Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup
(I do not understand why Yahoo responds to the list for some of you and for others it responds only to the sender. This is a resend to the list.) Hi Hal, That should have been Satstat, and yeah, after looking through the Z3801 User's Guide, I decided to just let it play by itself. It found the right date after it started acquiring sats, so I guess all is good. I think I figured out why only the REF-0 unit was responding. And that's because there are two units, and the one that's not active doesn't reply. At the moment, REF-0 which is responding has the ON light lit, and REF-1 says it's in STBY. So I think I finally have a better phase reference than the 10811 I've been using. At least the phase plot against my GPSDO project is pretty stable over the last 2500 seconds, and a proper ADEV curve is starting to develop. Unfortunately, I've been battling what I think is a thermal problem, so it could all fall over sometime tonight. OTOH, the survey isn't complete, and I have no idea about the performance of this Z3812A during survey. And thanks for the Linux ideas. Bob From: Hal Murray hmur...@megapathdsl.net To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Cc: hmur...@megapathdsl.net Sent: Friday, October 24, 2014 10:55 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup b...@evoria.net said: The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Or just wait and see how well the location it finds matches your current data. The Z3801A manual is easy to find and contains a good description of the SCPI commands. Yes, I think there is a way to load the location and bypass the survey. I think there is a slot in Satsat where you can type in commands by hand. You don't need Satsat. You can talk to it from the command line. On Linux, for a Z3801A, I do things like: ln -s /dev/ttyS2 /dev/hpgps1 stty -F /dev/hpgps1 19200 cs7 parodd parenb igncr stty -F /dev/hpgps1 19200 oddp igncr -echo On one window: cat /dev/hpgps1 On another window: echo -e :ptime:tcode:format F2 /dev/hpgps1 echo -e :diag:gps:utc 1 /dev/hpgps1 # Needs reboot? echo -e :SYSTEM:STATUS? /dev/hpgps1 # fix for week wrap - maybe only works before survey echo -e :GPS:INIT:DATE 2011,12,26 /dev/hpgps1 -- These are my opinions. I hate spam. ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
b...@evoria.net said: The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Or just wait and see how well the location it finds matches your current data. The Z3801A manual is easy to find and contains a good description of the SCPI commands. Yes, I think there is a way to load the location and bypass the survey. I think there is a slot in Satsat where you can type in commands by hand. You don't need Satsat. You can talk to it from the command line. On Linux, for a Z3801A, I do things like: ln -s /dev/ttyS2 /dev/hpgps1 stty -F /dev/hpgps1 19200 cs7 parodd parenb igncr stty -F /dev/hpgps1 19200 oddp igncr -echo On one window: cat /dev/hpgps1 On another window: echo -e :ptime:tcode:format F2 /dev/hpgps1 echo -e :diag:gps:utc 1 /dev/hpgps1 # Needs reboot? echo -e :SYSTEM:STATUS? /dev/hpgps1 # fix for week wrap - maybe only works before survey echo -e :GPS:INIT:DATE 2011,12,26 /dev/hpgps1 -- These are my opinions. I hate spam. ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob If REF-0 is the only one that can output the data that would certainly put me in a shot myself in the foot position wouldn't it?:-) However, we do know from Arthur that REF-1 will operate stand alone, so assuming you haven't got a faulty unit, which I suspect is pretty unlikely, another option might be that data is only available from the currently active unit, which I believe defaults to REF-0?, although both units would presumably need to be conditioning all the time to maintain the redundancy configuration. Stewart is probably going to be best placed to answer that question, given his degree of experience in operating the two together, and it would certainly be interesting to hear his conclusions. Regards Nigel GM8PZR In a message dated 25/10/2014 03:48:20 GMT Daylight Time, b...@evoria.net writes: Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Let us know how this is progressing. I am waiting on a TNC connector, so can't get mine up and running this weekend as planned. I'll get my power supply sorted out and see if I can get SatStat connected. Do you know if the GPS input provides a 5v bias to drive an antenna? Anthony -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Stewart Sent: Friday, October 24, 2014 8:47 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi One of the interesting things about these little receiver modules is that they don’t all report the same survey location. There are NIST papers with examples. You could probably spend a lot of time on the “why”. If you are getting “poor geometry” errors, either you have an antenna issue, or your receiver is in trouble some other way. It should go into survey mode and stick there. It should be solidly into the survey after about 10 minutes power on. Bob On Oct 24, 2014, at 9:46 PM, Bob Stewart b...@evoria.net wrote: Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ 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] Changing ADEV, (was Phase, One edge or two?)
In message 544ad1d1.4040...@rubidium.dyndns.org, Magnus Danielson writes: A great way to illustrate the point of degrees of freedom and the number of sample-points needed to get tight confidence intervals is to see how the high-tau end of a curve updates in TimeLab and behaves as the jiggeling end of a long rope, and as more samples comes in, the jiggeling end moves towards higher taus, but for a particular tau, the amplitude of the jiggeling decreases until it almost stops. This is the effect of the confidence intervals becoming tighter, the range within the real value is becomes smaller and eventually is very tight. ADEV snakes about at the far right end primarily becuase of the phase jitter which dominates at your minimum tau. If you have a phase measurement white noise of 1 ns = ADEV(tau=1) and you expect your ADEV curve to bottom out around 1e-12 at some larger tau, then you have a factor thousand of noise to average out, before a valid ADEV comes out of the noise. This is not any different from any other average out the noise situation in any significant way, sqrt(N) rules, and there is nothing you can do about. *except* to decrease your phase measurement white noise, which is why tuning your 5370 for peak performance is worth days of measurements at the other end of the ADEV. -- 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] Changing ADEV, (was Phase, One edge or two?)
Some of the reasons that ADEV values change over time may be caused by one of these two things that I have seen cause poor plots. Either of which can cause changes in the ADEV values across a wide range of taus, and the effect can change over long run ins. Hopefully Magnus will comment if ADEV is even an appropriate tool to use if either of these noise types are present in the raw data. The first thing that can cause trouble is if a bad data point occurs every so often, aka an outlier. The other thing is popcorn noise, a sudden frequency shift that tends to hop between a few different values and happens at an unpredictable time but at a somewhat repeatable rate. I've seen Popcorn noise change over long time periods after days or weeks of run in, say from a typical 1e-10 freq hop a few times a minute to maybe 2e-11 hops a couple times every 5 minutes. Even when this happened on some of my poor oscillators the basic short tau ADEV values between hops stayed pretty much constant. . If either of these somewhat repeatable but random events are included in the raw data, ADEV plots can become pretty misleading or downright useless. For that reason Plotter allows outliers to be removed automatically. As far as I know outliers have to be manually removed when using TimeLab. ws PS, and Yes the fact that I've posted this shows that I have to be at least somewhat crazy, aren't all time nuts in one way or another?. From: Bob Camp Subject: Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?) Hi Grab an OCXO that has been powered off for a long time. Turn it on and start plotting ADEV. Do it from about 10 minutes after turn on. Run 15 to 30 minute tests every so often for the first few hours. Come back the next day and run the same series for a few hours. Repeat a week later, and a month later. Curve fit out the drift and run the ADEV numbers out to 100 seconds tau. That’s true even if you compare the best of each batch. It really is getting better. Do that on enough oscillators and you will indeed find many that do get better (like 2X better for some, 10 or 20% for others) on ADEV after they have been on a while. —— Run an OCXO and watch the ADEV on the Time Pod. Look at enough of them and you will find some that drop ADEV for a while (say 10 minutes or so) and then climb by a bit (say 1.5:1). Hmmm, what’s going on? Look at the phase plot and there’s an abrupt shift in phase over some period ( which depends on the cause, there’s more than one possibility). Let’s say it’s 10 seconds. The whole ADEV plot climbs, not just the part for 10 second tau. Why - there’s energy there both at short and long tau. —— Look at a GPSDO / disciplined oscillator / temperature compensated Rb. Let it run for a good long time. If it’s got a loop that steps out to *long* time constants, it may only bump the frequency once every 15 minutes or longer. Plot the ADEV over the time segment when it steps and compare it to the time period it does not step. Short tau ADEV is worse at the step. Look at a very normal OCXO on your TimePod. After 100 seconds, the 1 second ADEV *should* be pretty well determined. After 1000 seconds it should be *very* well determined. Flip on the error bars if you want an idea of how good it should be. Watch for a while, Does it move outside the error bars? H ….. It’s not the error bars that are the problem. The math is correct. The statistics are what is the issue. The ADEV hast changed for the worse as the run has gone on. It’s a very common thing. ——— Those are just the first few off the top of my head. Bob ** ADEV most certainly does change with time, even for short tau's. Can you elaborate? ___ 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] Changing ADEV, (was Phase, One edge or two?)
