the use of choke rings, because they would accumulate a lot of snow and ice, which would then cover the whole antenna. But at least, there is hardly any electronic interference, a good sky view (no trees), unless the system is mounted near a wall. And the antenna cable is quite short (it was 15cm in the previous version of the device and should be 50cm in the next) A simple test that could be done locally (refrigerator, sauna, etc.) would be to measure the tempco of the entire system (antenna, cables, LEA-6T) before they deploy it to a mountain. It may also be the case that the system has both a temperature coefficient and a temperature change coefficient so it's not a simple 2-point test. You can probably ignore humidity and barometric pressure. I think the ETH has climate chambers that could run such tests. But i'm not sure how you'd test the antenna in such a chamber. Another test would be to rotate the antenna at 1 RPH (revolution per hour) and then look for modulation in the post-processed solution. Hmm.. that's actually a quite nice test. Cool idea, thanks! This would give a hint of the quality of the antenna. As a baseline, try the same test using a precision gps antenna. I have spare pin-wheel, choke-ring, and ground-plane antennas that I could loan, but surely these are available where you are, and probably cheaper than postage from here. Yes. The problem is, antennas that perform well in a city environment, where temperature swings are quite limited, fail in high alpine environment. But that's what my question originally aimed at. How much better can we get using a better antenna? Is it worth doing? Or is it just a waste of time and money? BTW: what's a pin-wheel antenna? Google tells me contradictory things. It seems that everyone else that does sub-ns precision timing or mm positioning uses a large combination of tricks: dual-frequency antenna and receiver, geodetic-quality antenna, passive or active temperature control, phase-stabilized cables, GPS and Glonass, external frequency reference, and post-processing. Your customer is only using one from this long, expensive list. So there may be a lesson there. The problem with most of those techniques is, that they are not available for the price the customer can afford. A dual frequency
Re: [time-nuts] Sub mm measurements with gps timing antennas?
Just brainstorming here, but how about this un-conventional approach: Use a CSAC as a precise frequency reference for the LEA-6T. CSAC should operate at 0.12W, I know, that's a lot, but maybe just worth a try. To make the CSAC work, multiply the 10MHz up to the 26MHz the LEA uses. Then place a small antenna loop around the LEA part to injection-lock the internal 26MHz TCXO to the external antenna. That may work, or not. Or unsolder the LEA-6T metal shield, and remove the TCXO, and replace it with the externally generated stable 26MHz, then re-solder the shield. That's cheaper than buying 2000pcs reels from uBlox. It would be interesting to see how much more accurate the unit would become with a stable 26MHz rather than a low-cost 26MHz TCXO. AND: you can use the 1PPS output of the LEA-6T to actually discipline the CSAC to GPS :) bye, Said In a message dated 4/25/2012 11:42:52 Pacific Daylight Time, att...@kinali.ch writes: The problem with most of those techniques is, that they are not available for the price the customer can afford. A dual frequency receiver costs a lot more than an of the shelf LEA6-T. Also these modules are usually build with larger power budgets in mind, e.g. the Trimble BD920 uses 1.3W typical, while the 0.3W max(!) of the LEA6-T already hurt us a lot. Using an external frequency reference is not possible with the LEA6-T. It would be possible to do that when using one of the GPS chipsets from u-blox, but therefor we would need to take at least a full reel (iirc 2000 pieces), which isnt exactly cost efficient. Beside, we would still need to use a TCXO, because there is not enough power available for an OCXO or even an MCXO. ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 11:39 AM, Andrew Back and...@carrierdetect.comwrote: On 25 April 2012 19:09, Randy D. Hunt randy_hunt...@yahoo.com wrote: Then there is also the matter of surface mount components. Some people my not physically be able to work with them, learning to solder or not. I am rapidly joining that group be cause of my vision. Since Arduino has been mentioned I feel obliged to provide a link for Nanode, an Arduino-compatible that integrates Ethernet and low power wireless (e.g. 868MHz) for around the same price of an Arduino. It's supplied as a kit of through-hole components... Looks good, the advantage of Arduino is that compatible units are available from multiple sources in the US, Europe and Asia. You are not locked into a single supplier. The other good thing is the very easy development environs meant that runs under Windows, Mac OS and Linus pretty much identically and it is easy enough to use for beginners I'm a fan of using Linux too. but for stuff like this a bare uP with no OS usually gives better real-time performance. I've used real-time versions of Linux that do give you access to the bare hardware. But as much as I like it, real-time Linux on ARM or the like is hardly a beginner friendly environment. One has to know quite a lot got to get started. One important goal for most hobbyists is to learn something. So it should be SIMPLE so more people can understand it.IMO, firmware written in assembly language and real-time OSes don't pass the test for simple. You really have to have discipline and resist the for a little more money we could do feature creep I like the physical size of the Arduino shield too. It is so small that there is no room of feature creep without resorting to SMT parts. Then if some one really wants to add signal conditioning they can stack on a second shield, kind of a lego-like design with the micro controller as the base layer. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] In the atomclock repairshop...
