Re: [time-nuts] question Alan deviation measured with Timelab and counters
Thanks a lot for your comment Bruce, I need to feel a bit deeper the ins and outs of the methods so I guess I will anyway implement both methods on an evaluation PCB and characterize each method. This will bring to me some actual data to compare. I will share the results of course. The plan is to have an eval PCB with 4 independant 10 MHz squarers, isolation amplifiers, mixers, low pass filters and multistage limiting amplifier. Each block will have input/output connectors so that I can combine any architecture with these blocks. The PCB will receive a low noise PSU as well. Before I start the design if one thinks about something to add in the evaluation, this is very welcome. Stephane On Tue, 27 Jan 2015 03:24:44 + (UTC), Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: The performance of the 2 systems should be comparable provided the similar equivalent noise bandwidths are used.Every 10Mhz edge needs to be timestamped with ps resolution and the resulting phase samples low pass filtered and decimated to achieve this.The 10MSPS picosecond or better resolution time stamping with femtosecond integral linearity will be a bit of a challenge to achieve. Bruce On Tuesday, 27 January 2015 3:26 PM, Stéphane Rey steph@wanadoo.fr wrote: I do understand. Has anyone already compared the performances of squaring the 10 MHz vs squaring the IF ? Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Bob Camp Envoyé : dimanche 25 janvier 2015 19:01 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi The approach in the original NIST paper below was sort of a “best guess” about how to do the limiting and filtering. When the paper was presented, a number of us questioned how that part of the circuit was arrived at. The conversation more or less ended up with “that’s something we can investigate further”. The Collins paper (and Bruce’s work based on it) is a much better way to look at the 10 Hz squaring process. At 10 MHz, that stuff is not needed. Bob On Jan 25, 2015, at 10:44 AM, Stéphane Rey steph@wanadoo.fr wrote: Hi everyone. Many thanks for your very useful comments. I had already seen most of the documents you were pointing but not on the collins and Bruce discussion around the multistage filter. However I've already seen this approach in the document from Allan (http://tf.nist.gov/timefreq/general/pdf/84.pdf) At first I had in mind to square the 10 MHz but this is the aim of the evaluation board to evaluate various architectures. So I will implement several squarers including the Collins Approach both at 10 MHz and 100 Hz and all the blocks will have input and output connectors so that I will be able to test several layouts. I will show you the final design. Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Charles Steinmetz Envoyé : dimanche 25 janvier 2015 08:08 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Stephane wrote: I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. Note that squaring a 10MHz sine wave and squaring a 10 or 100Hz mixer output are two very different tasks. If you start at baseband, a Collins-style multi-stage limiting amp is a great benefit. That is generally not necessary if you start at 10MHz (or if you do use a Collins-style limiter it needs far fewer stages). All of the squarers you mention work well at 10MHz, but not as well at baseband. The LT1719 is easier to apply and faster than the LT1016. You may want to use that instead of the 1016. The LT1719 and LT1715 datasheets show the simplest possible implementation (see below). The MPSH81 devices in my version are available in surface-mount (MMBTH81) if that is more convenient. Other fast transistors will also work (BFT92, BFT93, BFG31). Best regards, Charles --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. http://www.avast.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. --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. http://www.avast.com
Re: [time-nuts] question Alan deviation measured with Timelab and counters
