Re: [time-nuts] Aging 5065A ?
Hi, The existing syntesizer is rich on spurs. Very rich in fact. Fairly strong. However these spurs is far enough not to cause much of a problem for the clock, but they will help to demodulate some noise. The noise being problematic is too far in for the spurs of the synthesis to generate any real danger. I replaced the 5.3 MHz syntesis with that from my HP3325B, which for sure isn't free from spurs either, but it turns out that the far in noise was filtered by the lock-up, so I ended improving the phase-noise for the 6.8 GHz synthesis such that the stability out at 1 s was improving by a factor of 2. So, don't over-do it with hunting spurs that ain't going to contribute significantly to the noise and systematics of the box. Increasing resolution is good. Enough bits to the DAC to keep the additional spurs from non-linear mixing down, because that is what truncation of the phase-accumulator state will do and mix the spurs from the current phase-accumulator setting. Step the frequency setting and the spurs move around and the mix products will also move around as with any mixer. As long as that is linear enough, additional spurs will be sufficiently low that we have other things dominating. Cheers, Magnus On 2020-10-08 01:33, Bob kb8tq wrote: > Hi > > Well….. the existing synth in the 5065 is no champion spur wise. Coming up > with a > DDS that is “as good as” is not all that crazy. > > The 5 MHz reference is multiplied to 6.x GHz and then mixed with the synth. > The close in > phase noise of the multiplied signal is mixed with the synth. The output is > the sum of the two. > Going from 5 MHz to 6.x GHz gets you 20 log (N) … a bit over 60 db added > phase noise. > > The synth (at 100 ti 300 Hz offset) needs to be 60 db worse than the noise on > the 5 MHz > before it even gets in the game. That’s not a really tough spec to meet. > > Bob > >> On Oct 7, 2020, at 6:18 PM, Hal Murray wrote: >> >> >> kb...@n1k.org said: >>> If you want to run a fixed / well regulated C Field, a DDS with (say) 48 >>> bits >>> would allow you to tune the device well past parts in 10^-15. >> I don't know how to think about a DDS in this context. >> >> I remember years ago thinking that a DDS was the greatest thing since sliced >> bread. In the context of something like a PPS going into a PC for >> timekeeping, that's probably true. You get long term accuracy and the PC >> can't see the short term issues. >> >> But then, somebody mentioned close-in spurs. They get closer the more bits >> you have in the DDS magic number. (What is that number called?) >> >> >> Suppose I have a black box labeled "10 MHz" with a cable coming out. >> >> If you plug that cable into your ADEV measuring setup, can you tell if my >> box >> has a DDS in it? >> >> If you plug that cable into your spectrum analyzer, how good a setup do you >> need in order to see the spurs? Do they get lost in the close in noise? Or >> maybe the question should be how clean a signal do I need to start with >> before >> the spurs become visible? Or what should I be asking? >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
It seems to me that now since the register so much longer, yet the D/A is the same, updates to the D/A will take longer and therefore creating more close in spurs. That 20logN does suck, but is real. I may suggest running the output of the DDS through a 5 MHz crystal, or better yet a very narrow crystal filter. 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 -Original Message- From: time-nuts On Behalf Of Bob kb8tq Sent: Wednesday, October 7, 2020 7:34 PM To: Discussion of precise time and frequency measurement Cc: hmur...@megapathdsl.net Subject: Re: [time-nuts] Aging 5065A ? Hi Well….. the existing synth in the 5065 is no champion spur wise. Coming up with a DDS that is “as good as” is not all that crazy. The 5 MHz reference is multiplied to 6.x GHz and then mixed with the synth. The close in phase noise of the multiplied signal is mixed with the synth. The output is the sum of the two. Going from 5 MHz to 6.x GHz gets you 20 log (N) … a bit over 60 db added phase noise. The synth (at 100 ti 300 Hz offset) needs to be 60 db worse than the noise on the 5 MHz before it even gets in the game. That’s not a really tough spec to meet. Bob w the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Hi Well….. the existing synth in the 5065 is no champion spur wise. Coming up with a DDS that is “as good as” is not all that crazy. The 5 MHz reference is multiplied to 6.x GHz and then mixed with the synth. The close in phase noise of the multiplied signal is mixed with the synth. The output is the sum of the two. Going from 5 MHz to 6.x GHz gets you 20 log (N) … a bit over 60 db added phase noise. The synth (at 100 ti 300 Hz offset) needs to be 60 db worse than the noise on the 5 MHz before it even gets in the game. That’s not a really tough spec to meet. Bob > On Oct 7, 2020, at 6:18 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> If you want to run a fixed / well regulated C Field, a DDS with (say) 48 bits >> would allow you to tune the device well past parts in 10^-15. > > I don't know how to think about a DDS in this context. > > I remember years ago thinking that a DDS was the greatest thing since sliced > bread. In the context of something like a PPS going into a PC for > timekeeping, that's probably true. You get long term accuracy and the PC > can't see the short term issues. > > But then, somebody mentioned close-in spurs. They get closer the more bits > you have in the DDS magic number. (What is that number called?) > > > Suppose I have a black box labeled "10 MHz" with a cable coming out. > > If you plug that cable into your ADEV measuring setup, can you tell if my box > has a DDS in it? > > If you plug that cable into your spectrum analyzer, how good a setup do you > need in order to see the spurs? Do they get lost in the close in noise? Or > maybe the question should be how clean a signal do I need to start with > before > the spurs become visible? Or what should I be asking? > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
On Mittwoch, 7. Oktober 2020 22:25:40 CEST John Ackermann N8UR wrote: > It would be possible to lower the noise slightly by using a 16 MHz clock > rather than 10 MHz (but if you look at Figure 15, the improvement > wouldn't be very great). That would require reprogramming the PIC > divider chip, and may some Arduino code changes as well. (I *think* the > clock speed is set as a constant in the code that could be changed at > compile time, but I never tested to see if that would work without > breaking anything.) Besides giving only a marginal improvement, requiring a 16MHz reference clock would be rather unpractical... > > John > > > On 10/7/20 2:29 PM, Attila Kinali wrote: > > On Sat, 03 Oct 2020 10:37:59 +0200 > > > > Matthias Welwarsky wrote: > >> When I started to look more into the software side of the TICC and > >> especially the ominous "time dilation" parameter, I set up an experiment > >> where I feed the same event into both channels of the TICC, for > >> evaluating the sensitivity of the measurements to this parameter > >> (spoiler: there is a measurable influence but it's not as critical as I > >> originally thought). > > > > That is to be expected. There are two resons for this: > > > > First, the major limit to the measurement is the noise within > > the TDC7200. If you want to get lower, then you have to reduce > > this noise. If you look at Figure 17 in the TDC7200 manual, you > > will see that the noise of the TDC is highly dependent on the > > length of the measurement. Shortening the measurement will > > decrease the noise. For