Re: [time-nuts] GPS leap second pending (TBolt/Heather)
my monitor ( see http://www.romahn.info/tbolt2lcd/ ) also shows leap sec pending. This info is from Thunderbolt. Götz = I see no spurious indications from the NTP servers I happen to be using. I wrote a program to check: http://www.satsignal.eu/software/net.htm#NTPLeapTrace Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 2015 Leap Second
Hi Chuck, Thanks for the comprehensive list. Very nice work. This bug in many versions of the HP SmartClock-series has shown up before (but not always in the 90's, see below). What's going is yet another problem with how developers write code for leap seconds. It's really hard to get right. There is a distinction between when leap seconds are *announced*, usually 2 to 6 months in advance (somewhat variable, almost random) and the month in which a leap second actually *occurs* (a very specific instant). Unfortunately, the word pending is ambiguous since it does not distinguish between the casual advising that a leap second will occur many months in the future and the actual month in which the leap second occurs. This leads to both human and technical confusion. In addition, there is confusion about when a leap second *can* occur. The UTC specification implies a leap second may occur at the end of any month, although it is most likely the 6th or 12th month, and if not that, the 3rd and 9th month. Some vendors have misinterpreted this to mean, for example, that if a leap second is announced in January it will therefore occur in March (rather than June). Oops. These are difficult bugs to fix. For most of the 70's, 80's and 90's leap seconds were announced only a few months ahead of time. But in the past decade, IERS had been able to predict leap seconds almost 6 months in advance -- and this exposes bugs in software that used to work just fine. /tvb - Original Message - From: Charles Zabilski To: Tom Van Baak Sent: Saturday, January 24, 2015 9:47 AM Subject: 2015 Leap Second Tom: Unfortunately I no longer receiver emails from time nuts due to my @yahoo.com email address. In response to your desire to pull together a list of GPS receivers' handling of the upcoming leap second, please see the following: Receiver1st Reported dateReported Leap Sec Date Z3801A 22 Jan 201531 Mar 2015 Z3811A 22 Jan 201531 Mar 2015 Z3816A 22 Jan 201531 Mar 2015 58503A 22 Jan 201531 Mar 2015 58503B 22 Jan 201531 Mar 2015 59551A 22 Jan 201531 Mar 2015 Z3805A No Leap Second Indication Z3815A No Leap Second Indication Please note that I usually only check for the leap second notifications in the mornings. In all probability the notifications occurred some hours earlier. Also, I am communicating with the GPS receivers through the external Com port using my GPS Control Program and not examining the internal GPS module data stream. I hope this is of some assistance. Chuck Zabilski BD Systems, Inc. Evergreen, CO ___ 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] question Alan deviation measured with Timelab and counters
Hi guys. After several experiments I could discover that the bad ADEV from the two GPSDO DUT are due to GPS lock losses. This is probably because the antenna is outside the windows but half the sky is hidden. We can see the on the frequency plot the sharp change of 0.5Hz and the locking. Good point. I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. I will add two balanced mixers (minicircuits), IF filters and amplifiers. Does anyone has an idea of what I could add for this evaluation ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : mardi 20 janvier 2015 23:15 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi, Following the tests results in the previous email, today I've performed additional measurements showing that the repeatability of the GPSDO DUT is not great but is coming from the design. I've tested several over sources and repeatability is correct. I can already make some measurement. Good ! Now I'd like to improve. First I'm going to implement a squarer and then I will work on the DMTD... I'm thinking to make a setup on the table, and possibly make a small PCB then. Any comment for the tests results of yesterday here under ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : lundi 19 janvier 2015 22:32 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi Here are the results of today's experiments. plots and TIM files attached to this email. Setup #1 : dark blue I've done again the floor measurement with same conditions : HP58503 for 10 MHz Standard, 1PPS for the EXT gating and the Rb on channel A. Same result (hopefully) Setup #2 : Pink Then I've made what Magnus has suggested, i.e. using the 1 PPS on Channel A, the Rb on channel B and internal gating The ADEV has increased by more than 1 order of magnitude. I guess this confirms the 1PPS stability is lower than the 10 MHz Setup #3-6 : Dark Green, Red, Light blue and Dark yellow. I've measured several times the GPSDO DUT with SEParate inputs. 