Actually I'm working in the RF department of a big lab, designing RF electronics mainly in microwaves range. I'm luckilly having some tools around to play with and a lot of components like mixers/amplifiers/couplers/splitters/attenuators, ... almost whatever the frequency is up to several tens of GHz. At home since the last 20 years I could as well get nice instruments. The next two measuring tools really missing and for which I'm limited are the phase noise and stability measurement and possibly a good standard. My Effratom FRK Rb is old and probably not the best from a phase noise and stability point of view but until now has never been characterized. Otherwise I've almost everything I need up to 40 GHz I guess. I'm doing further measurement right now which sounds much much more consistent. I will share tonight. Cheers Stephane On Mon, 19 Jan 2015 08:59:58 -0500, Bob Camp kb...@n1k.org wrote: Hi On Jan 18, 2015, at 5:12 PM, Stéphane Rey steph@wanadoo.fr wrote: Bonsoir Magnus (Are you in Sweeden ?) Being able to measure high stability and low phase noise is definitely a need for me as I'm trying to design low noise synthesizers and I'm already reaching the limits of my current tools for phase noise and I can't afford an E5052 for my own. At work I've one but I will probably not stay after august. And anyway I need such tools in my lab at home… If you have tools at work, the best possible thing to do is to get some oscillators / standards characterized. If you *know* what this or that oscillator is doing in terms of ADEV or phase noise at this Tau or frequency offset, it’s much easier to figure a lot of this out. The most basic way to do phase noise in the basement is with a single mixer setup running into some sort of audio FFT device. A sound card can be used or an audio spectrum analyzer. Parts are $100 to get one setup once you can do the audio measurements. For ADEV, a DMTD or it’s cousin, the single mixer is the easy way to go. The single mixer does not get a lot of discussion these days. It is much easier to set up than a DMTD. It does require an offset oscillator. Once you have a single mixer phase noise setup, you are about half way to a single mixer ADEV setup. Cost for one is $100 in parts. You already have a counter to collect the data out of it. In both cases you are running a comparison device. Having a characterized OCXO to compare to is a really nice thing. Bob As low-noise and stable synthetizers depends on the standard used, I need as well to measure them as well... Let's start with this simple experiments and once I will understand the ins and outs I will try to improve. I know techniques of cross-correlations and you've already talked about DMTD that for sure I will have to come to... Good night Stephane -Message d'origine- De : Magnus Danielson [mailto:mag...@rubidium.se] Envoyé : dimanche 18 janvier 2015 22:46 À : Stéphane Rey; 'Discussion of precise time and frequency measurement' Cc : mag...@rubidium.se Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Bonsoir Stéphane, On 01/18/2015 10:34 PM, Stéphane Rey wrote: Thanks a lot Bob and Magnus for your very helpful comments. The HP5370a was indeed in TI mode. By the way what is the difference with +/-TI, the button just aside... But I guess I understand where I've missed something : I've tried to put the Rb on channel A and the DUT on channel B but result was always the same but I do understand now that there is indeed a switch to change from COMmon to SEParate and it was always on COM meaning I believe that channel B wasn't used. This explains a lot of things I did not understand. I'm sorry for these so basic issues that might have been solved if I had read carefully the HP5370a manual first. Good. This confirmation makes sense to be and Bob, now we can relax as the mystery is solved. So possible conclusions until now are that I have actually measured the ADEV floor of the system rather than my DUT... which is already nice. The second conclusion from these oscillations seen with the GPSDO under test is that there is very likely in this GPSDO design a systemic noise added to the 10 MHz output (power supply, PCB coupling, ... I'll make further investigations on it later on). It's a great opportunity to learn the tools, and once you have the tools, you can see if you can't improve things. I will experiment all the suggestions you made and will come back. For information the 1PPS from the HP58503b has a positive pulse width that is only few us length. This only makes it hard to view on a scope, but long enough to reliably trigger your counter and scope. Now, when considering that the method is to compare the DUT to an other source, I assume then that the other source shall be at least 1 order of magnitude better than the DUT. Otherwise this will be impossible to distinguish who is the instability
Re: [time-nuts] question Alan deviation measured with Timelab and counters
