Re: [time-nuts] Best phase detector / mixer for 100MHz?
Hi Would be nice to use something like the ADS1278. http://www.ti.com/product/ads1278 Lots of channels to cross correlate, and very little flicker noise. Bob On Nov 28, 2012, at 9:29 AM, Support HpW-Works.com supp...@hpw-works.com wrote: Hi Bruce, The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. The dBc/Hz normalization is based on this (also the sample rate). While the sample rate sample size = FFT Bin size (resolution or filter band width) is used to get the required correction factor of the spectrum to get the dBc / (1Hz) Y scaling back. So increasing the sample size isnt particularly useful for reducing the phase noise floor. By theory, yes... but we use a sound card with a lot of flicker noise on the lower end, also we have the 10...20Hz low freq. cutoff due the usage of a servo / single 5V power. Also the raising noise below 100Hz (ADC serve noise on the ADC power / input circuit) limits the performance. In my simple test increase of the sample size reduced the noise floor in better way than just using sample size with 1-2K and large averaging cycles. Keep in mind, Bin resolution is sample rate / sample size: Example: - 32khz / 32678 = about 1Hz - 32khz / 1024 = about 31 Hz However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Ideally the input circuit ADC of the 3562A would be nice but with much larger RAM buffer and ASIO interface O:) Hanspeter -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Dienstag, 27. November 2012 12:31 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? Support HpW-Works.com wrote: Bruce, There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. In the PSD (power density) PSP (power spectrum) there are cross power and cross power complex average implemented (selectable using the spectrum channel mixer)! Additional to this you may apply / add averaging of the resulting spectrum or use additional peak hold. Average of 10'000 cross points is a large count and often seen on 1-4k sample size. Better in my opinion is to use a higher sample size 32k-64k and then less averaging is required. The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. So increasing the sample size isnt particularly useful for reducing the phase noise floor. The increased frequency resolution achieved by increasing the sample size is only useful for measuring spurs. In the direct digital method of measuring phase noise a few terasamples (a few gigasamples at baseband) need to be processed to achieve a sufficiently low instrument noise floor. However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Just download the evaluation version with fully feature set. HpW 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. ___ 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] Best phase detector / mixer for 100MHz?
At 03:56 PM 11/29/2012 +, you wrote: By theory, yes... but we use a sound card with a lot of flicker noise on the lower end, also we have the 10...20Hz low freq. cutoff due the usage of a servo / single 5V power. Also the raising noise below 100Hz (ADC serve noise on the ADC power / input circuit) limits the performance. One way to avoid the problem in the 1/f noise region is to avoid it. Mix down to a few kHz and analyze you signal or if you must mix down to DC then chop it to bring it up to a kHz or so and analyze it using a program such as spectrum lab or in software to internally mix back down to DC using software digital mixer and then analyze. You can use a MOSFET analog switch to chop the signal. When you chop it you will have an carrier with upper and lower sidebands. You can simply take the FFT data and either shift the bins making the carrier (chopping frequency) the Zero or DC bin or even better yet add the upper and lower sidebands so that you get a 3db improvement in S/N. I will be db since the sidebands are identical mirror of each other, ie voltage doubles when they are added increasing the signal by 6db but noise introduced by electronics on upper and lower sidebands are not coherent and only increases by 3db. 73 Bill wa4lav ___ 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] Best phase detector / mixer for 100MHz?
