Re: [time-nuts] ADEV query Timelab and TICC
Look at ICD-GPS-060. 10V into 50ohm, sub 50ns risetime and 20us pulse lenght is specified in figure 3-2. -- Björn Sent from my smartphone. Original message From: Hal Murray Date: 21/03/2017 19:18 (GMT+01:00) To: Tom Van Baak , Discussion of precise time and frequency measurement Cc: hmur...@megapathdsl.net Subject: Re: [time-nuts] ADEV query Timelab and TICC t...@leapsecond.com said: > The TAPR dividers tend not to have "this problem" because they output at > wimpy TTL/CMOS levels. Modern CMOS drivers have fast rise times. As long as the rise time is short relative to the cable length, it gets doubled if the end of the cable is an open circuit. > Older equipment can have powerful outputs. 10V into 50R is, what, 1/5th of > an amp? Logarithmically, that puts a 5061A 1PPS closer to an automobile > starter motor or heart defibrillator compared to modern logic gates. There is a big difference across logic families. Many can drive 50 ohms. RS-232 drivers are explicitly limited to reduce EMI. -- 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. ___ 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] ADEV query Timelab and TICC
t...@leapsecond.com said: > The TAPR dividers tend not to have "this problem" because they output at > wimpy TTL/CMOS levels. Modern CMOS drivers have fast rise times. As long as the rise time is short relative to the cable length, it gets doubled if the end of the cable is an open circuit. > Older equipment can have powerful outputs. 10V into 50R is, what, 1/5th of > an amp? Logarithmically, that puts a 5061A 1PPS closer to an automobile > starter motor or heart defibrillator compared to modern logic gates. There is a big difference across logic families. Many can drive 50 ohms. RS-232 drivers are explicitly limited to reduce EMI. -- 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] ADEV query Timelab and TICC
I know the the open load output of some instrument is 10Vpp and I think this is right because if we want to connect this output on a 50Ohm line is correct to close the cable with the proper load impedance. I have found this level also on some trak System equipment. All my test are done using a 50 Ohm load in parallel to the HP and Trak outputs. I have tested two HP5065A and one HP5061B with the 1PPS option installed with the same spikes problem. The Trak , instead, work correctly, so I suspect some design problems on the HP dividers. I remember the same problem on the HP, and only HP, appear using an HP53132A TIC. To avoid any TAPR TICC input problem I am working on a small interface board with a 1M and 50Ohm input selection and a protection circuit for negative or non TTL signals. Luciano www.timeok.it Da "time-nuts" time-nuts-boun...@febo.com A "Discussion of precise time and frequency measurement" time-nuts@febo.com Cc Data Mon, 20 Mar 2017 09:48:24 -0700 Oggetto Re: [time-nuts] ADEV query Timelab and TICC Luciano, This should not happen with the hp 5065A or 5061B frequency standards. I'm glad you worked around it by using a TAPR divider, but let's see if we can figure out the actual problem. One thing to know is that the 1PPS output level from the 5061 and 5065 is *HUGE*, even up to 10 volts. If you send this to most counters it will blow the inputs or cause other undesirable side-effects, like the bouncing and spikes that you speak of. So always check your output and input signal levels and waveforms using a 'scope. Do this in-circuit, with all cables attached. Use attenuators and termination as appropriate for your counter's input specs. Set your DC trigger level to best match the actual waveform seen by the counter (not the waveform sent by the frequency standard). Yes, the usual way you find out about this is that your ADEV measurements don't look right. The good news is that you can often tell within seconds that something is wrong. It's almost always a signal conditioning or trigger level issue, not a flaw in the instrument itself. The TAPR dividers tend not to have "this problem" because they output at wimpy TTL/CMOS levels. Older equipment can have powerful outputs. 10V into 50R is, what, 1/5th of an amp? Logarithmically, that puts a 5061A 1PPS closer to an automobile starter motor or heart defibrillator compared to modern logic gates. /tvb - Original Message - From: "timeok" To: Sent: Monday, March 20, 2017 12:56 AM Subject: Re: [time-nuts] ADEV query Timelab and TICC > > All, > the similar problem I have verified using the HP5065A and HP5061B 1PPS output, the dividers are pratically unusable for ADEV measurements. The 5/10MHz output of the same instruments using the TAPR divider are ok, so these dividers have some spike noise problems. It can be seen even using other TIC as The HP53132A. > Luciano > www.timeok.it > > > Da "time-nuts" time-nuts-boun...