Fellow time-nuts, Oh, ok. So now it is public, so I better tell you about it... Jörgen Städje is a tech-writer which enjoys writing articles where he dips into some system and writes about it. Trying to teach things. Demystify things. So, when you read it, please recall that the audience is not very into the subject. It's in Swedish, but since you all know it by heart (or maybe using Babelfish) I think you surely enjoy it... http://www.idg.se/2.1085/1.443818/i-atomurmakarens-verkstad The photo-session was not all that well-planned, but enjoy the more intimate photos of among others my Russian CH1-78 / HG414A. Various splashes of instruments. One of the photos has direct inspiration from an LP. Extra points from identifying which album. :) Oh well. Hope you enjoy it for what it is. Hope you can handle the chock of seeing photos of me. Cheers, Magnus - another time-nut outed by a journalist ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, 25 Apr 2012 08:45:52 -0700 Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Apr 25, 2012 at 5:50 AM, Bill Dailey docdai...@gmail.com wrote: I have wondered the same thing. It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. May i ask what makes the arduino programable by __anyone__ ? Sofar, i only had a look at the hardware of arduino, but never looked at the software side, as for me, who is regularly writing C code for bare metal uC applications, the software part is solved if i know that gcc can generate code for the architecture in question. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master The thing is, we want to get into a region of mesurment precision, that requires good and high quality devices and/or heavy post processing. Most of the devices needed are pretty advanced. A PICTIC II like Nutt Interpolator can be build using a higher frequency XO with lower jitter and using higher quality components (eg ECL devices instead of 74HC, or better ADCs) which could lead to a magnitude or two of precision enhancement. But these devices are not as easy to handle as the ones used in the PICTIC II. They would be all SMD with smaller pitch than 1.27mm (mostly 0.63mm, some 0.5mm), nothing you'd solder by hand if you have not at least some experience and an either a good sight or a microscope or similar. On the other hand, i am pretty sure that a 100 pieces production run could be done with all the interest on this mailinglist. And with that you'd get probably below 100USD for a PICTIC II like system. Even if using more expensive components. 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] PICTIC II ready-made?
Chris Albertson wrote: On Wed, Apr 25, 2012 at 9:37 AM, Don Lathamd...@montana.com wrote: I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Yes, MOST of the design could be re-used. As an Arduino shield there is no need for a PIC or RS-232 interface becusethe Arduino does that function. You'd need to replace the 74ACT175 part but that is not hard. About changing the cap values without soldering. I guess you could push the leads into a 0.1 inch header strip or install several and use a DIP switch to select which are in. But I don't know if the extra inductance al that wiring adds is enough to worry about. The time to digital converter (TDC) section is merely an interpolator that measures the delay of a synchroniser. The TDC range should be about 2 clock periods to accommodate the range of synchroniser delays and to facilitate calibration. Unless one is changing the synchroniser clock period there is no need to vary the TDC gain. The SR620 uses a similar interpolator and has only a single interpolator range. The range is extended by counting the number of synchroniser clock periods between synchroniser output transitions of interest. When measuring the time interval between 2 signals a pair of synchronisers and interpolators are used. Interpolator nonlinearity can be measured by using a statistical fill the buckets technique which uses nothing but a pair of noisy asynchronous oscillators with high reverse isolation to avoid injection locking. If a suitable ADC is used the interpolator can be simplified considerably whilst improving its performance. Minor nonlinearities are of little significance, as long as they are repeatable and relatively stable they can be easily corrected in software. 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] PICTIC II ready-made?
If you guys go the PIC route, I'm always happy to burn them for the group for cheap. I think in the past I was doing 5 bucks for the first one (including delivery) plus $2.50 for each additional. I still have a ton of those plastic chip tubes for mailing them so the pins don't get bent. -Bob On Wed, Apr 25, 2012 at 11:44 AM, Stanley timen...@n4iqt.com wrote: I still have a supply of boards and most parts including the 74ac175 but no interest in assembly or the kitting process. If someone would like to take this on then I could provide the boards etc ... in bulk. Because of my limited space the kitting process takes several hours to do them one at time :-( Stanley - Original Message - From: Don Latham d...@montana.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, April 25, 2012 11:37 AM Subject: Re: [time-nuts] PICTIC II ready-made? I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Don It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. Other suggestions to do something like this have come up on this list but then someone starts talking about using some specialized technology that 99.99% of the readers don't know (like FPGAs) I'd like to see it done with 25 cent parts and technology a beginner can master -- 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. -- 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. ___ time-nuts mailing 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] Sub mm measurements with gps timing antennas?