Bill, One way to avoid the problem in the 1/f noise region is to avoid it. Mix down to a few kHz and analyze you signal This is a good point! Using my SW (www.hpw-works.com) simple set the x-scaling to a center frequency bandwidth of your choice with enough space in the lower region. This is implemented out of the box. It's like a measurement using the d-jitter but with a costume center frequency. See also the pictures on my homepage with zooming into the 0.005 Hz region using a large sample size. Required is that the source oscillators are stable... Hanspeter -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Fuqua Sent: Donnerstag, 29. November 2012 18:02 To: time-nuts@febo.com Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? At 03:56 PM 11/29/2012 +, you wrote: By theory, yes... but we use a sound card with a lot of flicker noise on the lower end, also we have the 10...20Hz low freq. cutoff due the usage of a servo / single 5V power. Also the raising noise below 100Hz (ADC serve noise on the ADC power / input circuit) limits the performance. One way to avoid the problem in the 1/f noise region is to avoid it. Mix down to a few kHz and analyze you signal or if you must mix down to DC then chop it to bring it up to a kHz or so and analyze it using a program such as spectrum lab or in software to internally mix back down to DC using software digital mixer and then analyze. You can use a MOSFET analog switch to chop the signal. When you chop it you will have an carrier with upper and lower sidebands. You can simply take the FFT data and either shift the bins making the carrier (chopping frequency) the Zero or DC bin or even better yet add the upper and lower sidebands so that you get a 3db improvement in S/N. I will be db since the sidebands are identical mirror of each other, ie voltage doubles when they are added increasing the signal by 6db but noise introduced by electronics on upper and lower sidebands are not coherent and only increases by 3db. 73 Bill wa4lav ___ 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] Best phase detector / mixer for 100MHz?
Hi Bruce, The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. The dBc/Hz normalization is based on this (also the sample rate). While the sample rate sample size = FFT Bin size (resolution or filter band width) is used to get the required correction factor of the spectrum to get the dBc / (1Hz) Y scaling back. So increasing the sample size isnt particularly useful for reducing the phase noise floor. By theory, yes... but we use a sound card with a lot of flicker noise on the lower end, also we have the 10...20Hz low freq. cutoff due the usage of a servo / single 5V power. Also the raising noise below 100Hz (ADC serve noise on the ADC power / input circuit) limits the performance. In my simple test increase of the sample size reduced the noise floor in better way than just using sample size with 1-2K and large averaging cycles. Keep in mind, Bin resolution is sample rate / sample size: Example: - 32khz / 32678 = about 1Hz - 32khz / 1024 = about 31 Hz However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Ideally the input circuit ADC of the 3562A would be nice but with much larger RAM buffer and ASIO interface O:) Hanspeter -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Dienstag, 27. November 2012 12:31 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? Support HpW-Works.com wrote: Bruce, There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. In the PSD (power density) PSP (power spectrum) there are cross power and cross power complex average implemented (selectable using the spectrum channel mixer)! Additional to this you may apply / add averaging of the resulting spectrum or use additional peak hold. Average of 10'000 cross points is a large count and often seen on 1-4k sample size. Better in my opinion is to use a higher sample size 32k-64k and then less averaging is required. The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. So increasing the sample size isnt particularly useful for reducing the phase noise floor. The increased frequency resolution achieved by increasing the sample size is only useful for measuring spurs. In the direct digital method of measuring phase noise a few terasamples (a few gigasamples at baseband) need to be processed to achieve a sufficiently low instrument noise floor. However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Just download the evaluation version with fully feature set. HpW 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. ___ 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] Best phase detector / mixer for 100MHz?
Support HpW-Works.com wrote: Hi Bruce, The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. The dBc/Hz normalization is based on this (also the sample rate). While the sample rate sample size = FFT Bin size (resolution or filter band width) is used to get the required correction factor of the spectrum to get the dBc / (1Hz) Y scaling back. So increasing the sample size isnt particularly useful for reducing the phase noise floor. By theory, yes... but we use a sound card with a lot of flicker noise on the lower end, also we have the 10...20Hz low freq. cutoff due the usage of a servo / single 5V power. Also the raising noise below 100Hz (ADC serve noise on the ADC power / input circuit) limits the performance. In my simple test increase of the sample size reduced the noise floor in better way than just using sample size with 1-2K and large averaging cycles. Keep in mind, Bin resolution is sample rate / sample size: Example: - 32khz / 32678 = about 1Hz - 32khz / 1024 = about 31 Hz Your sample sizes are far too small to be particularly useful in measuring phase noise down to offsets of 1-10Hz or so, Phase noise is highly coloured at such offsets necessitating the use of bin sizes substantially smaller than the lowest offset frequency of interest. However decreasing the bin size beyond a small fraction of the lowest frequency of interest is counter productive in that one forgoes the effect of averaging to reduce the variance of the noise signal power within each bin. There is a NIST paper on the effect of equivalent filter bandwidth on the accuracy of coloured noise measurements. Indeed one can break the frequency range into a set of bands, the higher frequency bands having larger bin sizes and greater averaging and hence (lower bin noise signal power variance) than the lower frequency bands. However for the purposes of spur identification using as small a bin size as possible can be useful. However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Ideally the input circuit ADC of the 3562A would be nice but with much larger RAM buffer and ASIO interface O:) Hanspeter Using a high end PC should allow real time signal processing with 200ksps or greater, this is certainly the case for some external USB instruments. 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] Best phase detector / mixer for 100MHz?
Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. 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] Best phase detector / mixer for 100MHz?
Bruce Griffiths schrieb: Richard (Rick) Karlquist wrote: On 11/23/2012 9:38 AM, Bruce Griffiths wrote: NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce Do you have a citation to where they said that? What you quoted doesn't make sense, at least, out of context. We need to clarify phase detector sensitivity specs. For conventional (IE 50 ohm) phase detectors, it is apples vs apples to just go by the volts per radian number. However, mixers like the ZRPD1 artificially triple the voltage sensitivity by operating at 500 ohms, and using transformers to connect to 50 ohm equipment. Doing this doesn't increase the possible signal to noise ratio. Consider this thought experiment. Build your best 500 ohm phase detector and postamp. Now replace with a 50 ohm phase detector and connect 3 postamps in parallel. It is a wash. Of course, you don't have to actually do this. You can simply use an op amp like the LT1028 with very low noise voltage. To actually put a 500 ohm detector on a par with a 50 ohm detector, the 500 ohm detector would need to use 3 diodes in series compared to one in the 50 ohm case. With only one diode per arm, the maximum drive power utilization is considerably lower. Rick Karlquist N6RK http://tf.boulder.nist.gov/general/pdf/2556.pdf Where all the high level mixers measured have a higher phase noise than lower level mixers/phase detectors like the ZRPD1. Bruce I can't confirm their results, at least not when plugged into a HP 11848A which loads the PD with 50 Ohms. Too bad they are unclear about the applied power. (1) Is it 'LO Power = maximum mixer power = 11 dBm', that is +11 dBm into both ports? (2) Is it +17 dBm due to 'mixers with a nominal LO rating of +7 dBm and maximum rating of +17 dBm'? Or, is it 50 mW as specified by Minicircuits, which would be the maximum mixer power as by (1)? With +16...+17 dBm signals I'm getting a noise floor of -175 dBc/Hz which is quite poor but understandable as in order to drive it at nominal input power, I have to put 6 dB attenuators between the oscillators and the phase detector. With only 3 dB attenuation, I'm getting -178 dBc/Hz. I wasn't sure if the 50 mW spec refers to the total RF power into the ZRPD-1 or if that is the max. power into each input, so I didn't try +17 dBm. I would have expected to see -180...-181 dBc/Hz. At that input level the 11848A internal PD gets me -179 dBc/Hz (no attenuators required). A WJ M9GC was 1 dB worse than the internal PD (also w/o attenuators). Surprisingly I've got the best results (-181) with a +23 dBm mixer (w/o attenuators of course). I did not have +23 dBm signals at hands, but I don't see that the ZRPD-1 can compete with the 11848A PD or an external +23 dBm mixer at input levels of +17 dBm and above. Adrian ___ 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] Best phase detector / mixer for 100MHz?
Bruce Griffiths schrieb: Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. Bruce Here is one that does cross spectrum and more: http://www.sigview.com/ A while ago I tried it with a Xonar Essence XT sound card and the results looked quite promising. Then I got a 3562A to get to 100 kHz (don't follow me there! These can be challenging to fix if not impossible. PAL's and other unobtainable 'field programmables' appear to die faster than anything else in that boxes. Finally, I needed three of them to get one working unit...) Adrian ___ 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] Best phase detector / mixer for 100MHz?
Adrian wrote: Bruce Griffiths schrieb: Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. Bruce Here is one that does cross spectrum and more: http://www.sigview.com/ A while ago I tried it with a Xonar Essence XT sound card and the results looked quite promising. Then I got a 3562A to get to 100 kHz (don't follow me there! These can be challenging to fix if not impossible. PAL's and other unobtainable 'field programmables' appear to die faster than anything else in that boxes. Finally, I needed three of them to get one working unit...) Adrian Tried that as well, how does one get a log y scale on the cross spectrum plot? 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] Best phase detector / mixer for 100MHz?