@febo.com > A "Discussion of precise time and frequency measurement" time-nuts@febo.com > Cc > Data Sun, 19 Mar 2017 20:03:29 -0700 > Oggetto Re: [time-nuts] ADEV query Timelab and TICC > > I have sent a couple of files to Tom. They were taken simultaneously from > > an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to > > 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so > > I'm fairly confident the TICC was working correctly. > > > > Orin. > > Hi Orin, > > Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). Everything looks fine with the exception of 8 glitches. These are sometimes obvious jumps in phase, which cause massive spikes in frequency. Two plots attached. > > Almost every data point is within a few ns of each other. This is good. The standard deviation is a fraction of 1 ns. But once in a while there is a relatively massive phase jump. This is bad. Interestingly these 8 phase jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full list is (ns units): > > 24.575 > 24.724 > 24.831 > 25.047 > 25.087 > 25.549 > 25.589 > 49.623 > > 25 * N ns is not random. So I think this is not a Windows problem, not a USB problem, not a TimeLab problem, not a TICC problem either. > > It makes me wonder if this is a LTE-Lite problem. If Said or Keith from Jackson Labs is around -- is there anything on the LTE-Lite board that's close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I kind of trust the TICC. So when I see monster 25 ns phase jumps it
Re: [time-nuts] ADEV query Timelab and TICc
The 1 PPS signal is derived from an 81 MHz clock (12 ns) on the GPS chip according to the Skytraq manual. So that would mean n * 12ns. From: time-nuts-requ...@febo.com<mailto:time-nuts-requ...@febo.com> Sent: 3/20/2017 9:00 AM To: time-nuts@febo.com<mailto:time-nuts@febo.com> Subject: time-nuts Digest, Vol 152, Issue 32 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: ADEV query Timelab and TICC (Orin Eman) 2. ADEV query Timelab and TICC (Mark Sims) 3. Re: ADEV query Timelab and TICC (gandal...@aol.com) 4. Re: ADEV query Timelab and TICC (Dave Martindale) -- Message: 1 Date: Sun, 19 Mar 2017 22:09:57 -0700 From: Orin Eman To: Tom Van Baak , Discussion of precise time and frequency measurement Subject: Re: [time-nuts] ADEV query Timelab and TICC Message-ID: Content-Type: text/plain; charset="utf-8" On Sun, Mar 19, 2017 at 8:03 PM, Tom Van Baak wrote: > > Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 > points). Everything looks fine with the exception of 8 glitches. These are > sometimes obvious jumps in phase, which cause massive spikes in frequency. > Two plots attached. > First, thanks to Tom for taking a look at these files. > Almost every data point is within a few ns of each other. This is good. > The standard deviation is a fraction of 1 ns. But once in a while there is > a relatively massive phase jump. This is bad. Interestingly these 8 phase > jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The > full list is (ns units): > > 24.575 > 24.724 > 24.831 > 25.047 > 25.087 > 25.549 > 25.589 > 49.623 > > 25 * N ns is not random. So I think this is not a Windows problem, not a > USB problem, not a TimeLab problem, not a TICC problem either. > Personally, I didn't think it was any of the the above either. The PicDiv trace showed no such glitches, so I was fairly confident that the TICC was working well. But just to verify that, I connected the LTE-Lite PPS to the 5370A and let it run for a few hours. The 5370A captures similar glitches. I have sent the file on to Tom. For entertainment value, I have attached the current Lady Heather screenshot for the LTE-Lite. It has little relationship to the .tim files I sent to Tom since I generated those a few weeks ago. FWIW, it shows an off by two error writing some text, for example: "PDTDT". This seems to happen if you go to some other screen (I think it was help in this case) then returning. Orin. [image: Inline image 3] -- next part -- A non-text attachment was scrubbed... Name: LTE.gif Type: image/gif Size: 32710 bytes Desc: not available URL: <http://www.febo.com/pipermail/time-nuts/attachments/20170319/c729e050/attachment-0001.gif> -- Message: 2 Date: Mon, 20 Mar 2017 06:35:35 + From: Mark Sims To: "time-nuts@febo.com" Subject: [time-nuts] ADEV query Timelab and TICC Message-ID: Content-Type: text/plain; charset="iso-8859-1" Yes, programs like Timelab and Stable32 are definitely the way to go for post-processing and analyzing your data in depth. Lady Heather is more of a real-time monitoring and data acquisition program. The sensitivity of ADEV to data hiccups can be a good thing. If your ADEV data goes to crap you know you have a problem and need to examine the data in more depth to find out why. You can go in and remove / fixup the outliers to get a better understanding of the typical device performance but leaving in the "zingers" tells you what the device is truly doing. -- > And without preaching too much, this is why I recommend no one does > statistical work (e.g., ADEV) without first looking at the raw phase and > frequency data. A doubting Thomas attitude and the human eye are valuable > tools in science. Both Stable32 and TimeLab make it easy to display phase and > frequency, not just ADEV. This is not by accident. Maybe we have hyped ADEV too much on this list. This rant is especially addressed at several LH and NTP authors who think analyzing clock data and making ADEV plots is just something you blindly code or script or automate, as if working with clock measurement data was as pure as mathe
