Re: [time-nuts] DMTD - analog multiplier vs. diode mixer ?
On 1/5/2016 12:07 PM, Bruce Griffiths wrote: The noise of such Gilbert cell based analog multipliers far exceeds that of the traditional mixer. Bruce Read Gilbert's paper or Gray and Meyers analog IC textbook and you will see that the whole theory of operation of these depends on keeping the signal levels in them very small, especially if linearity (actually translinearity) is important. They always have current sources in the emitters that contribute a lot of noise. So you have small signals and large noise. The IC's that are designed to be DC coupled have even more sources of extra noise. IMHO, they only make sense in low performance applications where the lack of transformers is important or in DC coupled applications. The only time I have used an analog multiplier IC was in Costas loop to demodulate QPSK from weather satellite. It needed to be DC coupled. Rick Karlquist N6RK On Wednesday, 6 January 2016 9:01 AM, Poul-Henning Kamp wrote: My little HP5065 project is continually running into the jitter of my HP5370B counter which is annoying me, so I'm looking int DMTD. Everybody seems to be using traditional diode-mixers for DMTD, and to be honest I fail to see the attraction. Why wouldn't a analog multiplier like AD835 be better idea ? What am I overlooking ? ___ 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] Loran Europe Lessay seems to be back on air?
Yeah well its all done by computers now you dont need qualified navigators, the Captain can easily run it aground on his own :-)) It took a little longer than dumping ROs but not much. Alan G3NYK - Original Message - From: "Brian Inglis" To: Sent: Wednesday, January 06, 2016 9:44 PM Subject: Re: [time-nuts] Loran Europe Lessay seems to be back on air? On 2016-01-04 14:11, Alan Melia wrote: I remember being told by a senior member of the RIN that he thought it was a "dead duck" and a waste of money. It appears someone also thought RIN was a "dead duck" and a waste of money as it too shut down at the end of 2015! -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] DMTD - analog multiplier vs. diode mixer ?
Yes must have been a year or so ago there was a thread I recall that someone was doing that. Thats one expensive approach to the problem. Regards Paul WB8TSL On Wed, Jan 6, 2016 at 2:37 PM, Bruce Hunter via time-nuts < time-nuts@febo.com> wrote: > I realize this would not measure frequency or phase difference; but has > anyone used a lock-in amplifier to compare two 10 MHz signals -- for > example to adjust a rubidium oscillator to agree with a GPS reference? > > Bruce, KG6OJI > ___ > 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] Loran Europe Lessay seems to be back on air?
I would give Anthorn some time to settle down. It will. Its a shame no one here has actual contacts with the people that run it. Regards Paul WB8TSL On Wed, Jan 6, 2016 at 4:44 PM, Brian Inglis < brian.ing...@systematicsw.ab.ca> wrote: > On 2016-01-04 14:11, Alan Melia wrote: > >> I remember being told by a senior member of the RIN that he thought it >> was a "dead duck" and a waste of money. >> > > It appears someone also thought RIN was a "dead duck" and a waste of money > as it too shut down at the end of 2015! > > -- > Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada > > ___ > 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] Loran Europe Lessay seems to be back on air?
On 2016-01-04 14:11, Alan Melia wrote: I remember being told by a senior member of the RIN that he thought it was a "dead duck" and a waste of money. It appears someone also thought RIN was a "dead duck" and a waste of money as it too shut down at the end of 2015! -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] (OT) Looking for a paper from NAV01 (RIN International Conference on Navigation)
Hi Phil, On 01/06/2016 07:14 PM, Philip Pemberton wrote: > I've contacted TIB (the German university library in Hannover). Sadly > they can't send the paper because it's not covered by their Europe-wide > copyright licence -- so they can only supply it to persons inside Germany First off it looks like they won't even give out the 450 page work, but only photocopies of requested articles/pages ("bestellbar / nur Kopie"). As I live close to Hannover, I will give it a try the next days to obtain a copy of the Hartinger,Willson,Cousins paper. Nothing is lost, but keep your fingers crossed. I will then see to it that it is made accessible for you and Attila and the others interested. Greetings, Jochen ___ 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] DMTD - analog multiplier vs. diode mixer ?
