Re: [time-nuts] Determining Allan Deviation From Interpolated Peak Frequency Readings
On Sat, Dec 16, 2017 at 7:36 AM, Gerhard Hoffmannwrote: I'm about to buy a RedPitaya Stemlab 125-14. Cost is just €310 in .de, > seems to have respectable performance, can emulate the > GnuRadio hardware boards more or less right out of the box, > Win & Linux. > > And it is a nice stepping stone to what I really want: a bigger ZYNC > with JESD204B support, AD9680/ADC32RF45 ADCs & AD9142 or > similar DACs for direct L-band digitizing. No more > phase-shifting preselector or IF filters. > There seem to appear better ADC/DAC chips every month for Gen5. > > That could be a Timepod++ :-) > > You know you guys are going to wind up costing me more money! The RedPitya looks like an amazing product for the price, dual ADCs and DACs and a Zync for that price! And, they are available at Digikey in the US for pretty good prices. Again, a project for the future possibly. Thanks, Mark W7MLG ___ 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] Determining Allan Deviation From Interpolated Peak Frequency Readings
On Sat, Dec 16, 2017 at 3:57 AM, Attila Kinaliwrote: > > > Apparently the Perseus is supported by GnuRadio[1]. Which means you can > just click your control system together (similar to LabView). According > to [2] the driver uses libusb and works on windows as well. > > If you want to use GnuRadio, I suggest you go to one of the many > Hackfests[3] > they have and let them jump-start you (I started this way years ago). > There are issues with the Perseus, Windows 10 and USB3. It is hit and miss with various software. I am not sure it would actually work with GnuRadio on the computer I use in my Ham Radio / Electronics lab. I do have three computers running Linux but they are elsewhere. Simon Brown has posted some positive messages about the cause of this being found on the Perseus Forum. Hopefully it can be fixed. The creator of the Perseus has had to move on to other things and can only provide limited help. It would be a big project fro me though. I have lots of projects, but will consider it. I do have a friend that is much more of an expert with GnuRadio. Thanks, Mark W7MLG ___ 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] Determining Allan Deviation From Interpolated Peak Frequency Readings
Am 16.12.2017 um 11:57 schrieb Attila Kinali: [1] "Oscillator metrology with software defined radio", by Sherman and Jördens, 2016 https://arxiv.org/abs/1605.03505 I have seen this paper before. Unfortunately, it is a lot more work to implement than what I have already done. I am really a hardware engineer, with decades old education in control systems that has not been used in a long time. It would take getting my brain back in gear and re-studying, not a bad thing actually! The other issue is the Perseus drivers have issues under Windows 10 that may or may not be solved. I was able to get it to work with Spectrum Lab, but it does not work with many other tools that would be able to implement this algorithm. That said, I may look into it further in the future. Apparently the Perseus is supported by GnuRadio[1]. Which means you can just click your control system together (similar to LabView). According to [2] the driver uses libusb and works on windows as well. If you want to use GnuRadio, I suggest you go to one of the many Hackfests[3] they have and let them jump-start you (I started this way years ago). I'm about to buy a RedPitaya Stemlab 125-14. Cost is just €310 in .de, seems to have respectable performance, can emulate the GnuRadio hardware boards more or less right out of the box, Win & Linux. And it is a nice stepping stone to what I really want: a bigger ZYNC with JESD204B support, AD9680/ADC32RF45 ADCs & AD9142 or similar DACs for direct L-band digitizing. No more phase-shifting preselector or IF filters. There seem to appear better ADC/DAC chips every month for Gen5. That could be a Timepod++ :-) regards, Gerhard < https://www.redpitaya.com/c96/stemsuplabsup-125-14 > < http://pavel-demin.github.io/red-pitaya-notes/sdr-transceiver-hpsdr/ > ___ 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] Determining Allan Deviation From Interpolated Peak Frequency Readings
On Fri, 15 Dec 2017 10:08:29 -0700 Mark Goldbergwrote: > > The approach using FFT works, but just using the peak frequency, you throw > > away half of the data (the phase) and also limit yourself in precision > > to the bin width. It's not 100% clear that estimating the frequency > > using an FFT is unbiased in this case, thus you might get worse (or better) > > results than what the oscillator actually does. > > > > Since I do not know the exact algorithm used to interpolate peak frequency, > I don't know the effect on precision. They do claim that the peak frequency > determination precision is much smaller than the bin width, which seems to > be shown by the data. > > The results are good enough to discern between "bad" and "good" units under > test, but I have no way to compare my results to any other method of > measurement. This is all I have access to. If all you want is to discern good and bad units, this is good enough. > > [1] "Oscillator metrology with software defined radio", > > by Sherman and Jördens, 2016 > > https://arxiv.org/abs/1605.03505 > > > > I have seen this paper before. Unfortunately, it is a lot more work to > implement than what I have already done. I am really a hardware engineer, > with decades old education in control systems that has not been used in a > long time. It would take getting my brain back in gear and re-studying, not > a bad thing actually! > > The other