this you need to use a higher clock > > of the stop signal to measure against, than the 1ms that the TICC > > does. But that will not work with the Arduino. You can get around > > this if you use a faster µC like an STM32F4. See Tobias Pluess GPSDO > > design for an example how to do this. > > > > Second, both inputs of the TICC measure against the same divided > > 1kHz clock with a modified half-Nutt interpolator. I.e. most of > > the measurement time will be common to both input signals and thus > > most of the noise seen due to the TDC and the reference clock are > > common. > > > > > > On Wed, 07 Oct 2020 18:34:00 +0200 > > > > Matthias Welwarsky wrote: > >> the noise is likely not white, but it really depends on what is the > >> dominant noise source in the system. I guess there is some correlation > >> but still enough entropy to make a difference. I'll try with different > >> cable lengths next to see if it makes a measureable difference, but > >> ideally you'd use two TICCs and two non-coherent reference clocks. But > >> they'd need to be somehow frequency locked.. You'd need some mechanism > >> that causes enough jitter to break the correlation. A delay line > >> controlled by some noise source? > > > > Adding noise will not break any correlation. It will only mask it. > > I.e., the correlation will pop up once again, when you start > > using methods to remove the added noise. > > > > Adding noise helps only if your noise is mostly quantization noise, > > then it acts as a dithering mechanism which allows you to average > > over the quantisation (and added) noise, which wouldn't be possible > > otherwise. > > > > Attila Kinali > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow > the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
kb...@n1k.org said: > If you want to run a fixed / well regulated C Field, a DDS with (say) 48 bits > would allow you to tune the device well past parts in 10^-15. I don't know how to think about a DDS in this context. I remember years ago thinking that a DDS was the greatest thing since sliced bread. In the context of something like a PPS going into a PC for timekeeping, that's probably true. You get long term accuracy and the PC can't see the short term issues. But then, somebody mentioned close-in spurs. They get closer the more bits you have in the DDS magic number. (What is that number called?) Suppose I have a black box labeled "10 MHz" with a cable coming out. If you plug that cable into your ADEV measuring setup, can you tell if my box has a DDS in it? If you plug that cable into your spectrum analyzer, how good a setup do you need in order to see the spurs? Do they get lost in the close in noise? Or maybe the question should be how clean a signal do I need to start with before the spurs become visible? Or what should I be asking? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Hi If you look at the standard chips that do this, they expand the accumulator. The D/A is limited to the “normal” number of bits based on the max clock frequency. ( = no free lunch …). Bob > On Oct 7, 2020, at 5:37 PM, Mike Feher wrote: > > So, you are increasing the length of the accumulator. What about the D/A > then? 73 - Mike > > Mike B. Feher, N4FS > 89 Arnold Blvd. > Howell NJ 07731 > 848-245-9115 > > -Original Message- > From: time-nuts On Behalf Of Bob kb8tq > Sent: Wednesday, October 7, 2020 1:55 PM > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Aging 5065A ? > > Hi > > The “normal” 32 bit DDS chips only get you just so far in terms of tuning > resolution. > If you want to run a fixed / well regulated C Field, a DDS with (say) 48 bits > would allow you to tune the device well past parts in 10^-15. There are > several DDS chips out there that will do this. Some of the more common ones ( > = what you see on eBay) have issues …. > > Bob > >> On Oct 7, 2020, at 12:11 PM, Mike Feher wrote: >> >> Just curious Bob. What do you mean by higher resolution? Would that be >> a longer accumulator and more bits in the D/A? 73 - Mike >> >> Mike B. Feher, N4FS >> 89 Arnold Blvd. >> Howell NJ 07731 >> 848-245-9115 >> >> -Original Message- >> From: time-nuts On Behalf Of Bob >> kb8tq >> Sent: Wednesday, October 7, 2020 11:11 AM >> To: Discussion of precise time and frequency measurement >> >> Subject: Re: [time-nuts] Aging 5065A ? >> >> Hi >> >> Yup, Bert has lashed up at least one that way ( I have it here in the >> basement). >> I am working on a board with a higher resolution DDS than the typical eBay >> parts. >> >> Bob >> >> ions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go >> to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
So, you are increasing the length of the accumulator. What about the D/A then? 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 -Original Message- From: time-nuts On Behalf Of Bob kb8tq Sent: Wednesday, October 7, 2020 1:55 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Aging 5065A ? Hi The “normal” 32 bit DDS chips only get you just so far in terms of tuning resolution. If you want to run a fixed / well regulated C Field, a DDS with (say) 48 bits would allow you to tune the device well past parts in 10^-15. There are several DDS chips out there that will do this. Some of the more common ones ( = what you see on eBay) have issues …. Bob > On Oct 7, 2020, at 12:11 PM, Mike Feher wrote: > > Just curious Bob. What do you mean by higher resolution? Would that be > a longer accumulator and more bits in the D/A? 73 - Mike > > Mike B. Feher, N4FS > 89 Arnold Blvd. > Howell NJ 07731 > 848-245-9115 > > -Original Message- > From: time-nuts On Behalf Of Bob > kb8tq > Sent: Wednesday, October 7, 2020 11:11 AM > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Aging 5065A ? > > Hi > > Yup, Bert has lashed up at least one that way ( I have it here in the > basement). > I am working on a board with a higher resolution DDS than the typical eBay > parts. > > Bob > > ions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go > to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
Hi > On Oct 7, 2020, at 4:25 PM, John Ackermann N8UR wrote: > > Hi Attila -- > > Just a couple of corrections -- the "coarse clock" in the TICC runs at 10 kHz > (100 us), not 1 kHz, and therefore the TDC never sees a measurement interval > longer than 100 us, not 1 ms. > > More importantly, the chart in Figure 17 of the datasheet is for operation in > "Mode 1" of the TDC, which is recommended for time intervals of 500 > nanoseconds or less. But the TICC uses "Mode 2" which doesn't have that > limitation, and Figure 17 doesn't apply. > > It would be possible to lower the noise slightly by using a 16 MHz clock > rather than 10 MHz (but if you look at Figure 15, the improvement wouldn't be > very great). That would require reprogramming the PIC divider chip, and may > some Arduino code changes as well. (I *think* the clock speed is set as a > constant in the code that could be changed at compile time, but I never > tested to see if that would work without breaking anything.) ……. it would also require some sort of PLL / synth to come up with the 16 MHz *and* do so in a fashion that does not add more jitter. Not trivial … Bob > > John > > > On 10/7/20 2:29 PM, Attila Kinali wrote: >> On Sat, 03 Oct 2020 10:37:59 +0200 >> Matthias Welwarsky wrote: >>> When I started to look more into the software side of the TICC and >>> especially >>> the ominous "time dilation" parameter, I set up an experiment where I feed >>> the >>> same event into both channels of the TICC, for evaluating the sensitivity of >>> the measurements to this parameter (spoiler: there is a measurable influence >>> but it's not as critical as I originally