I realize this would not measure frequency or phase difference; but has anyone used a lock-in amplifier to compare two 10 MHz signals -- for example to adjust a rubidium oscillator to agree with a GPS reference? Bruce, KG6OJI ___ 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] Loran Europe Lessay seems to be back on air?
On Wed, Jan 06, 2016 at 05:05:37PM +, Poul-Henning Kamp wrote: > It seems to me that the code they use for the 6731M signal is botched, > anybody who can confirm ? Indeed, see the attached plot (from a recording I made earlier this evening): the master signal is totally lacking the 180 degree phase code modulation, while the slave signal does have it. Regards, Pieter-Tjerk, PA3FWM ___ 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] Loran Europe Lessay seems to be back on air?
It seems to me that the code they use for the 6731M signal is botched, anybody who can confirm ? Ah well, as of 1915 the FS700s seem to be locking ok again but still with the monitored signal dropping out from time to time so I guess we just need to be patient and treat it as work in progress. Regards Nigel GM8PZR ___ 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] Loran Europe Lessay seems to be back on air?
In message <5ce6d0.616cac05.43bec...@aol.com>, gandal...@aol.com writes: >--part1_5ce6d0.616cac05.43bec318_boundary >It seems to me that the code they use for the 6731M signal is botched, >anybody who can confirm ? > > >Ah well, as of 1915 the FS700s seem to be locking ok again but still with >the monitored signal dropping out from time to time so I guess we just need >to be patient and treat it as work in progress. I can lock too, but best lock is to the 3rd pulse in the master signal using the slave-code... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Loran Europe Lessay seems to be back on air?
FOlks, Whilst it's not e-LORAN, and it may not be of much help, I can at least now look for signals here in Edinburgh give the GRI. I'm using: - e-field vertical mounted in the loft (yes, it would be far better outside) - SpyVerter/Airspy receiver hardware - SDR# receiver software - Virtual Audio Cable to send the audio from SDR# to; - NDBfinder software from www.coaa.co.uk This doesn't do anything ultra clever, just shows the signals like you would see on a 'scope, but integrated to improve the S/N. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Loran Europe Lessay seems to be back on air?
It seems to me that the code they use for the 6731M signal is botched, anybody who can confirm ? Something's certainly not right at the moment. This morning all was working fine with both Master and Y stations locked on different receivers, but I had to go out for a few hours and when I returned sometime after 1400, although I could still see a loran transmission on 100KHz, nothing would lock and I was getting various errors reported, including "Can't match phase code". As of 1815 this situation continues, although I'm still seeing occasional signal dropouts and then recovery, so perhaps they're still working on it. Regards Nigel GM8PZR ___ 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] (OT) Looking for a paper from NAV01 (RIN International Conference on Navigation)
On 04/01/16 21:02, Attila Kinali wrote: > That's weird. The RIN website has an explicit conference proceedings download > page: > http://members.rin.org.uk/conferencepapers/conferencepapers.aspx > > They list there a special email address confere...@rin.org.uk as contact > to ask for access. I don't know what their requirements are but if they > are anything like the Royal Society, then there is a good chance you'll > get access. Yes, I've seen that, and been in contact with them -- sadly their archive only goes back as far as 2010. I asked about two papers and they offered to pass my request onto the co-author of the other one as they were still a RIN member, but were sadly unable to assist with this one. > Interesting. If you get access to the paper, i would be interested in > it as well. I've contacted TIB (the German university library in Hannover). Sadly they can't send the paper because it's not covered by their Europe-wide copyright licence -- so they can only supply it to persons inside Germany :( So close and yet so far! Thanks, -- Phil. li...@philpem.me.uk http://www.philpem.me.uk/ ___ 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] Loran Europe Lessay seems to be back on air?
It seems to me that the code they use for the 6731M signal is botched, anybody who can confirm ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Loran Europe Lessay seems to be back on air?