On Oct 24, 2014, at 6:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 10/24/2014 11:31 PM, Tom Van Baak wrote: ADEV most certainly does change with time, even for short tau's. Can you elaborate? Such as when, why, what kind of change, how much change, at how short of tau's, over how long of time, and using what type Oscillators? Do you know what in the freq or Phase plot is causing the ADEV to change? I'm happy to let Bob answer his own claim here. I'm curious as well. Unless he's talking about thermal noise, in which case I now believe him 100%. OTOH, for time intervals of minutes to hours or days, the plotted ADEV can often vary. When in doubt, enable error bars in your ADEV calculations or use DAVAR in Stable32, or use Trace History of TmeLab to expose how little or much the computed ADEV depends on tau and N. In general, never do an ADEV calculation without visually checking the phase or frequency time series first. You should make sure that you remove all forms of systematic effects before turning the residue random noise over to ADEV. If you have random noise being modulated in amplitude, you need to measure long enough for the averaging end not to have a great impact on the result. Is days long enough for a 1 second tau? If you define 1,000 x tau as “long enough” you are being way more conservative than just about anybody out there. My claim is that rather than telling everybody to run for 10,000 or 100,000 x tau, simply accept that ADEV does / may change. Removing this or that *before* you do ADEV can get you on a very slippery slope indeed. Removing drift (either time or frequency) - fine. Removing this or that couple of minutes of data because it makes the result look better, that’s likely to get you in trouble. Your customer (or system, or test setup) isn’t likely to accept a “ADEV is ok most of the time” specification. Is ADEV a good way to measure temperature stability - no of course not. We do indeed have rooms that vary in temperature. They do impact ADEV on a Rb. Removing the delta temperature related data from your ADEV input is not at all easy (1,000 to 10,000 second data …) and I believe it would mis-represent the part. Running in the real world, it’s going to have that ADEV hump. Yes indeed you can find FCS papers with all sorts of interesting “adjustments” or no processing at all. The consensus seems to be that if you go past drift correction, you really should have a footnote. Bob Of the many OCXO type Oscillators that I've tested (HP10811 MV89), seldom have I seen any significant change (say greater than 10%), in the short tau (0.01 sec to 1 sec) ADEV values, after the systematic type errors are removed. (even when starting soon after turn on) This is not my experience at all. Let's figure out what's happening to you. If all your standards look sort the same from tau 0.01 to tau 0.1 to tau 1 then either you need more oscillators to play with or maybe you have a measurement problem. This is especially true if you are doing post-comparator averaging. Averaging, by definition, tends to remove noise, to smooth things out. If your goal is to measure noise, the last thing you want to do is create any electronics or use any analog or digital or numerical filtering that removes or reduces the very thing you're trying to measure. I remind you of this page http://leapsecond.com/pages/adev-avg/ of the perils of averaging data. For most of the world, there's signal and noise. Signal good. Noise bad. But for us, measuring precision clocks, the noise is the signal. So don't do anything that removes or reduces noise. Systematic signals is however disturbances for the ADEV. ADEV is used to measure random types of noise so there are of course the statistical uncertainty variations that are a function of the number of valid data points. I find that using a minimum of a thousand points at each tau gives good consistent results. Are you crazy? The minimum is just 3 or 4 or 5 data points. Not 1000! You should not see much difference at 10 or 100 or 1000 points. If so, something is wrong with your measurement model. If ADEV(tau) is *that* dependent on tau, check the frequency time-series. Consider removing drift or using HDEV instead of ADEV. We need to talk. If your logic was true, we'd all have to wait 3 years before we could compute the ADEV of a GPSDO at tau 1 day. No, he is not crazy on this point. While the algorithm only needs 3 points to produce a value, that value will have so bad degrees of freedom that the confidence interval is WAAAY out there. The reason that we don't need to wait 3 years for tau of 1 day is that we learned to use interleaving spans of time. We have since had much more development in the algorithms to improve the degrees of freedom for the same N samples, all in an effort to achieve as small confidence interval as
Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?)
Hi In fact, even without any “weird” stuff in the data, you can see short tau ADEV drop as an OCXO runs for days / weeks / months. You can test this by taking your 15 to 30 minute test run and breaking it into three or four sub runs. Bob On Oct 25, 2014, at 7:04 AM, WarrenS via time-nuts time-nuts@febo.com wrote: Some of the reasons that ADEV values change over time may be caused by one of these two things that I have seen cause poor plots. Either of which can cause changes in the ADEV values across a wide range of taus, and the effect can change over long run ins. Hopefully Magnus will comment if ADEV is even an appropriate tool to use if either of these noise types are present in the raw data. The first thing that can cause trouble is if a bad data point occurs every so often, aka an outlier. The other thing is popcorn noise, a sudden frequency shift that tends to hop between a few different values and happens at an unpredictable time but at a somewhat repeatable rate. I've seen Popcorn noise change over long time periods after days or weeks of run in, say from a typical 1e-10 freq hop a few times a minute to maybe 2e-11 hops a couple times every 5 minutes. Even when this happened on some of my poor oscillators the basic short tau ADEV values between hops stayed pretty much constant. . If either of these somewhat repeatable but random events are included in the raw data, ADEV plots can become pretty misleading or downright useless. For that reason Plotter allows outliers to be removed automatically. As far as I know outliers have to be manually removed when using TimeLab. ws PS, and Yes the fact that I've posted this shows that I have to be at least somewhat crazy, aren't all time nuts in one way or another?. From: Bob Camp Subject: Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?) Hi Grab an OCXO that has been powered off for a long time. Turn it on and start plotting ADEV. Do it from about 10 minutes after turn on. Run 15 to 30 minute tests every so often for the first few hours. Come back the next day and run the same series for a few hours. Repeat a week later, and a month later. Curve fit out the drift and run the ADEV numbers out to 100 seconds tau. That’s true even if you compare the best of each batch. It really is getting better. Do that on enough oscillators and you will indeed find many that do get better (like 2X better for some, 10 or 20% for others) on ADEV after they have been on a while. —— Run an OCXO and watch the ADEV on the Time Pod. Look at enough of them and you will find some that drop ADEV for a while (say 10 minutes or so) and then climb by a bit (say 1.5:1). Hmmm, what’s going on? Look at the phase plot and there’s an abrupt shift in phase over some period ( which depends on the cause, there’s more than one possibility). Let’s say it’s 10 seconds. The whole ADEV plot climbs, not just the part for 10 second tau. Why - there’s energy there both at short and long tau. —— Look at a GPSDO / disciplined oscillator / temperature compensated Rb. Let it run for a good long time. If it’s got a loop that steps out to *long* time constants, it may only bump the frequency once every 15 minutes or longer. Plot the ADEV over the time segment when it steps and compare it to the time period it does not step. Short tau ADEV is worse at the step. Look at a very normal OCXO on your TimePod. After 100 seconds, the 1 second ADEV *should* be pretty well determined. After 1000 seconds it should be *very* well determined. Flip on the error bars if you want an idea of how good it should be. Watch for a while, Does it move outside the error bars? H ….. It’s not the error bars that are the problem. The math is correct. The statistics are what is the issue. The ADEV hast changed for the worse as the run has gone on. It’s a very common thing. ——— Those are just the first few off the top of my head. Bob ** ADEV most certainly does change with time, even for short tau's. Can you elaborate? ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi If the Z3810/11/12 is like the other HP / Symmetricom boxes (and I’d bet it is): 1) It will go into survey and sync relatively slowly compared to some of the other units. 2) It’s got a less sensitive / lower channel count receiver than stuff like Said’s new part. 3) It will take a *long* time to get to it’s best stability operating point. Think weeks / months not hours. 4) It has pretty good environmental rejection. You won’t see much (as in any) benefit in a normal basement / always locked installation. 5) It’s phase noise isn’t as good as some units. (like a TBolt ) 6) Lady Heather does not play well with one :( My guess is that the Z3805 has pretty much the same “stuff” in it. They both come from the same era and (may) have the same MTI OCXO in them. Bob On Oct 25, 2014, at 11:24 AM, Bob Stewart b...@evoria.net wrote: Hi Bob, During the first hour it reported poor geometry a number of times. Then it seemed to get its act together and was solidly into survey mode. A few hours later and it was satisfied with life and went into hold mode, with TFOM=3, FFOM=0. This morning, I see that there is some phase tracking difference of opinion between my GPSDO and this one WRT the 10MHz signal out from REF-0. http://evoria.net/AE6RV/GPSDOe/Z3812A.10.25.png The green is the phase difference plot, and the red is the ADEV. Given this is the first time I have done this against another GPSDO, I don't know whether this is good or bad. Looking at the phase plot on my unit, it wanders around a bit but not 100ns. http://evoria.net/AE6RV/GPSDOe/GPSDO.10.25.png Sorry the plot is so busy with debug traces. You can easily spot the same phase difference line as in the one above. The blue squiggle is my phase error. The red is my DAC. The phase in this plot is in hundreds of ps. I have shut the unit down numerous times recently, and the OXCO has been subjected to different thermal environments. Right now the case is closed, there are no vent holes, and the temperature in the box on my PCB is just a bit over 99 degrees F. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 7:09 AM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi One of the interesting things about these little receiver modules is that they don’t all report the same survey location. There are NIST papers with examples. You could probably spend a lot of time on the “why”. If you are getting “poor geometry” errors, either you have an antenna issue, or your receiver is in trouble some other way. It should go into survey mode and stick there. It should be solidly into the survey after about 10 minutes power on. Bob On Oct 24, 2014, at 9:46 PM, Bob Stewart b...@evoria.net wrote: Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob, During the first hour it reported poor geometry a number of times. Then it seemed to get its act together and was solidly into survey mode. A few hours later and it was satisfied with life and went into hold mode, with TFOM=3, FFOM=0. This morning, I see that there is some phase tracking difference of opinion between my GPSDO and this one WRT the 10MHz signal out from REF-0. http://evoria.net/AE6RV/GPSDOe/Z3812A.10.25.png The green is the phase difference plot, and the red is the ADEV. Given this is the first time I have done this against another GPSDO, I don't know whether this is good or bad. Looking at the phase plot on my unit, it wanders around a bit but not 100ns. http://evoria.net/AE6RV/GPSDOe/GPSDO.10.25.png Sorry the plot is so busy with debug traces. You can easily spot the same phase difference line as in the one above. The blue squiggle is my phase error. The red is my DAC. The phase in this plot is in hundreds of ps. I have shut the unit down numerous times recently, and the OXCO has been subjected to different thermal environments. Right now the case is closed, there are no vent holes, and the temperature in the box on my PCB is just a bit over 99 degrees F. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 7:09 AM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi One of the interesting things about these little receiver modules is that they don’t all report the same survey location. There are NIST papers with examples. You could probably spend a lot of time on the “why”. If you are getting “poor geometry” errors, either you have an antenna issue, or your receiver is in trouble some other way. It should go into survey mode and stick there. It should be solidly into the survey after about 10 minutes power on. Bob On Oct 24, 2014, at 9:46 PM, Bob Stewart b...@evoria.net wrote: Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Anthony, I'm pretty sure it does provide +5 to the antenna. I didn't understand what I was seeing for quite some time yesterday, and it seemed like it was telling me it didn't see an antenna. So, I pulled it off of the splitter and put it onto my second antenna. After a bit, it saw some sats so I think it was driving it fine. I put it back on my splitter and things were fine as well. The thing that was confusing me was that the unit with the green ON light is the one you need to hook the PC to. Use the J8-Diagnostic connector and Stewart's RS-422 to RS-232 adapter scheme. I didn't try it, but I assume a USB dongle wired appropriately would work, as well. As I'm out of serial ports on the server and had to turn on the laptop to interface this, I'll probably try that experiment soon. Bob From: Anthony Roby ar...@antamy.com To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 8:48 AM Subject: RE: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Let us know how this is progressing. I am waiting on a TNC connector, so can't get mine up and running this weekend as planned. I'll get my power supply sorted out and see if I can get SatStat connected. Do you know if the GPS input provides a 5v bias to drive an antenna? Anthony ___ 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] Changing ADEV, (was Phase, One edge or two?)