Re: [time-nuts] ADEV query Timelab and TICC
Luciano, This should not happen with the hp 5065A or 5061B frequency standards. I'm glad you worked around it by using a TAPR divider, but let's see if we can figure out the actual problem. One thing to know is that the 1PPS output level from the 5061 and 5065 is *HUGE*, even up to 10 volts. If you send this to most counters it will blow the inputs or cause other undesirable side-effects, like the bouncing and spikes that you speak of. So always check your output and input signal levels and waveforms using a 'scope. Do this in-circuit, with all cables attached. Use attenuators and termination as appropriate for your counter's input specs. Set your DC trigger level to best match the actual waveform seen by the counter (not the waveform sent by the frequency standard). Yes, the usual way you find out about this is that your ADEV measurements don't look right. The good news is that you can often tell within seconds that something is wrong. It's almost always a signal conditioning or trigger level issue, not a flaw in the instrument itself. The TAPR dividers tend not to have "this problem" because they output at wimpy TTL/CMOS levels. Older equipment can have powerful outputs. 10V into 50R is, what, 1/5th of an amp? Logarithmically, that puts a 5061A 1PPS closer to an automobile starter motor or heart defibrillator compared to modern logic gates. /tvb - Original Message - From: "timeok" To: Sent: Monday, March 20, 2017 12:56 AM Subject: Re: [time-nuts] ADEV query Timelab and TICC > > All, > the similar problem I have verified using the HP5065A and HP5061B 1PPS > output, the dividers are pratically unusable for ADEV measurements. The > 5/10MHz output of the same instruments using the TAPR divider are ok, so > these dividers have some spike noise problems. It can be seen even using > other TIC as The HP53132A. > Luciano > www.timeok.it > > > Da "time-nuts" time-nuts-boun...@febo.com > A "Discussion of precise time and frequency measurement" time-nuts@febo.com > Cc > Data Sun, 19 Mar 2017 20:03:29 -0700 > Oggetto Re: [time-nuts] ADEV query Timelab and TICC > > I have sent a couple of files to Tom. They were taken simultaneously from > > an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to > > 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so > > I'm fairly confident the TICC was working correctly. > > > > Orin. > > Hi Orin, > > Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). > Everything looks fine with the exception of 8 glitches. These are sometimes > obvious jumps in phase, which cause massive spikes in frequency. Two plots > attached. > > Almost every data point is within a few ns of each other. This is good. The > standard deviation is a fraction of 1 ns. But once in a while there is a > relatively massive phase jump. This is bad. Interestingly these 8 phase jumps > all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full > list is (ns units): > > 24.575 > 24.724 > 24.831 > 25.047 > 25.087 > 25.549 > 25.589 > 49.623 > > 25 * N ns is not random. So I think this is not a Windows problem, not a > USB problem, not a TimeLab problem, not a TICC problem either. > > It makes me wonder if this is a LTE-Lite problem. If Said or Keith from > Jackson Labs is around -- is there anything on the LTE-Lite board that's > close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I > kind of trust the TICC. So when I see monster 25 ns phase jumps it makes me > think there's a problem with the GSPDO board itself. > > (Please realize that only on time-nuts may we can use the words "monster" > and "25 ns" in the same sentence; the rest of the world has larger problems) > > /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] ADEV query Timelab and TICC
I noticed with the TICC that the very high peak voltage on the 5061, 5065, etc. PPS causes trigger errors. Putting a 50 ohm load at the TICC channel input helped a lot, or an attenuator might even be better. These HP units have a very short pulse width that peaks at something like 20v into a high impedance. It doesn't seem to hurt the TICC input circuit, but causes ringing that results in perceived jitter. Knocking that down to TTL level solves the problem. On Mar 20, 2017, 12:01 PM, at 12:01 PM, timeok wrote: > > All, >the similar problem I have verified using the HP5065A and HP5061B 1PPS >output, the dividers are pratically unusable for ADEV measurements. The >5/10MHz output of the same instruments using the TAPR divider are ok, >so these dividers have some spike noise problems. It can be seen even >using other TIC as The HP53132A. > Luciano > www.timeok.it > > > Da "time-nuts" time-nuts-boun...