thought). >> That is to be expected. There are two resons for this: >> First, the major limit to the measurement is the noise within >> the TDC7200. If you want to get lower, then you have to reduce >> this noise. If you look at Figure 17 in the TDC7200 manual, you >> will see that the noise of the TDC is highly dependent on the >> length of the measurement. Shortening the measurement will >> decrease the noise. For this you need to use a higher clock >> of the stop signal to measure against, than the 1ms that the TICC >> does. But that will not work with the Arduino. You can get around >> this if you use a faster µC like an STM32F4. See Tobias Pluess GPSDO >> design for an example how to do this. >> Second, both inputs of the TICC measure against the same divided >> 1kHz clock with a modified half-Nutt interpolator. I.e. most of >> the measurement time will be common to both input signals and thus >> most of the noise seen due to the TDC and the reference clock are >> common. >> On Wed, 07 Oct 2020 18:34:00 +0200 >> Matthias Welwarsky wrote: >>> the noise is likely not white, but it really depends on what is the dominant >>> noise source in the system. I guess there is some correlation but still >>> enough >>> entropy to make a difference. I'll try with different cable lengths next to >>> see if it makes a measureable difference, but ideally you'd use two TICCs >>> and >>> two non-coherent reference clocks. But they'd need to be somehow frequency >>> locked.. You'd need some mechanism that causes enough jitter to break the >>> correlation. A delay line controlled by some noise source? >> Adding noise will not break any correlation. It will only mask it. >> I.e., the correlation will pop up once again, when you start >> using methods to remove the added noise. >> Adding noise helps only if your noise is mostly quantization noise, >> then it acts as a dithering mechanism which allows you to average >> over the quantisation (and added) noise, which wouldn't be possible >> otherwise. >> Attila Kinali > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
Matthias,
Thanks for posting the raw data. You mention that both channels get the
same signal and so you expect a sqrt(2) improvement in noise
measurement. But consider...
1) sqrt(2) is only valid if both channels are equal to begin with. Plot
the ADEV of chA and chB and you'll see this isn't quite the case. It's
close, but not the same, so your improvement will not be a full sqrt(2).
It could board layout or the TDC7200 itself. When looking at picoseconds
one should not expect two counters or different channels of the same
counter to necessarily have identical noise. Next time plot both
channels (plus the combination), not just one channel plus the combination.
2) sqrt(2) is only valid if you ignore DUT and REF noise. What DUT did
you use for chA and chB, and what REF did you use for the 10 MHz? Your
ADEV plot is the combination of DUT *and* REF *and* TICC/chA *and*
TICC/chB so even if there's a sqrt(2) improvement in chA+chB it won't
appear as large as sqrt(2) if your DUT or REF has its own contributing
noise at e-10 or e-11 levels.
It seems to me your test would be valid, and you would in fact see
sqrt(2) in the ADEV plot, if your DUT and REF were both stable to low
e-12 levels and if the TICC's chA and chB h/w both had equal noise.
/tvb
On 10/3/2020 1:37 AM, Matthias Welwarsky wrote:
Dear all,
When I started to look more into the software side of the TICC and especially
the ominous "time dilation" parameter, I set up an experiment where I feed the
same event into both channels of the TICC, for evaluating the sensitivity of
the measurements to this parameter (spoiler: there is a measurable influence
but it's not as critical as I originally thought).
While looking at the phase measurements the idea evolved to see if the noise
floor could be lowered by combining the measurements of the two channels.
I have attached the resulting ADEV and the raw channel timestamps. The red
trace is one individual channel, the blue trace is the combination of both
channels. I used Octave to evaluate the measurements.
I used the following commands to get from timestamps to phase data:
A=detrend(cumsum(1-diff(load("chan-a.txt";
B=detrend(cumsum(1-diff(load("chan-b.txt";
The combination of both channels is the an element-wise arithmetic mean:
V=(A+B)/2;
As you can see in the ADEV chart, there is indeed a slight improvement of the
noise floor from 7.8e-11 @1s to 6.8e-11@1s.
Of course this combining doesn't work too well if the noise of the two
channels is correlated, and there's plenty opportunity in this setup for this
to happen. For one, both channels are driven by the same clock source, they
share the same power supply, connected to the same Arduino base board and the
cables from the event source to the channel inputs are of the same length. It
would be interesting to repeat the experiment with a more elaborate setup, for
example using two TICCs with individual clock sources (locked to each other
but not coherent), using different lengths of cables to feed the channels etc.
Regards,
Matthias
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Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
Hi Attila -- Just a couple of corrections -- the "coarse clock" in the TICC runs at 10 kHz (100 us), not 1 kHz, and therefore the TDC never sees a measurement interval longer than 100 us, not 1 ms. More importantly, the chart in Figure 17 of the datasheet is for operation in "Mode 1" of the TDC, which is recommended for time intervals of 500 nanoseconds or less. But the TICC uses "Mode 2" which doesn't have that limitation, and Figure 17 doesn't apply. It would be possible to lower the noise slightly by using a 16 MHz clock rather than 10 MHz (but if you look at Figure 15, the improvement wouldn't be very great). That would require reprogramming the PIC divider chip, and may some Arduino code changes as well. (I *think* the clock speed is set as a constant in the code that could be changed at compile time, but I never tested to see if that would work without breaking anything.) John On 10/7/20 2:29 PM, Attila Kinali wrote: On Sat, 03 Oct 2020 10:37:59 +0200 Matthias Welwarsky wrote: When I started to look more into the software side of the TICC and especially the ominous "time dilation" parameter, I set up an experiment where I feed the same event into both channels of the TICC, for evaluating the sensitivity of the measurements to this parameter (spoiler: there is a measurable influence but it's not as critical as I originally thought). That is to be expected. There are two resons for this: First, the major limit to the measurement is the noise within the TDC7200. If you want to get lower, then you have to reduce this noise. If you look at Figure 17 in the TDC7200 manual, you will see that the noise of the TDC is highly dependent on the length of the measurement. Shortening the measurement will decrease the noise. For this you need to use a higher clock of the stop signal to measure against, than the 1ms that the TICC does. But that will not work with the Arduino. You can get around this if you use a faster µC like an STM32F4. See Tobias Pluess GPSDO design for an example how to do this. Second, both inputs of the TICC measure against the same divided 1kHz clock with a modified half-Nutt interpolator. I.e. most of the measurement time will be common to both input signals and thus most of the noise seen due to the TDC and the reference clock are common. On Wed, 07 Oct 2020 18:34:00 +0200 Matthias Welwarsky wrote: the noise is likely not white, but it really depends on what is the dominant noise source in the system. I guess there is some correlation but still enough entropy to make a difference. I'll try with different cable lengths next to see if it makes a measureable difference, but ideally you'd use two TICCs and two non-coherent reference clocks. But they'd need to be somehow frequency locked.. You'd need some mechanism that causes enough jitter to break the correlation. A delay line controlled by some noise source? Adding noise will not break any correlation. It will only mask it. I.e., the correlation will pop up once again, when you start using methods to remove the added noise. Adding noise helps only if your noise is mostly quantization noise, then it acts as a dithering mechanism which allows you to average over the quantisation (and added) noise, which wouldn't be possible otherwise. Attila Kinali ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