Hi Bob, Many thanks for your prompt and detailled answer. My question on applications wasn't on good ADEV where I perfetcly understand the need, but actually what could be the applications of measuring BAD ADEV (10e-7). That was my point asking what king of application can we cover by measuring such high ADEV when you have counters with resolution not greater than 0.01Hz However you bring to me part of the answer when you talk about the reference and the way to get something cheap and better than 10e-12. I will investigate on DMTD. However, even if you have a beautiful Maser source, will you improve anything above the resolution of your counter. In other words, with my 0.01Hz counter, will I improve my measurement if I replace my GPSDO source with something much better ? I feel the resolution of the counter will anyway limit the ADEV floor, right ? If the last digit of the counter do not move how could we measure something smaller ? The counters I'm using are not running on their own reference (OCXO or TCXO) but with the HP58503b which is a GPS disciplined OCXO but with stability in the range of 10e-11 or 10e-12 at best. I'm working for a big lab where possibly I could have nice piece of equipment but this is always easier to find alternatives solutions at lower price. On the application I'm working on we're looking for phase stability in the range of fs at several GHz. One of the project I'm working will use a femtosecond laser modulated at 88 Mhz that some people want to use as RF reference for the 3 GHz source. I'm pretty sure this can't achieve the phase stability requirement and I'm trying to illustrate this. However even for my ham activites where I'm trying to design low noise LOs, I'd like to have a tool able to measure goog frequency and phase stability... Stephane On Fri, 9 Jan 2015 07:48:42 -0500, Bob Camp kb...@n1k.org wrote: Hi Welcome to the world of trying to measure this stuff … On Jan 9, 2015, at 6:53 AM, steph.rey steph@wanadoo.fr wrote: Dear all, I'm trying to measure Alan Deviations using Timelab and some frequency counters. The device under test is a GPSDO using a TCXO as référence I've an HP58503B GPSDO which feeds my counters. I've tried an HP5342A, 0-18 GHz, 1 Hz resolution and a Philipps PM6654C, 0.01Hz resolution. In Timelab, the plot with the HP5342A is around 10e-7 which correspond to 1Hz and with the PM6654C, the plot is around 10e-10. I would suspect that this is still the counter which limits the actual response of my device under test. Yes, the counters and TCXO are limiting your measurements. My question are : - how to measure Alan Deviations with levels below 10e-12/10e-13 ? How much money do you have to spend? ( There are expensive commercial ways to do this). No matter what, you will need a “better than” reference. That’s not going to be cheap. Most of us simply get a second GPSDO and compare them. The assumption is that they both are the same and you can allocate the error equally between them. With three you can more accurately allocate the error. A DMTD is the “cheap” way to get the actual measurement done. What can be the application of measurement Alan deviation 10e-10 ? I guess most of the low frequency There are a number of systems applications that very much need good ADEV. Getting into why this or that nav or com system needs it would take a bit of time. - The HP53503 GPS is given to be 10e-11 / 10e-12. I guess this will limit anyway the measurement floor. I've a Rb source, but it's stability is within the same range. What kind of reference would be more suitable for such measurements ? If you want to do it directly, a hydrogen maser is a good way to go. That’s silly expensive. Just compare GPSDO’s, that’s a lot cheaper. - With the PM6654C on 15h measurement, I can see some frequency jumps of 800 Hz which are not relevants with the GPSDO undertest. I suspect error in data transmission. This makes the overall measurement totally wrong (10e-5). The counter is in talk only mode. I'd like to get rid of these points maybe 40-50 points out of 1. Is there a way to do that from Timelab or the only option is to export the file and process manually the data ? You can expand the data and zap the offending segments. It’s done on the phase plot. Have Fun. Bob Thanks cheers Stephane ___ 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
[time-nuts] question Alan deviation measured with Timelab and counters
Dear all, I'm trying to measure Alan Deviations using Timelab and some frequency counters. The device under test is a GPSDO using a TCXO as référence I've an HP58503B GPSDO which feeds my counters. I've tried an HP5342A, 0-18 GHz, 1 Hz resolution and a Philipps PM6654C, 0.01Hz resolution. In Timelab, the plot with the HP5342A is around 10e-7 which correspond to 1Hz and with the PM6654C, the plot is around 10e-10. I would suspect that this is still the counter which limits the actual response of my device under test. My question are : - how to measure Alan Deviations with levels below 10e-12/10e-13 ? What can be the application of measurement Alan deviation 10e-10 ? I guess most of the low frequency - The HP53503 GPS is given to be 10e-11 / 10e-12. I guess this will limit anyway the measurement floor. I've a Rb source, but it's stability is within the same range. What kind of reference would be more suitable for such measurements ? - With the PM6654C on 15h measurement, I can see some frequency jumps of 800 Hz which are not relevants with the GPSDO undertest. I suspect error in data transmission. This makes the overall measurement totally wrong (10e-5). The counter is in talk only mode. I'd like to get rid of these points maybe 40-50 points out of 1. Is there a way to do that from Timelab or the only option is to export the file and process manually the data ? Thanks cheers Stephane ___ 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] newcomer