On Wed, Apr 25, 2012 at 11:42 AM, Attila Kinali att...@kinali.ch wrote: Moin, After installation the system runs on solar power with a backup battery. But this doesn't guarrantee power at all. The solar panel could be below a meter or two of snow. Hence the whole system has to cope with periodic power los and has to be as low power as possible (ie no OCXO, no Rb, no temperature stabilization). The snow also prevents the use of choke rings, because they would accumulate a lot of snow and ice, which would then cover the whole antenna. A few ideas.. 1) You could use a choke ring if you were willing to build a large size conical cover or (say) fiberglass 2) Seems that you might want a much taller mast for you solar cells. If they are covered by a meter of snal make the mast a meter taller, 3) This would take quite a bit of physical work but you can always find a stable temperature if you are willing to dig or drill a deep enough hole. I think even in your location there is a depth at with the temperature reins at the average yearly night/day temperature. Here in California, I think I only need to dig down about 12 feet to find a constant 58F. Maybe other places you need one of those tools use for water wells. I've been wanting to try an experiment where I bury A cheap XO 20 feet and see if that does not make it stable. Except for aging it should work. BTW a big hole in the ground is a good source of free energy because it is nearly always a different temperature than at the surface, some times by 10 or 40 degrees. Heat pumps can exploit the difference. People who can design and install these systems are working overtime and making a mint right now. No I would not powerwer your GPS with this, but maybe a house's heating and AC system. 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] Sub mm measurements with gps timing antennas?
You should be able to get the power for a OCXO way down with some very good insulation. Think Dewar container for the XTAL and heater. They just need a lot of power to get warmed up and you could do that prior to installation. As to using a choke ring antenna, just use a steep peaked radome. Tom - Original Message - From: Attila Kinali att...@kinali.ch To: Tom Van Baak t...@leapsecond.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, April 25, 2012 2:42 PM Subject: Re: [time-nuts] Sub mm measurements with gps timing antennas? Beside the harsh environment, this also means that the devices cannot be reached for most of the year (there is usually a 3 months window when the devices can be accessed)..and some years they cannot access them at all (adverse weather conditions preventing ascend). For installation, a helicopter has to fly everything up into the mountains, which means that pre-assembled stuff cannot be transported, because it's too bulky (prevents whole system calibration in a climate chamber). After installation the system runs on solar power with a backup battery. But this doesn't guarrantee power at all. The solar panel could be below a meter or two of snow. Hence the whole system has to cope with periodic power los and has to be as low power as possible (ie no OCXO, no Rb, no temperature stabilization). The snow also prevents the use of choke rings, because they would accumulate a lot of snow and ice, which would then cover the whole antenna. But at least, there is hardly any electronic interference, a good sky view (no trees), unless the system is mounted near a wall. And the antenna cable is quite short (it was 15cm in the previous version of the device and should be 50cm in the next) A simple test that could be done locally (refrigerator, sauna, etc.) would be to measure the tempco of the entire system (antenna, cables, LEA-6T) before they deploy it to a mountain. It may also be the case that the system has both a temperature coefficient and a temperature change coefficient so it's not a simple 2-point test. You can probably ignore humidity and barometric pressure. I think the ETH has climate chambers that could run such tests. But i'm not sure how you'd test the antenna in such a chamber. Another test would be to rotate the antenna at 1 RPH (revolution per hour) and then look for modulation in the post-processed solution. Hmm.. that's actually a quite nice test. Cool idea, thanks! This would give a hint of the quality of the antenna. As a baseline, try the same test using a precision gps antenna. I have spare pin-wheel, choke-ring, and ground-plane antennas that I could loan, but surely these are available where you are, and probably cheaper than postage from here. Yes. The problem is, antennas that perform well in a city environment, where temperature swings are quite limited, fail in high alpine environment. But that's what my question originally aimed at. How much better can we get using a better antenna? Is it worth doing? Or is it just a waste of time and money? BTW: what's a pin-wheel antenna? Google tells me contradictory things. It seems that everyone else that does sub-ns precision timing or mm positioning uses a large combination of tricks: dual-frequency antenna and receiver, geodetic-quality antenna, passive or active temperature control, phase-stabilized cables, GPS and Glonass, external frequency reference, and post-processing. Your customer is only using one from this long, expensive list. So there may be a lesson there. The problem with most of those techniques is, that they are not available for the price the customer can afford. A dual frequency receiver costs a lot more than an of the shelf LEA6-T. Also these modules are usually build with larger power budgets in mind, e.g. the Trimble BD920 uses 1.3W typical, while the 0.3W max(!) of the LEA6-T already hurt us a lot. Using an external frequency reference is not possible with the LEA6-T. It would be possible to do that when using one of the GPS chipsets from u-blox, but therefor we would need to take at least a full reel (iirc 2000 pieces), which isnt exactly cost efficient. Beside, we would still need to use a TCXO, because there is not enough power available for an OCXO or even an MCXO. Can you share any data they have collected already? I would be interested to know how far one could push a LEA-6T. We are only a supplier of the electronics and don't have access to the data. And i don't think they have finished analysing the data they collected already...But i can ask. What data do you have in mind? Attila Kinali [1] http://www.permasense.ch -- 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
Re: [time-nuts] Sub mm measurements with gps timing antennas?