Bruce Griffiths schrieb: Adrian wrote: Bruce Griffiths schrieb: Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. Bruce Here is one that does cross spectrum and more: http://www.sigview.com/ A while ago I tried it with a Xonar Essence XT sound card and the results looked quite promising. Then I got a 3562A to get to 100 kHz (don't follow me there! These can be challenging to fix if not impossible. PAL's and other unobtainable 'field programmables' appear to die faster than anything else in that boxes. Finally, I needed three of them to get one working unit...) Adrian Tried that as well, how does one get a log y scale on the cross spectrum plot? Bruce With Sigview? I'm sorry my trial version has long expired and even after installing the latest version it's now requiring a license key... Adrian ___ 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] Best phase detector / mixer for 100MHz?
Bruce, There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. In the PSD (power density) PSP (power spectrum) there are cross power and cross power complex average implemented (selectable using the spectrum channel mixer)! Additional to this you may apply / add averaging of the resulting spectrum or use additional peak hold. Average of 10'000 cross points is a large count and often seen on 1-4k sample size. Better in my opinion is to use a higher sample size 32k-64k and then less averaging is required. Just download the evaluation version with fully feature set. HpW ___ 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] Best phase detector / mixer for 100MHz?
Adrian wrote: Bruce Griffiths schrieb: Adrian wrote: Bruce Griffiths schrieb: Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. Bruce Here is one that does cross spectrum and more: http://www.sigview.com/ A while ago I tried it with a Xonar Essence XT sound card and the results looked quite promising. Then I got a 3562A to get to 100 kHz (don't follow me there! These can be challenging to fix if not impossible. PAL's and other unobtainable 'field programmables' appear to die faster than anything else in that boxes. Finally, I needed three of them to get one working unit...) Adrian Tried that as well, how does one get a log y scale on the cross spectrum plot? Bruce With Sigview? I'm sorry my trial version has long expired and even after installing the latest version it's now requiring a license key... Adrian The help file states that the cross power spectrum is the product of the individual spectra - this is only correct if the individual spectra are real. 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] Best phase detector / mixer for 100MHz?
Support HpW-Works.com wrote: Bruce, There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. In the PSD (power density) PSP (power spectrum) there are cross power and cross power complex average implemented (selectable using the spectrum channel mixer)! Additional to this you may apply / add averaging of the resulting spectrum or use additional peak hold. Average of 10'000 cross points is a large count and often seen on 1-4k sample size. Better in my opinion is to use a higher sample size 32k-64k and then less averaging is required. The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. So increasing the sample size isnt particularly useful for reducing the phase noise floor. The increased frequency resolution achieved by increasing the sample size is only useful for measuring spurs. In the direct digital method of measuring phase noise a few terasamples (a few gigasamples at baseband) need to be processed to achieve a sufficiently low instrument noise floor. However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Just download the evaluation version with fully feature set. HpW 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] Best phase detector / mixer for 100MHz?
Bruce Griffiths schrieb: Support HpW-Works.com wrote: Bruce, There's no evidence of a cross power spectrum function in this suite. One needs to be able to average at least 10,000 cross power spectra for some applications. In the PSD (power density) PSP (power spectrum) there are cross power and cross power complex average implemented (selectable using the spectrum channel mixer)! Additional to this you may apply / add averaging of the resulting spectrum or use additional peak hold. Average of 10'000 cross points is a large count and often seen on 1-4k sample size. Better in my opinion is to use a higher sample size 32k-64k and then less averaging is required. The equivalent phase noise (measured in dBc/Hz) is essentially independent of the sample size. So increasing the sample size isnt particularly useful for reducing the phase noise floor. The increased frequency resolution achieved by increasing the sample size is only useful for measuring spurs. In the direct digital method of measuring phase noise a few terasamples (a few gigasamples at baseband) need to be processed to achieve a sufficiently low instrument noise floor. However with a sound card plus a mixer a somewhat lower number of samples should suffice since there is no carrier. Just download the evaluation version with fully feature set. HpW Bruce A HP/Agilent VEE based solution would be much more flexible. There is a sound card driver available. I just didn't get deep enough into digital signal processing before the 3562A came... Adrian ___ 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] Best phase detector / mixer for 100MHz?
Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2NA mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to -180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? /Anders On Fri, Nov 23, 2012 at 4:42 PM, Anders Time anderst...@gmail.com wrote: I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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] Best phase detector / mixer for 100MHz?
thanks Bob Doug From: Anders Time anderst...@gmail.com To: time-nuts@febo.com Sent: Monday, 26 November 2012, 9:45 Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2NA mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to -180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? /Anders On Fri, Nov 23, 2012 at 4:42 PM, Anders Time anderst...@gmail.com wrote: I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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] Best phase detector / mixer for 100MHz?
I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. I got this guy to add cross correlation to his FFT software suite: http://www.hpw-works.com/ however I have not built hardware to try it. He has a 30 day trial and its not expensive for what it is, $300. I would use it with an ESI Juli@ card http://www.esi-audio.com/products/julia/ ($150 or less on eBay or elsewhere) since you can be pretty sure it won't do something to mess with the measurement and it runs at 192 KHz sample rate quite well. Around $450 for a cross correlation analyzer. Or you can go shopping for an old FFT with the capability and potential service nightmare. Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2NA mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to -180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? /Anders ** ___ 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] Best phase detector / mixer for 100MHz?
Anders, On 11/26/2012 10:45 AM, Anders Time wrote: Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2NA mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to-180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? If you can handle the frequency limitation of the audio-card, you can do that. Cross-correlation using FFT isn't that hard to achieve, and good FFT libraries exist. FFTW for instance and a handfull lines of code do it all. 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] Best phase detector / mixer for 100MHz?
Hi or you could see if somebody with it already in their free time related program would add a sound card or set of cards to the mix of devices they support. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Monday, November 26, 2012 2:52 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? Anders, On 11/26/2012 10:45 AM, Anders Time wrote: Thanks a lot guys for all the input! The nist articles was a very interesting read. I have ordered the minicircuits ZRPD-1 and will try to build the 2NA mixer to to see how far that will take it. I probably also will build a low noise jfet preamp to see if that will reduce the noise. But I probably have to go to build myself a crosscorrelation system to be able to-180dBc with confidence. Is there any cheap way into cross correlation measurement, using high quality soundcard for example? Or do I have to buy one of these big old expensive dual FFT analyzers? If you can handle the frequency limitation of the audio-card, you can do that. Cross-correlation using FFT isn't that hard to achieve, and good FFT libraries exist. FFTW for instance and a handfull lines of code do it all. 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] Best phase detector / mixer for 100MHz?
On 11/26/12 10:11 AM, Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. Isn't Marki making the old WJ mixers? That seems to be what someone told me a few years ago: they basically have all the tooling and designs, etc. ___ 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] Best phase detector / mixer for 100MHz?
Jim Lux wrote: On 11/26/12 10:11 AM, Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. Isn't Marki making the old WJ mixers? That seems to be what someone told me a few years ago: they basically have all the tooling and designs, etc. That's interesting, because MaCom Technology Solutions seems to be making WJ models as well. A few years back, there was another company (I think the name started with an S) that seemed to have inherited the WJ line. The company currently called WJ has nothing to do with these mixers at all. Rick ___ 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] Best phase detector / mixer for 100MHz?
Jim Lux wrote: On 11/26/12 10:11 AM, Demian Martin wrote: I asked Wenzel about mixers for phase noise measurement and they directed me to Marki Microwave as what they use: http://www.markimicrowave.com/2770/Mixers.aspx I have not obtained or tested any myself but it's a pretty solid recommendation I think. Isn't Marki making the old WJ mixers? That seems to be what someone told me a few years ago: they basically have all the tooling and designs, etc. That's interesting, because MaCom Technology Solutions seems to be making WJ models as well. A few years back, there was another company (I think the name started with an S) that seemed to have inherited the WJ line. The company currently called WJ has nothing to do with these mixers at all. Rick Did you see this information from Mini Circuits on WJ mixer replacements? http://217.34.103.131/pdfs/Surface-Mount%20Mixers%20Are%20WJ%20Replacements.pdf -- Björn ___ 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] Best phase detector / mixer for 100MHz?
