Re: [time-nuts] SSR-6t Connector
As long as you don't have to change the 12AU7, you are OK :) Didier KO4BB Sent from my Droid Razr 4G LTE wireless tracker. -Original Message- From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Fri, 21 Dec 2012 11:18 AM Subject: Re: [time-nuts] SSR-6t Connector Funny My 3801 has been working fine. But I had read on time-nuts the issues with the flaky rcvr and thats why I became interested. The 3801s are getting pretty old. I had to change a 6sk7 in the pre-amp. ;-) Regards Paul WB8TSL On Fri, Dec 21, 2012 at 12:00 PM, Ed Palmer ed_pal...@sasktel.net wrote: Since I have a Z3801A this is an interesting development. Do you expect to see improved performance or is this simply to replace a dead VP receiver and bring the Z3801A back to life? My 6 channel VP receiver was flaky so I replaced it with an 8 channel model. My Holdover Uncertainty Prediction is now oscillating between a high of 2 - 3 microseconds and a low of 200 - 300 ns with an oscillation period of 7-9 days. It's only been running for a few weeks so I'll have to wait and see if the oscillations die out. Depending on how things settle, there might not be any need (or room) for improvement. Ed On 12/21/2012 10:26 AM, W2GPS wrote: Tom, Synergy already has a carrier board to put the SSR-6T receiver into a VP, UT, UT+, etc. socket. All that is needed is firmware support for the old 8-channel messages. I am planning to implement this capability for Synergy. It's just a matter of time and priorities. Eventually Synergy will have the solution for this problem. If you could gather a list of Time-Nuts people who would like one or more of these and send it to Art that could speed the process along. Rick -Original Message- From: Tom Van Baak [mailto:t...@leapsecond.com] Sent: Friday, December 21, 2012 11:15 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] SSR-6t Connector Hi Paul, I'm pretty sure the hp Z3801A and 58503A/B (and perhaps other 1990's era) GPSDO use the Motorola Oncore VP receiver. It was, and still is, a famous GPS timing receiver. Later, many GPSDO evolved to use the Motorola/iLotus M12 receiver. The new Synergy SST-6T is a clever combination h/w and s/w that turns a uBlox 6T PIC into a PCB that is both h/w and s/w compatible with an M12. It's a drop-in replacement. But as such, it won't work in a device that is uses an old Motorola UT/GT/VP receiver. I suggested that they also come up with a board that is VP compatible, but you realize the number of 15-year-old Oncore VP's in the field is probably not that high. It would make an excellent labor-of-love project to create a VP-compatible uBlox 6T board, but it's probably not something you can make a business case for. /tvb __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Z3805A cooling requirements?
Hi Volker, On 12/22/2012 04:55 AM, Volker Esper wrote: Although I am dog-tired it gives me no peace... I come to the following conclusion: - The long term Allan deviation gets worse, as long, as the effect of EFC compensating is in the range of tau - But: It gets back to its normal value after that - The short term deviation, however, increases slowly, but it doesn't settle. It's increasing more and more. So it is the short term stability, that is affected, rather than the long term stability. Am I right or wrong? Perhaps I'm to tired to decide. You short term will rise with 1/tau in ADEV is due to white noise. This noise may be due to the oscillator or (many times) your measurement rig. This is expected from theory (see Allan Deviation on Wikipedia). A free-running OCXO will have a D*tau/sqrt(2) rise due to linear drift. If it is beeing steered it would captured by the control loop and depending on it's properties there will be some marginal errors due to it. A free-running OCXO will also experience temperature shifts and that will create a ripple effect in the ADEV/MDEV. If it is being steered the PLL loop would have issues fighting it which could leave traces in the ADEV/MDEV plot. For systematic effects like these, the ADEV/MDEV/TDEV plot isn't the ideal tool. phase/frequency/drift plots and FT of them might be more useful. However, as you might have realized, a single event of temperature event like this averages out on the large scale of things. ADEV and friends isn't a good tool for transient properties, as it is a statistical tool to establish noise levels of various types. For that purpose single freak events of systematic effect needs to be averaged out or even taken out. Doing your plots to show how they vary over time illustrates this in a good way. The event is not part of the long-term noise properties. 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] Questions about TAC frontend, and some measurements
I answer here to Bob Bill and Magnus. Hi I think I would grab some sort of USB thermometer and start logging the room temperature. CMOS input op-amps are a pretty good way to buffer the integrating capacitor. They are cheap and have very low bias currents. Bob The suspect is temperature, the first thing I'm suspecting is the FE5680A temp coefficient. I didnt grasp the real numbers, so I tried estimating the local drift, i.e. the drift value every 2k samples. Here the results: http://www.flickr.com/photos/14336723@N08/8296002061/ The drift stays around -3.2x10^-10 then abruptly goes to -2.4x10^-10, so if the culprit is the 5680, it's frequency should change about 1x10^-10, if I didnt screw up all the calculations. Does this make sense? As for the buffer opamp, I will try with MCP6001, cheap and it's input impedance is so high I will be limited by the pcb... By the way, my LM358 seem to be injecting 1.5nA into the ramp capacitor until it levels to around 1-1.5V. Like Bob said, start logging the temperature. Since you have about 86400 s period on this behaviour, I expect that heating up in the morning (sun or just habits of humans roughly aligned with sun patterns) be the reason, so this would be temperature dependent. Plotting supply voltage may be another reason. Magnus, I will log some temperatures and voltages. scope probe set to 10x, DC coupled. Do you really get 1-2 cycle long difference measures that way? You risk a high non-linearity at the small difference side otherwise, as it takes time to wake the transistors. ... As I commented, you might want 1-2 cycles to pass, so adding a second DFF might be needed for that task. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Like that you try your interpolator wings! Sorry, I didnt undestand this part. I do recommend you to check out the Wenzel clock input stage, which is being deployed in the TADD-2 divider. Squares up sine clocks nicely. Cheers, Magnus Hi Fabio, I am not crazy about your 10 MHz input circuit. You might want to consider investigating John Miles input arrangement at the following web site: http://www.ke5fx.com/ac.htm I used it to drive an input to a divider chip without the output resistor or capacitor. BillWB6BNQ Magnus and Bill, the input stage I'm using was inspired by the wenzel second schematic on this page: http://www.wenzel.com/documents/waveform.html But you both are right, I'm starting to see that it's not that stable. I will try the discrete solution on the wenzel page. Is the transformer mandatory or I can avoid it? In case I have some IF-cans but I've never used and dont know much about them. Thank you all, Fabio. ___ 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] Questions about TAC frontend, and some measurements
Hi It is often harder to measure a pulse that goes from 0 to 100 ns than it is to measure one that goes from 100 to 200 ns. The resolution on the 0 to 100 measure will be 2X, but the non-linearities at zero are quite difficult to deal with. The 100 to 200 measure can get to the same resolution with some analog tricks. If you are running into an ADC, the resolution may already be good enough. There may be no benefit from making it 2X better. For the measurement you are trying to do, 0.1 ns is probably good enough. A 10 bit ADC would do that at 100 ns span. A 12 bit ADC would do it at a 200 ns span. Bob On Dec 22, 2012, at 8:34 AM, fabi...@quipo.it wrote: I answer here to Bob Bill and Magnus. Hi I think I would grab some sort of USB thermometer and start logging the room temperature. CMOS input op-amps are a pretty good way to buffer the integrating capacitor. They are cheap and have very low bias currents. Bob The suspect is temperature, the first thing I'm suspecting is the FE5680A temp coefficient. I didnt grasp the real numbers, so I tried estimating the local drift, i.e. the drift value every 2k samples. Here the results: http://www.flickr.com/photos/14336723@N08/8296002061/ The drift stays around -3.2x10^-10 then abruptly goes to -2.4x10^-10, so if the culprit is the 5680, it's frequency should change about 1x10^-10, if I didnt screw up all the calculations. Does this make sense? As for the buffer opamp, I will try with MCP6001, cheap and it's input impedance is so high I will be limited by the pcb... By the way, my LM358 seem to be injecting 1.5nA into the ramp capacitor until it levels to around 1-1.5V. Like Bob said, start logging the temperature. Since you have about 86400 s period on this behaviour, I expect that heating up in the morning (sun or just habits of humans roughly aligned with sun patterns) be the reason, so this would be temperature dependent. Plotting supply voltage may be another reason. Magnus, I will log some temperatures and voltages. scope probe set to 10x, DC coupled. Do you really get 1-2 cycle long difference measures that way? You risk a high non-linearity at the small difference side otherwise, as it takes time to wake the transistors. ... As I commented, you might want 1-2 cycles to pass, so adding a second DFF might be needed for that task. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Like that you try your interpolator wings! Sorry, I didnt undestand this part. I do recommend you to check out the Wenzel clock input stage, which is being deployed in the TADD-2 divider. Squares up sine clocks nicely. Cheers, Magnus Hi Fabio, I am not crazy about your 10 MHz input circuit. You might want to consider investigating John Miles input arrangement at the following web site: http://www.ke5fx.com/ac.htm I used it to drive an input to a divider chip without the output resistor or capacitor. BillWB6BNQ Magnus and Bill, the input stage I'm using was inspired by the wenzel second schematic on this page: http://www.wenzel.com/documents/waveform.html But you both are right, I'm starting to see that it's not that stable. I will try the discrete solution on the wenzel page. Is the transformer mandatory or I can avoid it? In case I have some IF-cans but I've never used and dont know much about them. Thank you all, Fabio. ___ 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] Questions about TAC frontend, and some measurements