1PPS on EXT, Rb on channel A and DUT on channel B. This gives 4 different plots... When starting the measurement the plots starts directly at different values... Mmmm very strange. Is it coming for the setup of the GPSDO ? To be investigated further with other sources. This is the plan for tomorrow. However the overal shape of the plot sounds relevant to me. Setup #7-8 + #9 not showed here I've tested the suggested splitted same signal on both inputs with 1m coax for channel B. I've discovered that when swaping the GPSDO on the standard input and the Rb on the channel A I have a slight difference. In order to confirm I've made two time each measurement and this confirms that having the Rb on channel A and GPSDO on the standard input gives the lowest ADEV. The setup #9 which is the same than the light green gives the superimposed plot on that one... So what does it mean ? One of the two sources is better than the other, but which one ? Some other comments : - Swaping signals between channel A and B gives the same ADEV (setup #4 and 5, light blue and red) - On some measurement on the GPSDO DUT, (not displayed here), I could see during the measurement suddenly an increase of one order of magnitude. The HP5370A do not show any difference (the time interval value continues to move with a beat but visually impossible to quantify if the value between two values has increased. No explanation for that. I'll redo the test with some other sources to check if it comes for the measurement system or the GPSDO DUT In conclusion, 1. swaping the Rb and HP58503 doesn't give the same result. The GPSDO has standard seems the best (or the Rb measured) 2. the measurement on the GPSDO DUT gives different results with nearly one order of magnitude difference but shape is still the same. 3. the 1PPS must be connected on the EXT gating input What do you think ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de steph.rey Envoyé : lundi 19 janvier 2015 16:44 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Actually I'm working in the RF department of a big lab, designing RF electronics mainly in microwaves range. I'm luckilly having some tools around to play with and a lot of components like
Re: [time-nuts] question Alan deviation measured with Timelab and counters
Hi, Just a stupid question on Timelab. Why do I have the plot with 1/4 for the time actually used for the measurement ? I can see that the plot is updated every 4 samples but the scale is not relevant. The sample interval is correctly set (1s) Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : mardi 20 janvier 2015 23:15 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi, Following the tests results in the previous email, today I've performed additional measurements showing that the repeatability of the GPSDO DUT is not great but is coming from the design. I've tested several over sources and repeatability is correct. I can already make some measurement. Good ! Now I'd like to improve. First I'm going to implement a squarer and then I will work on the DMTD... I'm thinking to make a setup on the table, and possibly make a small PCB then. Any comment for the tests results of yesterday here under ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : lundi 19 janvier 2015 22:32 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi Here are the results of today's experiments. plots and TIM files attached to this email. Setup #1 : dark blue I've done again the floor measurement with same conditions : HP58503 for 10 MHz Standard, 1PPS for the EXT gating and the Rb on channel A. Same result (hopefully) Setup #2 : Pink Then I've made what Magnus has suggested, i.e. using the 1 PPS on Channel A, the Rb on channel B and internal gating The ADEV has increased by more than 1 order of magnitude. I guess this confirms the 1PPS stability is lower than the 10 MHz Setup #3-6 : Dark Green, Red, Light blue and Dark yellow. I've measured several times the GPSDO DUT with SEParate inputs. 1PPS on EXT, Rb on channel A and DUT on channel B. This gives 4 different plots... When starting the measurement the plots starts directly at different values... Mmmm very strange. Is it coming for the setup of the GPSDO ? To be investigated further with other sources. This is the plan for tomorrow. However the overal shape of the plot sounds relevant to me. Setup #7-8 + #9 not showed here I've tested the suggested splitted same signal on both inputs with 1m coax for channel B. I've discovered that when swaping the GPSDO on the standard input and the Rb on the channel A I have a slight difference. In order to confirm I've made two time each measurement and this confirms that having the Rb on channel A and GPSDO on the standard input gives the lowest ADEV. The setup #9 which is the same than the light green gives the superimposed plot on that one... So what does it mean ? One of the two sources is better than the other, but which one ? Some other comments : - Swaping signals between channel A and B gives the same ADEV (setup #4 and 5, light blue and red) - On some measurement on the GPSDO DUT, (not displayed here), I could see during the measurement suddenly an increase of one order of magnitude. The HP5370A do not show any difference (the time interval value continues to move with a beat but visually impossible to quantify if the value between two values has increased. No explanation for that. I'll redo the test with some other sources to check if it comes for the measurement system or the GPSDO DUT In conclusion, 1. swaping the Rb and HP58503 doesn't give the same result. The GPSDO has standard seems the best (or the Rb measured) 2. the measurement on the GPSDO DUT gives different