Hi all, I've been reading the ML for quite a long time. In the last weeks I managed to have some spare time to try some measurements, just to see how far is "reading" from "trying". My lab is made up of a pair of GPSDO (UCCM modules with an external antenna and good sky coverage), a 53131A and a pair of quartz oscillators that were ripped from some scrap instruments. Before trying to measure ADEV on a OCXO, I just wanted to see how deep is the noise floor with my setup. I read in old post (2012) that I could perform some tests using a the PPS output from the GPSDO, a power splitter and two coaxial cables of different lenght. So i put the counter in "t1 to T2" mode, auto-trigger on channel OFF and performed a very long ADEV analisys in TI mode. Results I found were, in some ways, encouraging (to me): 1s Sigma(tau) 6.59E-10 10s 6.96E-11 100s 7.12E-12 1000s 7.01E-13 Tomorrow I'm going to perform more tests in fequency mode, by looping the 10MHz out of the counter, to its channel 1 input and performing ADEV analisys to. According to what I read, results should be quite different. My question is: am I going on the right way? Are the tests I performed somewhat meaningful? Thanks in advance. Best regards. adelmo References: Best counter setting for ADEV? - Time-nuts ML Oct 1 2012 Recommended parameters for Timelab ADEV analysis - Time-nuts ML Nov 15 2012 Measuring ADEV for a beginner - Time-nuts ML Nov 1 2014

Hi One suggestion: While you have the counter sitting there, play with the trigger settings and input levels. You may find a way to improve things a little bit. No need to go to the 1000 second level. A 100 second run looking at 1 and 10 second data will tell you what you need to know. Bob > On May 14, 2023, at 1:21 PM, ordnit via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi all, > I've been reading the ML for quite a long time. In the last weeks I managed to have some spare time to try some measurements, just to see how far is "reading" from "trying". > > My lab is made up of a pair of GPSDO (UCCM modules with an external antenna and good sky coverage), a 53131A and a pair of quartz oscillators that were ripped from some scrap instruments. > > Before trying to measure ADEV on a OCXO, I just wanted to see how deep is the noise floor with my setup. I read in old post (2012) that I could perform some tests using a the PPS output from the GPSDO, a power splitter and two coaxial cables of different lenght. So i put the counter in "t1 to T2" mode, auto-trigger on channel OFF and performed a very long ADEV analisys in TI mode. > > Results I found were, in some ways, encouraging (to me): > 1s Sigma(tau) 6.59E-10 > 10s 6.96E-11 > 100s 7.12E-12 > 1000s 7.01E-13 > > Tomorrow I'm going to perform more tests in fequency mode, by looping the 10MHz out of the counter, to its channel 1 input and performing ADEV analisys to. According to what I read, results should be quite different. > > My question is: am I going on the right way? Are the tests I performed somewhat meaningful? > > Thanks in advance. > > Best regards. > > adelmo > > References: > Best counter setting for ADEV? - Time-nuts ML Oct 1 2012 > Recommended parameters for Timelab ADEV analysis - Time-nuts ML Nov 15 2012 > Measuring ADEV for a beginner - Time-nuts ML Nov 1 2014 > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Bob, thank you for the clever suggestion. I jumped the "have a look with a good oscilloscope at what is going on ". So, the point is: using the splitter, the voltage on the 50ohm line drops to 0.6V (peak). Triggering at 1V was a mist ake. I managed run 5 times Timelab for 1000s with different trigger levels, from 0.1V to 0.5V. 1second ADEV with increasing trigger level: 0.1V 6.88E-10 0.2V 7.05E-10 0.3V 7.00E-10 0.4V 7.14E-10 0.5V 7.28E-10 10seconds ADEV with increasing trigger level: 0.1V 7.05E-11 0.2V 7.07E-11 0.3V 7.03E-11 0.4V 6.89E-11 0.5V 7.40E-11 Performances are best with high trigger level. Let me attach a nice picture. Thank you for valuable help. I love to learn from my mistakes. adelmo iz6cus Il 14/05/2023 23:04, Bob Camp ha scritto: > Hi > > One suggestion: > > While you have the counter sitting there, play with the trigger settings and input levels. > You may find a way to improve things a little bit. No need to go to the 1000 second level. > A 100 second run looking at 1 and 10 second data will tell you what you need to know. > > Bob > >> On May 14, 2023, at 1:21 PM, ordnit via time-nuts <time-nuts@lists.febo.com> wrote: >> >> Hi all, >> I've been reading the ML for quite a long time. In the last weeks I managed to have some spare time to try some measurements, just to see how far is "reading" from "trying". >> >> My lab is made up of a pair of GPSDO (UCCM modules with an external antenna and good sky coverage), a 53131A and a pair of quartz oscillators that were ripped from some scrap instruments. >> >> Before trying to measure ADEV on a OCXO, I just wanted to see how deep is the noise floor with my setup. I read in old post (2012) that I could perform some tests using a the PPS output from the GPSDO, a power splitter and two coaxial cables of different lenght. So i put the counter in "t1 to T2" mode, auto-trigger on channel OFF and performed a very long ADEV analisys in TI mode. >> >> Results I found were, in some ways, encouraging (to me): >> 1s Sigma(tau) 6.59E-10 >> 10s 6.96E-11 >> 100s 7.12E-12 >> 1000s 7.01E-13 >> >> Tomorrow I'm going to perform more tests in fequency mode, by looping the 10MHz out of the counter, to its channel 1 input and performing ADEV analisys to. According to what I read, results should be quite different. >> >> My question is: am I going on the right way? Are the tests I performed somewhat meaningful? >> >> Thanks in advance. >> >> Best regards. >> >> adelmo >> >> References: >> Best counter setting for ADEV? - Time-nuts ML Oct 1 2012 >> Recommended parameters for Timelab ADEV analysis - Time-nuts ML Nov 15 2012 >> Measuring ADEV for a beginner - Time-nuts ML Nov 1 2014 >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com >