Dear Fabio, On 12/22/2012 02:34 PM, fabi...@quipo.it wrote: I answer here to Bob Bill and Magnus. Hi I think I would grab some sort of USB thermometer and start logging the room temperature. CMOS input op-amps are a pretty good way to buffer the integrating capacitor. They are cheap and have very low bias currents. Bob The suspect is temperature, the first thing I'm suspecting is the FE5680A temp coefficient. When it comes to phase, your interpolator may also be sensitive. I didnt grasp the real numbers, so I tried estimating the local drift, i.e. the drift value every 2k samples. Here the results: http://www.flickr.com/photos/14336723@N08/8296002061/ The drift stays around -3.2x10^-10 then abruptly goes to -2.4x10^-10, so if the culprit is the 5680, it's frequency should change about 1x10^-10, if I didnt screw up all the calculations. Does this make sense? Sounds a bit on the high side. As for the buffer opamp, I will try with MCP6001, cheap and it's input impedance is so high I will be limited by the pcb... By the way, my LM358 seem to be injecting 1.5nA into the ramp capacitor until it levels to around 1-1.5V. Like Bob said, start logging the temperature. Since you have about 86400 s period on this behaviour, I expect that heating up in the morning (sun or just habits of humans roughly aligned with sun patterns) be the reason, so this would be temperature dependent. Plotting supply voltage may be another reason. Magnus, I will log some temperatures and voltages. Goodie. scope probe set to 10x, DC coupled. Do you really get 1-2 cycle long difference measures that way? You risk a high non-linearity at the small difference side otherwise, as it takes time to wake the transistors. ... As I commented, you might want 1-2 cycles to pass, so adding a second DFF might be needed for that task. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Indeed. Some even let one more edge go and measure between 200 and 300 ns. Like that you try your interpolator wings! Sorry, I didnt undestand this part. Trivial, I like that you experiment and build your own interpolator design, build experience. I do recommend you to check out the Wenzel clock input stage, which is being deployed in the TADD-2 divider. Squares up sine clocks nicely. Cheers, Magnus Hi Fabio, I am not crazy about your 10 MHz input circuit. You might want to consider investigating John Miles input arrangement at the following web site: http://www.ke5fx.com/ac.htm I used it to drive an input to a divider chip without the output resistor or capacitor. BillWB6BNQ Magnus and Bill, the input stage I'm using was inspired by the wenzel second schematic on this page: http://www.wenzel.com/documents/waveform.html But you both are right, I'm starting to see that it's not that stable. I will try the discrete solution on the wenzel page. Good. It amplifies up the clock so that you will have low jitter. Is the transformer mandatory or I can avoid it? You can avoid it, just make sure that you get the transistors properly biased, so DC blocking cap and some resistors. In case I have some IF-cans but I've never used and dont know much about them. It's relative benign transistors being used. Good luck and look forward to your progress reports. You got me inspired to try something myself. :) 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] Z3805A cooling requirements?
On 12/22/2012 06:44 PM, Volker Esper wrote: Thank you for your statement, I have to think about it. It seems to be clear, that ADEV/MDEV aren't the convenient tools for characterizing such an event. My goal was to answere the question asked in the beginning of this thread: Does a constant ventilation of the OCXO affect the deviation curves and if so in what manner? More precisely: do I have worse deviation due to ventilation? Well, the deviation curves was only meant to separate various phase-noise forms, not systematic effects, even if they may be illustrated to some degree using the tool. However, since noise(s) and systematic effects have completely different properties in how confidence intervals builds, so they are better measured and treated separately before being put back together again. For longer taus the systematic effects dominates, so drift, temperature, supply voltage and pressure kicks in. ... phase/frequency/drift plots and FT of them might be more useful. So let's have a look at the time domain. The picture shows the PPS-TI of the Z3805 (blue: time difference between OCXO and GPS; red: EFC). In the middle of the diagram we recognize the reaction to the ventilation. Before that happens, the curve has a somewhat stable high frequency noise. After starting the ventilation this noise is extremely varying in amplitude. IMHO that might mean, that Allan deviation will be affected at the short term values of tau. This seems to coincide with the MDEV vs time curves of my diagrams. Agree? Agree. I wonder if the forced convection is to strong. You don't want to hit the limits of the oven control-range. Wonder if this is a long-term effect and if even small adjustment to the setup can remove the bursts of noise you are seeing. 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] How it was Done - A Day in the Life of Five PPSSources..
Thanks David. That's good to know. It's an interesting display. Regards, Tom - Original Message - From: David Martin drmar...@ivietechnologies.com To: time-nuts@febo.com Sent: Friday, December 21, 2012 1:41 PM Subject: [time-nuts] How it was Done - A Day in the Life of Five PPSSources.. How did he set up the video? What camera? The Rigol DS4024 Scope has a Record Function. Basically it stores internally a screen capture for each trigger event. Therefore the Scope itself takes a picture once a second when triggered by PPS events. You can then set the Scope to Replay the whole sequence at a given replay rate. I set the scope to Replay each captured screen at 1000 screens per second. The frame counter in the upper right corner of the screen gives you the delay from the Record Start. I then took a movie of the screen replay with a hand held camera. There does not appear to be any way to save or output the saved screens other than viewing them on the onboard display. Rigol has extensive USB Drive and LAN Support but nothing I've found allows me to save the Record Data. ___ 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] Z3805A cooling requirements?