Bob, On 10/25/2014 02:02 PM, Bob Camp wrote: On Oct 24, 2014, at 6:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 10/24/2014 11:31 PM, Tom Van Baak wrote: ADEV most certainly does change with time, even for short tau's. Can you elaborate? Such as when, why, what kind of change, how much change, at how short of tau's, over how long of time, and using what type Oscillators? Do you know what in the freq or Phase plot is causing the ADEV to change? I'm happy to let Bob answer his own claim here. I'm curious as well. Unless he's talking about thermal noise, in which case I now believe him 100%. OTOH, for time intervals of minutes to hours or days, the plotted ADEV can often vary. When in doubt, enable error bars in your ADEV calculations or use DAVAR in Stable32, or use Trace History of TmeLab to expose how little or much the computed ADEV depends on tau and N. In general, never do an ADEV calculation without visually checking the phase or frequency time series first. You should make sure that you remove all forms of systematic effects before turning the residue random noise over to ADEV. If you have random noise being modulated in amplitude, you need to measure long enough for the averaging end not to have a great impact on the result. Is days long enough for a 1 second tau? If you define 1,000 x tau as “long enough” you are being way more conservative than just about anybody out there. My claim is that rather than telling everybody to run for 10,000 or 100,000 x tau, simply accept that ADEV does / may change. I did not say that you need to do 1000xtau, that was what someone else said. If you paid attention I said that the number of samples N and the tau0-multiple m for a particular dominant noise (of that tau) creates a certain degree of freedom for a particular ADEV estimator algorithm. Discussing the length of the measure without discussing which estimator algorithm you're using and what confidence interval you aim to reach is just taking a single value and run with it without thinking about it. For ITU-T telecom standards, the measurement length is 12 times the maximum tau, using the overlapping estimator (see O.172, §10.5.1 for limit and G.810 §II.3 for TDEV algorithm). That was chosen to ensure comparability between different implementations for the same type of measure. See O.172 for other relevant details on limits for implementation, tau0 has an upper limit, so does bandwidth. Naturally, these limits is for this specific purpose, algorithms etc. which may not fit the needs of other needs or choices. It's only when you do old style non-overlapping that you need to go towards 1000*tau for some reasonable results. Removing this or that *before* you do ADEV can get you on a very slippery slope indeed. Removing drift (either time or frequency) - fine. Removing this or that couple of minutes of data because it makes the result look better, that’s likely to get you in trouble. Your customer (or system, or test setup) isn’t likely to accept a “ADEV is ok most of the time” specification. Agreed. But I've never advocated cutting away samples like that, but rather cancel out the systematics which is not part of the random noise. Is ADEV a good way to measure temperature stability - no of course not. We do indeed have rooms that vary in temperature. They do impact ADEV on a Rb. Removing the delta temperature related data from your ADEV input is not at all easy (1,000 to 10,000 second data …) and I believe it would mis-represent the part. Running in the real world, it’s going to have that ADEV hump. ADEV hump for such systematic is maybe an indication, but not the best way of represent that. It's also not part of the ADEV intended purpose, namely to estimate the random noise effects. Yes indeed you can find FCS papers with all sorts of interesting “adjustments” or no processing at all. The consensus seems to be that if you go past drift correction, you really should have a footnote. When you do not make a drift compensation, and that line shows up, you better explain that too. In the end, ADEV is overused to represent things for which it is not a good tool. You will need other tools in the tool-box to build a good estimation of how that oscillator will behave at some tau. 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob, So, to use this as a phase reference for testing my unit, I'd have to get the phase error out each second and correct for that? Or is it a matter of the OCXO getting happy over the next few weeks and it will settle down? In my mind's eye, I see its DAC moving on a slope just like mine is, as the OCXO ages in. It looks like I need to put a shelf on the wall and give this a permanent home. At the very least, that would get it out of my way so I can do other work. All things considered, it's a good problem to have. =) Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 11:12 AM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi If the Z3810/11/12 is like the other HP / Symmetricom boxes (and I’d bet it is): 1) It will go into survey and sync relatively slowly compared to some of the other units. 2) It’s got a less sensitive / lower channel count receiver than stuff like Said’s new part. 3) It will take a *long* time to get to it’s best stability operating point. Think weeks / months not hours. 4) It has pretty good environmental rejection. You won’t see much (as in any) benefit in a normal basement / always locked installation. 5) It’s phase noise isn’t as good as some units. (like a TBolt ) 6) Lady Heather does not play well with one :( My guess is that the Z3805 has pretty much the same “stuff” in it. They both come from the same era and (may) have the same MTI OCXO in them. Bob On Oct 25, 2014, at 11:24 AM, Bob Stewart b...@evoria.net wrote: Hi Bob, During the first hour it reported poor geometry a number of times. Then it seemed to get its act together and was solidly into survey mode. A few hours later and it was satisfied with life and went into hold mode, with TFOM=3, FFOM=0. This morning, I see that there is some phase tracking difference of opinion between my GPSDO and this one WRT the 10MHz signal out from REF-0. http://evoria.net/AE6RV/GPSDOe/Z3812A.10.25.png The green is the phase difference plot, and the red is the ADEV. Given this is the first time I have done this against another GPSDO, I don't know whether this is good or bad. Looking at the phase plot on my unit, it wanders around a bit but not 100ns. http://evoria.net/AE6RV/GPSDOe/GPSDO.10.25.png Sorry the plot is so busy with debug traces. You can easily spot the same phase difference line as in the one above. The blue squiggle is my phase error. The red is my DAC. The phase in this plot is in hundreds of ps. I have shut the unit down numerous times recently, and the OXCO has been subjected to different thermal environments. Right now the case is closed, there are no vent holes, and the temperature in the box on my PCB is just a bit over 99 degrees F. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 7:09 AM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi One of the interesting things about these little receiver modules is that they don’t all report the same survey location. There are NIST papers with examples. You could probably spend a lot of time on the “why”. If you are getting “poor geometry” errors, either you have an antenna issue, or your receiver is in trouble some other way. It should go into survey mode and stick there. It should be solidly into the survey after about 10 minutes power on. Bob On Oct 24, 2014, at 9:46 PM, Bob Stewart b...@evoria.net wrote: Sorry if these comments are a bit naive, but this is my first exposure to a Z38xx. I've got mine powered on and connected to the antenna. After referring to Stewart's original post (once again) I've managed to download HP's SATSTAT and get it running. When I connected to the REF-1 unit (with the receiver) all I get is comms errors. But when I connect to REF-0, Satstat seems quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one you can connect to, or is REF-1 mute till it's happy with the GPS receiver? The mode says Power-Up: GPS Acquisition, so I guess that's OK. I think things are progressing. It's attempting to survey, but reporting Suspended: poor geometry. I suppose with a little more time this will work itself out? It seems to be slowly tracking more sats, as it's now up to 5. I wonder if there's a way to shortcut the survey process using Satstat? I've got a 48 hour survey done on this antenna with the LEA-6T, so I should be able to input those figures, right? I'll see if I can find anything in a Satstat manual I found. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go
Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 3:39 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 544ad1d1.4040...@rubidium.dyndns.org, Magnus Danielson writes: A great way to illustrate the point of degrees of freedom and the number of sample-points needed to get tight confidence intervals is to see how the high-tau end of a curve updates in TimeLab and behaves as the jiggeling end of a long rope, and as more samples comes in, the jiggeling end moves towards higher taus, but for a particular tau, the amplitude of the jiggeling decreases until it almost stops. This is the effect of the confidence intervals becoming tighter, the range within the real value is becomes smaller and eventually is very tight. ADEV snakes about at the far right end primarily becuase of the phase jitter which dominates at your minimum tau. If you have a phase measurement white noise of 1 ns = ADEV(tau=1) and you expect your ADEV curve to bottom out around 1e-12 at some larger tau, then you have a factor thousand of noise to average out, before a valid ADEV comes out of the noise. This is not any different from any other average out the noise situation in any significant way, sqrt(N) rules, and there is nothing you can do about. In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob *except* to decrease your phase measurement white noise, which is why tuning your 5370 for peak performance is worth days of measurements at the other end of the ADEV. -- 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] Changing ADEV, (was Phase, One edge or two?)
In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? /tvb ___ 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] Efratom FRT-H Lamp removal and supply schematic
Thanks, Corby! Followed your advice, and made a 15x2mm screwdriver by grinding down a carbon steel scraper. A combination of 10min heating on the physical package, plus the tool and got the rubidium bulb out. I've had these oscillators running since 8:00 in the morning, doing a simple XY signal tracing comparing both. The older unit loses lock semi-periodically, and then relocks after a random time from 4 to 10 minutes. The newer unit hasn't lost lock, but there may be an issue with the sma connector. Regards, Sebastian On Fri, Oct 24, 2014 at 11:07 AM, cdel...@juno.com wrote: Sebastion, Let the unit warm up for 10 minutes, then power down and then try the lamp removal. It turns CCW to remove. Use a BIG screwdriver! Cheers, Corby ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
I can't remember when I initially powered up my RFTG-u REF 1 how long it took to give me the green light but I *believe* it was a long time, maybe the better part of 24 hours. I think after testing and being fustrated I forgot to turn it off one night and the next day things looked normal. I have since either lost power or unplugged the unit and when powered up it always takes 14 minutes to aquire satellites, go through the start-up secquence, and give me the green light. If I recall when I first tried getting it to work I had a problem with being impatient and not waiting for the unit to complete the survey or whatever it was doing. I didn't have a computer connected so I was kind of flying blind. To answer another question, the RFTG-u REF 1 does supply +5 volts to the antenna connector to power the active antennas. -Arthur ___ 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] LTE-Lite module
Bob wrote: PHK has a roughly 6 line code snippet that does a basic PLL. Add two more lines to check / clamp the integrator if you wish. That's 8 lines. If you want a D term (to give it an FLL component) add 2 more lines. We're up to 10 lines. It's just a control loop, not a full GPSDO. There's not a lot to it. There's a bit more to it than that. For any loop slow (narrowband) enough to be useful disciplining a good OCXO, I consider a dual- or triple-rate loop filter to be essential. There is also always a fair amount of error-trapping, and other overhead. These can add lines fairly quickly. I'm sure I have lots more to learn about writing efficient code. (But note that there is a difference between coding one's chosen algorithm more efficiently and choosing a different algorithm that is not really what you want, just because it is more efficient.) 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] Changing ADEV, (was Phase, One edge or two?)