results with nearly one order of magnitude difference but shape is still the same. 3. the 1PPS must be connected on the EXT gating input What do you think ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de steph.rey Envoyé : lundi 19 janvier 2015 16:44 À : Discussion of precise time and frequency measurement Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Actually I'm working in the RF department of a big lab, designing RF electronics mainly in microwaves range. I'm luckilly having some tools around to play with and a lot of components like mixers/amplifiers/couplers/splitters/attenuators, ... almost whatever the frequency is up to several tens of GHz. At home since the last 20 years I could as well get nice instruments. The next two measuring tools really missing and for which I'm limited are the phase noise and stability measurement and possibly a good standard. My Effratom FRK Rb is old and probably not the best from a phase noise and stability point of view but until now has never been characterized. Otherwise I've almost everything I
Re: [time-nuts] question Alan deviation measured with Timelab and counters
Hi If you go back in the archives and look for the discussions on “Collins hard limiter” they will lead you to some other areas to consider when trying to square low frequency sine wave signals. The quick summary is that you need a series of bandwidth limited limiter stages ahead of what ever you use as a squaring circuit. There are a number of ways to make these stages, each with their benefits and drawbacks. The limiting process has a much larger impact on the results than the choice of squaring circuit. Bob On Jan 24, 2015, at 3:07 PM, Stéphane Rey steph@wanadoo.fr wrote: Hi guys. After several experiments I could discover that the bad ADEV from the two GPSDO DUT are due to GPS lock losses. This is probably because the antenna is outside the windows but half the sky is hidden. We can see the on the frequency plot the sharp change of 0.5Hz and the locking. Good point. I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. I will add two balanced mixers (minicircuits), IF filters and amplifiers. Does anyone has an idea of what I could add for this evaluation ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : mardi 20 janvier 2015 23:15 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi, Following the tests results in the previous email, today I've performed additional measurements showing that the repeatability of the GPSDO DUT is not great but is coming from the design. I've tested several over sources and repeatability is correct. I can already make some measurement. Good ! Now I'd like to improve. First I'm going to implement a squarer and then I will work on the DMTD... I'm thinking to make a setup on the table, and possibly make a small PCB then. Any comment for the tests results of yesterday here under ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : lundi 19 janvier 2015 22:32 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi Here are the results of today's experiments. plots and TIM files attached to this email. Setup #1 : dark blue I've done again the floor measurement with same conditions : HP58503 for 10 MHz Standard, 1PPS for the EXT gating and the Rb on channel A. Same result (hopefully) Setup #2 : Pink Then I've made what Magnus has suggested, i.e. using the 1 PPS on Channel A, the Rb on channel B and internal gating The ADEV has increased by more than 1 order of magnitude. I guess this confirms the 1PPS stability is lower than the 10 MHz Setup #3-6 : Dark Green, Red, Light blue and Dark yellow. I've measured several times the GPSDO DUT with SEParate inputs. 1PPS on EXT, Rb on channel A and DUT on channel B. This gives 4 different plots... When starting the measurement the plots starts directly at different values... Mmmm very strange. Is it coming for the setup of the GPSDO ? To be investigated further with other sources. This is the plan for tomorrow. However the overal shape of the plot sounds relevant to me. Setup #7-8 + #9 not showed here I've tested the suggested splitted same signal on both inputs with 1m coax for channel B. I've discovered that when swaping the GPSDO on the standard input and the Rb on the channel A I have a slight difference. In order to confirm I've made two time each measurement and this confirms that having the Rb on channel A and GPSDO on the standard input gives the lowest ADEV. The setup #9 which is the same than the light green gives the superimposed plot on that one... So what does it mean ? One of the two sources is better than the other, but which one ? Some other comments : - Swaping signals between channel A and B gives the same ADEV (setup #4 and 5, light blue and red) - On some measurement on the GPSDO DUT, (not displayed here), I could see during the measurement suddenly an increase of one order of magnitude. The HP5370A do not show any difference (the time interval value continues to move with a beat but visually impossible to quantify if the value between two values has increased. No explanation for that. I'll redo the test with some other sources to check if it comes for the measurement system or the GPSDO DUT In conclusion, 1. swaping the Rb and HP58503 doesn't give the same result. The GPSDO has standard seems the best (or the Rb measured) 2. the measurement on the GPSDO DUT gives different results