@febo.com >A "Discussion of precise time and frequency measurement" >time-nuts@febo.com > Cc > Data Sun, 19 Mar 2017 20:03:29 -0700 > Oggetto Re: [time-nuts] ADEV query Timelab and TICC >> I have sent a couple of files to Tom. They were taken simultaneously >from >> an LTE Lite - one from the PPS and one from a PicDiv dividing the >10MHz to >> 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, >so > > I'm fairly confident the TICC was working correctly. > > > > Orin. > > Hi Orin, > >Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 >points). Everything looks fine with the exception of 8 glitches. These >are sometimes obvious jumps in phase, which cause massive spikes in >frequency. Two plots attached. > >Almost every data point is within a few ns of each other. This is good. >The standard deviation is a fraction of 1 ns. But once in a while there >is a relatively massive phase jump. This is bad. Interestingly these 8 >phase jumps all appear to be about 25 ns or a multiple of 25 ns in >magnitude. The full list is (ns units): > > 24.575 > 24.724 > 24.831 > 25.047 > 25.087 > 25.549 > 25.589 > 49.623 > >25 * N ns is not random. So I think this is not a Windows problem, not >a USB problem, not a TimeLab problem, not a TICC problem either. > >It makes me wonder if this is a LTE-Lite problem. If Said or Keith from >Jackson Labs is around -- is there anything on the LTE-Lite board >that's close to 20 or 40 or 80 MHz? At this point I kind of trust >Orin's data and I kind of trust the TICC. So when I see monster 25 ns >phase jumps it makes me think there's a problem with the GSPDO board >itself. > >(Please realize that only on time-nuts may we can use the words >"monster" and "25 ns" in the same sentence; the rest of the world has >larger problems) > > /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] ADEV query Timelab and TICC
All, the similar problem I have verified using the HP5065A and HP5061B 1PPS output, the dividers are pratically unusable for ADEV measurements. The 5/10MHz output of the same instruments using the TAPR divider are ok, so these dividers have some spike noise problems. It can be seen even using other TIC as The HP53132A. Luciano www.timeok.it Da "time-nuts" time-nuts-boun...@febo.com A "Discussion of precise time and frequency measurement" time-nuts@febo.com Cc Data Sun, 19 Mar 2017 20:03:29 -0700 Oggetto Re: [time-nuts] ADEV query Timelab and TICC > I have sent a couple of files to Tom. They were taken simultaneously from > an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to > 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so > I'm fairly confident the TICC was working correctly. > > Orin. Hi Orin, Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). Everything looks fine with the exception of 8 glitches. These are sometimes obvious jumps in phase, which cause massive spikes in frequency. Two plots attached. Almost every data point is within a few ns of each other. This is good. The standard deviation is a fraction of 1 ns. But once in a while there is a relatively massive phase jump. This is bad. Interestingly these 8 phase jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full list is (ns units): 24.575 24.724 24.831 25.047 25.087 25.549 25.589 49.623 25 * N ns is not random. So I think this is not a Windows problem, not a USB problem, not a TimeLab problem, not a TICC problem either. It makes me wonder if this is a LTE-Lite problem. If Said or Keith from Jackson Labs is around -- is there anything on the LTE-Lite board that's close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I kind of trust the TICC. So when I see monster 25 ns phase jumps it makes me think there's a problem with the GSPDO board itself. (Please realize that only on time-nuts may we can use the words "monster" and "25 ns" in the same sentence; the rest of the world has larger problems) /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] ADEV query Timelab and TICC
The LTE-Lite User Manual (version 1.3) says: 2.3.7 1 PPS Module outputs The LTE-Lite SMT Module provides GPS raw 1 PPS CMOS pulse on pin 15 with sawtooth present, and a clean TCXO-generated, sawtooth-removed, UTC(GPS) phase-locked 1PPS output on pin 4. It is the pin 4 output that connects to the 1PPS-OUT jack on the eval board. So it is supposed to be cleanly divided down from the TCXO. (But I don't think Jackson Labs has published any of the circuitry on the LTE-Lite module itself). - Dave On Mon, Mar 20, 2017 at 2:07 AM, Mark Sims wrote: > > It is also interesting that the LTE GPSDO 1PPS has such a wide range of > TIE. A Tbolt / Z38xx GPSDO typically has a TIE in the 1PPS signal of > around 1 nsec. The LTE TIE spans over 40 nanoseconds (not including the > spikes). It seems like the LTE 1PPS may be from the GPS and not derived > from dividing down the disciplined oscillator output. > ___ > ___ 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] ADEV query Timelab and TICC
Many thanks for the replies on this, what was initially intended as a quick "Hello World" test seems to have become far more interesting:-) I'll forward my results to Tom as requested and see where we go from there. Nigel GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] ADEV query Timelab and TICC