Hi All, On 05/01/16 20:03, paul swed wrote: The norm right now is 1 year. Enjoy while you can. On Tue, Jan 5, 2016 at 1:50 PM, GandalfG8--- via time-nuts < time-nuts@febo.com> wrote: Yes, they've been switching back and forth between one or two channels all day, with the one channel state always being just the usual Anthorn Y channel and the two channels always being Master plus the Y channel. Sometimes the overall signal levels have been fluctuating quite a bit at 100 Miles from Anthorn, more so than usual, and when in the two channel state both channels have always been at the same signal level, although on a few occasions the signal has shut down altogether for several minutes at a time. As it's now nearly 1850, and still transmitting Master and slave rather than reverting to just the slave as it did at the end of the day yesterday, I'm even more encouraged to hope this might become the norm for some time at least. I happen to receive the "GNSS Edition of Chronos Times" from chronos.co.uk. While a "newsletter" (read advertisement) style email, the like of which I'm sure we all get from various sources, the following paragraph contained a sentence about the recent European LORAN shutdown. I won't quote the entire "newsletter", but the paragraph in question reads: ---BEGIN QUOTE--- We wish you a happy and prosperous 2016 and welcome to the first GNSS edition of the Chronos Times. Apart from a number of new exciting products shown below, the best news we had just before Christmas was that eLoran transmissions for timing and data services will be maintained going forward. Whilst the rest of Europe has decided to close down its old Loran-C transmitters, the UK has confirmed that eLoran transmissions from Anthorn will continue. This is early days for this new service ---END QUOTE--- So, that's some good news at least. How long for, as Paul says is to be determined, but at least it's positive news Best Regards Iain ___ 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] CTS 1960017 OCXO
Broad parameters for CTS 196 series OCXO data: http://www.wellking.com/default/doc/cts/%E9%A2%91%E7%8E%87%E6%8E%A7%E5%88%B6%E4%BA%A7%E5%93%81/%E6%81%92%E6%B8%A9%E5%9E%8B%E6%99%B6%E6%8C%AF/196.pdf Frequency Stability Initial Calibration ∆f/fNOM; TA=25°C; at time of shipment @ 0.5 X Vc - - ± 200 ppb -10° to 70°C; ref. 25°C (Option A) - ±5 ±10 ppb vs Temperature -40° to 85°C; ref. 25°C (Option B) - ±10 ±20 ppb vs Supply Voltage ± 5% - - ± 5 ppb vs Load ± 10% - - ± 1 ppb at time of shipment - - ± 1 ppb/day Aging first year - - ± 100 ppb/year Short Term Stability In Still Air @ 0.1 sec tau - - 0.01 ppb Allan Deviation In Still Air @ 1.0 sec tau - - 0.01 ppb Warm-Up Time TA=25°C; to within 50ppb of freq. @ 30 min - - 4 minutes Phase Noise (Typical for 10 MHz) 1 Hz - -90 - dBc/Hz 10 Hz - -125 - dBc/Hz 100 Hz - -140 - dBc/Hz 1 kHz - -150 - dBc/Hz 10 kHz - -155 - dBc/Hz EFC Tuning range: +/- 0.7 ppm On Tue, Jan 5, 2016 at 10:43 PM, Gregory Muir wrote: > There seems to be a plethora of the CTS 1960017 OCXOs on eBay at the > moment. Would anyone have any stability specs on this device? > > Greg > ___ > 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] DMTD - analog multiplier vs. diode mixer ?
