[time-nuts] Sawtooth correction
Recent postings on 'sawtooth' hardware correction; several years ago SigNav Australia (no longer is business) had a timing product called TM3-02 that claimed to "Eliminate sawtooth correction" via some technology they had developed. https://web.archive.org/web/20091123094332/http://www.signav.com.au/ https://web.archive.org/web/20091013133934/http://www.signav.com.au/files/brochures/Brochure%20TM3-02%20module.pdf Any of our Australian contingent remenber this company? Did anyone on the list test one of these things? I belive Synergy was a US distributor - maybe Art can chime in with some details. Jerry ___ 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] AN/URQ-10A standard docs
My bad its in front and easily accessible. On Wed, Jul 10, 2019 at 7:36 PM paul swed wrote: > Walter looking at the manual. There is a coarse adjust in back of the unit > and the cap was c102. But its a test and install cap and I do not see it > listed in the parts. > Regards > Paul > WB8TSL > > On Wed, Jul 10, 2019 at 7:26 PM paul swed wrote: > >> Well I thought I might have an an/urq10 manual. Don't. I do have one more >> place to look. Do have the an urr/r1051a and URA-17 TTY converter and >> actually have both of those actual units in working condition. Though the >> 17 has not been on in a long time. Worked on all of them circa 1975. Our >> ship had 3 X URQ10s. They were considered something at the time. All >> relative in reality. >> Walter all that said, do let it bake in for several days to a week and >> see if it gets better. >> I suspect it may not after what 40 years?? There is a cap that can be >> changed in the oven and I want to say the inner assembly was not that >> difficult to deal with. The manual should indicate what the cap was tempco >> and such. But its been a really long time. >> >> With some humor I am one of many who wouldn't mind an URQ10. It sort of >> completes the micro-ship system I have. Complete with operating >> transceiver. Though the micro-ship was never really a goal. It just sort of >> happened. >> Last note. The nicads in the pack were very good. They did last a long >> time though the charging circuit was not really very good. The nicads today >> have fairly short operational life. I have purchased new non-surplus ones >> when they were available. They simply lasted maybe 3-4 years. I mention >> this because I had a stack of the URQ10 nicads and they lasted 30 years >> with reasonable run time. >> Enjoy your find Walter. >> Regards >> Paul >> WB8TSL >> >> On Wed, Jul 10, 2019 at 4:30 PM John Ackermann N8UR wrote: >> >>> I have several pages of schematics at: >>> >>> https://www.febo.com/pages/hardware/AN_URQ_10/ >>> >>> but unfortunately not the full manual. >>> >>> John >>> >>> >>> On 7/10/19 12:43 PM, Walter Shawlee 2 wrote: >>> > Does anybody have the manual for this old standard? mine works, but is >>> > a bit high, and needs internal adjustment, and a new battery pack. >>> > pretty good condition for this old unit, and the 5MHz output is only >>> > 4.8Hz off after heaven only knows how many years in a dark corner. it's >>> > only been running for 12 hours, so it might drift in after 30 days at >>> > the oven temperature, but my offset adjustment is maxed out. >>> > >>> > I have had good luck converting the older 5Mhz standards to 10Mhz using >>> > a cheap chinese doubler board off ebay and a 10Mhz bandpass filter. the >>> > results were great (although about 6dB down from the original level), >>> > and made them a bit more useful around the shop as an external >>> reference. >>> > >>> > Any PDF would be appreciated. All my web searches were total dead ends >>> > so far. >>> > all the best, >>> > walter >>> > >>> >>> >>> ___ >>> 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] Switching 1 pps signal
I took all of the advice and made what I thought was the most sensible thing. Not using switches of any kind at all. Out of TICC in a case, N connector comes out as input (1 pps). I made an external box that houses 5/10MHz to 1 pps. They are completely independent. No possibility for cross talks. Inside of pps converter is a short piece of a twisted pair. Only few inches. I am not quite sure about termination. There is really no guarantee that source or target is at 50 ohms. So reflection to some degree is unavoidable. What I'm concerned with is, at what point it will start to affect results. Thanks everybody for input! It has been quite interesting. --- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG On Saturday, July 6, 2019, 7:02:00 PM EDT, Glen English VK1XX wrote: Taka, It depends on the edge rate of the driver. You wont need an 18 GHz relay. The edge rate of the driver depends on many things, but it is likely not to be any faster than 1V/nS Now in all the trimbles I worked with, the falling edge , actively pulled to ground was the line with the deterministic transition time. Using 0.35 = Btr, the bandwidth is approx 350 MHz . the likelyhood is, with the way things are connected, the lack of