Hi If you plot the data versus the six sigma bars (should have been more precise), you will see it walk outside them as well. Bob On Oct 25, 2014, at 1:06 PM, Tom Van Baak t...@leapsecond.com wrote: In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? /tvb ___ 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] Changing ADEV, (was Phase, One edge or two?)
On 10/25/2014 07:06 PM, Tom Van Baak wrote: In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? Error bars works a little differently, as they indicate with some probability (say 1-sigma) within which range the real value is. By the way, sqrt(N) is not very accurate estimator. 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit. The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing. On Oct 25, 2014, at 12:05 PM, Bob Stewart b...@evoria.net wrote: Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is. Bob Bob - AE6RV ___ 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] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 12:19 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 02:02 PM, Bob Camp wrote: On Oct 24, 2014, at 6:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 10/24/2014 11:31 PM, Tom Van Baak wrote: ADEV most certainly does change with time, even for short tau's. Can you elaborate? Such as when, why, what kind of change, how much change, at how short of tau's, over how long of time, and using what type Oscillators? Do you know what in the freq or Phase plot is causing the ADEV to change? I'm happy to let Bob answer his own claim here. I'm curious as well. Unless he's talking about thermal noise, in which case I now believe him 100%. OTOH, for time intervals of minutes to hours or days, the plotted ADEV can often vary. When in doubt, enable error bars in your ADEV calculations or use DAVAR in Stable32, or use Trace History of TmeLab to expose how little or much the computed ADEV depends on tau and N. In general, never do an ADEV calculation without visually checking the phase or frequency time series first. You should make sure that you remove all forms of systematic effects before turning the residue random noise over to ADEV. If you have random noise being modulated in amplitude, you need to measure long enough for the averaging end not to have a great impact on the result. Is days long enough for a 1 second tau? If you define 1,000 x tau as “long enough” you are being way more conservative than just about anybody out there. My claim is that rather than telling everybody to run for 10,000 or 100,000 x tau, simply accept that ADEV does / may change. I did not say that you need to do 1000xtau, that was what someone else said. If you paid attention I said that the number of samples N and the tau0-multiple m for a particular dominant noise (of that tau) creates a certain degree of freedom for a particular ADEV estimator algorithm. Discussing the length of the measure without discussing which estimator algorithm you're using and what confidence interval you aim to reach is just taking a single value and run with it without thinking about it. For ITU-T telecom standards, the measurement length is 12 times the maximum tau, using the overlapping estimator (see O.172, §10.5.1 for limit and G.810 §II.3 for TDEV algorithm). That was chosen to ensure comparability between different implementations for the same type of measure. See O.172 for other relevant details on limits for implementation, tau0 has an upper limit, so does bandwidth. Naturally, these limits is for this specific purpose, algorithms etc. which may not fit the needs of other needs or choices. If you are using under 100 samples for the test (overlapping or not), your confidence is not as high as it might be. You can see ADEV “drift in” over a period of days, even with a lot more than 10 samples. It's only when you do old style non-overlapping that you need to go towards 1000*tau for some reasonable results. Removing this or that *before* you do ADEV can get you on a very slippery slope indeed. Removing drift (either time or frequency) - fine. Removing this or that couple of minutes of data because it makes the result look better, that’s likely to get you in trouble. Your customer (or system, or test setup) isn’t likely to accept a “ADEV is ok most of the time” specification. Agreed. But I've never advocated cutting away samples like that, but rather cancel out the systematics which is not part of the random noise. Is ADEV a good way to measure temperature stability - no of course not. We do indeed have rooms that vary in temperature. They do impact ADEV on a Rb. Removing the delta temperature related data from your ADEV input is not at all easy (1,000 to 10,000 second data …) and I believe it would mis-represent the part. Running in the real world, it’s going to have that ADEV hump. ADEV hump for such systematic is maybe an indication, but not the best way of represent that. It's also not part of the ADEV intended purpose, namely to estimate the random noise effects. Yes indeed you can find FCS papers with all sorts of interesting “adjustments” or no processing at all. The consensus seems to be that if you go past drift correction, you really should have a footnote. When you do not make a drift compensation, and that line shows up, you better explain that too. In the end, ADEV is overused to represent things for which it is not a good tool. You will need other tools in the tool-box to build a good estimation of how that oscillator will behave at some tau. Except that ADEV is used by many as an acceptance test on systems and oscillators. Saying it’s OK to pull data out of a test run makes for a very interesting test design. We certainly use ADEV (without subtractions) here on the list to compare things like GPSDO’s at the
Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?)
Hi How many hours / days/ months / years had the OCXO been off power before the run was started? How soon after turn on did you start taking data? Bob On Oct 25, 2014, at 12:35 PM, Tom Van Baak t...@leapsecond.com wrote: Let's take a real example. Use your own phase data, or grab any of my large data sets (http://leapsecond.com/pages/gpsdo-sim) like ocxo.dat.gz which is a good example of real-life OCXO performance (400,000 seconds of data). Attached are Stable32 plots of frequency, ADEV/MDEV, and dynamic ADEV. As a 3D plot, the latter shows how ADEV(tau) varies during the run. In this case the full data set is broken into about 90 pieces and ADEV is computed for each segment of data (window). If you study the frequency plot you may be able to convince yourself why the DADEV plot looks like it does; ADEV(small tau) is quite constant, while ADEV(larger tau) varies quite a bit. To me, this is as it should be, given how the raw data looks. To explore dynamic ADEV without Stable32 or to go deep with the effects of sample size, see adev6.c / adev6.exe in my tools directory (www.leapsecond.com/tools). Most programs compute ADEV based on the entire data set. But adev6 will compute ADEV(tau) in user defined subsets of data. So, for example, instead of computing ADEV(tau 1) from 400,000 points, you can compute ADEV(tau 1) 400 times in blocks of 1000 points each, or 4000 times in blocks of 100 points each, etc. The default is back-to-back segments but you can specify overlapping segments. Using various combination of parameters, it's pretty instructive to see the noise in computed value of ADEV. The 4th attachment is a TimeLab plot of the data set with trace = 1 (default), 10, and 100. In some cases I prefer this sort of display. One can get complacent with simple error bars and forget that 1 - 68% = 32% of the points must always lie outside the error bars, by definition. /tvbocxo-freq-1.gifocxo-amdev-1.gifocxo-dadev-1.gifocxo-trace-1-10-100.gif___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob, The thing is: I don't really need a frequency standard other than as a reference for my GPSDO project. I'll have to look into pulling out that message every second to see if the correction makes it a suitable phase reference. No, the nanosecond level probably isn't suitable for your needs, but I think it fits mine. My target audience remains the hobbyist, not the professional. It will be interesting, as it ages in, to see how it likes the antenna at the south window that it's sharing with my project. If I don't see any glitches, it may be time to pull the wire through the attic, rather than through the window. I guess I could also get some good information running it with the antenna in the attic for awhile. But you do make a good point about power supplies. Santa may bring a small UPS for Christmas to power this, my project, and the splitter. At the very least, this gives me a lot of information about GPSDOs that I didn't have in the past. And there's that EFC pin-out back near the OCXO that I could watch with my 3456A, to see what the dynamics are on a real GPSDO, once it ages in. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 1:22 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit. The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing. On Oct 25, 2014, at 12:05 PM, Bob Stewart b...@evoria.net wrote: Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is. Bob Bob - AE6RV ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
b...@evoria.net said: I'm pretty sure it does provide +5 to the antenna. I didn't understand what I was seeing for quite some time yesterday, and it seemed like it was telling me it didn't see an antenna. ... No, it's telling you that your antenna is not in a good location. When the satellites it can see are good enough, the survey makes progress. When they go behind a tree or whatever, it stops. Survey mode requires 4 satellites, and maybe the S/N has to be above some threshold. Remember it is using an old GPS module. They are far less sensitive than modern units. -- These are my opinions. I hate spam. ___ 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] LTE-Lite module