Re: [time-nuts] question Alan deviation measured with Timelab and counters
Bob et Stéphane, The Collins hard limiter is a fancy squarer circuit. In short, the Collins hard limiter is what I hinted about in my earlier message. Rather than hitting the hard limiter of the comparator directly, with the slew-rate issue I gave. Collins observed that if you provide a linear amplifier (with limiting), you can increase the slew-rate of the signal. At the same time you will add noise from the amplifier. Now, to limit the noise going forward, you bandwidth limit the amplifier, which is fine as long as it supports the outgoing slew-rate of that amp. This helps you a bit and many times a single linear stage suffice to make the trigger noise sufficiently low, but then you can cascade these, and for many research DMTD setups has some hand-hacked variant. Collins then made a systematic approach to optimize the bandwidth and gain for a number of stages. Collins did however not think about amplifiers with different noise-contributions, but Bruce Griffiths have then generalized it further. This makes sense, since for higher slew-rates, you need faster amps, but their noise-contribution will be fairly low considering the high slew-rate coming into it. The original Collins article is not freely available. Therefore I recommend you to dip your nose into Bruce pages: http://www.ko4bb.com/~bruce/ Zero Crossing Detectors and Collins: http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html paper: http://www.ko4bb.com/~bruce/GeneralisedCollinsHardLimiterPaperV3B.pdf So, squaring up with 74AC04 or comparator and similar stuff might be an interesting exercise, but you end up doing the same exercise as going straight into the counters comparator. Try to amplify yourself out of the situation, try different gain settings. Make the habit of measuring the slew-rate (at the trigger point). It's interesting to note that not many counter support the feature of measuring slew-rate directly, the closest one usually get is to get the rise-time, but it needs scaling with the difference of the start and stop trigger-points, and you want them not at 10%-90% but closer. Cheers, Magnus On 01/24/2015 11:36 PM, Bob Camp wrote: Hi If you go back in the archives and look for the discussions on “Collins hard limiter” they will lead you to some other areas to consider when trying to square low frequency sine wave signals. The quick summary is that you need a series of bandwidth limited limiter stages ahead of what ever you use as a squaring circuit. There are a number of ways to make these stages, each with their benefits and drawbacks. The limiting process has a much larger impact on the results than the choice of squaring circuit. Bob On Jan 24, 2015, at 3:07 PM, Stéphane Rey steph@wanadoo.fr wrote: Hi guys. After several experiments I could discover that the bad ADEV from the two GPSDO DUT are due to GPS lock losses. This is probably because the antenna is outside the windows but half the sky is hidden. We can see the on the frequency plot the sharp change of 0.5Hz and the locking. Good point. I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. I will add two balanced mixers (minicircuits), IF filters and amplifiers. Does anyone has an idea of what I could add for this evaluation ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : mardi 20 janvier 2015 23:15 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi, Following the tests results in the previous email, today I've performed additional measurements showing that the repeatability of the GPSDO DUT is not great but is coming from the design. I've tested several over sources and repeatability is correct. I can already make some measurement. Good ! Now I'd like to improve. First I'm going to implement a squarer and then I will work on the DMTD... I'm thinking to make a setup on the table, and possibly make a small PCB then. Any comment for the tests results of yesterday here under ? Cheers Stephane -Message d'origine- De : time-nuts [mailto:time-nuts-boun...@febo.com] De la part de Stéphane Rey Envoyé : lundi 19 janvier 2015 22:32 À : 'Discussion of precise time and frequency measurement' Objet : Re: [time-nuts] question Alan deviation measured with Timelab and counters Hi Here are the results of today's experiments. plots and TIM files attached to this email. Setup #1 : dark blue I've done again the floor measurement with same conditions : HP58503 for 10 MHz Standard, 1PPS for the EXT gating and the Rb on channel A. Same result (hopefully) Setup #2 : Pink Then I've made what Magnus has
[time-nuts] (no subject)
Bob, I am relatively new to the list and still learning the jargon and concepts. You wrote: There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. Could you or one of the other members elaborate on the what is meant by D above. Does it have anything to do with a flat spot in the loop? -- S. Cash Olsen KD5SSJ ARRL Technical Specialist Message: 10 Date: Sat, 24 Jan 2015 09:18:15 -0500 From: Bob Camp kb...@n1k.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Questions regarding tuning Thunderbolt with LadyHeather -- GPSDO's Message-ID: 6581eb02-9792-432f-b143-25b41fb29...@n1k.org Content-Type: text/plain; charset=utf-8 There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. ___ 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] question Alan deviation measured with Timelab and counters