any termination from the single ended pps signal etc, the bandwidth is unlikely to exceed 50 MHz. You may be well advised to atttempt to terminate the 1pps signal to provide a deterministic edge rate and control crosstalk and reflections. If you have short cables, the reflection bouncing around may cause jitter if the edge rate was low enough. . However, do be mindful of crosstalk from the alternate switch contact. The cross talk will be extremely low for signals up to 500 MHz for a good coaxial relay, especially into a high Z load. The high Z load will permit crosstalk due to the capacitance ont he relay contacts, so another good reason to hold the input resistance of the load of the 1pps down to less than a few hundred ohms You do have to be careful of rising crosstalk using ADG901 etc solid state switches . A logic multiplexer might be a good choice if the jitter introduced is not an issue. glen On 7/07/2019 4:06 AM, Taka Kamiya via time-nuts wrote: > I am trying to come up with a viable design to encase TICC along with 10MHz > -> 1 pps converter. My plan is to share the input connector and switch > in/out the converter. > > 1 pps, although technically a 1Hz signal, rise time and duration is awfully > short on some sources. I'm sure constituent signal will go way into RF > range. I am not capable of calculating this. But, that means I really have > to treat it as an RF signal, correct? Otherwise, slower rise will cause > error as it will cross the threshold later than initiation of the pulse. > Question is, how careful do I need to be? > My plan is to use two 18GHz microwave relay per channel to bypass/place-in > the converter. I know this would be OK but am I over-doing this? I also > have a miniature relay in DIP size but I'm afraid it may not be sufficient. > There is not a frequency spec, and consistency may be an issue. > Advise, please? > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > ___ > 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] Used Hydrogen Maser
I recently got some prices on Russian masers. The passive masers are about $us90K and the active masers are about $US250K. There’s apparently quite a bit of paperwork to do with the export licensing but it just needs a bit of patience :-) Cheers Michael On Thu, 11 Jul 2019 at 3:01 am, Bob kb8tq wrote: > Hi > > One of the gotcha’s if you are in the US is that the most often seen > “alternate > brand” of Maser comes out of Russia. Depending on the phase of the moon and > just what the rule book says this week, you may well not be able to bring > one > into the country. > > Back when things were a bit more cordial and trade was more rational, the > quoted > price was in the $150 $200K range. > > Bob > > > On Jul 10, 2019, at 8:57 AM, Dana Whitlow wrote: > > > > Perry, > > > > The only H-maser with which I've had direct experience (the MHM-2010) > costs > > around $250,000 new. But there are some other brands, mostly foreign. > > > > The immediate operating cost is that of AC power. IIRC, the '2010 uses > > about > > 100W or maybe 125W, *all the time*. The H-maser is *not* the kind of > thing > > one > > turns on when needed and back off in between uses. > > > > The hydrogen supply is usually large enough to last about 15 years or > more. > > > > A sort of hidden cost is that the unit must be operated in a > > temperature-controllled > > environment for best stability- hence there is also the purchase and > > operating costs > > of a suitable A/C system. > > > > Also note that H-masers *do* drift in frequency over time. The one we > had > > at Arecibo > > typically needed frequency correction of about 3.5E-14 about every 4 > months > > on average, > > to keep the observatory's master clock on time within 25-50 nsec as > needed > > for certain > > types of radio astronomy situations. We used the H-maser because it has > > the best > > stability (over the range of seconds to hours) of anything commercially > > available. > > > > The maser operated without difficulty for about the first 8 years before > it > > lost one of > > its two vacion pumps. We had to pay $12k for an engineer from > Symmetricom > > to > > bring down a pair of new pumps and oversee the installation. He replaced > > the failed > > one on one day while I took notes; then the next day I replaced the 2nd > one > > under > > his close supervision and scrutiny. Because the maser was well designed > > with vacuum > > isolation valves, both pump replacements were accomplished without > shutting > > down > > the maser and with no disturbance to observations. > > > > A few years later the maser's internal log data showed that the hydrogen > > pressure > > was oscillating, along with synchronized fluctuations in drive to the Pd > Pd > > "valve", > > with a period of about 11 days. At this point there was no noticeable > > effect on timing > > accuracy. A series of calls to Symmetricom customer service indicated > that > > they had > > no idea what was going on, and they counseled "watchful waiting". We did > > that for > > several