Sorry I was under the impression I was replying to Don's post. Sometimes my Windows machine seems to mess up the part of the thread to which I thought I was replying. My Linux box doesn't seem to have this problem. Bruce On Tuesday, January 05, 2016 09:26:14 PM Charles Steinmetz wrote: > Bruce wrote: > >You mean DMTD = dual mixer time differencenotDDMTD = Digital dual > >mixer timer difference.The latter uses a pair of synchronisers / > >shift registers instead of a pair of mixers. > > I don't see how your comment is relevant to my post -- I did not > mention either DMTDs or DDMTDs. I only noted that the AD835 is > noisier than a diode mixer, although not as noisy as many analog > multipliers -- and that some noise improvement has been demonstrated > by using parallel multipliers. > > Charles > > >On Wednesday, 6 January 2016 12:03 PM, Charles Steinmetz > > > > wrote: > > Poul-Henning wrote: > > >My little HP5065 project is continually running into the jitter of > > >my HP5370B counter which is annoying me, so I'm looking int DMTD. > > > > > >Everybody seems to be using traditional diode-mixers for DMTD, > > >and to be honest I fail to see the attraction. > > > > > >Why wouldn't a analog multiplier like AD835 be better idea ? > > > > > >What am I overlooking ? > > > >You could have mentioned any of dozens of popular analog multipliers, > >and the answer would have been, "because they are way too > >noisy." The AD835 is also substantially noisier than diode mixers, > >but it at least begins to bridge the gap. The folks at CERN have > >been improving phase detector S/N by averaging the output of several > >AD835s for the TPMON project, with promising results. There is a > >preliminary report in "EUROTeV Report 2006-005-1." > > > >See also: > > > >RF-based electron beam timing measurement with sub-10fs resolution, > >A. Andersson and J. P. H. Sladen, CERN (EUROTeV Report 2008-015) > >[phase detector with 8x AD835 analog multipliers]. > > > >ANDERSSON, A. and SLADEN, J. P. H.: "First tests of a precision beam > >phase measurement system in CTF3" (Proc. PAC07). > > > >"PRECISION BEAM TIMING MEASUREMENT SYSTEM FOR CLIC SYNCHRONIZATION," > >A. Andersson, J. P. H. Sladen, CERN (Proceedings of EPAC 2006). > > > >Best regards, > > > >Charles > > ___ > 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] CTS 1960017 OCXO
Hi According to the CTS web site, this: http://www.ctscorp.com/wp-content/uploads/2015/12/OCXO196.pdf has the basic specs on it. The seller mentions that it’s a 5V supply and sine wave output unit. Bob > On Jan 5, 2016, at 10:43 PM, Gregory Muir wrote: > > There seems to be a plethora of the CTS 1960017 OCXOs on eBay at the moment. > Would anyone have any stability specs on this device? > > Greg > ___ > 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] beaglebone black, debian, NTP client
That's one thing that annoys me with those graphs. If you average jitter it loses its meaning. What you then get is the mean deviation (aka offset). Without an accompanying standard deviation (and a test that you actually have a gausian distribution) this value is not worth much. What I am talking about is http://www.satsignal.eu/ntp/2015-03-21-23-BBB_offset.png The before ("full" OS) and after ("console" OS) is strange by itself. What kind of process is running that increases interrupt latency jitter by a factor of 2-3? Why does the "console" OS still exhibit a jitter that is a factor 2 to 3 higher than what i'd expect as interrupt jitter? Attila Kinali PS: could you please quote mails properly? It makes them much easier to read. http://pub.tsn.dk/how-to-quote.php == Attila, The jitter is not averaged, and the RMS value is given in: http://www.satsignal.eu/ntp/2015-03-21-23-BBB_offset.png The Console BBB OS was recommended here. Likely the two were: Full: bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img Console: bone-debian-7.8-console-armhf-2015-03-01-2gb.img The GPS has a jitter well under a a tenth of a microsecond, so someone else will need to investigate why the jitter does not meet you expected levels, as I have abandoned the BBB as it created too much RF interference, and has far less support than the Raspberry Pi. Timekeeping on the RPi is quite good enough for my purposes. Unfortunately, my e-mail software makes it very difficult to do proper quoting. I always do correct quoting with NNTP using Thunderbird, but I'm unwilling to start putting chevrons at the start of every quoted line in e-mail with my inferior e-mail software. Perhaps one day I'll change e-mail software - it annoys me as well. At least it doesn't top-post, or use HTML! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Loran Europe Lessay seems to be back on air?
Right but they are both the same station. Note the levels are pretty much the same. On Tue, Jan 5, 2016 at 12:29 PM, Poul-Henning Kamp wrote: > > > I see both a master and slave on 6731 from Denmark now. > > Same signal strength: > > http://phk.freebsd.dk/misc/_.svg > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > ___ > 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] Loran Europe Lessay seems to be back on air?