Richard (Rick) Karlquist wrote: On 11/23/2012 9:38 AM, Bruce Griffiths wrote: NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce Do you have a citation to where they said that? What you quoted doesn't make sense, at least, out of context. We need to clarify phase detector sensitivity specs. For conventional (IE 50 ohm) phase detectors, it is apples vs apples to just go by the volts per radian number. However, mixers like the ZRPD1 artificially triple the voltage sensitivity by operating at 500 ohms, and using transformers to connect to 50 ohm equipment. Doing this doesn't increase the possible signal to noise ratio. Consider this thought experiment. Build your best 500 ohm phase detector and postamp. Now replace with a 50 ohm phase detector and connect 3 postamps in parallel. It is a wash. Of course, you don't have to actually do this. You can simply use an op amp like the LT1028 with very low noise voltage. To actually put a 500 ohm detector on a par with a 50 ohm detector, the 500 ohm detector would need to use 3 diodes in series compared to one in the 50 ohm case. With only one diode per arm, the maximum drive power utilization is considerably lower. Rick Karlquist N6RK http://tf.boulder.nist.gov/general/pdf/2556.pdf Where all the high level mixers measured have a higher phase noise than lower level mixers/phase detectors like the ZRPD1. 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] Best phase detector / mixer for 100MHz?
Bruce Griffiths wrote: Richard (Rick) Karlquist wrote: On 11/23/2012 9:38 AM, Bruce Griffiths wrote: NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce http://tf.boulder.nist.gov/general/pdf/2556.pdf Where all the high level mixers measured have a higher phase noise than lower level mixers/phase detectors like the ZRPD1. Bruce This data is surprising. I am wondering if it is being corrupted by AM noise on the source? They do not mention what the source is. They could be measuring AM noise suppression differences in the phase detectors. Rick ___ 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] Best phase detector / mixer for 100MHz?
Rick Karlquist wrote: Bruce Griffiths wrote: Richard (Rick) Karlquist wrote: On 11/23/2012 9:38 AM, Bruce Griffiths wrote: NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce http://tf.boulder.nist.gov/general/pdf/2556.pdf Where all the high level mixers measured have a higher phase noise than lower level mixers/phase detectors like the ZRPD1. Bruce This data is surprising. I am wondering if it is being corrupted by AM noise on the source? They do not mention what the source is. They could be measuring AM noise suppression differences in the phase detectors. Rick Another potential issue is the relatively high input current noise of the IF amplifiers (see the paper's Reference 9). In the cross correlation setup used the IF amps both see the noise produced by the sum of the IF amp input noise current flowing in the mixer output impedance. This noise common to both IF amps isn't rejected by cross correlation. It can be more effective to use IF amps with very low input noise current that may have a higher input voltage noise. The effect of the amplifier input voltage noise is reduced by cross correlation. For offset frequencies =10Hz a well designed low noise amplifier with a discrete JFET input stage can have comparable voltage noise to the IF amp used with much lower input current noise. 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] Best phase detector / mixer for 100MHz?
The old Watkins Johnson M9 series was the state of the art for stacked diode mixers. You can still get the M9E and M9H from MaCom Technology Solutions. The M9E is better, but only if you have the 1/2 watt! of LO drive needed. As you have done already, it is probably possible to homebrew something like these. There were a series of papers written by WJ people 20 years ago or so in Microwave Journal or maybe it was Microwaves and RF that explained all about these things. These should be required reading if you are going to homebrew. Try to match the diodes so you get low DC offset. Some mixers also use resistors and capacitors to assist the diodes; again read the WJ papers. The horsepower race in phase detectors was somewhat rendered unnecessary by the cross correlation techniques developed 10 or 15 years ago. You can extend the effective noise floor by dozens of dB this way. Rick Karlquist N6RK On 11/23/2012 7:42 AM, Anders Time wrote: I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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] Best phase detector / mixer for 100MHz?