more years up until I retired in Dec 2016, with the only change > > being a very > > gradual drift in oscillation period and amplitude. The in late Dec 2018, > > the maser > > basically died outright, and Symmetricom (then part of Micro-Semi) was > > unable to > > provide a definite diagnosis- just a couple of theories. But they > advised > > against > > trying to fully diagnose and repair the unit, considering its advanced > age > > (approx > > 15 years at the time). > > > > Hope this helps ... > > > > Dana > > > > > > > > > > On Wed, Jul 10, 2019 at 7:00 AM Perry Sandeen via time-nuts < > > time-nuts@lists.febo.com> wrote: > > > >> Yo Bubba Dudes!, > >> OK, I'll finally ask the question that probably a lot of list members > >> wanted to know but were reticent to ask. > >> First, what is the price of one of a new Hydrogen Maser? (This is > >> important if I win the lottery.) > >> Second, what would be prices for used Hydrogen Maser in *reasonable* > >> working condition and what might be the long term costs to keep it > running? > >> Thirdly, what are the chances of finding a used one? > >> Then again, might it be better, money wise just to limp along with used > HP > >> Cs? > >> Regards, > >> Perrier > >> > >> > >> > >> ___ > >> 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
Re: [time-nuts] Used Hydrogen Maser
about 20 years ago, JPL was operating a Hg ion clock at the Tidbinbilla tracking station just outside Canberra, Australia. I think they installed a few at various nodes in the Deep Space Network at the time. It operated for a few years but never reliably enough to be a useful UTC clock ( we were submitting the data to BIPM). I don’t know what happened to it. Cheers Michael On Thu, 11 Jul 2019 at 3:01 am, jimlux wrote: > On 7/10/19 6:10 AM, Azelio Boriani wrote: > > Tom Van Baak said on Aug 29, 2013: > > > >> The pursuit of precision tends to be exponential rather than linear. > > ... > >> As a rough example in the ADEV world: > >> - for 1e-11, you can buy almost any XO, TCXO, or risky OCXO for $10. > >> - for 1e-12, you can find a reputable OCXO on eBay for under $100. > >> - for 1e-13, you can find an old but maybe working cesium clock for 1 > k$. > >> - for 1e-14, spend 10 k$ and get a certified working hp 5071A. > >> - for 1e-15, spend 100 k$ and find a used active H-maser. > >> - for 1e-16, spend 1 M$ to hire physicists and build a Cs fountain. > >> - for 1e-17, spend 10 M$ to fund a national research institute to build > ion or > >> optical clocks. > > > > > > Add the 1k USD running cost per year just to keep the active maser > running. > > I think that chances of finding an active H-maser used are near 0. > > Better to stick with GPSDOs: they bring into your home the stability > > and accuracy of the USNO UTC (well, close to...). > > > > > I wonder what it would cost to build a trapped Hg ion clock - I don't > think it's $10M, but it might be in the range of $500k-1M if you pay > people to do the work. Things like the quadrupole trap and ion sources > are catalog items. The whole vacuum system, including a turbo pump, is > probably in the $10k range (looking at the Cole Parmer catalog, first > hit on google), maybe another $5k in various vacuum plumbing bits and > pieces. > > back in 2005-2006 (published in 2007), Prestage et al had a lab version > https://ieeexplore.ieee.org/document/4319251 > > pumped, backfilled with Ne, then sealed > > > > > > > > > > > ___ > 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] GPS frequency uncertainty
Hi > On Jul 10, 2019, at 4:26 PM, Hal Murray wrote: > > >> Would someone please expand on what the practical frequency calibration limit >> might be? > > That's not quite a well formed question yet. You need to say something about > the time scale. What are you trying to calibrate? > > Poke around for some ADEV curves. Find one for your device (or similar) and > another for a GPSDO. > > Most devices will be V shaped. The GPSDO curve will go down to the right. > Where do they cross over? How hard do you want to work at tracing this and that back to Paris? Ultimately there is a connection that can be followed back. You then get into the somewhat rhetorical debate of “is it really that time when the official stamps it as such?”. On a more practical basis, most typical GPSDO’s start to struggle in the 40K to 170K second range. A lot of things start to “bleed” into the solution. Just what comes in is always going to be a “that depends” sort of thing. Right now sun spots aren’t a big deal. They will be in a few years ….. Bob > > > -- > 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] Used Hydrogen Maser
jim...@earthlink.net said: > I wonder what it would cost to build a trapped Hg ion clock - I don't think > it's $10M, but it might be in the range of $500k-1M if you pay people to do > the work. Things like the quadrupole trap and ion sources are catalog > items. If you are lucky, you might get the labor for free. The Computer History Museum has working IBM 1401s including card readers, printers, and tape drives. The restoration was all done by volunteer labor. They collected a handful of retired IBM fix-it guys and arranged for them to get together once a week. There is probably a good PhD thesis in there. -- 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] AN/URQ-10A standard docs