On Sun, Mar 19, 2017 at 8:03 PM, Tom Van Baak wrote: > > Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 > points). Everything looks fine with the exception of 8 glitches. These are > sometimes obvious jumps in phase, which cause massive spikes in frequency. > Two plots attached. > First, thanks to Tom for taking a look at these files. > Almost every data point is within a few ns of each other. This is good. > The standard deviation is a fraction of 1 ns. But once in a while there is > a relatively massive phase jump. This is bad. Interestingly these 8 phase > jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The > full list is (ns units): > > 24.575 > 24.724 > 24.831 > 25.047 > 25.087 > 25.549 > 25.589 > 49.623 > > 25 * N ns is not random. So I think this is not a Windows problem, not a > USB problem, not a TimeLab problem, not a TICC problem either. > Personally, I didn't think it was any of the the above either. The PicDiv trace showed no such glitches, so I was fairly confident that the TICC was working well. But just to verify that, I connected the LTE-Lite PPS to the 5370A and let it run for a few hours. The 5370A captures similar glitches. I have sent the file on to Tom. For entertainment value, I have attached the current Lady Heather screenshot for the LTE-Lite. It has little relationship to the .tim files I sent to Tom since I generated those a few weeks ago. FWIW, it shows an off by two error writing some text, for example: "PDTDT". This seems to happen if you go to some other screen (I think it was help in this case) then returning. Orin. [image: Inline image 3] ___ 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] ADEV query Timelab and TICC
Hi Orin, More info... If you try to manually remove the 25 ns glitches you get a data set that looks much better. Attached are the ADEV plots for (1) your raw data and (2) your data minus those 8 glitches. You can see the dramatic difference that just 8 points make. Blue is raw data, red is data without those 8 glitches. Now, this is not likely your fault. Also, I'm not saying we know yet what causes the glitches. This posting is merely to show how 8 bad points out of 8,000 points can totally mess up an ADEV plot. And without preaching too much, this is why I recommend no one does statistical work (e.g., ADEV) without first looking at the raw phase and frequency data. A doubting Thomas attitude and the human eye are valuable tools in science. Both Stable32 and TimeLab make it easy to display phase and frequency, not just ADEV. This is not by accident. Maybe we have hyped ADEV too much on this list. This rant is especially addressed at several LH and NTP authors who think analyzing clock data and making ADEV plots is just something you blindly code or script or automate, as if working with clock measurement data was as pure as mathematics. /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] ADEV query Timelab and TICC
These look a lot like the 25ns pops I was getting when I first started generating the 1PPS output from the PIC. In my case, the PIC uses a PLL to multiply the external clock from 10MHz to 80MHz, which is then divided to 40MHz and used as an instruction clock. This gave an occasional early or late pulse, which was off by 25ns. I wound up fixing my problem by arranging it so that the timer used to generate the 1PPS was offset by 2 instructions (so that the timer fired between two successive 100ns pulses from the OCXO) and then gating the generated pulse with the OCXO so that the OCXO was the thing generating the actual 1PPS output. Of course, this could be something entirely different: For example, the quantization error on the 1PPS from the GPSDO as Tom mentions. But, in that case, it seems like there should be a lot more of them. Bob From: Tom Van Baak To: Discussion of precise time and frequency measurement Sent: Sunday, March 19, 2017 10:04 PM Subject: Re: [time-nuts] ADEV query Timelab and TICC > I have sent a couple of files to Tom. They were taken simultaneously from > an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to > 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so > I'm fairly confident the TICC was working correctly. > > Orin. Hi Orin, Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). Everything looks fine with the exception of 8 glitches. These are sometimes obvious jumps in phase, which cause massive spikes in frequency. Two plots attached. Almost every data point is within a few ns of each other. This is good. The standard deviation is a fraction of 1 ns. But once in a while there is a relatively massive phase jump. This is bad. Interestingly these 8 phase jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full list is (ns units): 24.575 24.724 24.831 25.047 25.087 25.549 25.589 49.623 25 * N ns is not random. So I think this is not a Windows problem, not a USB problem, not a TimeLab problem, not a TICC problem either. It makes me wonder if this is a LTE-Lite problem. If Said or Keith from Jackson Labs is around -- is there anything on the LTE-Lite board that's close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I kind of trust the TICC. So when I see monster 25 ns phase jumps it makes me think there's a problem with the GSPDO board itself. (Please realize that only on time-nuts may we can use the words "monster" and "25 ns" in the same sentence; the rest of the world has larger problems) /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] ADEV query Timelab and TICC