Hi We are not talking about a system (like GPS) that has junk data coming in. In this case, the phase detector gives you a very good estimate of the delta between input and output in real time. The error trapping / shifting / multi this and that simply isn’t needed in this case. The solution is much easier than the GPSDO. Let the OCXO warm up for a day or two. Yes it could be a week. Adjust it with a pot to be close to frequency. (This is a basement project). Fire up the loop. Let it settle. Come back in an hour or two and all is well. Confirm this by watching a (good) DVM on the EFC line. It’s a low gain / long time constant loop. It will take a bit to settle. Yes, if code is what gets you excited, put in an array for the coefficients. Then add a timer to step the index. The timer will add about 4 lines. The step process will be on auto-pilot, but that makes it easy. You will settle faster, the net result after settling will be about the same. If a year from now it’s unlocked, re-adjust the pot. Maybe check it with a DVM every so often and adjust it before it unlocks. Not a lot to it. Simple code to write Easy board to build. Does just what it needs to do. Not a commercial system at all. It does not need to be. It’s going to do everything you need to do and be much easier to get running than something far more complex. The idea is to make the simplest system that will do the trick, not make it so hard that nobody ever tries. The target audience is a basement experimenter not NIST. It’s ok in this case to replace a bunch of code with an inquiring mind. Bob On Oct 25, 2014, at 11:23 AM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote: PHK has a roughly 6 line code snippet that does a basic PLL. Add two more lines to check / clamp the integrator if you wish. That's 8 lines. If you want a D term (to give it an FLL component) add 2 more lines. We're up to 10 lines. It's just a control loop, not a full GPSDO. There's not a lot to it. There's a bit more to it than that. For any loop slow (narrowband) enough to be useful disciplining a good OCXO, I consider a dual- or triple-rate loop filter to be essential. There is also always a fair amount of error-trapping, and other overhead. These can add lines fairly quickly. I'm sure I have lots more to learn about writing efficient code. (But note that there is a difference between coding one's chosen algorithm more efficiently and choosing a different algorithm that is not really what you want, just because it is more efficient.) 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] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 2:18 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/25/2014 07:06 PM, Tom Van Baak wrote: In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? Error bars works a little differently, as they indicate with some probability (say 1-sigma) within which range the real value is. By the way, sqrt(N) is not very accurate estimator. But it is a common way to express the fact that your data is unlikely to converge any faster than sqrt(N)… Bob 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob, I was just going to say it would be cool if Lady Heather eventually would work. You read my mind. I can hope!! 73, Bill, WA2DVU Cape May -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, October 25, 2014 12:12 PM To: Bob Stewart; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi If 6) Lady Heather does not play well with one :( My guess is that the Z3805 has pretty much the same “stuff” in it. They both come from the same era and (may) have the same MTI OCXO in them. Bob --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. The PPS output on these is not typically designed as a “smoothed’ time reference. The HP / Symmetricom design philosophy seems to have been that dropping or adding time was an ok thing to do. Your 90 ns to 50 ns change is a prefect example of this in action. One simple experiment: Set up a divider on the 10 or 15 MHz output. A dead bug mounted PIC will do, there are many other alternatives. Compare that PPS to the PPS out of the device. If your divider works properly, it should give you a quick way to see if they are slipping the PPS relative to the OCXO. Bob On Oct 25, 2014, at 2:44 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, The thing is: I don't really need a frequency standard other than as a reference for my GPSDO project. I'll have to look into pulling out that message every second to see if the correction makes it a suitable phase reference. No, the nanosecond level probably isn't suitable for your needs, but I think it fits mine. My target audience remains the hobbyist, not the professional. It will be interesting, as it ages in, to see how it likes the antenna at the south window that it's sharing with my project. If I don't see any glitches, it may be time to pull the wire through the attic, rather than through the window. I guess I could also get some good information running it with the antenna in the attic for awhile. But you do make a good point about power supplies. Santa may bring a small UPS for Christmas to power this, my project, and the splitter. At the very least, this gives me a lot of information about GPSDOs that I didn't have in the past. And there's that EFC pin-out back near the OCXO that I could watch with my 3456A, to see what the dynamics are on a real GPSDO, once it ages in. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 1:22 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit. The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing. On Oct 25, 2014, at 12:05 PM, Bob Stewart b...@evoria.net wrote: Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is. Bob Bob - AE6RV ___ 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] Efratom FRT-H Lamp removal and supply schematic
Sebastion, Try swapping the lamps and see if the loosing lock problem follows the lamp! Corby ___ 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] Changing ADEV, (was Phase, One edge or two?)
How many hours / days/ months / years had the OCXO been off power before the run was started? How soon after turn on did you start taking data? Hi Bob, On the ocxo.dat data set, the frequency drift rate was down to just 5e-11 a day so it's likely the OCXO had been powered for many days, even weeks. I don't know for sure w/o finding an old log book. The web page says the data came from run3004/log50187.txt, which is was a free-running TBolt in November 2008 measured with a TSC 5120 against a locked HP 58503B. I can re-run the measurement if you wish. Why do you ask? I have many data sets here, both with lower drift (e.g., rubidium or masers), or higher drift, or a variety of phase measurement instruments. Lots of samples is usually better than few samples, but it doesn't take a lot to pin the stability of an oscillator down to a couple of dB. In some cases, computed ADEV is not a number that gets more precise or more accurate the more data you collect. You can hit a floor and it starts to diverge if you collect for too many weeks or months. This is expected. HDEV would be better. An analogy: no one is interested in the mean of 1,000,000 days of earth temperature data. Yes, it will be a very precise number, if you apply the mindless sqrt(N) rule-of-thumb. But once you get enough data, looking at periodicity, jumps, outliers, and trends over time is usually far more important than blindly calculating a simple mean or standard deviation from an entire data set. You can argue all day if the ADEV(tau 1000s) should be 3.7e-12 or 3.75e-12 or 4e-12. Regardless, it's clearly about halfway between 1e-12 and 1e-11. Below 1 dB, the rest is what day it is, what hour you started the run, how long you collected data, or how your lab feels that day. Here's an example of ADEV(tau 1000) from adev6: C:\Tmpadev6 /a ocxo.dat 1000 1000 0/40 a 3.706451e-012 398000 C:\Tmpadev6 /a ocxo.dat 1000 4 1000 0/40 a 4.100519e-012 38000 1000 4/40 a 3.912714e-012 38000 1000 8/40 a 3.736134e-012 38000 1000 12/40 a 4.413685e-012 38000 1000 16/40 a 3.050424e-012 38000 1000 20/40 a 3.692079e-012 38000 1000 24/40 a 3.367214e-012 38000 1000 28/40 a 3.223972e-012 38000 1000 32/40 a 3.742055e-012 38000 1000 36/40 a 3.897041e-012 38000 C:\Tmpadev6 /a ocxo.dat 1000 4000 1000 0/40 a 7.804138e-012 2000 10004000/40 a 4.085721e-012 2000 10008000/40 a 3.368610e-012 2000 1000 12000/40 a 2.890283e-012 2000 1000 16000/40 a 2.408464e-012 2000 1000 2/40 a 5.823737e-012 2000 1000 24000/40 a 4.127749e-012 2000 1000 28000/40 a 4.310555e-012 2000 1000 32000/40 a 3.375545e-012 2000 1000 36000/40 a 4.166632e-012 2000 1000 4/40 a 3.052641e-012 2000 1000 44000/40 a 4.718652e-012 2000 1000 48000/40 a 4.238576e-012 2000 1000 52000/40 a 5.275587e-012 2000 1000 56000/40 a 5.695453e-012 2000 1000 6/40 a 3.669497e-012 2000 1000 64000/40 a 3.107038e-012 2000 1000 68000/40 a 4.863025e-012 2000 1000 72000/40 a 1.882393e-012 2000 1000 76000/40 a 2.395768e-012 2000 1000 8/40 a 1.606562e-012 2000 1000 84000/40 a 6.180515e-012 2000 1000 88000/40 a 3.201972e-012 2000 1000 92000/40 a 2.023414e-012 2000 1000 96000/40 a 1.515005e-012 2000 1000 10/40 a 2.343072e-012 2000 1000 104000/40 a 4.249873e-012 2000 1000 108000/40 a 2.676816e-012 2000 1000 112000/40 a 1.656133e-012 2000 1000 116000/40 a 2.411179e-012 2000 1000 12/40 a 4.081474e-012 2000 1000 124000/40 a 2.997803e-012 2000 1000 128000/40 a 2.095393e-012 2000 1000 132000/40 a 5.760947e-012 2000 1000 136000/40 a 7.075811e-012 2000 1000 14/40 a 1.769521e-012 2000 1000 144000/40 a 3.358276e-012 2000 1000 148000/40 a 4.893182e-012 2000 1000 152000/40 a 1.936321e-012 2000 1000 156000/40 a 1.578596e-012 2000 1000 16/40 a 3.601683e-012 2000 1000 164000/40 a 2.287769e-012 2000 1000 168000/40 a 3.073412e-012 2000 1000 172000/40 a 2.291148e-012 2000 1000 176000/40 a 5.813071e-012 2000 1000 18/40 a 3.669111e-012 2000 1000 184000/40 a 1.766833e-012 2000 1000 188000/40 a 2.527836e-012 2000 1000 192000/40 a 1.982012e-012 2000 1000 196000/40 a 2.387086e-012 2000 1000 20/40 a 4.483388e-012 2000 1000 204000/40 a 1.825970e-012 2000 1000 208000/40 a 1.405565e-012 2000 1000 212000/40 a 5.431766e-012 2000 1000 216000/40 a 1.325479e-012 2000
Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup
These units are ideal for powering via a float charged lead acid battery. Use two 12 volt / 7 AH batteries in series and adjust the regulated float power supply to 28.0 volts. Be sure to use a diode from the supply to the battery just in case the supply can't be back fed during a power fail. Tom - Original Message - From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 3:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. Bob ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Bob, The antenna is actually outside. It's mounted to the eave just below the roof line. It seems to be a better antenna than the one in the attic. It's the best I can do at the moment. I'll have to do a comparison of the PPS from this and the PPS from my LEA-6T. I think they're reporting the phase offset of the 10MHz to the PPS, but as you say, I haven't measured it yet. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 2:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. The PPS output on these is not typically designed as a “smoothed’ time reference. The HP / Symmetricom design philosophy seems to have been that dropping or adding time was an ok thing to do. Your 90 ns to 50 ns change is a prefect example of this in action. One simple experiment: Set up a divider on the 10 or 15 MHz output. A dead bug mounted PIC will do, there are many other alternatives. Compare that PPS to the PPS out of the device. If your divider works properly, it should give you a quick way to see if they are slipping the PPS relative to the OCXO. Bob On Oct 25, 2014, at 2:44 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, The thing is: I don't really need a frequency standard other than as a reference for my GPSDO project. I'll have to look into pulling out that message every second to see if the correction makes it a suitable phase reference. No, the nanosecond level probably isn't suitable for your needs, but I think it fits mine. My target audience remains the hobbyist, not the professional. It will be interesting, as it ages in, to see how it likes the antenna at the south window that it's sharing with my project. If I don't see any glitches, it may be time to pull the wire through the attic, rather than through the window. I guess I could also get some good information running it with the antenna in the attic for awhile. But you do make a good point about power supplies. Santa may bring a small UPS for Christmas to power this, my project, and the splitter. At the very least, this gives me a lot of information about GPSDOs that I didn't have in the past. And there's that EFC pin-out back near the OCXO that I could watch with my 3456A, to see what the dynamics are on a real GPSDO, once it ages in. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 1:22 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit. The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing. On Oct 25, 2014, at 12:05 PM, Bob Stewart b...@evoria.net wrote: Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is. Bob Bob - AE6RV ___ 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
Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?)