I have several pages of schematics at: https://www.febo.com/pages/hardware/AN_URQ_10/ but unfortunately not the full manual. John On 7/10/19 12:43 PM, Walter Shawlee 2 wrote: > Does anybody have the manual for this old standard? mine works, but is > a bit high, and needs internal adjustment, and a new battery pack. > pretty good condition for this old unit, and the 5MHz output is only > 4.8Hz off after heaven only knows how many years in a dark corner. it's > only been running for 12 hours, so it might drift in after 30 days at > the oven temperature, but my offset adjustment is maxed out. > > I have had good luck converting the older 5Mhz standards to 10Mhz using > a cheap chinese doubler board off ebay and a 10Mhz bandpass filter. the > results were great (although about 6dB down from the original level), > and made them a bit more useful around the shop as an external reference. > > Any PDF would be appreciated. All my web searches were total dead ends > so far. > all the best, > walter > ___ 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] GPS frequency uncertainty
> Would someone please expand on what the practical frequency calibration limit > might be? That's not quite a well formed question yet. You need to say something about the time scale. What are you trying to calibrate? Poke around for some ADEV curves. Find one for your device (or similar) and another for a GPSDO. Most devices will be V shaped. The GPSDO curve will go down to the right. Where do they cross over? -- 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] AN/URQ-10A standard docs
Walter Shawlee 2 wrote: Does anybody have the manual for this old standard? mine works, but is a bit high, and needs internal adjustment, and a new battery pack. pretty good condition for this old unit, and the 5MHz output is only 4.8Hz off after heaven only knows how many years in a dark corner. it's only been running for 12 hours, so it might drift in after 30 days at the oven temperature, but my offset adjustment is maxed out. I have had good luck converting the older 5Mhz standards to 10Mhz using a cheap chinese doubler board off ebay and a 10Mhz bandpass filter. the results were great (although about 6dB down from the original level), and made them a bit more useful around the shop as an external reference. Any PDF would be appreciated. All my web searches were total dead ends so far. all the best, walter Download Navships 0967-170-3010 for the URQ-10A at http://www.navy-radio.com/manuals/urq10a-man-0967-170-3010-6609.pdf Seems to be pretty complete, with schematics, maintenance and calibration. Wish I had a URQ-10A; they were pretty good instruments in their day. Cheers, Dave M ___ 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] Used Hydrogen Maser
On 7/10/19 10:55 AM, Richard (Rick) Karlquist wrote: FWIW, about 20 years ago, Len Cutler and Robin Giffard of 5071A fame built several Hg ion clocks to be shipped to some govt customer I don't remember. One of the clocks was dropped by the shipping company UPS or FedEX) and destroyed. Only then did Len learn that HP was self insured, probably as part of a package deal to get a low corporate shipping rate. HP products were packed extremely well, so the only real risk was the unit getting stolen. I vaguely remember Len saying they were out $10K, which was probably just the cost of parts. Nevertheless, it didn't seem like building an Hg clock was all that big of a project. Way simpler than the 5071A. Now a days, the electronics would be considerably easier and cheaper. The mechanical parts would all be CNC'ed by an online machine shop. Rick N6RK Just because, after all, you might get better performance from your homebuilt Hg-ion than your homebuilt H-maser - at a fraction of the cost. The diagrams look simple, but of course, with this kind of stuff, it never is really simple. Certainly, the UV source, PM tube and electronics is easier these days. 40.5 GHz isn't as exotic as it once was. https://ieeexplore.ieee.org/abstract/document/7437483 On 7/10/2019 9:41 AM, jimlux wrote: I wonder what it would cost to build a trapped Hg ion clock - I don't think it's $10M, but it might be in the range of $500k-1M if you pay people to do the work. Things like the quadrupole trap and ion sources are catalog items. The whole vacuum system, including a turbo pump, is probably in the $10k range (looking at the Cole Parmer catalog, first hit on google), maybe another $5k in various vacuum plumbing bits and pieces. back in 2005-2006 (published in 2007), Prestage et al had a lab version https://ieeexplore.ieee.org/document/4319251 pumped, backfilled with Ne, then sealed ___ 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] Neural net to control oven temperature ?