On Wed, 25 Apr 2012 12:29:59 -0700 Chris Albertson albertson.ch...@gmail.com wrote: 1) You could use a choke ring if you were willing to build a large size conical cover or (say) fiberglass I thought about that... customer doesn't seem to like it. 2) Seems that you might want a much taller mast for you solar cells. If they are covered by a meter of snal make the mast a meter taller, The panels are not on a mast but mounted on walls and nearby boulders. For one thing they are too heavy for a mast (think about a mast you can carry alone in 3000m height and deep snow), for another the whole thing would be taken apart by the wind in the first thunderstorm. Did i already mention the harsh environment? ;-) 3) This would take quite a bit of physical work but you can always find a stable temperature if you are willing to dig or drill a deep enough hole. You don't drill into permafrost. Not unless you really have to. If you are lucky and you have just frozen soil, you only have to deal with something that has the mechanical properties of steal. If you are unlucky and you are on a rock, you've to drill into granite with small pockets of ice. 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] PICTIC II ready-made?
Attila Kinali wrote: Hi Bruce, On Thu, 26 Apr 2012 07:15:41 +1200 Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: If a suitable ADC is used the interpolator can be simplified considerably whilst improving its performance. Could you tell a little bit more about what a suitable ADC for a time interpolator is? And how exactly does it help to simplify the interpolator? Attila Kinali If a capacitive input charge redistribution ADC is used the interpolator output capacitor can be directly connected to it. This eliminates the output buffer amp with its unknown settling time as well as the associated gain and offset adjustements. The TDC capacitor merely acts as temporary charge storage to ensure the ADC input voltage limits arent exceeded during the charging phase. The charge is redistributed between the external capacitor and the ADC sampling capacitance with a time constant set the ADC sampling switch on resistance. All the calibration adjustments can be eliminated and replaced by software calibration if reasonably close tolerance parts are used. Most of the ADCs built into current microprocessors are capacitive input charge redistribution ADCs. One just needs to ensure that the ADC input leakage current is sufficiently small. The specified pin leakage current test limits are considerably higher than the actual leakage. If an external ADC is used higher resolution is possible. The addition of a ground plane to the PCB should also improve the perfformance. The current source also needs a little tweaking (high frequency decoupling of the transistor emitter and base from the opamp) to improve its transient response. 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] PICTIC II ready-made?
On Thu, 26 Apr 2012 08:00:17 +1200 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: If a capacitive input charge redistribution ADC is used the interpolator output capacitor can be directly connected to it. This eliminates the output buffer amp with its unknown settling time as well as the associated gain and offset adjustements. Quite interesting... Thanks a lot! 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] In the atomclock repairshop...
Very cool, Magnus. Congratulations on your new-found fame! John On 4/25/2012 3:06 PM, Magnus Danielson wrote: Fellow time-nuts, Oh, ok. So now it is public, so I better tell you about it... Jörgen Städje is a tech-writer which enjoys writing articles where he dips into some system and writes about it. Trying to teach things. Demystify things. So, when you read it, please recall that the audience is not very into the subject. It's in Swedish, but since you all know it by heart (or maybe using Babelfish) I think you surely enjoy it... http://www.idg.se/2.1085/1.443818/i-atomurmakarens-verkstad The photo-session was not all that well-planned, but enjoy the more intimate photos of among others my Russian CH1-78 / HG414A. Various splashes of instruments. One of the photos has direct inspiration from an LP. Extra points from identifying which album. :) Oh well. Hope you enjoy it for what it is. Hope you can handle the chock of seeing photos of me. Cheers, Magnus - another time-nut outed by a journalist ___ time-nuts mailing 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] In the atomclock repairshop...
Hi Magnus, Don't you just love that Rubidium color! Like nothing else. With Chrome's translator I was able to follow the article ok. On the other hand it starts out with: Is your atomic clock for? Grinds it a little and needs to be lubricated? Does the atoms on the end? Then it's time to go to the atomic clock watchmaker and get checked against a frequency standard. The photos and diagrams are great. This article goes into far more technical detail than any other one covering our hobby. I'm impressed. How much work would it be to make a quality English version available? /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] PICTIC II ready-made?