Hi Stéphane, have you read W. Riley's paper on a DMTD system? http://www.wriley.com/A%20Small%20DMTD%20System.pdf Cheers, Adrian Stéphane Rey schrieb: Hi guys. After several experiments I could discover that the bad ADEV from the two GPSDO DUT are due to GPS lock losses. This is probably because the antenna is outside the windows but half the sky is hidden. We can see the on the frequency plot the sharp change of 0.5Hz and the locking. Good point. I'm now trying to evaluate various architectures of 2-channels squarers and a DMDT. For that I'm designing a PCB with 4 squarers : simple 74ac04 gate biased at VCC/2, a LT1016 comparator, the transistor based differential amplifier from Winzel and the one from Charles. I will add two balanced mixers (minicircuits), IF filters and amplifiers. Does anyone has an idea of what I could add for this evaluation ? Cheers Stephane snip ___ 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] (no subject)
Hi A classic control loop in it’s simplest form has only one term. That is often referred to as a proportional term. When the control signal (or error) changes by A the output changes by A times that term. Often in shorthand notation this term is refereed to as a P term. The next thing that some people add to a control loop is an integrator. It looks at the control signal (or error) has a constant offset of A, the integrator sums up the A’s. The output of an integrator would eventually go to infinity with a constant control input (or error) into it. This term is often referred to as an I term. Lastly people add a term to the control loop that responds to the rate of change in the control signal (or error). The faster the change, the bigger this signal gets. This is commonly refereed to as a Derivative term. In shorthand it’s talked about as the D term. The net result is a three element control loop running what’s called a PID algorithm . The P and I can also be described by a time constant and a damping. That’s what the Trimble software lets you do. The implication is that it’s just a PI loop. In fact it appears to be a PID loop and you can’t get at the D term. For a much more clearly worded explanation of all this, there’s http://en.wikipedia.org/wiki/PID_controller Bob On Jan 24, 2015, at 6:35 PM, Cash Olsen radio.kd5...@gmail.com wrote: Bob, I am relatively new to the list and still learning the jargon and concepts. You wrote: There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. Could you or one of the other members elaborate on the what is meant by D above. Does it have anything to do with a flat spot in the loop? -- S. Cash Olsen KD5SSJ ARRL Technical Specialist Message: 10 Date: Sat, 24 Jan 2015 09:18:15 -0500 From: Bob Camp kb...@n1k.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Questions regarding tuning Thunderbolt with LadyHeather -- GPSDO's Message-ID: 6581eb02-9792-432f-b143-25b41fb29...@n1k.org Content-Type: text/plain; charset=utf-8 There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. ___ 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] (no subject)
Cash, Typically a PLL loop uses a PI loop-filter, making it a PI-control system with a steered integrator in the form of the oscillator. Many other control systems prefer to use the PID controller, and Bob found that there is a D factor in there. The factors at hand is: P = Proportinal I = Integrate D = Diffrentiate If you have the reference phase phi_ref and the oscillator output phase of phi_out, the detected phase difference Vd is Vd = Kd * (phi_ref - phi_out) The oscillator steering is Vf can then be formulated as VD = Vd - Vd_prev Vd_prep = Vd VI = VI + I*Vd Vf = D*VD + P*Vd + VI Thus, the D factor steers how much of the time-derivate of the phase goes into the frequency steering. The P factor steers the phase and the I factor the amount of integrated signal. A loop in stable condition will have the integrator force Vd to be around zero, so VI will hold the frequency correction needed. The I will scale how quickly it will learn this frequency. The P will scale the AC part of Vd for dynamics, typically you set the damping. The D factor can play an important part in the track-in process and the dynamics of that. A key factor is the sample-time T. I and D needs to be scaled with T to get the same behavior for alternate values sampling periods. Cheers, Magnus On 01/25/2015 12:35 AM, Cash Olsen wrote: Bob, I am relatively new to the list and still learning the jargon and concepts. You wrote: There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. Could you or one of the other members elaborate on the what is meant by D above. Does it have anything to do with a flat spot in the loop? ___ 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] GPS leap second pending (TBolt/Heather)
My Ball/EFRATOM MFS-209's MGPS receiver has announced there is a leap second scheduled for 6/30/2015 at midnite. The MGPS's engine is a 6 channel Trimble of some sort. -Chuck Harris Götz Romahn wrote: my monitor ( see http://www.romahn.info/tbolt2lcd/ ) also shows leap sec pending. This info is from Thunderbolt. Götz ___ 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] 2015 Leap Second