I wonder if the forced convection is to strong. You don't want to hit the limits of the oven control-range. Wonder if this is a long-term effect and if even small adjustment to the setup can remove the bursts of noise you are seeing. Now, some hours after switching off the fan, I'm discovering such noise bursts even without ventilation :-( That means, I can't be sure, that the change in deviation for small tau is caused by the ventilation. May be it's just within the natural variation. I have to state, that this experiment can't proof the assumtion that a constant air flow affects the deviation curves of an HP 10811 significantly. Except for the humps in the greater tau ranges - what averages out. In fact, if there is any effect, the effect is small. What could be worked on further: Not comparing the OCXO with the internal GPS signal (which is quite noisy in short term) but with an external oscillator. I've got an HP 10544 (similar to the 10811), which could be the reference for external time interval measurement. I'll need some more days... Volker Am 22.12.2012 19:14, schrieb Magnus Danielson: On 12/22/2012 06:44 PM, Volker Esper wrote: Thank you for your statement, I have to think about it. It seems to be clear, that ADEV/MDEV aren't the convenient tools for characterizing such an event. My goal was to answere the question asked in the beginning of this thread: Does a constant ventilation of the OCXO affect the deviation curves and if so in what manner? More precisely: do I have worse deviation due to ventilation? Well, the deviation curves was only meant to separate various phase-noise forms, not systematic effects, even if they may be illustrated to some degree using the tool. However, since noise(s) and systematic effects have completely different properties in how confidence intervals builds, so they are better measured and treated separately before being put back together again. For longer taus the systematic effects dominates, so drift, temperature, supply voltage and pressure kicks in. ... phase/frequency/drift plots and FT of them might be more useful. So let's have a look at the time domain. The picture shows the PPS-TI of the Z3805 (blue: time difference between OCXO and GPS; red: EFC). In the middle of the diagram we recognize the reaction to the ventilation. Before that happens, the curve has a somewhat stable high frequency noise. After starting the ventilation this noise is extremely varying in amplitude. IMHO that might mean, that Allan deviation will be affected at the short term values of tau. This seems to coincide with the MDEV vs time curves of my diagrams. Agree? Agree. I wonder if the forced convection is to strong. You don't want to hit the limits of the oven control-range. Wonder if this is a long-term effect and if even small adjustment to the setup can remove the bursts of noise you are seeing. 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] Questions about TAC frontend, and some measurements
Magnus Danielson wrote: Dear Fabio, On 12/22/2012 02:34 PM, fabi...@quipo.it wrote: I answer here to Bob Bill and Magnus. Hi I think I would grab some sort of USB thermometer and start logging the room temperature. CMOS input op-amps are a pretty good way to buffer the integrating capacitor. They are cheap and have very low bias currents. Bob The suspect is temperature, the first thing I'm suspecting is the FE5680A temp coefficient. When it comes to phase, your interpolator may also be sensitive. I didnt grasp the real numbers, so I tried estimating the local drift, i.e. the drift value every 2k samples. Here the results: http://www.flickr.com/photos/14336723@N08/8296002061/ The drift stays around -3.2x10^-10 then abruptly goes to -2.4x10^-10, so if the culprit is the 5680, it's frequency should change about 1x10^-10, if I didnt screw up all the calculations. Does this make sense? Sounds a bit on the high side. As for the buffer opamp, I will try with MCP6001, cheap and it's input impedance is so high I will be limited by the pcb... By the way, my LM358 seem to be injecting 1.5nA into the ramp capacitor until it levels to around 1-1.5V. Like Bob said, start logging the temperature. Since you have about 86400 s period on this behaviour, I expect that heating up in the morning (sun or just habits of humans roughly aligned with sun patterns) be the reason, so this would be temperature dependent. Plotting supply voltage may be another reason. Magnus, I will log some temperatures and voltages. Goodie. scope probe set to 10x, DC coupled. Do you really get 1-2 cycle long difference measures that way? You risk a high non-linearity at the small difference side otherwise, as it takes time to wake the transistors. ... As I commented, you might want 1-2 cycles to pass, so adding a second DFF might be needed for that task. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Indeed. Some even let one more edge go and measure between 200 and 300 ns. Like that you try your interpolator wings! Sorry, I didnt undestand this part. Trivial, I like that you experiment and build your own interpolator design, build experience. I do recommend you to check out the Wenzel clock input stage, which is being deployed in the TADD-2 divider. Squares up sine clocks nicely. Cheers, Magnus Hi Fabio, I am not crazy about your 10 MHz input circuit. You might want to consider investigating John Miles input arrangement at the following web site: http://www.ke5fx.com/ac.htm I used it to drive an input to a divider chip without the output resistor or capacitor. BillWB6BNQ Magnus and Bill, the input stage I'm using was inspired by the wenzel second schematic on this page: http://www.wenzel.com/documents/waveform.html But you both are right, I'm starting to see that it's not that stable. I will try the discrete solution on the wenzel page. Good. It amplifies up the clock so that you will have low jitter. Is the transformer mandatory or I can avoid it? You can avoid it, just make sure that you get the transistors properly biased, so DC blocking cap and some resistors. In case I have some IF-cans but I've never used and dont know much about them. It's relative benign transistors being used. Good luck and look forward to your progress reports. You got me inspired to try something myself. :) Cheers, Magnus Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce 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] time-nuts Digest, Vol 101, Issue 152