About replacing the 74ACT175... there´s a company called Potato Semi (well.. they make chips, right?) whose sole business is to make damn fast 74 logic. Their chips can be bought at ebay in small quantities. Look at this 600MHz D flip flop: http://www.potatosemi.com/potatosemiweb/datasheet/PO74G74A.pdf Daniel Em 25/04/2012 16:15, Bruce Griffiths escreveu: Chris Albertson wrote: On Wed, Apr 25, 2012 at 9:37 AM, Don Lathamd...@montana.com wrote: I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Yes, MOST of the design could be re-used. As an Arduino shield there is no need for a PIC or RS-232 interface becusethe Arduino does that function. You'd need to replace the 74ACT175 part but that is not hard. About changing the cap values without soldering. I guess you could push the leads into a 0.1 inch header strip or install several and use a DIP switch to select which are in. But I don't know if the extra inductance al that wiring adds is enough to worry about. The time to digital converter (TDC) section is merely an interpolator that measures the delay of a synchroniser. The TDC range should be about 2 clock periods to accommodate the range of synchroniser delays and to facilitate calibration. Unless one is changing the synchroniser clock period there is no need to vary the TDC gain. The SR620 uses a similar interpolator and has only a single interpolator range. The range is extended by counting the number of synchroniser clock periods between synchroniser output transitions of interest. When measuring the time interval between 2 signals a pair of synchronisers and interpolators are used. Interpolator nonlinearity can be measured by using a statistical fill the buckets technique which uses nothing but a pair of noisy asynchronous oscillators with high reverse isolation to avoid injection locking. If a suitable ADC is used the interpolator can be simplified considerably whilst improving its performance. Minor nonlinearities are of little significance, as long as they are repeatable and relatively stable they can be easily corrected in software. 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. ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 12:11 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Apr 2012 08:45:52 -0700 Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Apr 25, 2012 at 5:50 AM, Bill Dailey docdai...@gmail.com wrote: I have wondered the same thing. It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. May i ask what makes the arduino programable by __anyone__ ? Sofar, i only had a look at the hardware of arduino, but never looked at the software side, as for me, who is regularly writing C code for bare metal uC applications, the software part is solved if i know that gcc can generate code for the architecture in question. I can do the same thing too. But there is a steep learning curve for most people. What makes the Arduino easy for beginners is the combination of... 1) A boot loader that makes the Adruino self programmable over USB. No other hardware is required. This also means EVERYONE has the same programming hardware so the software can hide the fact that it is even being used. No settings to figure out 2) The IDE is written in Java and is portable. It is truly identical on all platforms. Yes it uses gcc but the end user never has to deal with gcc or even know what gcc is. Same with saving your code, hit just puts it some place and keeps track of it 3) There is a library of functions that work together. and the library is the SAME on even Arduino so all the example code just works. you can cut and paste code between projects. Most people when they write programs are really stringing together library calls. So it takes two lines of code to get the value from an ADC and send it over USB to a PC. 4) There are lot of books and on-line training materials and all the examples work on all platforms and on all Arduino compatible devices. 5) it is fast. I can change a line of code and then hit the load button and seconds later the changed code is running on the Arduino. It is almost like programming an interpreted language 6) The whole system was designed so that artists and designers could us microcontrollersin their projects. The first test project I did was to read the voltage from the wiper on a 100K pot and display it on an LCD screen. It took a little over an hour and that included wiring up the hardware, plugging the Arduino into the computer. Then I unplug the USB cable and connect a 9V battery and I have a portable toy project. 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] In the atomclock repairshop...
The portrait of your good self on page 4 A night seance in rubidium lamp light is superb, I would guess that this is inspired by a LP sleeve. It looks like it was painted by Joseph Wright of Derby, who lived about 250 years ago and who was the first painter to paint scientific subjects, and who was the master of lighting his subjects with a single candle. On 26 April 2012 05:06, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, Oh, ok. So now it is public, so I better tell you about it... Jörgen Städje is a tech-writer which enjoys writing articles where he dips into some system and writes about it. Trying to teach things. Demystify things. So, when you read it, please recall that the audience is not very into the subject. It's in Swedish, but since you all know it by heart (or maybe using Babelfish) I think you surely enjoy it... http://www.idg.se/2.1085/1.**443818/i-atomurmakarens-**verkstadhttp://www.idg.se/2.1085/1.443818/i-atomurmakarens-verkstad The photo-session was not all that well-planned, but enjoy the more intimate photos of among others my Russian CH1-78 / HG414A. Various splashes of instruments. One of the photos has direct inspiration from an LP. Extra points from identifying which album. :) Oh well. Hope you enjoy it for what it is. Hope you can handle the chock of seeing photos of me. Cheers, Magnus - another time-nut outed by a journalist __**_ 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. -- Tom Harris celephi...@gmail.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] In the atomclock repairshop...