More info from Charles (stuck in time-nuts @yahoo @aol prison): /tvb - Original Message - From: Charles Zabilski To: Tom Van Baak Sent: Saturday, January 24, 2015 1:52 PM Subject: Re: 2015 Leap Second Tom: Thanks for the update. I got around that problem in later versions of the GPS Control Program with alternate menu selections: Set Leap Second as Indicated and Set Leap Second Only in Jun, Dec If the GPS Receiver indicates the incorrect month (as the HP ones do), you select the Jun, Dec menu and it forces the programs display to hold off until June and reflects this fact in the display of the pending leap second. Last time I recalled that the GPS receiver performed the leap second in June 2012, notwithstanding the incorrect indicated date. The GPS Control Program also jams the program's display to force the correct counting sequence 58, 59, 60, 00, 01 etc. notwithstanding the incorrect sequence the receiver itself performs. However al lof these fixes are downstream of the receiver, There have been postings about the Datum TS-2100 being a second slow once it detected a pending leap second in the GPS data. I was able to correct this issue by forcing a -1 leap second in the 2100 today with the Leap -1 01/24/2015 21:32:00 command. The 2100 is now displaying the correct time. I also followed it up with the correct leap second command Leap 1 07/01/2015 00:00:00 so that it will keep proper time following the actual leap second. I would appreciate it if you could post this info. Thanks Chuck Zabilski On Saturday, January 24, 2015 2:35 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Chuck, Thanks for the comprehensive list. Very nice work. This bug in many versions of the HP SmartClock-series has shown up before (but not always in the 90's, see below). What's going is yet another problem with how developers write code for leap seconds. It's really hard to get right. There is a distinction between when leap seconds are *announced*, usually 2 to 6 months in advance (somewhat variable, almost random) and the month in which a leap second actually *occurs* (a very specific instant). Unfortunately, the word pending is ambiguous since it does not distinguish between the casual advising that a leap second will occur many months in the future and the actual month in which the leap second occurs. This leads to both human and technical confusion. In addition, there is confusion about when a leap second *can* occur. The UTC specification implies a leap second may occur at the end of any month, although it is most likely the 6th or 12th month, and if not that, the 3rd and 9th month. Some vendors have misinterpreted this to mean, for example, that if a leap second is announced in January it will therefore occur in March (rather than June). Oops. These are difficult bugs to fix. For most of the 70's, 80's and 90's leap seconds were announced only a few months ahead of time. But in the past decade, IERS had been able to predict leap seconds almost 6 months in advance -- and this exposes bugs in software that used to work just fine. /tvb - Original Message - From: Charles Zabilski To: Tom Van Baak Sent: Saturday, January 24, 2015 9:47 AM Subject: 2015 Leap Second Tom: Unfortunately I no longer receiver emails from time nuts due to my @yahoo.com email address. In response to your desire to pull together a list of GPS receivers' handling of the upcoming leap second, please see the following: Receiver1st Reported dateReported Leap Sec Date Z3801A 22 Jan 201531 Mar 2015 Z3811A 22 Jan 201531 Mar 2015 Z3816A 22 Jan 201531 Mar 2015 58503A 22 Jan 201531 Mar 2015 58503B 22 Jan 201531 Mar 2015 59551A 22 Jan 201531 Mar 2015 Z3805A No Leap Second Indication Z3815A No Leap Second Indication Please note that I usually only check for the leap second notifications in the mornings. In all probability the notifications occurred some hours earlier. Also, I am communicating with the GPS receivers through the external Com port using my GPS Control Program and not examining the internal GPS module data stream. I hope this is of some assistance. Chuck Zabilski BD Systems, Inc. Evergreen, CO ___ 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] GPS leap second pending (TBolt/Heather)
my monitor ( see http://www.romahn.info/tbolt2lcd/ ) also shows leap sec pending. This info is from Thunderbolt. Götz Am 23.01.2015 um 04:38 schrieb Didier Juges: Re: Note that this is not a GPS problem, nor a Trimble problem. It's just a problem with user written software. I agree with Mark's comment. His software makes no attempt to interpret or correct the information put out by the Thunderbolt, it simply reports it. My Thunderbolt Monitor does the same thing. I can imagine a different tool with a different objective doing something different with good reason, but that is not what Lady Heather does, by choice rather than by mistake. It's a problem with user's expectations :) On Thu, Jan 22, 2015 at 8:05 PM, Mark Sims hol...@hotmail.com wrote: Nope, it's not an error or a problem. That column of data is showing a decode of the 16 status bits that the Tbolt is providing.The Trimble docs say that bit is a Leap Pending bit, so that is what Heather displays. It would be wrong to try and mask/adjust the report of the receiver's status word. Lady Heather is a monitor and display program for Trimble timing receivers. It shows the values that the receiver is reporting (usually to the precision that the receiver provides... think that micro-degree temperature value is really that accurate? I have a lovely bridge that you might want to purchase) But that's what the receiver is sending, so that's what gets displayed. - Note that this is not a GPS problem, nor a Trimble problem. It's just a problem with user written software. ___ 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] GPS leap second pending (TBolt/Heather)