The norm right now is 1 year. Enjoy while you can. On Tue, Jan 5, 2016 at 1:50 PM, GandalfG8--- via time-nuts < time-nuts@febo.com> wrote: > Yes, they've been switching back and forth between one or two channels all > day, with the one channel state always being just the usual Anthorn Y > channel and the two channels always being Master plus the Y channel. > Sometimes the overall signal levels have been fluctuating quite a bit at > 100 Miles from Anthorn, more so than usual, and when in the two channel > state both channels have always been at the same signal level, although > on a > few occasions the signal has shut down altogether for several minutes at a > time. > > As it's now nearly 1850, and still transmitting Master and slave rather > than reverting to just the slave as it did at the end of the day > yesterday, > I'm even more encouraged to hope this might become the norm for some time > at > least. > > Regards > > Nigel > GM8PZR > > > In a message dated 05/01/2016 17:29:11 GMT Standard Time, > p...@phk.freebsd.dk writes: > > > > I see both a master and slave on 6731 from Denmark now. > > Same signal strength: > > http://phk.freebsd.dk/misc/_.svg > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by > incompetence. > > ___ > 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] CTS 1960017 OCXO
There seems to be a plethora of the CTS 1960017 OCXOs on eBay at the moment. Would anyone have any stability specs on this device? Greg ___ 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] DMTD - analog multiplier vs. diode mixer ?
Bruce wrote: You mean DMTD = dual mixer time differencenotDDMTD = Digital dual mixer timer difference.The latter uses a pair of synchronisers / shift registers instead of a pair of mixers. I don't see how your comment is relevant to my post -- I did not mention either DMTDs or DDMTDs. I only noted that the AD835 is noisier than a diode mixer, although not as noisy as many analog multipliers -- and that some noise improvement has been demonstrated by using parallel multipliers. Charles On Wednesday, 6 January 2016 12:03 PM, Charles Steinmetz wrote: Poul-Henning wrote: >My little HP5065 project is continually running into the jitter of >my HP5370B counter which is annoying me, so I'm looking int DMTD. > >Everybody seems to be using traditional diode-mixers for DMTD, >and to be honest I fail to see the attraction. > >Why wouldn't a analog multiplier like AD835 be better idea ? > >What am I overlooking ? You could have mentioned any of dozens of popular analog multipliers, and the answer would have been, "because they are way too noisy." The AD835 is also substantially noisier than diode mixers, but it at least begins to bridge the gap. The folks at CERN have been improving phase detector S/N by averaging the output of several AD835s for the TPMON project, with promising results. There is a preliminary report in "EUROTeV Report 2006-005-1." See also: RF-based electron beam timing measurement with sub-10fs resolution, A. Andersson and J. P. H. Sladen, CERN (EUROTeV Report 2008-015) [phase detector with 8x AD835 analog multipliers]. ANDERSSON, A. and SLADEN, J. P. H.: "First tests of a precision beam phase measurement system in CTF3" (Proc. PAC07). "PRECISION BEAM TIMING MEASUREMENT SYSTEM FOR CLIC SYNCHRONIZATION," A. Andersson, J. P. H. Sladen, CERN (Proceedings of EPAC 2006). Best regards, Charles ___ 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] KS-24361 off by 45 seconds for 13 minutes, end of Jan 01 UTC
On 2016-01-05 11:59, Hal Murray wrote: Is anybody watching the output of their KS-24361? Mine was off by 45 seconds for 13 minutes at the end of Jan 01. I didn't see any problems on a Z3801A. Receiver time output may have been delayed while receiving an almanac update at the end of the UTC day? Almanac takes about 12.5 minutes to transmit, which would jive with ~13 minutes. Clockstats should output the last message received about once per poll period - is minpoll 6? TFOM byte after time stayed the same at 3 => < 1us uncertainty if same as Z3801A; FFOM two bytes after time went from 0 to 2 so the PLL unlocked and went into holdover, and at the end of that period went to 1 so stabilizing; presumably got back to 0 later. The following Leap, Request for Service, and Valid bytes did not change. Assumptions are