Re: [time-nuts] Help with my ADEV measurement setup
Oddly enough I do have a PPS output from the TCXO I was measuring. It's on a little board I made and there is a PicDiv right on it. I'll have to play around with that. I did notice the aliasing issue trying to measure a 12MHz crystal. It appeared to have incredible stability and accuracy for a plain old XO... Also it has a frequency offset of over 1kHz, and I noticed that I had to manually type in the correct initial frequency during setup to have meaningful data in the frequency difference view. i.e, 12001053 instead of 12E6. But of course with a marginally stably oscillator, that poses a problem. How long do I wait to find a mean frequency to type in...? It makes total sense why this is so in TI mode, but still it's one more thing to deal with. I think I'll stick with frequency mode for most things. Many of the oscillators I want to measure are right around 10^-8 or 10^-9, and I'd hate to constantly be fighting the noise floor of the instrument. I'll treat the data from frequency mode as relative and that should get me what I need. At least until I own a better instrument. Thanks Dan On Tue, Jun 30, 2015 at 10:49 PM, John Miles j...@miles.io wrote: Yep, it will ignore any non-numeric data like us suffixes. It will always interpret incoming data as seconds, so the 1E-6 scale factor is appropriate if the counter is returning microseconds. I'll tweak the mouseover help text for the scale factor field to clarify that. I think you're basically getting valid data. The 53131A's one-shot resolution is 0.5 ns, and you're seeing about 2E-9 residual ADEV at t=1s. It's in the right ballpark, anyway... e.g., on a 20-ps HP 5370, the residual ADEV at t=1s will usually be in the neighborhood of 30-60 ps. I would, however, be worried about aliasing with a TCXO. If its frequency is more than 5E-8 off -- meaning it drifts more than 50 nanoseconds per second with 10 MHz at the STOP jack -- its error will end up underrepresented in the measurement. In this case your oscillator is drifting quite a bit (as expected) -- look at the 'w' view of the original phase compared to the unwrapped 'p' phase. You could try putting 1pps on both the START and STOP jacks but that'll require more futzing with scale factors, 1pps dividers and the like, and may leave you more vulnerable to trigger uncertainty from various causes. For measurement of a TCXO, I'd stick with frequency mode. The ADEV plots won't be 100% kosher but they'll be fine for relative comparisons with other plots from the same measurement setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 5:05 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Help with my ADEV measurement setup I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W
Re: [time-nuts] Help with my ADEV measurement setup
I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W adevtest.png___ 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] Help with my ADEV measurement setup
Hi Your OCXO and the TBolt *should* be down around 1x10^-11 to 1x10^-12 at one second. That’s a factor of 10 to 100X better than the 53131 can do at a random frequency. At exactly 10 MHz it may be even worse than that. Effectively what you will be doing is measuring the noise floor of the counter out to a few hundred seconds. To get useful data, plan on runs of at least several hours, if not a few days. Bob On Jun 30, 2015, at 8:05 PM, Dan Watson watsondani...@gmail.com wrote: I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W adevtest.png___ 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. adevplot_PPS.png___ 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] Help with my ADEV measurement setup
Let's see a snapshot of your acquisition dialog, just before you hit 'Start'. (Or send me a .tim file directly.) It can be tricky to configure the test setup for a TI measurement, since so many more things can go wrong compared to a frequency-based setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 11:48 AM To: time-nuts@febo.com Subject: [time-nuts] Help with my ADEV measurement setup Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup... ___ 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] Help with my ADEV measurement setup
Attached is a screenshot of the setup window. I manually typed in 1E-6 as the units. I also hit Monitor and let it average the reporting interval for a while until it settled at 1.00 seconds. Originally I was leaving the time unit as 1, and microseconds in in the serial string was not being detected to set the units automatically. I'd be happy to send you a tim file as well if necessary. Let me know. Thanks Dan On Tue, Jun 30, 2015 at 8:51 PM, John Miles j...@miles.io wrote: Let's see a snapshot of your acquisition dialog, just before you hit 'Start'. (Or send me a .tim file directly.) It can be tricky to configure the test setup for a TI measurement, since so many more things can go wrong compared to a frequency-based setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 11:48 AM To: time-nuts@febo.com Subject: [time-nuts] Help with my ADEV measurement setup Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup... ___ 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] Help with my ADEV measurement setup
Yep, it will ignore any non-numeric data like us suffixes. It will always interpret incoming data as seconds, so the 1E-6 scale factor is appropriate if the counter is returning microseconds. I'll tweak the mouseover help text for the scale factor field to clarify that. I think you're basically getting valid data. The 53131A's one-shot resolution is 0.5 ns, and you're seeing about 2E-9 residual ADEV at t=1s. It's in the right ballpark, anyway... e.g., on a 20-ps HP 5370, the residual ADEV at t=1s will usually be in the neighborhood of 30-60 ps. I would, however, be worried about aliasing with a TCXO. If its frequency is more than 5E-8 off -- meaning it drifts more than 50 nanoseconds per second with 10 MHz at the STOP jack -- its error will end up underrepresented in the measurement. In this case your oscillator is drifting quite a bit (as expected) -- look at the 'w' view of the original phase compared to the unwrapped 'p' phase. You could try putting 1pps on both the START and STOP jacks but that'll require more futzing with scale factors, 1pps dividers and the like, and may leave you more vulnerable to trigger uncertainty from various causes. For measurement of a TCXO, I'd stick with frequency mode. The ADEV plots won't be 100% kosher but they'll be fine for relative comparisons with other plots from the same measurement setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 5:05 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Help with my ADEV measurement setup I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W adevtest.png___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Help with my ADEV measurement setup
Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W ___ 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] Help with my ADEV measurement setup
Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W adevtest.png___ 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.