> I have sent a couple of files to Tom. They were taken simultaneously from > an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to > 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so > I'm fairly confident the TICC was working correctly. > > Orin. Hi Orin, Thanks for the raw data. It's very nice (2 hours 16 minutes = 8219 points). Everything looks fine with the exception of 8 glitches. These are sometimes obvious jumps in phase, which cause massive spikes in frequency. Two plots attached. Almost every data point is within a few ns of each other. This is good. The standard deviation is a fraction of 1 ns. But once in a while there is a relatively massive phase jump. This is bad. Interestingly these 8 phase jumps all appear to be about 25 ns or a multiple of 25 ns in magnitude. The full list is (ns units): 24.575 24.724 24.831 25.047 25.087 25.549 25.589 49.623 25 * N ns is not random. So I think this is not a Windows problem, not a USB problem, not a TimeLab problem, not a TICC problem either. It makes me wonder if this is a LTE-Lite problem. If Said or Keith from Jackson Labs is around -- is there anything on the LTE-Lite board that's close to 20 or 40 or 80 MHz? At this point I kind of trust Orin's data and I kind of trust the TICC. So when I see monster 25 ns phase jumps it makes me think there's a problem with the GSPDO board itself. (Please realize that only on time-nuts may we can use the words "monster" and "25 ns" in the same sentence; the rest of the world has larger problems) /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] ADEV query Timelab and TICC
USB is not tied to anything specific so that could well be the case. Another interest of mine is CNC machining (mill conversion and looking at a Chinese laser) using MACH3 software. People have tried everything to get the motors to run from a USB connection as machines with parallel ports are getting rare. No success at all. A couple of companies are using an Ethernet connection from the host computer to their own CPU board (https://www.poscope.com/) - this works great. USB no. Dave > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf > Of Tom McDermott > Sent: Sunday, March 19, 2017 15:00 > To: Discussion of precise time and frequency measurement > Cc: gandal...@aol.com > Subject: Re: [time-nuts] ADEV query Timelab and TICC > > I had this happen this morning. (Running Windows 10). Had 7 > hours of good > data > running overnight, (good ADEV, Freq Diff plots). > > Then There was a big pop' in the frequency difference trace. > ADEV messed up > suddenly. > > It happened coincident with starting up Microsoft Edge (which > had not been > run > since the start of the data run). My guess is that perhaps > Windows got too > busy > and USB samples were dropped. > > -- Tom, N5EG > ___ > 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] ADEV query Timelab and TICC
I saw a similar higher-than-expected ADEV from another user who was measuring GPSDO PPS vs. 10 MHz from the same GPSDO. Using a T2-Mini from the 10 MHz yields the expected results. I suspect that the GPSDO PPS in that unit is derived from GPS PPS rather than the OCXO, and thus is noisier in the short term than might otherwise be expected. John PS -- we just got into our new house and still don't have internet access, so I've not been on line as much as usual. another few days and things should!D be getting back to normal. On Mar 19, 2017, 8:01 PM, at 8:01 PM, Orin Eman wrote: >On Sun, Mar 19, 2017 at 3:00 PM, Tom Van Baak >wrote: > >> > I've seen similar with my TICC when observing a PPS - can't >remember >> > whether the PPS was from the Thunderbolt or LTE Lite. >> > >> > There was a distinct glitch on the frequency plot when it happened >and it >> > was pretty easy in timelab to expand the trace around the glitch to >take >> a >> > better look. >> >> Orin -- Thanks for that report. If you still have the TIM file, can >you >> send it to me? >> > > >I have sent a couple of files to Tom. They were taken simultaneously >from >an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz >to >1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, >so >I'm fairly confident the TICC was working correctly. > >Orin. >___ >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] ADEV query Timelab and TICC
On Sun, Mar 19, 2017 at 3:00 PM, Tom Van Baak wrote: > > I've seen similar with my TICC when observing a PPS - can't remember > > whether the PPS was from the Thunderbolt or LTE Lite. > > > > There was a distinct glitch on the frequency plot when it happened and it > > was pretty easy in timelab to expand the trace around the glitch to take > a > > better look. > > Orin -- Thanks for that report. If you still have the TIM file, can you > send it to me? > I have sent a couple of files to Tom. They were taken simultaneously from an LTE Lite - one from the PPS and one from a PicDiv dividing the 10MHz to 1Hz. The glitches were on the PPS trace, but not on the PicDiv trace, so I'm fairly confident the TICC was working correctly. Orin. ___ 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] ADEV query Timelab and TICC
I had this happen this morning. (Running Windows 10). Had 7 hours of good data running overnight, (good ADEV, Freq Diff plots). Then There was a big pop' in the frequency difference trace. ADEV messed up suddenly. It happened coincident with starting up Microsoft Edge (which had not been run since the start of the data run). My guess is that perhaps Windows got too busy and USB samples were dropped. -- Tom, N5EG ___ 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] ADEV query Timelab and TICC