Hi Tom, On 04/25/2012 10:54 PM, Tom Van Baak wrote: Hi Magnus, Don't you just love that Rubidium color! Like nothing else. Rubidium actually has a deep red colour to it, it was found using the flaming new flame spectroscopy method and is named so from the ruby-red colour it has. So you have a combined spectrum of the Argon and rubidium to get that colour. Oh, and it's a 36 mm wide optical path in there... complete with a copper reflector for the lamp. Ah well. With Chrome's translator I was able to follow the article ok. On the other hand it starts out with: Is your atomic clock for? Grinds it a little and needs to be lubricated? Does the atoms on the end? Then it's time to go to the atomic clock watchmaker and get checked against a frequency standard. This is a better start: Is your atomic clock slow? Does it grind a little and needs lubrication? Does it run out of atoms? Then it's time to go to the atomic clock watchmaker and get it checked against a frequency standard. There is also a bad pub in the second picture-text. Oh, and I actually don't know of any clock which isn't built with atoms The photos and diagrams are great. This article goes into far more technical detail than any other one covering our hobby. I'm impressed. Jörgen Stedje was really enjoying himself. He read up on the LPRO 101 and I added bits and pieces. When doing the review of the article, it was really just minor details and corrections, some rephrasing to get the technical details into decent shape. It's indeed a good article. Not that there isn't caesiums in that lab, but we decided to concentrate it to rubidiums just to get one aspect clear, but still touching on the advanced stuff. How much work would it be to make a quality English version available? Probably not too much. There might be some IPR issues involved, but I can ask. I think Jörgen would love the extra attention. :) He has written many good articles, including one about the Aricebo laboratory. As always many good photos. 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] In the atomclock repairshop...
On 04/26/2012 12:37 AM, Tom Harris wrote: The portrait of your good self on page 4 A night seance in rubidium lamp light is superb, I would guess that this is inspired by a LP sleeve. Yes, indeed it is. Now, which LP sleeve is it? We have the age for it here. It looks like it was painted by Joseph Wright of Derby, who lived about 250 years ago and who was the first painter to paint scientific subjects, and who was the master of lighting his subjects with a single candle. Lovely description. This time it was a single Maglite that Jörgen's wife held. Oh, and the rubidium-lamp and stray light from my array of instruments of course. :) We had fun taking those photos. 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] PICTIC II ready-made?
Chris, Your undying devotion to the Arduino is laudable. However, the point that i think you are missing is such functionality is also available on other platforms with the same amount of ease and support. If you take someone who has never seen, touched nor had any knowledge of any computing process, then you would find that they would have just as much beginning trouble with the Arduino as any other platform. A true computer NERD would have the ability to flexibly deal with different platforms, as each have their strengths and weaknesses. Thus no one platform is perfect and you chose the one that best fits the project. BillWB6BNQ Chris Albertson wrote: On Wed, Apr 25, 2012 at 12:11 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Apr 2012 08:45:52 -0700 Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Apr 25, 2012 at 5:50 AM, Bill Dailey docdai...@gmail.com wrote: I have wondered the same thing. It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. May i ask what makes the arduino programable by __anyone__ ? Sofar, i only had a look at the hardware of arduino, but never looked at the software side, as for me, who is regularly writing C code for bare metal uC applications, the software part is solved if i know that gcc can generate code for the architecture in question. I can do the same thing too. But there is a steep learning curve for most people. What makes the Arduino easy for beginners is the combination of... 1) A boot loader that makes the Adruino self programmable over USB. No other hardware is required. This also means EVERYONE has the same programming hardware so the software can hide the fact that it is even being used. No settings to figure out 2) The IDE is written in Java and is portable. It is truly identical on all platforms. Yes it uses gcc but the end user never has to deal with gcc or even know what gcc is. Same with saving your code, hit just puts it some place and keeps track of it 3) There is a library of functions that work together. and the library is the SAME on even Arduino so all the example code just works. you can cut and paste code between projects. Most people when they write programs are really stringing together library calls. So it takes two lines of code to get the value from an ADC and send it over USB to a PC. 4) There are lot of books and on-line training materials and all the examples work on all platforms and on all Arduino compatible devices. 5) it is fast. I can change a line of code and then hit the load button and seconds later the changed code is running on the Arduino. It is almost like programming an interpreted language 6) The whole system was designed so that artists and designers could us microcontrollersin their projects. The first test project I did was to read the voltage from the wiper on a 100K pot and display it on an LCD screen. It took a little over an hour and that included wiring up the hardware, plugging the Arduino into the computer. Then I unplug the USB cable and connect a 9V battery and I have a portable toy project. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II ready-made?...nanode
Mmmm not too impressive a web site thoughthe link to the buy page doesnt work backing up to the home the tabs in light grey on a white background are almost unreadabletoo must geewhizz and not the right HF input I suspectstill looks an interesting product. Alan G3NYK - Original Message - From: Andrew Back and...@carrierdetect.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, April 25, 2012 7:39 PM Subject: Re: [time-nuts] PICTIC II ready-made? On 25 April 2012 19:09, Randy D. Hunt randy_hunt...@yahoo.com wrote: Then there is also the matter of surface mount components. Some people my not physically be able to work with them, learning to solder or not. I am rapidly joining that group be cause of my vision. Since Arduino has been mentioned I feel obliged to provide a link for Nanode, an Arduino-compatible that integrates Ethernet and low power wireless (e.g. 868MHz) for around the same price of an Arduino. It's supplied as a kit of through-hole components... http://wiki.london.hackspace.org.uk/view/Project:Nanode Or a nice alternative might be a daughterboard for a Raspberry Pi, which would give you an ARM/Linux base for not much more money, and you could use it to create a standalone system that drives an old monitor for a display. http://en.wikipedia.org/wiki/Raspberry_Pi Regards, Andrew -- Andrew Back http://carrierdetect.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] PICTIC II ready-made?