Agreed that simply showing the status of the leap-pending bit is the logical thing to do, and it's definitely not something I would call a bug. It would be extremely cool, though, if it used the data from packet 0x58 to display a countdown timer. I'd volunteer to make the change, but I have an excellent excuse to avoid doing so, namely that I'm going to be offline for a few days while I move. :) This also means that the test/demo server at ke5fx.dyndns.org:45000 will be down for a while, probably at least a week. If you click on the KE5FX TBolt (Seattle, USA) link and it times out, that'll be why. -- john, KE5FX Miles Design LLC Nope, it's not an error or a problem. That column of data is showing a decode of the 16 status bits that the Tbolt is providing.The Trimble docs say that bit is a Leap Pending bit, so that is what Heather displays. It would be wrong to try and mask/adjust the report of the receiver's status word. Lady Heather is a monitor and display program for Trimble timing receivers. It shows the values that the receiver is reporting (usually to the precision that the receiver provides... think that micro-degree temperature value is really that accurate? I have a lovely bridge that you might want to purchase) But that's what the receiver is sending, so that's what gets displayed. ___ 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] Questions regarding tuning Thunderbolt with Lady Heather
Hello Nuts, I have been playing a bit tuning a Thunderbolt with Lady Heather and now have more questions than answers. The collective time-nut brain would be appreciated. 1. Using the '' command I can change the damping and time constant in LH. Are these values immediately transferred to the TB? 2. Do I have to use the LH 'e' command to permenantly save new damping and time constant values to the TB? 3. After using the '' and 'e' command the lock-in behaviour of the TB does not seem to change. Is this normal behaviour? Is one set of values used when locking and the adjusted values used once it is phase locked? 4.Is there some way to read out the values stored in the TB? When I use the 'e' command on the TB, change values in LH, then restart LH and the TB I see the last values given to LH, and not what I thought was saved with the 'e' command. 5. If the TB is placed in hold mode and the DAC set to 0.0 volts it actually goes to 0.2 volts (min is at -5, max is at +5, and iv is 0.0 which it actually starts at on power up). Anyone know why? Thanks in advance for any guidance! Regards, Skip Withrow ___ 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] LTE Lite time error
I see a one second error in the NMEA string from my LTE Lite. It lost a second between 23:33:34 and 23:33:42 21-Jan-2015 UTC. I happened to check because a report of a one second error in some NTP pool servers. Just a heads up -- I'll be following up with JL directly. -- Paul ___ 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] Symmetricom TymServe 2100-GPS currently fails with GPS offset
I'm seeing the same thing with my TS-2100 - it is one second behind WWV based on the front panel display. My ET-6000 appears to be in sync. What's interesting though is that I have a little applet on my iPhone (NetTime) that connects to nist.time.gov and it is also a second behind. -Bob On 01/23/2015 03:36 PM, Esa Heikkinen wrote: Hi! It seems that there's serious bug in Symmetricom Tymserve 2100 most recent firmware (V4.1). When leap second pending flag was added to GPS transmission (according to data shown by Lady Heather) the Tymserve's time started to be exactly 1 second late from UTC! Currently it claims that current UTC offset is 17 seconds, while Lady Heather shows 16 seconds. Also if I compare the NTP time with another NTP servers it is really 1 seconds late. Playing with telnet: ? utcoffset GPS -- UTC Offset = 17 (And of course there's no way to set this manually) However in the utcinfo data the dTLs value received from GPS is correct (16) but it seems that Tymserver firmware uses wrong value dTLsf, which is the future value of UTC offset after leap second event: ? utcinfo A0:0.000 A1:0.000 dTLs:16 ToT:61440.000 WNt:1829 WNLsf:1851 DN:3 dTLsf:17 It seems that there's no way to fix this. There's also leap second command available, having no efffect on this. Everyone who owns this device please check what's going on with it... To me this is somehow suprising, assumed this to be professional grade, reliable and trouble free instrument, but obviously it's not. No wonder why these are sold so cheap on Ebay (where I got mine). Maybe only way is to run this with 1PPS from Thunderbolt until the leap second period is over. ___ 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] Symmetricom TymServe 2100-GPS currently fails with GPS offset