On Sat, 03 Oct 2020 10:37:59 +0200 Matthias Welwarsky wrote: > When I started to look more into the software side of the TICC and especially > the ominous "time dilation" parameter, I set up an experiment where I feed > the > same event into both channels of the TICC, for evaluating the sensitivity of > the measurements to this parameter (spoiler: there is a measurable influence > but it's not as critical as I originally thought). That is to be expected. There are two resons for this: First, the major limit to the measurement is the noise within the TDC7200. If you want to get lower, then you have to reduce this noise. If you look at Figure 17 in the TDC7200 manual, you will see that the noise of the TDC is highly dependent on the length of the measurement. Shortening the measurement will decrease the noise. For this you need to use a higher clock of the stop signal to measure against, than the 1ms that the TICC does. But that will not work with the Arduino. You can get around this if you use a faster µC like an STM32F4. See Tobias Pluess GPSDO design for an example how to do this. Second, both inputs of the TICC measure against the same divided 1kHz clock with a modified half-Nutt interpolator. I.e. most of the measurement time will be common to both input signals and thus most of the noise seen due to the TDC and the reference clock are common. On Wed, 07 Oct 2020 18:34:00 +0200 Matthias Welwarsky wrote: > the noise is likely not white, but it really depends on what is the dominant > noise source in the system. I guess there is some correlation but still > enough > entropy to make a difference. I'll try with different cable lengths next to > see if it makes a measureable difference, but ideally you'd use two TICCs and > two non-coherent reference clocks. But they'd need to be somehow frequency > locked.. You'd need some mechanism that causes enough jitter to break the > correlation. A delay line controlled by some noise source? Adding noise will not break any correlation. It will only mask it. I.e., the correlation will pop up once again, when you start using methods to remove the added noise. Adding noise helps only if your noise is mostly quantization noise, then it acts as a dithering mechanism which allows you to average over the quantisation (and added) noise, which wouldn't be possible otherwise. Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Hi The “normal” 32 bit DDS chips only get you just so far in terms of tuning resolution. If you want to run a fixed / well regulated C Field, a DDS with (say) 48 bits would allow you to tune the device well past parts in 10^-15. There are several DDS chips out there that will do this. Some of the more common ones ( = what you see on eBay) have issues …. Bob > On Oct 7, 2020, at 12:11 PM, Mike Feher wrote: > > Just curious Bob. What do you mean by higher resolution? Would that be a > longer accumulator and more bits in the D/A? 73 - Mike > > Mike B. Feher, N4FS > 89 Arnold Blvd. > Howell NJ 07731 > 848-245-9115 > > -Original Message- > From: time-nuts On Behalf Of Bob kb8tq > Sent: Wednesday, October 7, 2020 11:11 AM > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] Aging 5065A ? > > Hi > > Yup, Bert has lashed up at least one that way ( I have it here in the > basement). > I am working on a board with a higher resolution DDS than the typical eBay > parts. > > Bob > > ions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Experiment in lowering the TAPR TICC noise floor
Hi John,
the noise is likely not white, but it really depends on what is the dominant
noise source in the system. I guess there is some correlation but still enough
entropy to make a difference. I'll try with different cable lengths next to
see if it makes a measureable difference, but ideally you'd use two TICCs and
two non-coherent reference clocks. But they'd need to be somehow frequency
locked.. You'd need some mechanism that causes enough jitter to break the
correlation. A delay line controlled by some noise source?
On Dienstag, 6. Oktober 2020 21:24:07 CEST John Ackermann N8UR wrote:
> That's very interesting, Matthias! The lower noise floor intuitively
> and the sqrt(2) improvement comes to mind, except that would apply only
> if the two measurements were uncorrelated. Here, you have a common 10
> MHz reference, so there's correlation.
>
> But... the high-speed ring counters inside the two TDC7200 chips are
> free-running and independent, so when looking at picoseconds, maybe the
> non-correlation requirement is met, at least to some extent.
For the next run I'll have a look at the individual result registers. The
entropy source is maybe identifiable this way. Either the time1 results is
already random enough, or the cal1 and cal2. A cross-correlation between the
raw register readings between the two channels might reveal something.
I expect to find a high correlation between the time1 results of the two
channels, and no correlation for cal1/cal2.
>
> John
>
>
> On 10/3/20 4:37 AM, Matthias Welwarsky wrote:
> > Dear all,
> >
> > When I started to look more into the software side of the TICC and
> > especially the ominous "time dilation" parameter, I set up an experiment
> > where I feed the same event into both channels of the TICC, for
> > evaluating the sensitivity of the measurements to this parameter
> > (spoiler: there is a measurable influence but it's not as critical as I
> > originally thought).
> >
> > While looking at the phase measurements the idea evolved to see if the
> > noise floor could be lowered by combining the measurements of the two
> > channels.
> >
> > I have attached the resulting ADEV and the raw channel timestamps. The red
> > trace is one individual channel, the blue trace is the combination of both
> > channels. I used Octave to evaluate the measurements.
> >
> > I used the following commands to get from timestamps to phase data:
> >
> > A=detrend(cumsum(1-diff(load("chan-a.txt";
> > B=detrend(cumsum(1-diff(load("chan-b.txt";
> >
> > The combination of both channels is the an element-wise arithmetic mean:
> >
> > V=(A+B)/2;
> >
> > As you can see in the ADEV chart, there is indeed a slight improvement of
> > the noise floor from 7.8e-11 @1s to 6.8e-11@1s.
> >
> > Of course this combining doesn't work too well if the noise of the two
> > channels is correlated, and there's plenty opportunity in this setup for
> > this to happen. For one, both channels are driven by the same clock
> > source, they share the same power supply, connected to the same Arduino
> > base board and the cables from the event source to the channel inputs are
> > of the same length. It would be interesting to repeat the experiment with
> > a more elaborate setup, for example using two TICCs with individual clock
> > sources (locked to each other but not coherent), using different lengths
> > of cables to feed the channels etc.