Plot 1: MDEV of the time interval reported by GPSDO Yes, Said, that are important issues. By the way: I'm now writing in two threads, I don't know, why the original thread (Z3805A cooling requirements?) was splitted... Can we please move to the original thread? I am sure, that the noise of the GPSDO PPS-TI data is much to high to recognize the effects. I'm going to make a new setup, where I'll compare the GPSDO PPS with an external oscilator, e.g. an HP 10544 or the high stability reference within my SMX signal generator. Volker Am 22.12.2012 05:07, schrieb Said Jackson: Hi Volker, What is being plotted here? Efc? Time interval as reported by the GPSDO? External counter versus a stable reference? It looks like the resolution is approaching 10ns/s (1E-08 at 1s), and that the short term effects may be hidden in this noise? The effects are clearly visible in your first GPSCon plot, not sure if we can see the short term noise in these plots.. The 10811 I had tested went from ~3E-012 at 100s to ~2E-011 when the fan was on, I think both values are quite a bit below the noise floor of your plot so probably hard to measure. Bye, Said Sent from my iPad On Dec 21, 2012, at 6:47 PM, Volker Esperail...@t-online.de wrote: Said, Unfortunately I don't have the equipment to measure the phase noise of an HP 10811 (yet). But I did some work on evaluating the results of my fan experiment. Within this posting you'll find two diagrams. The first (named 1_DF9PL...) shows five MDEV curves (Modified Allan Deviation), each of them measured at different times. Total time span is 30.5 hours. At small tau values (up to 1000 s) only a slight increase of sigma over time can be noticed. However, at a tau of 5000 s or greater you can watch sigma making a big bump. Ok, that's what we expected before. In diagram no. 1 it's somewhat fussy to recognize the change of a particular sigma(tau). Now, that we've got curious, we want to see, how the sigma(tau) changes over time. So I've been providing a second diagram (2_...), where sigma(tau) is a function of the time. You can see, for example, the curve of tau=20480s developing a big hump, and falling back to a proper value after about 1800 minutes. All curves at a tau greater or equal 2560 do so. At smaller values the curves are esentially less affected, but - they are not back at their starting value after 1800 minutes (30 hours)! You could guess, that the hump moves up to longer times with increasing sigma - but it doesn't. There is something significantly different below tau=2560s. 1 hour ago, I switched off the fan and laid back the aluminium cover. We wait and see. And now, dear time nuts, it's time to go to bed. Volker Am 21.12.2012 18:53, schrieb Said Jackson: Mark, Your plot still shows excursions of +/-1E-010, about 100x higher base noise than the Z3801A/Z3805A are capable of achieving. Wonder where that noise is coming from? This noise is probably much higher than the thermal effects. The original post was the question does my Z380xA have reduced stability if I add a fan or similar, I think the answer is shown to be yes. Volker, I wonder if you also see fan-induced spurs in the phase noise from 1Hz to 100Hz. I would not be surprised if the fan vibration adds significant spurs to the 10811A crystal. Bye, Said Sent from my iPad On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca wrote: This plot should show the frequency change more clearly. (Same data just presented differently.) It seems to me that the noise goes may be going down a bit for a minute or so just after the fan is turned on but I don't believe these plots provide conclusive evidence of this. Regards Mark Spencer Message: 7 Date: Fri, 21 Dec 2012 09:27:29 -0800 From: Said Jacksonsaidj...@aol.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Z3805A cooling requirements? Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com Content-Type: text/plain; charset=us-ascii Great plots guys! Looking at these results I think my original claim still holds: ADEV goes up when a fan is involved versus no fan, even on a double oven 10811.. Clearly visible on the 10811, maybe not so much on the MV89 but that unit seems to have frequency moves into the xE-010 region on Marks plot so maybe the effect is just a bit hidden? Bye, Said Sent from my iPad On Dec 21, 2012, at 5:44 AM, Volker Esperail...@t-online.de wrote: ...and the picture of the experiment... The picture enclosed can give you a first impression. What we see is the difference time between the GPS signal and the OCXO (blue) (PPS-TI), which is an HP 10811. In red we can see the EFC. The total span is 24 h. Before I applied the fan, the noise was at a maximum of about +/- 20 ns. Some hours after starting the fan the noise is much
Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152