Bob, On 10/25/2014 08:15 PM, Bob Camp wrote: Hi On Oct 25, 2014, at 12:19 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 02:02 PM, Bob Camp wrote: On Oct 24, 2014, at 6:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 10/24/2014 11:31 PM, Tom Van Baak wrote: ADEV most certainly does change with time, even for short tau's. Can you elaborate? Such as when, why, what kind of change, how much change, at how short of tau's, over how long of time, and using what type Oscillators? Do you know what in the freq or Phase plot is causing the ADEV to change? I'm happy to let Bob answer his own claim here. I'm curious as well. Unless he's talking about thermal noise, in which case I now believe him 100%. OTOH, for time intervals of minutes to hours or days, the plotted ADEV can often vary. When in doubt, enable error bars in your ADEV calculations or use DAVAR in Stable32, or use Trace History of TmeLab to expose how little or much the computed ADEV depends on tau and N. In general, never do an ADEV calculation without visually checking the phase or frequency time series first. You should make sure that you remove all forms of systematic effects before turning the residue random noise over to ADEV. If you have random noise being modulated in amplitude, you need to measure long enough for the averaging end not to have a great impact on the result. Is days long enough for a 1 second tau? If you define 1,000 x tau as “long enough” you are being way more conservative than just about anybody out there. My claim is that rather than telling everybody to run for 10,000 or 100,000 x tau, simply accept that ADEV does / may change. I did not say that you need to do 1000xtau, that was what someone else said. If you paid attention I said that the number of samples N and the tau0-multiple m for a particular dominant noise (of that tau) creates a certain degree of freedom for a particular ADEV estimator algorithm. Discussing the length of the measure without discussing which estimator algorithm you're using and what confidence interval you aim to reach is just taking a single value and run with it without thinking about it. For ITU-T telecom standards, the measurement length is 12 times the maximum tau, using the overlapping estimator (see O.172, §10.5.1 for limit and G.810 §II.3 for TDEV algorithm). That was chosen to ensure comparability between different implementations for the same type of measure. See O.172 for other relevant details on limits for implementation, tau0 has an upper limit, so does bandwidth. Naturally, these limits is for this specific purpose, algorithms etc. which may not fit the needs of other needs or choices. If you are using under 100 samples for the test (overlapping or not), your confidence is not as high as it might be. You can see ADEV “drift in” over a period of days, even with a lot more than 10 samples. Yes. One needs to look at what happens to judge when you can trust the values. In the standard case, there would be a lot of samples, with a minumum of 360 for the extreme-case. Yes indeed you can find FCS papers with all sorts of interesting “adjustments” or no processing at all. The consensus seems to be that if you go past drift correction, you really should have a footnote. When you do not make a drift compensation, and that line shows up, you better explain that too. In the end, ADEV is overused to represent things for which it is not a good tool. You will need other tools in the tool-box to build a good estimation of how that oscillator will behave at some tau. Except that ADEV is used by many as an acceptance test on systems and oscillators. Saying it’s OK to pull data out of a test run makes for a very interesting test design. We certainly use ADEV (without subtractions) here on the list to compare things like GPSDO’s at the system level. I use ADEV, TDEV, phase-plot and frequency plot to best illustrate and understand what is happening. Would be using FFT for long-term if only TimeLab would support it for normal counter measures. Would be using phase-noise more if I had a TimePod at work. 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] LTE-Lite module
Mostly we don't even write the guts of those algorithms. For example, you'd use a PID library. One line to create a PID controller object then one line to call the PID for each phase measurement. This goes double for, say, drawing a graph of the phase over time to an LCD display, you'd use a graphic library for that. And for communicating over USB to a computer. Who would want to take time to learn the details of USB and LCD graphic controllers? Most code we write is just glue that connects functions. After a a few decades doing this I'd have to say that reinventing well-tested wheels is the certain mark of a beginner/amateur. Either they don't understand how to use these libraries or they don't know they exist or think they can do it better. They spend 4X longer to get something working and then it still does not cover all the corner cases and exceptions those libraries might cover. Ages ago CPU performance or space might mean you HAD to tightly code, but now even a $1.79 8-bit AVR chip can hold well over the equivalent of 1,000 lines of C++ code. OK there is the case a manufactures who wants to be able to use the $1.69 chip and save 10 cents but most projects are not going to be built in high qualities. Back on-tpic. Now that we have many low cast ($10 and under) uP development boards building a GPSDO is simple. You don't even need a custom PCB or many chips. And the simple $10 controller can have a fancy LCD screen and connect to a computer and log stats and it can all be up and running in a day or two. If someone today wanted a harder challenge type project that would push the state of that art out a little, why not build an ensemble type device? One that accepts PPS timing from several sources, figures out in realtime which of them to accept then runs several local oscillators, perhaps an Rb and a couple OCXOs and compares their outputs. So now you use both Rb and GPS, maybe a few of each to track timing. A while back I tried to prove to myself how easy it is now to build a GPSDO that was good enough to drive typical lab equipment. Something like a dozen lines of C code and $8 did it. It's no longer cutting edge to built these. Time to think about the next generation kind of low-cost device. So maybe one could combine the best properties of several different kinds of devices? Has this been done yet? On Sat, Oct 25, 2014 at 8:23 AM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote: PHK has a roughly 6 line code snippet that does a basic PLL. Add two more lines to check / clamp the integrator if you wish. That's 8 lines. If you want a D term (to give it an FLL component) add 2 more lines. We're up to 10 lines. It's just a control loop, not a full GPSDO. There's not a lot to it. There's a bit more to it than that. For any loop slow (narrowband) enough to be useful disciplining a good OCXO, I consider a dual- or triple-rate loop filter to be essential. There is also always a fair amount of error-trapping, and other overhead. These can add lines fairly quickly. I'm sure I have lots more to learn about writing efficient code. (But note that there is a difference between coding one's chosen algorithm more efficiently and choosing a different algorithm that is not really what you want, just because it is more efficient.) 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. -- Chris Albertson Redondo Beach, California ___ 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] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 4:04 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 08:15 PM, Bob Camp wrote: Hi On Oct 25, 2014, at 12:19 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 02:02 PM, Bob Camp wrote: On Oct 24, 2014, at 6:25 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Tom, On 10/24/2014 11:31 PM, Tom Van Baak wrote: ADEV most certainly does change with time, even for short tau's. Can you elaborate? Such as when, why, what kind of change, how much change, at how short of tau's, over how long of time, and using what type Oscillators? Do you know what in the freq or Phase plot is causing the ADEV to change? I'm happy to let Bob answer his own claim here. I'm curious as well. Unless he's talking about thermal noise, in which case I now believe him 100%. OTOH, for time intervals of minutes to hours or days, the plotted ADEV can often vary. When in doubt, enable error bars in your ADEV calculations or use DAVAR in Stable32, or use Trace History of TmeLab to expose how little or much the computed ADEV depends on tau and N. In general, never do an ADEV calculation without visually checking the phase or frequency time series first. You should make sure that you remove all forms of systematic effects before turning the residue random noise over to ADEV. If you have random noise being modulated in amplitude, you need to measure long enough for the averaging end not to have a great impact on the result. Is days long enough for a 1 second tau? If you define 1,000 x tau as “long enough” you are being way more conservative than just about anybody out there. My claim is that rather than telling everybody to run for 10,000 or 100,000 x tau, simply accept that ADEV does / may change. I did not say that you need to do 1000xtau, that was what someone else said. If you paid attention I said that the number of samples N and the tau0-multiple m for a particular dominant noise (of that tau) creates a certain degree of freedom for a particular ADEV estimator algorithm. Discussing the length of the measure without discussing which estimator algorithm you're using and what confidence interval you aim to reach is just taking a single value and run with it without thinking about it. For ITU-T telecom standards, the measurement length is 12 times the maximum tau, using the overlapping estimator (see O.172, §10.5.1 for limit and G.810 §II.3 for TDEV algorithm). That was chosen to ensure comparability between different implementations for the same type of measure. See O.172 for other relevant details on limits for implementation, tau0 has an upper limit, so does bandwidth. Naturally, these limits is for this specific purpose, algorithms etc. which may not fit the needs of other needs or choices. If you are using under 100 samples for the test (overlapping or not), your confidence is not as high as it might be. You can see ADEV “drift in” over a period of days, even with a lot more than 10 samples. Yes. One needs to look at what happens to judge when you can trust the values. In the standard case, there would be a lot of samples, with a minumum of 360 for the extreme-case. Yes indeed you can find FCS papers with all sorts of interesting “adjustments” or no processing at all. The consensus seems to be that if you go past drift correction, you really should have a footnote. When you do not make a drift compensation, and that line shows up, you better explain that too. In the end, ADEV is overused to represent things for which it is not a good tool. You will need other tools in the tool-box to build a good estimation of how that oscillator will behave at some tau. Except that ADEV is used by many as an acceptance test on systems and oscillators. Saying it’s OK to pull data out of a test run makes for a very interesting test design. We certainly use ADEV (without subtractions) here on the list to compare things like GPSDO’s at the system level. I use ADEV, TDEV, phase-plot and frequency plot to best illustrate and understand what is happening. Would be using FFT for long-term if only TimeLab would support it for normal counter measures. Would be using phase-noise more if I had a TimePod at work. I would suggest adding the Hadamard deviation to that list. It highlights some things that the others do not. Bob 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] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 3:34 PM, Tom Van Baak t...