> >
> > Regards,
> > Matthias
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and
> > follow the instructions there.
>
> ___
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Re: [time-nuts] Aging 5065A ?
Just curious Bob. What do you mean by higher resolution? Would that be a longer accumulator and more bits in the D/A? 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 -Original Message- From: time-nuts On Behalf Of Bob kb8tq Sent: Wednesday, October 7, 2020 11:11 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Aging 5065A ? Hi Yup, Bert has lashed up at least one that way ( I have it here in the basement). I am working on a board with a higher resolution DDS than the typical eBay parts. Bob ions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Is there a good web page introducing ADEV?
On 9/30/2020 12:47 PM, Magnus Danielson wrote: This is all true, except for the last part, since you really need to consider the duo of Jim Barnes and David Allan. If you look at the early work, their work and contribution overlap. Some of the important math was actually discovered by Jim Barnes. They had to work hard to figure out a way to overcome the lack of a meaningful mean value, and they did that by reducing the mean to a minimum, over 2 frequency values and then average over that. Wow, I never realized that. My bad. It does possibly explain the fact that Dave never used the term "Allan variance" but rather always called it the "two-sample variance." Although I suspect that he would have done that anyway even if he were the undisputed inventor of ADEV. He also used "sigma sub-y of (2,tau)" rather than the usual "sigma sub-y of tau" nomenclature. Rick N6RK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Hi Bob like the DDS pcboards? On Wed, Oct 7, 2020 at 10:40 AM Bob kb8tq wrote: > Hi > > People have successfully mounted eBay synthesizers in 5065’s. They work > and it is one way to take care of that. > > Bob > > > On Oct 6, 2020, at 10:49 PM, paul swed wrote: > > > > Will agree I would hack something in. The same for the synthesiser. I > could > > swear someone on time-nuts already has. The phase detection circuit is > > audio and it would take some experimentation. I think Corby supplied an > > alternative approach on the A7 opamp so a lot of good work. > > But the charcoal problem mentions really would be the worst problem to > deal > > with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for > chuckle? > > Regards > > Paul > > WB8TSL > > > > On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq wrote: > > > >> Hi > >> > >> Replacing the synthesizer with something more modern is certainly > >> possible. I have > >> a project (slowly moving along) to do just that. There is nothing crazy > on > >> the logic board, > >> it could easily be replaced with something more modern for not a lot of > >> money. > >> > >> The phase detector / photo amp / modulator chain is a bit more > >> problematic. My guess is that > >> a replacement of both the photo amp (preamp) and the phase detector at > the > >> same time > >> would make sense. Both are “audio” circuits. There is nothing in them > that > >> makes them > >> totally nutty to replace. > >> > >> The physics package *is* the long term question. When the lamps die, I > >> doubt we can find > >> ( or fab) replacements. If the temperature controller fails in a fashion > >> that the entire “tube” > >> turns into a chunk of charcoal, that would be a long tough fixer upper. > >> > >> Fun !!! > >> > >> Bob > >> > >>> On Oct 6, 2020, at 3:39 PM, Ulf Kylenfall via time-nuts < > >> time-nuts@lists.febo.com> wrote: > >>> > >>> > >>> Having been shut of for several months I fired up the > >>> refurbished 5065A a few weeks ago. > >>> > >>> It has since been equipped with a new AC-amplifier > >>> (A7) and a new Rubidium cell with the repaired lamp > >>> (thanks to Corby Dawson) and a receiver with a > >>> TED that was connected according to HP instructions. > >>> > >>> Also the 5 MHz original crystal oscillator has been replaced > >>> with an 10811 upgrade kit. > >>> > >>> Almost immedeately, the FET's in the 60 MHz Multiplier A3 > >>> not replaced during the first repair all failed. > >>> They were replaced with metal can 2N4416 and all was well. > >>> > >>> The next thing that happened was that the amber > >>> pilot light "Continuous Operation" > >>> went out. From just a single event, the lamp started > >>> going out just every time I turned my back on the > >>> instrument. Since there were no sign of out-off lock > >>> conditions and I had no clue other that removing the > >>> logic assy A14 and checking the lamp driver Q18 > >>> (1854-0003, selected from 2N1711) I found the transistor > >>> to be leaky. After replacing it with a 2N1893, I have > >>> only had one single such event in a week. Looking at > >>> the 1854-0003 from the bottom, the TO-5 package is most > >>> likely sealed with brown epoxy. And the A14 board > >>> is littered with them. > >>> > >>> I could of course replace all these > >>> small signal transistors, be it NPN or PNP with modern > >>> types but contemplating on this, I wonder how long a 5065 > >>> can be operational if the heater windings in the Rb cavity > >>> remains OK and the synthesizer with its unobtanium > >>> logics are OK. From the records on the inside > >>> of the meter and switch parts on the front panel, I can > >>> see that the photo current of the original unit > >>> slowly decreased over the years. I have one more > >>> Rb TX unit but the Rb bulb in that one is really "brownish" > >>> and not in any way clear as the one presently used. > >>> > >>> Standard "non-critical" semiconductors can of course > >>> be replaced, even the integrator IC. But what about > >>> transistors in the phase detector assy A8? There > >>> are some oddly looking packages and trying to find > >>> data sheets only returns bad photocopies from > >>> years ago, not really detailing what criteria > >>> I should be looking for. > >>> > >>> Many web-pages from time nuts displays modern > >>> versions of the 5065 (digital clock). The one > >>> in my lab dates back from 1968 so it is over > >>> 50 years old. > >>> > >>> Any research made on possible replacement > >>> types for those exotic semiconductors used > >>> in the critical parts as eg. the phase detector? > >>> Best Regards > >>> Ulf KylenfallSM6GXV > >>> > >>> > >>> > >>> ___ > >>> time-nuts mailing list -- time-nuts@lists.febo.com > >>> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >> > >> > >> ___ > >> time-nuts mailing list
Re: [time-nuts] Aging 5065A ?