Volker.look at the subject line, the posting is in your hands, you dont need to just use the reply button, as somone did with a digest which forked the thread.. This means all the posing under Digest are hidden from view and searching. You can edit the subject line but this does not always return to the old thread if you use he reply button. I think it depends on the mail client. Alan G3NYK - Original Message - From: Volker Esper ail...@t-online.de To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 22, 2012 8:44 PM Subject: Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152 Plot 1: MDEV of the time interval reported by GPSDO Yes, Said, that are important issues. By the way: I'm now writing in two threads, I don't know, why the original thread (Z3805A cooling requirements?) was splitted... Can we please move to the original thread? I am sure, that the noise of the GPSDO PPS-TI data is much to high to recognize the effects. I'm going to make a new setup, where I'll compare the GPSDO PPS with an external oscilator, e.g. an HP 10544 or the high stability reference within my SMX signal generator. Volker Am 22.12.2012 05:07, schrieb Said Jackson: Hi Volker, What is being plotted here? Efc? Time interval as reported by the GPSDO? External counter versus a stable reference? It looks like the resolution is approaching 10ns/s (1E-08 at 1s), and that the short term effects may be hidden in this noise? The effects are clearly visible in your first GPSCon plot, not sure if we can see the short term noise in these plots.. The 10811 I had tested went from ~3E-012 at 100s to ~2E-011 when the fan was on, I think both values are quite a bit below the noise floor of your plot so probably hard to measure. Bye, Said Sent from my iPad On Dec 21, 2012, at 6:47 PM, Volker Esperail...@t-online.de wrote: Said, Unfortunately I don't have the equipment to measure the phase noise of an HP 10811 (yet). But I did some work on evaluating the results of my fan experiment. Within this posting you'll find two diagrams. The first (named 1_DF9PL...) shows five MDEV curves (Modified Allan Deviation), each of them measured at different times. Total time span is 30.5 hours. At small tau values (up to 1000 s) only a slight increase of sigma over time can be noticed. However, at a tau of 5000 s or greater you can watch sigma making a big bump. Ok, that's what we expected before. In diagram no. 1 it's somewhat fussy to recognize the change of a particular sigma(tau). Now, that we've got curious, we want to see, how the sigma(tau) changes over time. So I've been providing a second diagram (2_...), where sigma(tau) is a function of the time. You can see, for example, the curve of tau=20480s developing a big hump, and falling back to a proper value after about 1800 minutes. All curves at a tau greater or equal 2560 do so. At smaller values the curves are esentially less affected, but - they are not back at their starting value after 1800 minutes (30 hours)! You could guess, that the hump moves up to longer times with increasing sigma - but it doesn't. There is something significantly different below tau=2560s. 1 hour ago, I switched off the fan and laid back the aluminium cover. We wait and see. And now, dear time nuts, it's time to go to bed. Volker Am 21.12.2012 18:53, schrieb Said Jackson: Mark, Your plot still shows excursions of +/-1E-010, about 100x higher base noise than the Z3801A/Z3805A are capable of achieving. Wonder where that noise is coming from? This noise is probably much higher than the thermal effects. The original post was the question does my Z380xA have reduced stability if I add a fan or similar, I think the answer is shown to be yes. Volker, I wonder if you also see fan-induced spurs in the phase noise from 1Hz to 100Hz. I would not be surprised if the fan vibration adds significant spurs to the 10811A crystal. Bye, Said Sent from my iPad On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca wrote: This plot should show the frequency change more clearly. (Same data just presented differently.) It seems to me that the noise goes may be going down a bit for a minute or so just after the fan is turned on but I don't believe these plots provide conclusive evidence of this. Regards Mark Spencer Message: 7 Date: Fri, 21 Dec 2012 09:27:29 -0800 From: Said Jacksonsaidj...@aol.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Z3805A cooling requirements? Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com Content-Type: text/plain; charset=us-ascii Great plots guys! Looking at these results I think my original claim still holds: ADEV goes up when a fan is involved versus no fan, even on a double oven
Re: [time-nuts] Questions about TAC frontend, and some measurements
When it comes to phase, your interpolator may also be sensitive. Dont know if I was clear enough, just in case I wasnt able to explain well before: the data I collected didnt came from the analog interpolator, but from the OutD that is a digital out. The interpolator is still in it's infancy. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Indeed. Some even let one more edge go and measure between 200 and 300 ns. I modified the schematic this way to use the second edge: http://www.flickr.com/photos/14336723@N08/8297438155/ Like that you try your interpolator wings! Sorry, I didnt undestand this part. Trivial, I like that you experiment and build your own interpolator design, build experience. Thanks, I like to experiment directly when I can. This puts me in front of the real problems. And by the way playing with the interpolator is something that I'm enjoing; that few transistors are making something that was sort of magic for me before: converting nanoseconds pulses in something that can be easily read. In this work I'm only starting and I'm already on the edge of my little knowledge on electronics, and I'm learning much from the resources and contributors to this list. Good luck and look forward to your progress reports. I will happily keep sharing the work. You got me inspired to try something myself. :) Wow :) Thank you, Fabio. ___ 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] Questions about TAC frontend, and some measurements