that operation and status are the same as for HP Smart Clocks. Here is part of ntpd's clockstats. The second column is the system time - seconds this day. The 4th column is the data from the KS-24361 The 220160101 is the date. Following that is HHMMSS. The <== mark the first and last samples that are off. 57388 85270.045 127.127.26.0 T2201601012341113001031 48 0 57388 85330.045 127.127.26.0 T2201601012341263201039 52 0 <== 57388 85394.045 127.127.26.0 T2201601012342303201035 52 0 57388 85458.045 127.127.26.0 T220160101234334320103A 56 0 57388 85522.045 127.127.26.0 T220160101234438320103F 56 0 57388 85586.045 127.127.26.0 T220160101234542320103B 52 0 57388 85650.045 127.127.26.0 T2201601012346463201040 48 0 57388 85714.045 127.127.26.0 T220160101234750320103C 44 0 57388 85778.045 127.127.26.0 T2201601012348543201041 56 0 57388 85842.045 127.127.26.0 T2201601012349583201046 48 0 57388 85906.045 127.127.26.0 T2201601012351023201034 36 0 57388 85970.045 127.127.26.0 T2201601012352063201039 52 0 57388 86034.045 127.127.26.0 T2201601012353103201035 48 0 <== 57388 86098.045 127.127.26.0 T2201601012354593101042 60 0 -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada ___ 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] DMTD - analog multiplier vs. diode mixer ?
Hi Ok, so what needs to be done with the output of the mixer (no matter how you do it)? Assume you start from 10 MHz and head down to 10 Hz. Assume you are mad at your 5370 and want significantly better performance. Where does that get you? The 5370 already is in the ~ 20 ps range. A lot depends on your definitions and how good your sample is running. Let’s call that 2x10^-11 at tau = 1 second. You could indeed call it a couple of other things as well. Simply moving up a decade with a whole bunch of gear and it’s limitations seems like a waste. To me you want to go for 1 to 2x10^-13 as your target. It is an achievable target and there are a number of papers that validate it as a reasonable DMTD target. You get a 1x10^6 “amplification due to your down mix from 10 MHz to 10 Hz. You then need another 1x10^7 to get you to your target. All errors from everything included, you need to work out the location of the zero crossings to within 100 ns. The practical examples of doing it include some fairly tight lowpass filtering as well as high pass filtering ahead of the detection process. I have never seen it done without this filtering as part of the setup. There is just to much noise at the detector otherwise. Most systems have something like a 15 Hz lowpass and a 5 Hz high pass for a 10 Hz note. With fairly good diode ring phase detectors and a less than perfect (not 25 stage Collins style) analog limiter, you can indeed get to the target. Doing it digitally assumes you have a pretty good clock and sampler. If you look at it as a 3V p-p triangle waveform at 10 Hz, you have a 60V / second slew rate. (a 1 V p-p sine wave is pretty close to the same number). You need to filter that at 15 Hz and then resolve it to about 6 uV at the zero crossing. You can either keep a high sample rate and make your filter a major nightmare or you can decimate ahead of the filter and turn the resolver into a headache. Either way, there is some work to be done. A couple of op-amp packages is about all it takes to do the limiter with the analog approach …. Bob > On Jan 5, 2016, at 6:58 PM, Magnus Danielson > wrote: > > Hi Poul-Henning, > > On 01/06/2016 12:28 AM, Poul-Henning Kamp wrote: >> >> In message <568c46b9.4020...@rubidium.dyndns.org>, Magnus Danielson writes: >> >>> The white noise will be particularly annoying as it then converts to >>> jitter through the slew-rate limitation as you go into the >>> trigger-circuit. >> >> Digitize the LPF output and do a curve-fit to find the zero-crossings ? >> > > That would work. You could least-square fit it with very cheap processing. > The LPF would mainly need to reject the sum frequencies to act as > anti-aliasing filter, and the noise would be filtered out by the least-square > processing. > > Estimating the phase and slew-rate, and then use those to calculate the > actual through-zero phase would not be too hard. As a consequence you get a > slew-rate monitor, which act as an observation of signal level. > > 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.