Hi People have successfully mounted eBay synthesizers in 5065’s. They work and it is one way to take care of that. Bob > On Oct 6, 2020, at 10:49 PM, paul swed wrote: > > Will agree I would hack something in. The same for the synthesiser. I could > swear someone on time-nuts already has. The phase detection circuit is > audio and it would take some experimentation. I think Corby supplied an > alternative approach on the A7 opamp so a lot of good work. > But the charcoal problem mentions really would be the worst problem to deal > with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for chuckle? > Regards > Paul > WB8TSL > > On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq wrote: > >> Hi >> >> Replacing the synthesizer with something more modern is certainly >> possible. I have >> a project (slowly moving along) to do just that. There is nothing crazy on >> the logic board, >> it could easily be replaced with something more modern for not a lot of >> money. >> >> The phase detector / photo amp / modulator chain is a bit more >> problematic. My guess is that >> a replacement of both the photo amp (preamp) and the phase detector at the >> same time >> would make sense. Both are “audio” circuits. There is nothing in them that >> makes them >> totally nutty to replace. >> >> The physics package *is* the long term question. When the lamps die, I >> doubt we can find >> ( or fab) replacements. If the temperature controller fails in a fashion >> that the entire “tube” >> turns into a chunk of charcoal, that would be a long tough fixer upper. >> >> Fun !!! >> >> Bob >> >>> On Oct 6, 2020, at 3:39 PM, Ulf Kylenfall via time-nuts < >> time-nuts@lists.febo.com> wrote: >>> >>> >>> Having been shut of for several months I fired up the >>> refurbished 5065A a few weeks ago. >>> >>> It has since been equipped with a new AC-amplifier >>> (A7) and a new Rubidium cell with the repaired lamp >>> (thanks to Corby Dawson) and a receiver with a >>> TED that was connected according to HP instructions. >>> >>> Also the 5 MHz original crystal oscillator has been replaced >>> with an 10811 upgrade kit. >>> >>> Almost immedeately, the FET's in the 60 MHz Multiplier A3 >>> not replaced during the first repair all failed. >>> They were replaced with metal can 2N4416 and all was well. >>> >>> The next thing that happened was that the amber >>> pilot light "Continuous Operation" >>> went out. From just a single event, the lamp started >>> going out just every time I turned my back on the >>> instrument. Since there were no sign of out-off lock >>> conditions and I had no clue other that removing the >>> logic assy A14 and checking the lamp driver Q18 >>> (1854-0003, selected from 2N1711) I found the transistor >>> to be leaky. After replacing it with a 2N1893, I have >>> only had one single such event in a week. Looking at >>> the 1854-0003 from the bottom, the TO-5 package is most >>> likely sealed with brown epoxy. And the A14 board >>> is littered with them. >>> >>> I could of course replace all these >>> small signal transistors, be it NPN or PNP with modern >>> types but contemplating on this, I wonder how long a 5065 >>> can be operational if the heater windings in the Rb cavity >>> remains OK and the synthesizer with its unobtanium >>> logics are OK. From the records on the inside >>> of the meter and switch parts on the front panel, I can >>> see that the photo current of the original unit >>> slowly decreased over the years. I have one more >>> Rb TX unit but the Rb bulb in that one is really "brownish" >>> and not in any way clear as the one presently used. >>> >>> Standard "non-critical" semiconductors can of course >>> be replaced, even the integrator IC. But what about >>> transistors in the phase detector assy A8? There >>> are some oddly looking packages and trying to find >>> data sheets only returns bad photocopies from >>> years ago, not really detailing what criteria >>> I should be looking for. >>> >>> Many web-pages from time nuts displays modern >>> versions of the 5065 (digital clock). The one >>> in my lab dates back from 1968 so it is over >>> 50 years old. >>> >>> Any research made on possible replacement >>> types for those exotic semiconductors used >>> in the critical parts as eg. the phase detector? >>> Best Regards >>> Ulf KylenfallSM6GXV >>> >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to >
Re: [time-nuts] Aging 5065A ?
Hi With the advent of cheap PCB houses that also do cheap assembly, the ability to cobble up this or that has moved from the “nutty” into the “pretty easy” category. Indeed with very specific parts (integrator cap, fancy op-amp) you might have to hand solder one or two leaded parts on the board. On the integrator, with modern op-amps, there are a lot of parts to pick between. A lot of the stuff that was in the original board went away when HP did the later version of the integrator. Since that board seems to work just fine, I’d stick pretty close to that design. One *might* allow for some larger value integrator caps. I don’t know of many people using the 100 KHz, 1 MHz, or 1 pps outputs from the 5065. Those empty board locations provide a *lot* of room for expansion projects. There’s also the battery charger board and the space for the batteries. To me the clock and clock driver “stuff” is in that same category. it’s a big empty chassis. Not a lot of need to cram extra boards in by double stacking …. Yes, each of us gets to do this their way. I’m sure there are several people raising their hands in exception to at least one item in the paragraph above. I’d still bet at least a half a bottle of beer that something above 80% of the “running in my basement” 5065’s line up pretty well with what’s in that paragraph. If you are going to do compensation on the device, you need to feed that comp in somewhere. Variable C field is one way, but it has it’s issues. A high resolution synth would be another way. In addition to working out the control approach, you probably will want some sort of MCU to filter the data. I’d suggest that one of the “abandoned” board locations is a reasonable place to put all this “stuff”. So, lots of variables, lots of routes from A to B. Bob > On Oct 7, 2020, at 7:09 AM, tim...@timeok.it wrote: > > > Hi, > > I would also like to update the 5065A but so far there are no kits or pcb > available. I think that the first things to update are also the "simplest > ones" like the voltage regulation, the C field generator but first, the > integrator board, because there are many old HP5065A that keep the primordial > version. > > I would like redesign and implement the simplest board, the A9 the > integrator. > > The main features that I have identified are > > 1) the board must be physically compatible with the standard one. > > 2) given the large space, provide for a future daughter board that can > be mounted with columns anchored on the A9. > > 3) smd assembly. > > 4) positive and negative regulators 15V. > > 5) low noise operational amplifier model? > > 6) 5uF capacitor type? > > 7) offset regulation? > > 8) large breadboard area for future changes ex:pressure sensor to > compensate for delta f. > > 9) gold coated connector if possible. > > I would like to have your opinions, and I turn to all the teachers who read > the emails of this group which are many. However, I am available to > collaborate with all those interested in updating the HP5065A. I would like > there to be some common guidelines, once identified, and projects with a > relatively constant flow of work. > > thank you, > > Luciano > > Luciano P. S. Paramithiotti > tim...@timeok.it > www.timeok.it > > Da "time-nuts" time-nuts-boun...@lists.febo.com > A "Discussion of precise time and frequency measurement" > time-nuts@lists.febo.com > Cc "Ulf Kylenfall" ulf_...@yahoo.com > Data Tue, 6 Oct 2020 22:49:30 -0400 > Oggetto Re: [time-nuts] Aging 5065A ? > Will agree I would hack something in. The same for the synthesiser. I could > swear someone on time-nuts already has. The phase detection circuit is > audio and it would take some experimentation. I think Corby supplied an > alternative approach on the A7 opamp so a lot of good work. > But the charcoal problem mentions really would be the worst problem to deal > with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for chuckle? > Regards > Paul > WB8TSL > > On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq wrote: > >> Hi >> >> Replacing the synthesizer with something more modern is certainly >> possible. I have >> a project (slowly moving along) to do just that. There is nothing crazy on >> the logic board, >> it could easily be replaced with something more modern for not a lot of >> money. >> >> The phase detector / photo amp / modulator chain is a bit more >> problematic. My guess is that >> a replacement of both the photo amp (preamp) and the phase detector at the >> same time >> would make sense. Both are “audio” circuits. There is nothing in them that >> makes them >> totally nutty to replace. >> >> The physics package *is* the long term question. When the lamps die, I >> doubt we can find >> ( or fab) replacements. If the temperature controller fails in a fashion >> that the entire “tube” >> turns
Re: [time-nuts] Aging 5065A ?