Glen English VK1XX writes: > Has anyone tried to use a Neural net to control oven tmep, rather than > the ye olde PID ? If you believe the marketing, that is why the Nest thermostat is connected to the cloud. > IE the algorithm learns from previous beheviour and successfully > predicts behaviour (or not). This part is (unsupervised) learning, not control. Depending on how much knowledge you bake into the neural network about the system, you either need to learn just the system parameters (say the PID constants) of a fixed system or figure out the system structure itself, the latter part is called system identification. Unless you expect the system to change over time it is usually (much) more practical to stop the learning at some point and just run the system with the best model available so far. Incidentally that is one reason why different hardware for neural network acceleration exists: the network for learning is usually much more complex and needs higher precision than the network running the extracted model. If you need to keep learning after the initial training (and if it has to be online learning rather than periodic offline re-training), the learning rate often has to be reduced significantly in order for the control to stay inside reasonable bounds. > I'm sure there are a few out there proficient with machine learning > algorithms. Neural networks are best applied to sparse, low-dimensional signals embedded in high-dimensional spaces. Oven temperature control doesn't fit that description, so more traditional methods are likely more efficient. > Might make a good masters thesis I bet. Maybe so, but there are probably sexier topics around for a master-to-be to pick up. > Given that oven control based on inputs and whatever is not random, > unlike say flicker etc. Randomness actually helps in many learning tasks. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ SD adaptation for Waldorf microQ V2.22R2: http://Synth.Stromeko.net/Downloads.html#WaldorfSDada ___ 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] Used Hydrogen Maser
FWIW, about 20 years ago, Len Cutler and Robin Giffard of 5071A fame built several Hg ion clocks to be shipped to some govt customer I don't remember. One of the clocks was dropped by the shipping company UPS or FedEX) and destroyed. Only then did Len learn that HP was self insured, probably as part of a package deal to get a low corporate shipping rate. HP products were packed extremely well, so the only real risk was the unit getting stolen. I vaguely remember Len saying they were out $10K, which was probably just the cost of parts. Nevertheless, it didn't seem like building an Hg clock was all that big of a project. Way simpler than the 5071A. Now a days, the electronics would be considerably easier and cheaper. The mechanical parts would all be CNC'ed by an online machine shop. Rick N6RK On 7/10/2019 9:41 AM, jimlux wrote: I wonder what it would cost to build a trapped Hg ion clock - I don't think it's $10M, but it might be in the range of $500k-1M if you pay people to do the work. Things like the quadrupole trap and ion sources are catalog items. The whole vacuum system, including a turbo pump, is probably in the $10k range (looking at the Cole Parmer catalog, first hit on google), maybe another $5k in various vacuum plumbing bits and pieces. back in 2005-2006 (published in 2007), Prestage et al had a lab version https://ieeexplore.ieee.org/document/4319251 pumped, backfilled with Ne, then sealed ___ 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] Used Hydrogen Maser
> https://www.microsemi.com/product-directory/active-hydrogen-maser/4123-mhm-2010-active-hydrogen-maser Corby, Did you notice a week or two ago there's an updated version: https://www.microsemi.com/product-directory/active-hydrogen-maser/5548-mhm-2020-active-hydrogen-maser There are links to PDF data sheets on both pages. I'll post more info as I run across it. Note also the evolution in the company name: Sigma Tau -> Datum -> Symmetricom -> Microsemi -> Microchip. Yes, the same company that makes my favorite $1 PIC microcontrollers now makes H-masers too... Copies of the press release: https://news.thomasnet.com/fullstory/new-mhm-2020-features-color-touch-panel-display-40026262 https://www.milexia.fr/en/components-systems/news/mhm-2020 https://www.milexia.fr/sites/milexia.fr/files/mc1467en_-_approved_-_mhm-2020_maser_release_r_1.pdf /tvb ___ 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] AN/URQ-10A standard docs