> I've seen similar with my TICC when observing a PPS - can't remember > whether the PPS was from the Thunderbolt or LTE Lite. > > There was a distinct glitch on the frequency plot when it happened and it > was pretty easy in timelab to expand the trace around the glitch to take a > better look. Orin -- Thanks for that report. If you still have the TIM file, can you send it to me? Everyone -- If you do see any anomalies with the new TICC please let me know, on- or off-list. A copy of the TIM file (if you use TimeLab) would be useful to me. Or if you're just logging the raw ascii output that's fine too. Once we collect enough examples we can update the user manual, or FAQ or even the firmware. Anytime you work with an instrument that can measure down to 60 ps (single-shot) or down to 1 ps (with sufficient over-sampling or averaging) you may see things you normally don't see. This includes walking, closing doors, sneezing, touching cables or connectors. HVAC, FedEx trucks, sunlight, kids, pets, wife are also known to affect measurements at the ps level. I'm currently running a TICC in TI (Time Interval) mode, in parallel with a hp 53132 counter in TI mode, in parallel with a TimePod. So it's really easy to see when one or the other or both have an issue. For use as a headless time interval counter, John's TICC is living up to its goal of an inexpensive alternative to a 53131A/53132A. /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] ADEV query Timelab and TICC
Hi It’s a pretty good bet that the “upper” trace has a noise pop in it. One of the wonderful things about ADEV is that a single noise event can impact the whole curve. That is a bit non-intuitive. It is indeed how the math works and how the testing comes out in the real world. Bob > On Mar 19, 2017, at 12:08 PM, GandalfG8--- via time-nuts > wrote: > > Yesterday I used one of John's excellent TICC modules for the first time > and initially set up a quick test using the 10MHz output from a Thunderbolt > as the frequency reference to measure the 1PPS from an Oscilloquartz Star4 > GPSDO, with the TICC output feeding a USB3 port on a Windows 10 PC running > the 64 bit version of Timelab 1.29. > > I'll attach a copy of the test plots I'm referring to but just in case > this doesn't get through I've also uploaded it to > > https://www.mediafire.com/?9bue90yp1e8ueu6 > > Using the basic settings as described in the TICC manual the first run was > for 1 hour and seemed fine so I decided to extend the run time to 6 hours. > The first 6 hour test started to follow the 1 hour plot as expected and I > watched this on and off and can confirm it did so up to somewhere between > the 100s and 1000s points on the x-axis, but some time after that the > complete plot shifted upwards and then continued to completion to produce > the > magenta trace. > > I wasn't watching when it shifted so don't know if it was a jump or a > gradual shift but did see it continue until completion. When I repeated the 6 > > hour test, again without changing anything, and hoping to observe the effect > as it happened, it produced the green trace which was what I'd been > expecting to start with. Since then I've made other test runs and again all > seems > to be as expected. > > I'm probably missing something obvious but don't understand what's > happened here so any suggestions would be welcome. > > Throughout the tests I have been simultaneously streaming data from the > Star4 to Lady Heather via a "proper" serial port on the same PC so did > wonder > if there might be some form of data conflict but it doesn't seem to have > shown up as any obvious form of corruption and hasn't repeated itself. > > Nigel, GM8PZR 170318.png>___ > 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] ADEV query Timelab and TICC
I've seen similar with my TICC when observing a PPS - can't remember whether the PPS was from the Thunderbolt or LTE Lite. There was a distinct glitch on the frequency plot when it happened and it was pretty easy in timelab to expand the trace around the glitch to take a better look. I did not see any such problem when dividing the 10MHz to 1PPS with a PICDIV so I figured it was due to the GPSDO steering the PPS signal as satellites appear/disappear - my antenna location is far from optimal. On Sun, Mar 19, 2017 at 12:57 PM, Tom Van Baak wrote: > > I'm probably missing something obvious but don't understand what's > > happened here so any suggestions would be welcome. > > Hi Nigel, > > Your setup sounds fine. Off-list, send me the TIM files and I'll see what > happened. > > I know we all love ADEV but in general always look at the phase, phase > residual, and frequency plots first before you bother with ADEV. These > strip chart plots better show your raw data and measurement. Even a single > glitch will be visible. Only if these plots are "clean" should you go ahead > and use ADEV. Another trick is using the TimeLab "Trace" feature which > splits the data into N segments