Regarding the quest to keep a 5065A running... The 5065 in my hobby corner was equipped with the firstversion of the AC-Amplifier (A7) that did not have a frequency selective 2nd harmonic detector. So I copied the later design but made possible the use of selected polyester precision audio capacitors for the resonant parts and also replaced the 709's not with 741's but OP07. That design was uploaded to KO4BB (Complete with layout and gerber /NC-data should anyone want to copy it.) I have not received any comments but it works really fine. The Rb cavity was equipped with a thermal breaker recommended by Corby D. The linear power supply was replaced with a switched 24V unit (with DC filtering!) and the instrument now runs pretty cool. The only heat I can feel with my hands are just right above the Rb cavity. I wonder how many 5065A's that are in professional use today. Or if all have been salvaged by time-nuts... Ulf KylenfallSM6GXV ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] David Allan amusing notes on ADEV, MDEV, TDEV etc.
On 10/7/20 6:00 AM, Tom Van Baak wrote: "Dave's Story on how GPS helped NASA/JPL synchronize their Deep Space Network tracking stations" https://ethw.org/w/images/a/ac/Allan_OH_-_GPSandtheDeepSpaceNetwork.pdf "they flew me out to Goldstone in their corporate jet to look at that facility, " That would be a NASA plane.. I know we used to fly a Beech QueenAir out to Goldstone. Now, it's just a long drive through the desert. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] David Allan amusing notes on ADEV, MDEV, TDEV etc.
FYI: The main interview (about 50 pages) with David Allan is a really good read: https://ethw.org/Oral-History:David_W._Allan The set of 5 PDF addenda (~2 pages each) to the main interview are: "Technical Background on the Fundamental Noise Problem" https://ethw.org/w/images/e/e5/Allan_OH_-_FundamentalNoiseProblem.pdf "The Development of MVAR and TVAR" https://ethw.org/w/images/5/5f/Allan_OH_-_MVAR_TVAR_and_OptimumPrediction.pdf "Perspectives on the Development of Commercial Cesium Beam Clocks" https://ethw.org/w/images/0/02/Allan_OH_-_CommercialCesiumClockDevelopment.pdf "Dave's Story on how GPS helped NASA/JPL synchronize their Deep Space Network tracking stations" https://ethw.org/w/images/a/ac/Allan_OH_-_GPSandtheDeepSpaceNetwork.pdf "Sound of Music Experience in Italy (1969)" https://ethw.org/w/images/b/b3/Allan_OH_-_MoreTravelStories.pdf In general, the Engineering and Technology History Wiki (ETHW) is a fantastic historical resource. https://ethw.org/Main_Page /tvb On 10/7/2020 3:05 AM, Magnus Danielson wrote: Hi, I found this little text that may be an amusing read on how ADEV and MDEV came to be among other things. https://ethw.org/w/images/5/5f/Allan_OH_-_MVAR_TVAR_and_OptimumPrediction.pdf The Lighthill book is very important little thing, which few seems to know. It works on Fourier transform quite differently than any other book on Fourier transforms I've seen. It is not meant as a strict book, but a book to help students on their way, and it did help Jim and Dave in their studies for sure. Similarly the Snyder pre-cursor to MDEV seems to be read by few. It provides the necessary sqrt(N) improvement as achieved with overlapping frequency estimations. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] David Allan amusing notes on ADEV, MDEV, TDEV etc.
Hi, I found this little text that may be an amusing read on how ADEV and MDEV came to be among other things. https://ethw.org/w/images/5/5f/Allan_OH_-_MVAR_TVAR_and_OptimumPrediction.pdf The Lighthill book is very important little thing, which few seems to know. It works on Fourier transform quite differently than any other book on Fourier transforms I've seen. It is not meant as a strict book, but a book to help students on their way, and it did help Jim and Dave in their studies for sure. Similarly the Snyder pre-cursor to MDEV seems to be read by few. It provides the necessary sqrt(N) improvement as achieved with overlapping frequency estimations. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Hi, I would also like to update the 5065A but so far there are no kits or pcb available. I think that the first things to update are also the "simplest ones" like the voltage regulation, the C field generator but first, the integrator board, because there are many old HP5065A that keep the primordial version. I would like redesign and implement the simplest board, the A9 the integrator. The main features that I have identified are 1) the board must be physically compatible with the standard one. 2) given the large space, provide for a future daughter board that can be mounted with columns anchored on the A9. 3) smd assembly. 4) positive and negative regulators 15V. 5) low noise operational amplifier model? 6) 5uF capacitor type? 7) offset regulation? 8) large breadboard area for future changes ex:pressure sensor to compensate for delta f. 9) gold coated connector if possible. I would like to have your opinions, and I turn to all the teachers who read the emails of this group which are many. However, I am available to collaborate with all those interested in updating the HP5065A. I would like there to be some common guidelines, once identified, and projects with a relatively constant flow of work. thank you, Luciano Luciano P. S. Paramithiotti tim...@timeok.it www.timeok.it Da "time-nuts" time-nuts-boun...@lists.febo.com A "Discussion of precise time and frequency measurement" time-nuts@lists.febo.com Cc "Ulf Kylenfall" ulf_...@yahoo.com Data Tue, 6 Oct 2020 22:49:30 -0400 Oggetto Re: [time-nuts] Aging 5065A ? Will agree I would hack something in. The same for the synthesiser. I could swear someone on time-nuts already has. The phase detection circuit is audio and it would take some experimentation. I think Corby supplied an alternative approach on the A7 opamp so a lot of good work. But the charcoal problem mentions really would be the worst problem to deal with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for chuckle? Regards Paul WB8TSL On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq wrote: > Hi > > Replacing the synthesizer with something more modern is certainly > possible. I have > a project (slowly moving along) to do just that. There is nothing crazy on > the logic board, > it could easily be replaced with something more modern for not a lot of > money. > > The phase detector / photo amp / modulator chain is a bit more > problematic. My guess is that > a replacement of both the photo amp (preamp) and the phase detector at the > same time > would make sense. Both are “audio” circuits. There is nothing in them that > makes them > totally nutty to replace. > > The physics package *is* the long term question. When the lamps die, I > doubt we can find > ( or fab) replacements. If the temperature controller fails in a fashion > that the entire “tube” > turns into a chunk of charcoal, that would be a long tough fixer upper. > > Fun !!! > > Bob > > > On Oct 6, 2020, at 3:39 PM, Ulf Kylenfall via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > > > Having been shut of for several months I fired up the > > refurbished 5065A a few weeks ago. > > > > It has since been equipped with a new AC-amplifier > > (A7) and a new Rubidium cell with the repaired lamp > > (thanks to Corby Dawson) and a receiver with a > > TED that was connected