issue is the Perseus drivers have issues under Windows 10 that > may or may not be solved. I was able to get it to work with Spectrum Lab, > but it does not work with many other tools that would be able to implement > this algorithm. > > That said, I may look into it further in the future. Apparently the Perseus is supported by GnuRadio[1]. Which means you can just click your control system together (similar to LabView). According to [2] the driver uses libusb and works on windows as well. If you want to use GnuRadio, I suggest you go to one of the many Hackfests[3] they have and let them jump-start you (I started this way years ago). Attila Kinali [1] https://gnuradio.org/ [2] https://github.com/Microtelecom/libperseus-sdr [3] https://www.gnuradio.org/event-type/hackfest/ -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] Determining Allan Deviation From Interpolated Peak Frequency Readings
Thanks for the detailed response. On Fri, Dec 15, 2017 at 5:42 AM, Attila Kinaliwrote: > Hey Mark > > On Wed, 6 Dec 2017 15:43:49 -0700 > Mark Goldberg wrote: > > > https://sites.google.com/site/perseusmods/ > > and > > https://sites.google.com/site/spectrumlabtesting/ > > > > using wide FFT bins and Spectrum Lab's peak frequency interpolation > > function. I would appreciate comments as to the effectiveness of this > > approach. I have a thick skin, so any criticism is welcome if it improves > > the process. > > The approach using FFT works, but just using the peak frequency, you throw > away half of the data (the phase) and also limit yourself in precision > to the bin width. It's not 100% clear that estimating the frequency > using an FFT is unbiased in this case, thus you might get worse (or better) > results than what the oscillator actually does. > Since I do not know the exact algorithm used to interpolate peak frequency, I don't know the effect on precision. They do claim that the peak frequency determination precision is much smaller than the bin width, which seems to be shown by the data. The results are good enough to discern between "bad" and "good" units under test, but I have no way to compare my results to any other method of measurement. This is all I have access to. > > What you are trying to do is spectral estimation from a limited number of > samples. You want to have some kind of continuity, that might allow you to > track minute changes from block you are processing to the next block. > The easiest way to do this would be to downconvert the signal on the PC > to zero Hz and take the phase information (simplest way: use a NCO as a > reference, then pass the reference and signal into a CORDIC to get the > phase > difference). Recording this phase difference should give you a lower floor > for *DEV than your FFT method. It will also alow you to track small phase > changes (aka small frequency fluctuations) that happen over long periods. > Sherman and Jördens[1] describe the approach in more detail. > > Other than that, the general approach looks ok. > > > Attila Kinali > > > [1] "Oscillator metrology with software defined radio", > by Sherman and Jördens, 2016 > https://arxiv.org/abs/1605.03505 > I have seen this paper before. Unfortunately, it is a lot more work to implement than what I have already done. I am really a hardware engineer, with decades old education in control systems that has not been used in a long time. It would take getting my brain back in gear and re-studying, not a bad thing actually! The other issue is the Perseus drivers have issues under Windows 10 that may or may not be solved. I was able to get it to work with Spectrum Lab, but it does not work with many other tools that would be able to implement this algorithm. That said, I may look into it further in the future. Mark ___ 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] Determining Allan Deviation From Interpolated Peak Frequency Readings
Hey Mark On Wed, 6 Dec 2017 15:43:49 -0700 Mark Goldbergwrote: > https://sites.google.com/site/perseusmods/ > and > https://sites.google.com/site/spectrumlabtesting/ > > using wide FFT bins and Spectrum Lab's peak frequency interpolation > function. I would appreciate comments as to the effectiveness of this > approach. I have a thick skin, so any criticism is welcome if it improves > the process. The approach using FFT works, but just using the peak frequency, you throw away half of the data (the phase) and also limit yourself in precision to the bin width. It's not 100% clear that estimating the frequency using an FFT is unbiased in this case, thus you might get worse (or better) results than what the oscillator actually does. What you are trying to do is spectral estimation from a limited number of samples. You want to have some kind of continuity, that might allow you to track minute changes from block you are processing to the next block. The easiest way to do this would be to downconvert the signal on the PC to zero Hz and take the phase information (simplest way: use a NCO as a reference, then pass the reference and signal into a CORDIC to get the phase difference). Recording this phase difference should give you a lower floor for *DEV than your FFT method. It will also alow you to track small phase changes (aka small frequency fluctuations) that happen over long periods. Sherman and Jördens[1] describe the approach in more detail. Other than that, the general approach looks ok. Attila Kinali [1] "Oscillator metrology with software defined radio", by Sherman and Jördens, 2016 https://arxiv.org/abs/1605.03505 -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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.