Does anybody have the manual for this old standard? mine works, but is a bit high, and needs internal adjustment, and a new battery pack. pretty good condition for this old unit, and the 5MHz output is only 4.8Hz off after heaven only knows how many years in a dark corner. it's only been running for 12 hours, so it might drift in after 30 days at the oven temperature, but my offset adjustment is maxed out. I have had good luck converting the older 5Mhz standards to 10Mhz using a cheap chinese doubler board off ebay and a 10Mhz bandpass filter. the results were great (although about 6dB down from the original level), and made them a bit more useful around the shop as an external reference. Any PDF would be appreciated. All my web searches were total dead ends so far. all the best, walter -- Walter Shawlee 2 Sphere Research Corp. 3394 Sunnyside Rd. West Kelowna, BC, V1Z 2V4 CANADA Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca +We're all in one boat, no matter how it looks to you. (WS2) +All you need is love. (John Lennon) +But, that doesn't mean other things don't come in handy. (WS2) +Nature is trying very hard to make us succeed, but nature does not depend on us. We are not the only experiment. (R. Buckminster Fuller) ___ 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] Used Hydrogen Maser
On 7/10/19 6:10 AM, Azelio Boriani wrote: Tom Van Baak said on Aug 29, 2013: The pursuit of precision tends to be exponential rather than linear. ... As a rough example in the ADEV world: - for 1e-11, you can buy almost any XO, TCXO, or risky OCXO for $10. - for 1e-12, you can find a reputable OCXO on eBay for under $100. - for 1e-13, you can find an old but maybe working cesium clock for 1 k$. - for 1e-14, spend 10 k$ and get a certified working hp 5071A. - for 1e-15, spend 100 k$ and find a used active H-maser. - for 1e-16, spend 1 M$ to hire physicists and build a Cs fountain. - for 1e-17, spend 10 M$ to fund a national research institute to build ion or optical clocks. Add the 1k USD running cost per year just to keep the active maser running. I think that chances of finding an active H-maser used are near 0. Better to stick with GPSDOs: they bring into your home the stability and accuracy of the USNO UTC (well, close to...). I wonder what it would cost to build a trapped Hg ion clock - I don't think it's $10M, but it might be in the range of $500k-1M if you pay people to do the work. Things like the quadrupole trap and ion sources are catalog items. The whole vacuum system, including a turbo pump, is probably in the $10k range (looking at the Cole Parmer catalog, first hit on google), maybe another $5k in various vacuum plumbing bits and pieces. back in 2005-2006 (published in 2007), Prestage et al had a lab version https://ieeexplore.ieee.org/document/4319251 pumped, backfilled with Ne, then sealed ___ 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] Used Hydrogen Maser
Hi One of the gotcha’s if you are in the US is that the most often seen “alternate brand” of Maser comes out of Russia. Depending on the phase of the moon and just what the rule book says this week, you may well not be able to bring one into the country. Back when things were a bit more cordial and trade was more rational, the quoted price was in the $150 $200K range. Bob > On Jul 10, 2019, at 8:57 AM, Dana Whitlow wrote: > > Perry, > > The only H-maser with which I've had direct experience (the MHM-2010) costs > around $250,000 new. But there are some other brands, mostly foreign. > > The immediate operating cost is that of AC power. IIRC, the '2010 uses > about > 100W or maybe 125W, *all the time*. The H-maser is *not* the kind of thing > one > turns on when needed and back off in between uses. > > The hydrogen supply is usually large enough to last about 15 years or more. > > A sort of hidden cost is that the unit must be operated in a > temperature-controllled > environment for best stability- hence there is also the purchase and > operating costs > of a suitable A/C system. > > Also note that H-masers *do* drift in frequency over time. The one we had > at Arecibo > typically needed frequency correction of about 3.5E-14 about every 4 months > on average, > to keep the observatory's master clock on time within 25-50 nsec as needed > for certain > types of radio astronomy situations. We used the H-maser because it has > the best > stability (over the range of seconds to hours) of anything commercially > available. > > The maser operated without difficulty for about the first 8 years before it > lost one of > its two vacion pumps. We had to pay $12k for an engineer from Symmetricom > to > bring down a pair of new pumps and oversee the installation. He replaced > the failed > one