@leapsecond.com wrote: How many hours / days/ months / years had the OCXO been off power before the run was started? How soon after turn on did you start taking data? Hi Bob, On the ocxo.dat data set, the frequency drift rate was down to just 5e-11 a day so it's likely the OCXO had been powered for many days, even weeks. I don't know for sure w/o finding an old log book. The web page says the data came from run3004/log50187.txt, which is was a free-running TBolt in November 2008 measured with a TSC 5120 against a locked HP 58503B. I can re-run the measurement if you wish. Why do you ask? I ask because the most common place I see ADEV changing over time without systematic issues is when they have been off power for a long time. If you warm them up and run them for a while, the ADEV tends to become much more predictable. Bob I have many data sets here, both with lower drift (e.g., rubidium or masers), or higher drift, or a variety of phase measurement instruments. Lots of samples is usually better than few samples, but it doesn't take a lot to pin the stability of an oscillator down to a couple of dB. In some cases, computed ADEV is not a number that gets more precise or more accurate the more data you collect. You can hit a floor and it starts to diverge if you collect for too many weeks or months. This is expected. HDEV would be better. An analogy: no one is interested in the mean of 1,000,000 days of earth temperature data. Yes, it will be a very precise number, if you apply the mindless sqrt(N) rule-of-thumb. But once you get enough data, looking at periodicity, jumps, outliers, and trends over time is usually far more important than blindly calculating a simple mean or standard deviation from an entire data set. You can argue all day if the ADEV(tau 1000s) should be 3.7e-12 or 3.75e-12 or 4e-12. Regardless, it's clearly about halfway between 1e-12 and 1e-11. Below 1 dB, the rest is what day it is, what hour you started the run, how long you collected data, or how your lab feels that day. Here's an example of ADEV(tau 1000) from adev6: C:\Tmpadev6 /a ocxo.dat 1000 1000 0/40 a 3.706451e-012 398000 C:\Tmpadev6 /a ocxo.dat 1000 4 1000 0/40 a 4.100519e-012 38000 1000 4/40 a 3.912714e-012 38000 1000 8/40 a 3.736134e-012 38000 1000 12/40 a 4.413685e-012 38000 1000 16/40 a 3.050424e-012 38000 1000 20/40 a 3.692079e-012 38000 1000 24/40 a 3.367214e-012 38000 1000 28/40 a 3.223972e-012 38000 1000 32/40 a 3.742055e-012 38000 1000 36/40 a 3.897041e-012 38000 C:\Tmpadev6 /a ocxo.dat 1000 4000 1000 0/40 a 7.804138e-012 2000 10004000/40 a 4.085721e-012 2000 10008000/40 a 3.368610e-012 2000 1000 12000/40 a 2.890283e-012 2000 1000 16000/40 a 2.408464e-012 2000 1000 2/40 a 5.823737e-012 2000 1000 24000/40 a 4.127749e-012 2000 1000 28000/40 a 4.310555e-012 2000 1000 32000/40 a 3.375545e-012 2000 1000 36000/40 a 4.166632e-012 2000 1000 4/40 a 3.052641e-012 2000 1000 44000/40 a 4.718652e-012 2000 1000 48000/40 a 4.238576e-012 2000 1000 52000/40 a 5.275587e-012 2000 1000 56000/40 a 5.695453e-012 2000 1000 6/40 a 3.669497e-012 2000 1000 64000/40 a 3.107038e-012 2000 1000 68000/40 a 4.863025e-012 2000 1000 72000/40 a 1.882393e-012 2000 1000 76000/40 a 2.395768e-012 2000 1000 8/40 a 1.606562e-012 2000 1000 84000/40 a 6.180515e-012 2000 1000 88000/40 a 3.201972e-012 2000 1000 92000/40 a 2.023414e-012 2000 1000 96000/40 a 1.515005e-012 2000 1000 10/40 a 2.343072e-012 2000 1000 104000/40 a 4.249873e-012 2000 1000 108000/40 a 2.676816e-012 2000 1000 112000/40 a 1.656133e-012 2000 1000 116000/40 a 2.411179e-012 2000 1000 12/40 a 4.081474e-012 2000 1000 124000/40 a 2.997803e-012 2000 1000 128000/40 a 2.095393e-012 2000 1000 132000/40 a 5.760947e-012 2000 1000 136000/40 a 7.075811e-012 2000 1000 14/40 a 1.769521e-012 2000 1000 144000/40 a 3.358276e-012 2000 1000 148000/40 a 4.893182e-012 2000 1000 152000/40 a 1.936321e-012 2000 1000 156000/40 a 1.578596e-012 2000 1000 16/40 a 3.601683e-012 2000 1000 164000/40 a 2.287769e-012 2000 1000 168000/40 a 3.073412e-012 2000 1000 172000/40 a 2.291148e-012 2000 1000 176000/40 a 5.813071e-012 2000 1000 18/40 a 3.669111e-012 2000 1000 184000/40 a 1.766833e-012 2000
Re: [time-nuts] Changing ADEV, (was Phase, One edge or two?)
Bob, On 10/25/2014 08:54 PM, Bob Camp wrote: Hi On Oct 25, 2014, at 2:18 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/25/2014 07:06 PM, Tom Van Baak wrote: In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? Error bars works a little differently, as they indicate with some probability (say 1-sigma) within which range the real value is. By the way, sqrt(N) is not very accurate estimator. But it is a common way to express the fact that your data is unlikely to converge any faster than sqrt(N)… Yes, but it gives you false hope of how quickly it really converged, as the cross-correlations make you converge even slower than sqrt(N). 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi The gotcha may be that they only slip time under unusual conditions. Warmup / settling in could be one such condition. It may take some detailed looking to spot it. Bob On Oct 25, 2014, at 3:45 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, The antenna is actually outside. It's mounted to the eave just below the roof line. It seems to be a better antenna than the one in the attic. It's the best I can do at the moment. I'll have to do a comparison of the PPS from this and the PPS from my LEA-6T. I think they're reporting the phase offset of the 10MHz to the PPS, but as you say, I haven't measured it yet. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 2:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. The PPS output on these is not typically designed as a “smoothed’ time reference. The HP / Symmetricom design philosophy seems to have been that dropping or adding time was an ok thing to do. Your 90 ns to 50 ns change is a prefect example of this in action. One simple experiment: Set up a divider on the 10 or 15 MHz output. A dead bug mounted PIC will do, there are many other alternatives. Compare that PPS to the PPS out of the device. If your divider works properly, it should give you a quick way to see if they are slipping the PPS relative to the OCXO. Bob On Oct 25, 2014, at 2:44 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, The thing is: I don't really need a frequency standard other than as a reference for my GPSDO project. I'll have to look into pulling out that message every second to see if the correction makes it a suitable phase reference. No, the nanosecond level probably isn't suitable for your needs, but I think it fits mine. My target audience remains the hobbyist, not the professional. It will be interesting, as it ages in, to see how it likes the antenna at the south window that it's sharing with my project. If I don't see any glitches, it may be time to pull the wire through the attic, rather than through the window. I guess I could also get some good information running it with the antenna in the attic for awhile. But you do make a good point about power supplies. Santa may bring a small UPS for Christmas to power this, my project, and the splitter. At the very least, this gives me a lot of information about GPSDOs that I didn't have in the past. And there's that EFC pin-out back near the OCXO that I could watch with my 3456A, to see what the dynamics are on a real GPSDO, once it ages in. Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 1:22 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Remember - these gizmos are designed as a CDMA base station reference, not as a Time Nut frequency (or time) standard. They (likely) had a +/- 100 ns spec on the gizmo for static time error when locked to GPS. The little trained squirrel inside makes an executive decision to move the PPS when it gets to close to that (or some other) limit. The filter algorithm in these adapts to the rate of change of the OCXO. On a unit that has been on the shelf since 2000 or 2001, it probably will take a while for the OCXO to settle down and hit a low aging rate. Until it does, the filter will not “stretch out” to it’s longest tau / lowest bandwidth. You can watch the thing switch, it’s pretty obvious on a phase plot when it does. The switch points are where the back and forth phase change slows way down compared to what it was doing. On Oct 25, 2014, at 12:05 PM, Bob Stewart b...@evoria.net wrote: Regarding my comment earlier that my GPSDO and this Z3812A don't agree on phase. I see just now a fairly quick phase movement of the phase between the two, and I see that there is a line on the Satstat program that may explain this: 1PPS TI +50.0 ns relative to GPS. Just a few minutes ago, it said -90.0 ns. Watching a bit more closely, the phase difference seems to track this figure +/- the phase error on my unit. Can anyone shed any light on this? Bottom line: Hook it up on an independent power supply. Give it it’s own antenna. Put it in a corner away from drafts and crazy temperature changes. Just forget about it. Let it run forever and ever. It will (eventually) settle down and do a pretty good job. How far it settles depends on a lot of things, including just how good the particular OCXO you have is. Bob Bob - AE6RV
[time-nuts] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time An Inside Look | PBS
Hi: I don't have TV and wonder if anyone who has PBS can comment on this program? preview at: https://www.youtube.com/watch?v=RhDvGhFbpq8 -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time AnInside Look | PBS
Well, there is no mention of precision or time measurement. Seems like a simple, harmless presentation to me. I will admit that from time to time my wife does object to some of his work! We do watch Frontline and are grateful for many of the topics they cover. Lee A. Mushel - Original Message - From: Brooke Clarke bro...@pacific.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, October 25, 2014 12:51 PM Subject: [time-nuts] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time AnInside Look | PBS Hi: I don't have TV and wonder if anyone who has PBS can comment on this program? preview at: https://www.youtube.com/watch?v=RhDvGhFbpq8 -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html ___ 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] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time An Inside Look | PBS
I just heard about this book on NPR. On 10/25/2014 12:51 PM, Brooke Clarke wrote: Hi: I don't have TV and wonder if anyone who has PBS can comment on this program? preview at: https://www.youtube.com/watch?v=RhDvGhFbpq8 ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Might want to dial that back a bit. Since 12V/7ah batteries are mentioned I am assuming standard small gelcell units. Proper float voltage for a deep cycle is lower than a SLI type, and gellcell even lower. Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right on for long life use of _small_ batteries. Equalizing charge wold be 14 - 14.2. Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff between 12 - 24 months v.s. 5 - 7 years service life. On 10/25/14, 11:39 AM, Tom Miller wrote: These units are ideal for powering via a float charged lead acid battery. Use two 12 volt / 7 AH batteries in series and adjust the regulated float power supply to 28.0 volts. Be sure to use a diode from the supply to the battery just in case the supply can't be back fed during a power fail. Tom - Original Message - From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 3:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. Bob ___ 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] Changing ADEV, (was Phase, One edge or two?)