Rasberry pi appears to have fallen victim to poor pre market research. Essentially vapor for now. Don't know when you can get one. I have been looking to get one since march. RadioShack carries arduino. Doc KX0O ___ time-nuts mailing 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] In the atomclock repairshop...
That we even know what an LP sleeve is gives a pretty good clue about what a bunch of old goats we are ;-) -Chuck Magnus Danielson wrote: On 04/26/2012 12:37 AM, Tom Harris wrote: The portrait of your good self on page 4 A night seance in rubidium lamp light is superb, I would guess that this is inspired by a LP sleeve. Yes, indeed it is. Now, which LP sleeve is it? We have the age for it here. ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, Apr 25, 2012 at 4:24 PM, WB6BNQ wb6...@cox.net wrote: Chris, Your undying devotion to the Arduino is laudable. However, the point that i think you are missing is such functionality is also available on other platforms with the same amount of ease and support. If you take someone who has never seen, touched nor had any knowledge of any computing process, then you would find that they would have just as much beginning trouble with the Arduino as any other platform. No, some platforms are harder than others. Building an FPGA powered project at home is harder than writing a Perl script. Using a bare AVR chip is harder then using the same chip inside an Arduino. Try listing all the skills one must learn to make an LED blink on various platforms. You are correct about no platform being perfect. Arduio is not well suited to anything that you are going to manufacture. The unit cost and size are both 10X to high and it lacks enough power for things like signal processing. It is well suited to building one off projects that don't require much compute power. It's advantage is that it makes uP development slightly easier than writing a Perl script. The user does not need to know much. I've used all kinds of computers, Mainframe machines to control radars and uPs to control head movement on a disk drive and I used a Linux system once inside a CCD camera. In this case I thought if the PicTic were to be redone I'd like for it to be hackable by beginners who don't know a lot about TICs or uPs. If you make it to complex people will see it as a black box A true computer NERD would have the ability to flexibly deal with different platforms, as each have their strengths and weaknesses. Thus no one platform is perfect and you chose the one that best fits the project. BillWB6BNQ Chris Albertson wrote: On Wed, Apr 25, 2012 at 12:11 PM, Attila Kinali att...@kinali.ch wrote: On Wed, 25 Apr 2012 08:45:52 -0700 Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Apr 25, 2012 at 5:50 AM, Bill Dailey docdai...@gmail.com wrote: I have wondered the same thing. It might be time for a group project to design a Pictic III that uses parts that are readily available. Today I'd build it around an Arduino rather than a PIC even if the cost is more. Arduino is programmable by __anyone__ and plugs into a USB port, no onwwouldhave to supply programed chips and because it is so easy to program maybe some users would try to make improvements and offer them to others. May i ask what makes the arduino programable by __anyone__ ? Sofar, i only had a look at the hardware of arduino, but never looked at the software side, as for me, who is regularly writing C code for bare metal uC applications, the software part is solved if i know that gcc can generate code for the architecture in question. I can do the same thing too. But there is a steep learning curve for most people. What makes the Arduino easy for beginners is the combination of... 1) A boot loader that makes the Adruino self programmable over USB. No other hardware is required. This also means EVERYONE has the same programming hardware so the software can hide the fact that it is even being used. No settings to figure out 2) The IDE is written in Java and is portable. It is truly identical on all platforms. Yes it uses gcc but the end user never has to deal with gcc or even know what gcc is. Same with saving your code, hit just puts it some place and keeps track of it 3) There is a library of functions that work together. and the library is the SAME on even Arduino so all the example code just works. you can cut and paste code between projects. Most people when they write programs are really stringing together library calls. So it takes two lines of code to get the value from an ADC and send it over USB to a PC. 4) There are lot of books and on-line training materials and all the examples work on all platforms and on all Arduino compatible devices. 5) it is fast. I can change a line of code and then hit the load button and seconds later the changed code is running on the Arduino. It is almost like programming an interpreted language 6) The whole system was designed so that artists and designers could us microcontrollersin their projects. The first test project I did was to read the voltage from the wiper on a 100K pot and display it on an LCD screen. It took a little over an hour and that included wiring up the hardware, plugging the Arduino into the computer. Then I unplug the USB cable and connect a 9V battery and I have a portable toy project. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] Antique Rubidium Standard Questions