Robert Watzlavick kirjoitti: I'm seeing the same thing with my TS-2100 - it is one second behind WWV based on the front panel display. My ET-6000 appears to be in sync. Ok - then this is verified... So the only way (for me) is to run this with 1PPS from Thunderbolt. Good thing is that Tymserve itself support leap second and when 1PPS is used it can be set manually. I did some quick tests and noticed that correct command to set the leap second event is: tim leap 1 07/01/2015 00:00:00 SPOLER ALERT - if you want to see the leap yourself, stop reading... It did not go 23:59:60, it was stopped at 23:59:59 two seconds. -- 73s! Esa OH4KJU ___ 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] Questions regarding tuning Thunderbolt with Lady Heather
Hi On Jan 23, 2015, at 10:58 PM, Skip Withrow skip.with...@gmail.com wrote: Hello Nuts, I have been playing a bit tuning a Thunderbolt with Lady Heather and now have more questions than answers. The collective time-nut brain would be appreciated. 1. Using the '' command I can change the damping and time constant in LH. Are these values immediately transferred to the TB? yes, but … 2. Do I have to use the LH 'e' command to permenantly save new damping and time constant values to the TB? yes 3. After using the '' and 'e' command the lock-in behaviour of the TB does not seem to change. Is this normal behaviour? Is one set of values used when locking and the adjusted values used once it is phase locked? only used in phase lock, not in frequency lock or phase alignment. 4.Is there some way to read out the values stored in the TB? When I use the 'e' command on the TB, change values in LH, then restart LH and the TB I see the last values given to LH, and not what I thought was saved with the 'e' command at least on mine, LH reports the saved values. 5. If the TB is placed in hold mode and the DAC set to 0.0 volts it actually goes to 0.2 volts (min is at -5, max is at +5, and iv is 0.0 which it actually starts at on power up). Anyone know why? It will use the stored value if it does not have adequate confidence in the holdover value. In holdover mode it will go back to it’s “best guess” holdover value rather than just locking at the current DAC. Bob Thanks in advance for any guidance! Regards, Skip Withrow ___ 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] Questions regarding tuning Thunderbolt with Lady Heather -- GPSDO's
Hi Maybe a bit more information, much of it applies to all GPSDO’s : The TBolt first goes through a process to get the OCXO roughly on frequency and to get the PPS approximately aligned. That process is not impacted by the time constant and damping. The OCXO goes a bit crazy during this process. It then starts the phase lock process with a short time constant. As the OCXO settles in, it will step out to a progressively longer time constant. It does this based on it’s internal estimates of lock quality. Unless you are already at maximum time constant and have a good internal estimate, changing the time constant has no immediate impact. On most GPSDO’s and with most OCXO’s under most conditions, the step out process takes days or weeks. The damping number does impact the performance in the maximum time constant mode. It may be scaled as the time constant is changed. There does appear to be a D in the TBolt loop. For what ever reason, that’s not a changeable value. The D does scale with the time constant. When in lock mode, the TBolt is a PLL and not a FLL. As the “phase in” (the pps from the gps) moves, the frequency of the OCXO will change to keep the “phase out” (PPS output) aligned. As the unit is running, it keeps track of the average DAC value that puts the OCXO on frequency. Since it’s a PLL, that number may or may not be the last instantaneous value of the DAC when it goes into holdover. Since it’s running a PLL, the PPS output will indeed be the best value, so no correction is needed there when it goes into holdover (not quite true, but that is the assumption made). This operation is very typical of all of the cell site GPSDO’s. The only part that is unique to the TBolt is the ability to fiddle the loop characteristics a bit. Bob On Jan 23, 2015, at 10:58 PM, Skip Withrow skip.with...@gmail.com wrote: Hello Nuts, I have been playing a bit tuning a Thunderbolt with Lady Heather and now have more questions than answers. The collective time-nut brain would be appreciated. 1. Using the '' command I can change the damping and time constant in LH. Are these values immediately transferred to the TB? 2. Do I have to use the LH 'e' command to permenantly save new damping and time constant values to the TB? 3. After using the '' and 'e' command the lock-in behaviour of the TB does not seem to change. Is this normal behaviour? Is one set of values used when locking and the adjusted values used once it is phase locked? 4.Is there some way to read out the values stored in the TB? When I use the 'e' command on the TB, change values in LH, then restart LH and the TB I see the last values given to LH, and not what I thought was saved with the 'e' command. 5. If the TB is placed in hold mode and the DAC set to 0.0 volts it actually goes to 0.2 volts (min is at -5, max is at +5, and iv is 0.0 which it actually starts at on power up). Anyone know why? Thanks in advance for any guidance! Regards, Skip Withrow ___ 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.