Hi On Oct 25, 2014, at 4:08 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 08:54 PM, Bob Camp wrote: Hi On Oct 25, 2014, at 2:18 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/25/2014 07:06 PM, Tom Van Baak wrote: In the case of the TimePod, the data can be presented when you have *very* few samples to work with. That said, it is interesting to watch it bring up error bars (which are indeed correctly calculated) and then see the trace walk outside those error bars as the run progresses. There are other measurements that are a bit less susceptible to this. None of them have any magic to get around sqrt(N). Bob Maybe I don't understand error bars. For a dynamic display like TimeLab, walking outside (1 sigma) error bars is expected about 1/3 of the time, no? Error bars works a little differently, as they indicate with some probability (say 1-sigma) within which range the real value is. By the way, sqrt(N) is not very accurate estimator. But it is a common way to express the fact that your data is unlikely to converge any faster than sqrt(N)… Yes, but it gives you false hope of how quickly it really converged, as the cross-correlations make you converge even slower than sqrt(N). Except that management would really like it to converge as N … Bob 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] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time An Inside Look | PBS
It's a series. The first night there were two shows back-to-back and I think the 2nd one was the time-related one. Its vaguely like the old Connections PBS series where; this thing lead to that thing, which led to... I was multitasking so might not be the best critic, but I found it very grade school level. Most of the interesting stuff was glossed over. I was unimpressed enough that I never watched any of the following shows after those two. Maybe others have other opinions. -Rex On 10/25/2014 11:51 AM, Brooke Clarke wrote: Hi: I don't have TV and wonder if anyone who has PBS can comment on this program? preview at: https://www.youtube.com/watch?v=RhDvGhFbpq8 ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
Hi Assuming the supplies are rated for a (fairy normal) 32V max, there is plenty of room to get everything arranged right. You *might* need to dig up a supply that is 28V nominal versus 24V nominal. The 10 or 15% adjust range likely will not quite get the 24V unit up where you would want it to be. The (say) 29V supply goes to one of your voting diodes and runs the unit when it’s off battery. The other voting diode goes to the top end of the battery stack. Your charger circuit puts what ever it wants on the battery to keep it happy. Yes, when you go on battery you loose .7 V (or less) due to the diode. If you want to get fancy, put a FET across the diode and eliminate the diode drop once everything gets going. The bigger question is - how do you disconnect the battery after it’s done its thing for long enough? Deep discharge of the cells is not good for them either. Yes this gets more complex by the minute …. where is that guy who was getting all preachy about keeping things simple :)….. Bob On Oct 25, 2014, at 5:32 PM, Christopher Brown cbr...@woods.net wrote: Might want to dial that back a bit. Since 12V/7ah batteries are mentioned I am assuming standard small gelcell units. Proper float voltage for a deep cycle is lower than a SLI type, and gellcell even lower. Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right on for long life use of _small_ batteries. Equalizing charge wold be 14 - 14.2. Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff between 12 - 24 months v.s. 5 - 7 years service life. On 10/25/14, 11:39 AM, Tom Miller wrote: These units are ideal for powering via a float charged lead acid battery. Use two 12 volt / 7 AH batteries in series and adjust the regulated float power supply to 28.0 volts. Be sure to use a diode from the supply to the battery just in case the supply can't be back fed during a power fail. Tom - Original Message - From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 3:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. Bob ___ 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] Changing ADEV, (was Phase, One edge or two?)
Bob, On 10/25/2014 11:45 PM, Bob Camp wrote: Hi On Oct 25, 2014, at 4:08 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Bob, On 10/25/2014 08:54 PM, Bob Camp wrote: Hi Error bars works a little differently, as they indicate with some probability (say 1-sigma) within which range the real value is. By the way, sqrt(N) is not very accurate estimator. But it is a common way to express the fact that your data is unlikely to converge any faster than sqrt(N)… Yes, but it gives you false hope of how quickly it really converged, as the cross-correlations make you converge even slower than sqrt(N). Except that management would really like it to converge as N … I bet they do, until you explain to them the consequence of that... with over-optimistic numbers making the product look bad when it hits reality and smearing the trust in the company and product names... There is a certain art to potty-train management. 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] Lucent KS-24361/Z3812A GPSDO initial setup
use nickel-iron battery [Edison Accumulator] which is not sensitive to deep discharge, over charge and last for min twenty years - unfortunately it does not fit into the American business model --because it last to long--so it is not produced in the US any more. 73 Alex On 10/25/2014 5:30 PM, Bob Camp wrote: Hi Assuming the supplies are rated for a (fairy normal) 32V max, there is plenty of room to get everything arranged right. You *might* need to dig up a supply that is 28V nominal versus 24V nominal. The 10 or 15% adjust range likely will not quite get the 24V unit up where you would want it to be. The (say) 29V supply goes to one of your voting diodes and runs the unit when it’s off battery. The other voting diode goes to the top end of the battery stack. Your charger circuit puts what ever it wants on the battery to keep it happy. Yes, when you go on battery you loose .7 V (or less) due to the diode. If you want to get fancy, put a FET across the diode and eliminate the diode drop once everything gets going. The bigger question is - how do you disconnect the battery after it’s done its thing for long enough? Deep discharge of the cells is not good for them either. Yes this gets more complex by the minute …. where is that guy who was getting all preachy about keeping things simple :)….. Bob ___ 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] Lucent KS-24361/Z3812A GPSDO initial setup
I really don't disagree with you. I did say run the supply at 28.0 and use a diode off the supply to the battery. That would place the float voltage at 27.3 or so. Best would be to follow the manufacturers float service recommendations. Ideally it should also be temperature compensated with a -2.4 mV/°C slope. Not a problem with how we use these in the lab though. And yes to get the longest run time, just power the main unit from the battery as Bob suggested. Now I am just waiting on some DB-9 connectors. I ran out of them and the local RatShak went TU. Tom - Original Message - From: Christopher Brown cbr...@woods.net To: time-nuts@febo.com Sent: Saturday, October 25, 2014 5:32 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Might want to dial that back a bit. Since 12V/7ah batteries are mentioned I am assuming standard small gelcell units. Proper float voltage for a deep cycle is lower than a SLI type, and gellcell even lower. Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right on for long life use of _small_ batteries. Equalizing charge wold be 14 - 14.2. Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff between 12 - 24 months v.s. 5 - 7 years service life. On 10/25/14, 11:39 AM, Tom Miller wrote: These units are ideal for powering via a float charged lead acid battery. Use two 12 volt / 7 AH batteries in series and adjust the regulated float power supply to 28.0 volts. Be sure to use a diode from the supply to the battery just in case the supply can't be back fed during a power fail. Tom - Original Message - From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net Cc: Time Nuts time-nuts@febo.com Sent: Saturday, October 25, 2014 3:01 PM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi Spend the effort, get an antenna outside the house. Beg / borrow / steal a UPS. Even a brand new one is less than you paid for the 3812. Bob ___ 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] Cheap Frequency chip with serial output
Hello, just wanted to know if there is any very cheap pre programmed pic or something similar to get frequency of a Yaesu FT-102 radio. I need it to know its frequency, either the VFO alone (sub 6MHz) or possibly its real rx and tx frequency (up to 30MHz). Using the VFO would be easier but then I will have to probe the mechanical band commutator. I know Arduino could be a solution, just wanted to know if something smaller is available, possibly with rs232. TIA Giuseppe Marullo IW2JWW - JN45RQ ___ 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] HOW WE GOT TO NOW WITH STEVEN JOHNSON | Time An Inside Look | PBS
I'd agree that the shows are very basic, but if it was full of stuff equivalent to time-nuts level in any of the topics he covers, very few would be able to understand it and might not watch it. It is a lot like the old Connections series. I've found both interesting. In the case of the time eposode, we get a bit about the longitude problem, how the growth of railroad travel drove time zones in the US, etc. The average person probably never learned any of that in school. (Don't remember it if I did.) Hopefully it will make a few folks understand that a lot of things taken for granted now weren't always that way and how different life was before development of modern time keeping devices. The same with most other technology - it doesn't just magically appear without a lot of earlier developements. Unfortunately, being on PBS, it probably won't reach a lot of people who could use a bit of exposure to the idea that sometimes technology or knowledge ends up being useful in ways that weren't thought of at the time so some of those seemingly useless wastes of money turn out to be just the opposite. I just watched the one on glass a couple of days ago. As an example, he made the argument that the development of printing and the use of eyeglasses went together. Before printed books most people had less need for good near vision (or at least made do without it), but as books became more common more people wanted to read them driving the need for eyeglasses which wouldn't have been possible without clear glass and the technology to make lenses. I can't say that is really true or not, but it sounds reasonable and it wasn't something I had thought much about before. Alan On Sat, Oct 25, 2014 at 6:01 PM, Rex r...@sonic.net wrote: It's a series. The first night there were two shows back-to-back and I think the 2nd one was the time-related one. Its vaguely like the old Connections PBS series where; this thing lead to that thing, which led to... I was multitasking so might not be the best critic, but I found it very grade school level. Most of the interesting stuff was glossed over. I was unimpressed enough that I never watched any of the following shows after those two. Maybe others have other opinions. -Rex On 10/25/2014 11:51 AM, Brooke Clarke wrote: Hi: I don't have TV and wonder if anyone who has PBS can comment on this program? preview at: https://www.youtube.com/watch?v=RhDvGhFbpq8 ___ 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.