according to HP instructions. > > > > Also the 5 MHz original crystal oscillator has been replaced > > with an 10811 upgrade kit. > > > > Almost immedeately, the FET's in the 60 MHz Multiplier A3 > > not replaced during the first repair all failed. > > They were replaced with metal can 2N4416 and all was well. > > > > The next thing that happened was that the amber > > pilot light "Continuous Operation" > > went out. From just a single event, the lamp started > > going out just every time I turned my back on the > > instrument. Since there were no sign of out-off lock > > conditions and I had no clue other that removing the > > logic assy A14 and checking the lamp driver Q18 > > (1854-0003, selected from 2N1711) I found the transistor > > to be leaky. After replacing it with a 2N1893, I have > > only had one single such event in a week. Looking at > > the 1854-0003 from the bottom, the TO-5 package is most > > likely sealed with brown epoxy. And the A14 board > > is littered with them. > > > > I could of course replace all these > > small signal transistors, be it NPN or PNP with modern > > types but contemplating on this, I wonder how long a 5065 > > can be operational if the heater windings in the Rb cavity > > remains OK and the synthesizer with its unobtanium > > logics are OK. From the records on the
[time-nuts] CDMA NTP servers beginning to fail
In the past few months I've noticed problems on multiple US-based public NTP stratum 1 servers that use CDMA as their stratum 0 clock.. EndRun Technologies Tempus LX ( https://endruntechnologies.com/pdf/USM3014--000.pdf) is an example. This is not a surprise. In the US Verizon has announced plans to shut down its legacy CDMA service though the end-date keeps changing ( https://usatcorp.com/verizon-extends-cdma-network-date/). As the number of CDMA channels and base stations drops the NTP servers have difficulty finding an acceptable signal. Failure modes include: rapidly increasing root dispersion, reported time drifting over the course of many weeks, 1024-week rollover(!), and complete failure. I don't know how users will adapt. Other radio-based technologies have poorer in-building coverage. Steve Sommars ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Aging 5065A ?
Will agree I would hack something in. The same for the synthesiser. I could swear someone on time-nuts already has. The phase detection circuit is audio and it would take some experimentation. I think Corby supplied an alternative approach on the A7 opamp so a lot of good work. But the charcoal problem mentions really would be the worst problem to deal with. I guess it would be ebay parts. $$$ Whats a dead 5065 go for chuckle? Regards Paul WB8TSL On Tue, Oct 6, 2020 at 6:27 PM Bob kb8tq wrote: > Hi > > Replacing the synthesizer with something more modern is certainly > possible. I have > a project (slowly moving along) to do just that. There is nothing crazy on > the logic board, > it could easily be replaced with something more modern for not a lot of > money. > > The phase detector / photo amp / modulator chain is a bit more > problematic. My guess is that > a replacement of both the photo amp (preamp) and the phase detector at the > same time > would make sense. Both are “audio” circuits. There is nothing in them that > makes them > totally nutty to replace. > > The physics package *is* the long term question. When the lamps die, I > doubt we can find > ( or fab) replacements. If the temperature controller fails in a fashion > that the entire “tube” > turns into a chunk of charcoal, that would be a long tough fixer upper. > > Fun !!! > > Bob > > > On Oct 6, 2020, at 3:39 PM, Ulf Kylenfall via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > > > Having been shut of for several months I fired up the > > refurbished 5065A a few weeks ago. > > > > It has since been equipped with a new AC-amplifier > > (A7) and a new Rubidium cell with the repaired lamp > > (thanks to Corby Dawson) and a receiver with a > > TED that was connected according to HP instructions. > > > > Also the 5 MHz original crystal oscillator has been replaced > > with an 10811 upgrade kit. > > > > Almost immedeately, the FET's in the 60 MHz Multiplier A3 > > not replaced during the first repair all failed. > > They were replaced with metal can 2N4416 and all was well. > > > > The next thing that happened was that the amber > > pilot light "Continuous Operation" > > went out. From just a single event, the lamp started > > going out just every time I turned my back on the > > instrument. Since there were no sign of out-off lock > > conditions and I had no clue other that removing the > > logic assy A14 and checking the lamp driver Q18 > > (1854-0003, selected from 2N1711) I found the transistor > > to be leaky. After replacing it with a 2N1893, I have > > only had one single such event in a week. Looking at > > the 1854-0003 from the bottom, the TO-5 package is most > > likely sealed with brown epoxy. And the A14 board > > is littered with them. > > > > I could of course replace all these > > small signal transistors, be it NPN or PNP with modern > > types but contemplating on this, I wonder how long a 5065 > > can be operational if the heater windings in the Rb cavity > > remains OK and the synthesizer with its unobtanium > > logics are OK. From the records on the inside > > of the meter and switch parts on the front panel, I can > > see that the photo current of the original unit > > slowly decreased over the years. I have one more > > Rb TX unit but the Rb bulb in that one is really "brownish" > > and not in any way clear as the one presently used. > > > > Standard "non-critical" semiconductors can of course > > be replaced, even the integrator IC. But what about > > transistors in the phase detector assy A8? There > > are some oddly looking packages and trying to find > > data sheets only returns bad photocopies from > > years ago, not really detailing what criteria > > I should be looking for. > > > > Many web-pages from time nuts displays modern > > versions of the 5065 (digital clock). The one > > in my lab dates back from 1968 so it is over > > 50 years old. > > > > Any research made on possible replacement > > types for those exotic semiconductors used > > in the critical parts as eg. the phase detector? > > Best Regards > > Ulf KylenfallSM6GXV > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] TimeLab display issue
Hello Time-Nuts, Just wondering if anyone has run into the following with TimeLab, and has a solution. I have been running TimeLab on a Windows 7 laptop for some time now and it has been working great. A while back, I installed on a Windows All-In-One (HP) and had display issues. The display area was not working for ADEV, but would display phase data. However, the vertical and horizontal display areas for the labels seemed to be off the display area (for everything). Made things really useless. Now, I have installed TimeLab on a Windows desktop and have run into exactly the same problem. I have talked to John Miles about this and we could never get the issue ironed out. BTW, I am importing ASCII phase data but I don't think it would make any difference if I was collecting data real time. It seems to be a display issue and not a data problem. Any insight would be appreciated. Thanks, Skip Withrow ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