Hi the list, Just wanted to introduce myself for my 1st message. I'm Stephane, 40, living in France, at the moment working in RF electronics for a particles accelerator lab. I'm hamradio as well, and I do enjoy especially weak and accurate signals. I'm desiging various RF circuits. Current design is a universal PLL able to operate from 0.5 to 6 GHz depending on the VCO and supposed to be low-jitter (1ps) regarding the application. I'm also starting a new design of low noise PLL and there will be probably a lot of question arising... I'm starting with the 1 GHz LO made upon a 100 MHz VCXO + multipliers/filters/MMICs. I want to focus deeper on low phase noise/jitter, synchronization and low-noise PLL techniques. I believe this is a good place for most of these topics. Cheers Stephane ___ 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] newcomer
Hello Said, Thanks for the answer. Sounds interresting. Do you have a description of that ? Especially a phase noise plot ? As said, I'm planning to use a VCXO (low cost and low noise) at 100 MHz followed by a MMIC (ERA) and a 500 MHz 3-cells helical filter from Temwell. Then a doubler from minicircuit, an other MMIC and a 3-cell helical filter at 1 GHz... Cheers Stephane On Mon, 15 Sep 2014 09:17:01 -0700, Said Jackson via time-nuts time-nuts@febo.com wrote: Hi Stephanie, Welcome to the list! We designed a 1GHz crystal LO for PLLs (the ULN-1G) using an off the shelf miniature 500MHz crystal oscillator which is run at 3 rd overtone internally then using a diode doubler and a steep bandpass filter using several Mini Circuits ceramic filters and a 20dBm amp. Works like a charm and has phase noise very close to theoretical.. Bye, Said Sent From iPhone On Sep 15, 2014, at 5:50, steph.rey steph@wanadoo.fr wrote: Hi the list, Just wanted to introduce myself for my 1st message. I'm Stephane, 40, living in France, at the moment working in RF electronics for a particles accelerator lab. I'm hamradio as well, and I do enjoy especially weak and accurate signals. I'm desiging various RF circuits. Current design is a universal PLL able to operate from 0.5 to 6 GHz depending on the VCO and supposed to be low-jitter (1ps) regarding the application. I'm also starting a new design of low noise PLL and there will be probably a lot of question arising... I'm starting with the 1 GHz LO made upon a 100 MHz VCXO + multipliers/filters/MMICs. I want to focus deeper on low phase noise/jitter, synchronization and low-noise PLL techniques. I believe this is a good place for most of these topics. Cheers Stephane ___ 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] newcomer
Hi, It sounds like all my messages need moderator approbation. Is it the rule on the list or a technical problem at my side ? Cheers Stephane On Mon, 15 Sep 2014 09:17:01 -0700, Said Jackson via time-nuts time-nuts@febo.com wrote: Hi Stephanie, Welcome to the list! We designed a 1GHz crystal LO for PLLs (the ULN-1G) using an off the shelf miniature 500MHz crystal oscillator which is run at 3 rd overtone internally then using a diode doubler and a steep bandpass filter using several Mini Circuits ceramic filters and a 20dBm amp. Works like a charm and has phase noise very close to theoretical.. Bye, Said Sent From iPhone On Sep 15, 2014, at 5:50, steph.rey steph@wanadoo.fr wrote: Hi the list, Just wanted to introduce myself for my 1st message. I'm Stephane, 40, living in France, at the moment working in RF electronics for a particles accelerator lab. I'm hamradio as well, and I do enjoy especially weak and accurate signals. I'm desiging various RF circuits. Current design is a universal PLL able to operate from 0.5 to 6 GHz depending on the VCO and supposed to be low-jitter (1ps) regarding the application. I'm also starting a new design of low noise PLL and there will be probably a lot of question arising... I'm starting with the 1 GHz LO made upon a 100 MHz VCXO + multipliers/filters/MMICs. I want to focus deeper on low phase noise/jitter, synchronization and low-noise PLL techniques. I believe this is a good place for most of these topics. Cheers Stephane ___ 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.