Hello, Bruce Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. This is something I'd like to understand better. I'm referring to this schematic here: http://www.flickr.com/photos/14336723@N08/8293076065/ Q2 and Q5 are saturating toward the end of the ramp pulse, when the ramp capacitor C1 starts to go up. I was prepared to see the circuit I designed fail miserably on switch time, but it seem to be working, as far as I could see on the DSO. As far I can understand, the fact that Q2 and Q6 don't saturate, saves the circuit, since at the end of the ramp, when Q1 and Q5 are into saturation, Q6 is able to steer the current to ground, and reverse bias BE (and CB) of Q5. Is this correct, or I was only lucky with the specific parts I used? Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce I was planning to read the voltage with a microcontroller's ADC. I will set a fixed delay from the PPS rising edge and start sampling there. To do so I need that the voltage on integrating capacitor to stay reasonably stable during the delay. Fabio ___ 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] Questions about TAC frontend, and some measurements
Hi Fabio taking BJTs deep into saturation stores a lot of charge in the collector base capacitance. this must br discharged before a state change can occur. LSTTL gets round this and gets the speed at lower currents by clamping the collector to only just in saturation with a schottky diode between base and collector. Higher speeds are obtained with a long-tail pair like configuration, which switches (diverts) the current flow between left and right transistors for the two logic states. The current and power dissipation is high but speeds 10 times saturated logic are obtainable. see ECL, MECL, or PECL logic family schematics. Alan G3NYK - Original Message - From: Fabio Eboli fabi...@quipo.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 22, 2012 11:00 PM Subject: Re: [time-nuts] Questions about TAC frontend, and some measurements Hello, Bruce Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. This is something I'd like to understand better. I'm referring to this schematic here: http://www.flickr.com/photos/14336723@N08/8293076065/ Q2 and Q5 are saturating toward the end of the ramp pulse, when the ramp capacitor C1 starts to go up. I was prepared to see the circuit I designed fail miserably on switch time, but it seem to be working, as far as I could see on the DSO. As far I can understand, the fact that Q2 and Q6 don't saturate, saves the circuit, since at the end of the ramp, when Q1 and Q5 are into saturation, Q6 is able to steer the current to ground, and reverse bias BE (and CB) of Q5. Is this correct, or I was only lucky with the specific parts I used? Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce I was planning to read the voltage with a microcontroller's ADC. I will set a fixed delay from the PPS rising edge and start sampling there. To do so I need that the voltage on integrating capacitor to stay reasonably stable during the delay. Fabio ___ 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] Questions about TAC frontend, and some measurements
Google baker clamp for more on this. Tom - Original Message - From: Alan Melia alan.me...@btinternet.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 22, 2012 6:28 PM Subject: Re: [time-nuts] Questions about TAC frontend, and some measurements Hi Fabio taking BJTs deep into saturation stores a lot of charge in the collector base capacitance. this must br discharged before a state change can occur. LSTTL gets round this and gets the speed at lower currents by clamping the collector to only just in saturation with a schottky diode between base and collector. Higher speeds are obtained with a long-tail pair like configuration, which switches (diverts) the current flow between left and right transistors for the two logic states. The current and power dissipation is high but speeds 10 times saturated logic are obtainable. see ECL, MECL, or PECL logic family schematics. Alan G3NYK - Original Message - From: Fabio Eboli fabi...@quipo.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 22, 2012 11:00 PM Subject: Re: [time-nuts] Questions about TAC frontend, and some measurements Hello, Bruce Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. This is something I'd like to understand better. I'm referring to this schematic here: http://www.flickr.com/photos/14336723@N08/8293076065/ Q2 and Q5 are saturating toward the end of the ramp pulse, when the ramp capacitor C1 starts to go up. I was prepared to see the circuit I designed fail miserably on switch time, but it seem to be working, as far as I could see on the DSO. As far I can understand, the fact that Q2 and Q6 don't saturate, saves the circuit, since at the end of the ramp, when Q1 and Q5 are into saturation, Q6 is able to steer the current to ground, and reverse bias BE (and CB) of Q5. Is this correct, or I was only lucky with the specific parts I used? Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce I was planning to read the voltage with a microcontroller's ADC. I will set a fixed delay from the PPS rising edge and start sampling there. To do so I need that the voltage on integrating capacitor to stay reasonably stable during the delay. Fabio ___ 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] time-nuts Digest, Vol 101, Issue 152