Paul, Good suggestion, but I don't think pop rivets had been invented when they built this thing! :-D It's built like a piece of mil-spec equipment. When I google for individual parts, I keep tripping over NSN numbers. Now that I look closely at it, I realize that the case is just the case with no electrical connection between it and the circuit other than the BNC jacks on the front panel. The concept of 'chassis ground' is an unknown concept. I don't think there's even one chassis ground lug anywhere. Even when I'm poking around inside the unit, there are no live wires that I can touch, everything is insulated. The build quality is very high. But now that you've got me thinking about it, I think there's something weird about the grounding in the physics package. I've got to take another look at that. Thanks! Ed On 4/25/2012 8:59 PM, paul swed wrote: Ed look for pop rivetted ground logs. Famous for going bad. HP even used them. Drill em out and put real bolts and lock washers in On Tue, Apr 24, 2012 at 7:34 PM, Ed Palmered_pal...@sasktel.net wrote: Paul, On 4/24/2012 5:24 PM, paul swed wrote: When all else fails check the grounds. Especially 40 year old screws. Been there, done that. This unit had multiple problems with bad soldered ground connections. I went through the unit and resoldered everything that looked the least bit odd. I didn't find any screws that were electrically significant. Maybe I should look again! Ed On Tue, Apr 24, 2012 at 6:13 PM, ed breyae...@telight.com wrote: Ed, Tuning the cavity should peak everything - it just maximizes the excitation power at the microwave frequency, so you get the most output from the Rb light wavelengths. A mechanical cavity resonator will have a very wide (compared to the modulation frequencies you're looking for) bandwidth, so unless something happened to it physically, it should be OK as originally built or adjusted. However, you may want to look at the multiplier chain and SRD bias circuit components and adjustments - those could have drifted quite a bit over forty years, limiting the microwave power due to being off-frequency, or having poor multiplication efficiency. I'm guessing that the second harmonic is indeed present, but just buried in the noise, and the loop still can lock because of the further signal processing, even though you don't see the evidence - remember it's a lock-in amplifier capable of digging a tiny signal out of the noise. If you go through the multiplier and check and tweak things, you may get more excitation power and signs that it's getting back to normal. Once you get enough power, if the Rb cells are still good, the second harmonic signal should show up large enough for the circuit to detect sufficient S/N ratio and provide a valid lock indication. Ed Breya Ed Palmer wrote: Could the drift be at least partially responsible for the lack of second harmonic? A message on the list ( http://www.febo.com/pipermail/time-nuts/2006-April/020562.htmlhttp://www.febo.com/**pipermail/time-nuts/2006-**April/020562.html) said that you could peak the second harmonic by adjusting the cavity tuning. If the cell and the cavity are out of sync would that kill the second harmonic? How close to they have to be? If this thing has a cavity tuning adjustment I haven't found it. ___ time-nuts mailing 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] PICTIC II ready-made?
two thumbs up for Radio Shack - they sure have their problems but they are all we have in a lot of places. with the new Velleman and Arduino and Basic Stamp kits, they are clearly trying. they have a ways to go, but I try to vote with my $$$ a little bit. Cliff K6CLS On 2012-04-25 16:41, Bill Dailey wrote: Rasberry pi appears to have fallen victim to poor pre market research. Essentially vapor for now. Don't know when you can get one. I have been looking to get one since march. RadioShack carries arduino. Doc KX0O ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, 25 Apr 2012 11:13:42 -0700, Chris Albertson albertson.ch...@gmail.com wrote: On Wed, Apr 25, 2012 at 9:37 AM, Don Latham d...@montana.com wrote: I forgot to add that a simple redrafting of the II as an Arduino shield with appropriate chips and chip passives would accomplish the desired end without losing the very careful engineering and testing that has already been done? Would be nice to have a way to change caps without soldering as well, maybe just some .1 jumpers? Yes, MOST of the design could be re-used. As an Arduino shield there is no need for a PIC or RS-232 interface becusethe Arduino does that function. You'd need to replace the 74ACT175 part but that is not hard. About changing the cap values without soldering. I guess you could push the leads into a 0.1 inch header strip or install several and use a DIP switch to select which are in. But I don't know if the extra inductance al that wiring adds is enough to worry about. One problem with the design in this case is that it requires 8 or 9 I/O pins making the use of additional Arduino shields difficult. Would you add tri-state buffering and a chip select? ___ time-nuts mailing 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] PICTIC II ready-made?
On Wed, 25 Apr 2012 21:26:25 +0200, Attila Kinali att...@kinali.ch wrote: Hi Bruce, On Thu, 26 Apr 2012 07:15:41 +1200 Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: If a suitable ADC is used the interpolator can be simplified considerably whilst improving its performance. Could you tell a little bit more about what a suitable ADC for a time interpolator is? And how exactly does it help to simplify the interpolator? If you add a second lower current source or sink, then you can get away with a LM311 class comparator and one fast timer channel in the microcontroller. The input pulse width charges the capacitor and the timer counts how long it takes to slowly discharge. Since the conversion is integrating instead of sampling, it has better noise immunity. The Tektronix 2440 uses this technique to get about 50ps resolution. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