Hi Anders, isn't this format exactly what is inside the high level mixers (spec'e +17dBm) from Minicircuits? Alan G3NYK - Original Message - From: Anders Time anderst...@gmail.com To: time-nuts@febo.com Sent: Friday, November 23, 2012 3:42 PM Subject: [time-nuts] Best phase detector / mixer for 100MHz? I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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] Best phase detector / mixer for 100MHz?
NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce Alan Melia wrote: Hi Anders, isn't this format exactly what is inside the high level mixers (spec'e +17dBm) from Minicircuits? Alan G3NYK - Original Message - From: Anders Time anderst...@gmail.com To: time-nuts@febo.com Sent: Friday, November 23, 2012 3:42 PM Subject: [time-nuts] Best phase detector / mixer for 100MHz? I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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] Best phase detector / mixer for 100MHz?
On 11/23/2012 9:38 AM, Bruce Griffiths wrote: NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce Do you have a citation to where they said that? What you quoted doesn't make sense, at least, out of context. We need to clarify phase detector sensitivity specs. For conventional (IE 50 ohm) phase detectors, it is apples vs apples to just go by the volts per radian number. However, mixers like the ZRPD1 artificially triple the voltage sensitivity by operating at 500 ohms, and using transformers to connect to 50 ohm equipment. Doing this doesn't increase the possible signal to noise ratio. Consider this thought experiment. Build your best 500 ohm phase detector and postamp. Now replace with a 50 ohm phase detector and connect 3 postamps in parallel. It is a wash. Of course, you don't have to actually do this. You can simply use an op amp like the LT1028 with very low noise voltage. To actually put a 500 ohm detector on a par with a 50 ohm detector, the 500 ohm detector would need to use 3 diodes in series compared to one in the 50 ohm case. With only one diode per arm, the maximum drive power utilization is considerably lower. Rick Karlquist N6RK ___ 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] Best phase detector / mixer for 100MHz?
Not unreasonable Bruce..no free lunches etc. :-)) Alan G3NYK - Original Message - From: Bruce Griffiths bruce.griffi...@xtra.co.nz To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, November 23, 2012 5:38 PM Subject: Re: [time-nuts] Best phase detector / mixer for 100MHz? NIST have shown (at least at 10MHz) that the high level mixers they tested are noisier than the ZRPD1. Bruce Alan Melia wrote: Hi Anders, isn't this format exactly what is inside the high level mixers (spec'e +17dBm) from Minicircuits? Alan G3NYK - Original Message - From: Anders Time anderst...@gmail.com To: time-nuts@febo.com Sent: Friday, November 23, 2012 3:42 PM Subject: [time-nuts] Best phase detector / mixer for 100MHz? I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders ___ 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 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] Best phase detector / mixer for 100MHz?
Hi Anders, On 11/23/2012 04:42 PM, Anders Time wrote: I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders Craig Nelson and friends over at NIST had a little different stab at mixer which might interest you: http://tf.boulder.nist.gov/general/pdf/2554.pdf This was intended for 5 MHz, but I am sure you would enjoy reading about it never the less. 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] Best phase detector / mixer for 100MHz?
Magnus Danielson wrote: Hi Anders, On 11/23/2012 04:42 PM, Anders Time wrote: I have been using an minicircuits mixer as a phase detector for measuring low frequency(5-10MHz) and it is usually good enough. But when I want to measure 100MHz the sensitivity of the mixer decreases a lot, so when I want to measure some really low noise 100MHz(Pascall -178dBc floor with 18dBm out) oscillators the sensitivity is not good enough. I read in an old article by Walls, Stein et al(Design considerations in state-of-the-art signal processing and phase noise measurement system) that one can use two diodes in series in the double balanced mixer to increase the sensitivity. I tried this with some standard 1n5711 Schottky and the sensitivity is now 1V/rad, but is there a easier way to do this? /Anders Craig Nelson and friends over at NIST had a little different stab at mixer which might interest you: http://tf.boulder.nist.gov/general/pdf/2554.pdf This was intended for 5 MHz, but I am sure you would enjoy reading about it never the less. Cheers, Magnus They've subsequently used it at 10MHz, 20MHz and 40MHz in regenerative dividers. 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.