Thank you very much for the advice, I didn't know that at all... Volker Am 22.12.2012 22:26, schrieb Alan Melia: Volker.look at the subject line, the posting is in your hands, you dont need to just use the reply button, as somone did with a digest which forked the thread.. This means all the posing under Digest are hidden from view and searching. You can edit the subject line but this does not always return to the old thread if you use he reply button. I think it depends on the mail client. Alan G3NYK - Original Message - From: Volker Esper ail...@t-online.de To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, December 22, 2012 8:44 PM Subject: Re: [time-nuts] time-nuts Digest, Vol 101, Issue 152 Plot 1: MDEV of the time interval reported by GPSDO Yes, Said, that are important issues. By the way: I'm now writing in two threads, I don't know, why the original thread (Z3805A cooling requirements?) was splitted... Can we please move to the original thread? I am sure, that the noise of the GPSDO PPS-TI data is much to high to recognize the effects. I'm going to make a new setup, where I'll compare the GPSDO PPS with an external oscilator, e.g. an HP 10544 or the high stability reference within my SMX signal generator. Volker Am 22.12.2012 05:07, schrieb Said Jackson: Hi Volker, What is being plotted here? Efc? Time interval as reported by the GPSDO? External counter versus a stable reference? It looks like the resolution is approaching 10ns/s (1E-08 at 1s), and that the short term effects may be hidden in this noise? The effects are clearly visible in your first GPSCon plot, not sure if we can see the short term noise in these plots.. The 10811 I had tested went from ~3E-012 at 100s to ~2E-011 when the fan was on, I think both values are quite a bit below the noise floor of your plot so probably hard to measure. Bye, Said Sent from my iPad On Dec 21, 2012, at 6:47 PM, Volker Esperail...@t-online.de wrote: Said, Unfortunately I don't have the equipment to measure the phase noise of an HP 10811 (yet). But I did some work on evaluating the results of my fan experiment. Within this posting you'll find two diagrams. The first (named 1_DF9PL...) shows five MDEV curves (Modified Allan Deviation), each of them measured at different times. Total time span is 30.5 hours. At small tau values (up to 1000 s) only a slight increase of sigma over time can be noticed. However, at a tau of 5000 s or greater you can watch sigma making a big bump. Ok, that's what we expected before. In diagram no. 1 it's somewhat fussy to recognize the change of a particular sigma(tau). Now, that we've got curious, we want to see, how the sigma(tau) changes over time. So I've been providing a second diagram (2_...), where sigma(tau) is a function of the time. You can see, for example, the curve of tau=20480s developing a big hump, and falling back to a proper value after about 1800 minutes. All curves at a tau greater or equal 2560 do so. At smaller values the curves are esentially less affected, but - they are not back at their starting value after 1800 minutes (30 hours)! You could guess, that the hump moves up to longer times with increasing sigma - but it doesn't. There is something significantly different below tau=2560s. 1 hour ago, I switched off the fan and laid back the aluminium cover. We wait and see. And now, dear time nuts, it's time to go to bed. Volker Am 21.12.2012 18:53, schrieb Said Jackson: Mark, Your plot still shows excursions of +/-1E-010, about 100x higher base noise than the Z3801A/Z3805A are capable of achieving. Wonder where that noise is coming from? This noise is probably much higher than the thermal effects. The original post was the question does my Z380xA have reduced stability if I add a fan or similar, I think the answer is shown to be yes. Volker, I wonder if you also see fan-induced spurs in the phase noise from 1Hz to 100Hz. I would not be surprised if the fan vibration adds significant spurs to the 10811A crystal. Bye, Said Sent from my iPad On Dec 21, 2012, at 9:42 AM, Mark Spencermspencer12...@yahoo.ca wrote: This plot should show the frequency change more clearly. (Same data just presented differently.) It seems to me that the noise goes may be going down a bit for a minute or so just after the fan is turned on but I don't believe these plots provide conclusive evidence of this. Regards Mark Spencer Message: 7 Date: Fri, 21 Dec 2012 09:27:29 -0800 From: Said Jacksonsaidj...@aol.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Z3805A cooling requirements? Message-ID:83ce0384-2996-4155-b51b-9d79910b2...@aol.com Content-Type: text/plain; charset=us-ascii Great plots guys! Looking at these results I think my original claim still holds: ADEV goes up when a fan is involved
Re: [time-nuts] Questions about TAC frontend, and some measurements
Hi One very simple question - how good would it do if you just did it all with logic gates? Tri-state buffers and things like that…. Now that you are up to a 100 to 200 ns long pulse, a lot of the fiddly stuff about can't get a 2 ns pulse through it goes away. I'm not suggesting you tear up what you have. It's just something else to try and compare. Bob On Dec 22, 2012, at 6:00 PM, Fabio Eboli fabi...@quipo.it wrote: Hello, Bruce Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. This is something I'd like to understand better. I'm referring to this schematic here: http://www.flickr.com/photos/14336723@N08/8293076065/ Q2 and Q5 are saturating toward the end of the ramp pulse, when the ramp capacitor C1 starts to go up. I was prepared to see the circuit I designed fail miserably on switch time, but it seem to be working, as far as I could see on the DSO. As far I can understand, the fact that Q2 and Q6 don't saturate, saves the circuit, since at the end of the ramp, when Q1 and Q5 are into saturation, Q6 is able to steer the current to ground, and reverse bias BE (and CB) of Q5. Is this correct, or I was only lucky with the specific parts I used? Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce I was planning to read the voltage with a microcontroller's ADC. I will set a fixed delay from the PPS rising edge and start sampling there. To do so I need that the voltage on integrating capacitor to stay reasonably stable during the delay. Fabio ___ 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.