and computes ADEV for each one > independently. > > But in this particular case where you are comparing two GPSDO a phase > difference plot will likely be more informative than an ADEV plot anyway. > You may also want to play around with the averaging value (command 'g'). > > /tvb > > - Original Message - > From: "GandalfG8--- via time-nuts" > To: > Sent: Sunday, March 19, 2017 9:08 AM > Subject: [time-nuts] ADEV query Timelab and TICC > > > > Yesterday I used one of John's excellent TICC modules for the first time > > and initially set up a quick test using the 10MHz output from a > Thunderbolt > > as the frequency reference to measure the 1PPS from an Oscilloquartz > Star4 > > GPSDO, with the TICC output feeding a USB3 port on a Windows 10 PC > running > > the 64 bit version of Timelab 1.29. > > > > I'll attach a copy of the test plots I'm referring to but just in case > > this doesn't get through I've also uploaded it to > > > > https://www.mediafire.com/?9bue90yp1e8ueu6 > > > > Using the basic settings as described in the TICC manual the first run > was > > for 1 hour and seemed fine so I decided to extend the run time to 6 > hours. > > The first 6 hour test started to follow the 1 hour plot as expected and I > > watched this on and off and can confirm it did so up to somewhere between > > the 100s and 1000s points on the x-axis, but some time after that the > > complete plot shifted upwards and then continued to completion to > produce the > > magenta trace. > > > > I wasn't watching when it shifted so don't know if it was a jump or a > > gradual shift but did see it continue until completion. When I repeated > the 6 > > hour test, again without changing anything, and hoping to observe the > effect > > as it happened, it produced the green trace which was what I'd been > > expecting to start with. Since then I've made other test runs and again > all seems > > to be as expected. > > > > > > Throughout the tests I have been simultaneously streaming data from the > > Star4 to Lady Heather via a "proper" serial port on the same PC so did > wonder > > if there might be some form of data conflict but it doesn't seem to have > > shown up as any obvious form of corruption and hasn't repeated itself. > > > > Nigel, GM8PZR > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ 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] ADEV query Timelab and TICC
> I'm probably missing something obvious but don't understand what's > happened here so any suggestions would be welcome. Hi Nigel, Your setup sounds fine. Off-list, send me the TIM files and I'll see what happened. I know we all love ADEV but in general always look at the phase, phase residual, and frequency plots first before you bother with ADEV. These strip chart plots better show your raw data and measurement. Even a single glitch will be visible. Only if these plots are "clean" should you go ahead and use ADEV. Another trick is using the TimeLab "Trace" feature which splits the data into N segments and computes ADEV for each one independently. But in this particular case where you are comparing two GPSDO a phase difference plot will likely be more informative than an ADEV plot anyway. You may also want to play around with the averaging value (command 'g'). /tvb - Original Message - From: "GandalfG8--- via time-nuts" To: Sent: Sunday, March 19, 2017 9:08 AM Subject: [time-nuts] ADEV query Timelab and TICC > Yesterday I used one of John's excellent TICC modules for the first time > and initially set up a quick test using the 10MHz output from a Thunderbolt > as the frequency reference to measure the 1PPS from an Oscilloquartz Star4 > GPSDO, with the TICC output feeding a USB3 port on a Windows 10 PC running > the 64 bit version of Timelab 1.29. > > I'll attach a copy of the test plots I'm referring to but just in case > this doesn't get through I've also uploaded it to > > https://www.mediafire.com/?9bue90yp1e8ueu6 > > Using the basic settings as described in the TICC manual the first run was > for 1 hour and seemed fine so I decided to extend the run time to 6 hours. > The first 6 hour test started to follow the 1 hour plot as expected and I > watched this on and off and can confirm it did so up to somewhere between > the 100s and 1000s points on the x-axis, but some time after that the > complete plot shifted upwards and then continued to completion to produce > the > magenta trace. > > I wasn't watching when it shifted so don't know if it was a jump or a > gradual shift but did see it continue until completion. When I repeated the 6 > > hour test, again without changing anything, and hoping to observe the effect > as it happened, it produced the green trace which was what I'd been > expecting to start with. Since then I've made other test runs and again all > seems > to be as expected. > > > Throughout the tests I have been simultaneously streaming data from the > Star4 to Lady Heather via a "proper" serial port on the same PC so did > wonder > if there might be some form of data conflict but it doesn't seem to have > shown up as any obvious form of corruption and hasn't repeated itself. > > Nigel, GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.