on one day while I took notes; then the next day I replaced the 2nd one > under > his close supervision and scrutiny. Because the maser was well designed > with vacuum > isolation valves, both pump replacements were accomplished without shutting > down > the maser and with no disturbance to observations. > > A few years later the maser's internal log data showed that the hydrogen > pressure > was oscillating, along with synchronized fluctuations in drive to the Pd Pd > "valve", > with a period of about 11 days. At this point there was no noticeable > effect on timing > accuracy. A series of calls to Symmetricom customer service indicated that > they had > no idea what was going on, and they counseled "watchful waiting". We did > that for > several more years up until I retired in Dec 2016, with the only change > being a very > gradual drift in oscillation period and amplitude. The in late Dec 2018, > the maser > basically died outright, and Symmetricom (then part of Micro-Semi) was > unable to > provide a definite diagnosis- just a couple of theories. But they advised > against > trying to fully diagnose and repair the unit, considering its advanced age > (approx > 15 years at the time). > > Hope this helps ... > > Dana > > > > > On Wed, Jul 10, 2019 at 7:00 AM Perry Sandeen via time-nuts < > time-nuts@lists.febo.com> wrote: > >> Yo Bubba Dudes!, >> OK, I'll finally ask the question that probably a lot of list members >> wanted to know but were reticent to ask. >> First, what is the price of one of a new Hydrogen Maser? (This is >> important if I win the lottery.) >> Second, what would be prices for used Hydrogen Maser in *reasonable* >> working condition and what might be the long term costs to keep it running? >> Thirdly, what are the chances of finding a used one? >> Then again, might it be better, money wise just to limp along with used HP >> Cs? >> Regards, >> Perrier >> >> >> >> ___ >> 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] GPS frequency uncertainty
Hi The whole clock error / orbit error thing can be corrected after the fact with data from various agencies. It impacts survey work at least as much as timing. Looking at it that way, it does not really present a hard limit. The “what’s the frequency limit?” question depends on just what you mean by frequency. Is it the phase change over a second? ( = a one second counter gate time). In that case you are closer to the ppb range than ppt. Is it 50% of the time, 90% of the time or 99% of the time? Each step you take makes things look a bit worse. There (effectively) is no "100% of the time” answer to the question. ADEV was invented to some degree because this had people very much tied up in knots “back in the day”. Do you average your readings in some way (like to get them on a frequency vs time plot)? That will impact what you “see” as the answer ( = 86,000 data points don’t fit on a normal monitor screen … or printed page). Lots of qualifiers …. Bob > On Jul 10, 2019, at 2:44 AM, Perry Sandeen via time-nuts > wrote: > > Yo Bubba Dudes! > In a number of fascinating and highly educational for me were the explanation > of accuracy by TVB and others. I learned quite a lot, thank you. > Bob mentioned about slight orbital variations in the GPS satellites. > IIRC those slight variations meant that you could only reliably get about > 1x10^12.accuracy. > Would someone please expand on what the practical frequency calibration limit > might be? > Regards, > Perrier > ___ > 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] Advantages of GNSS ???
Hi It depends a lot on the offset you are looking at. For close in phase noise, you probably don’t want high drive. If you are only after phase noise past 10KHz, you may not want / need an OCXO in the first place. Selecting crystals (like one in a hundred) for very high drive / low phase noise setups *is* done. It’s just not very practical. Bob > On Jul 10, 2019, at 3:49 AM, Leo Bodnar wrote: > >> From: Bob kb8tq >> Drive power on an OCXO will pretty much always be below a milli-watt. A >> typical design will be in >> the range of 1/10 to 1/100 of that power level. > > It depends whether OCXO is designed for long term stability and low ageing or > low phase noise. > Low ageing requires low drive but low phase noise needs as much drive as > humanely possible - often approaching mW levels. > > Leo > ___ > 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] Used Hydrogen Maser
Perrier, Hi! Depends on the type and model, Active or Passive Maser etc. I believe new active Masers run in the 1/4 million dollar range. T4 science offers some nice Passive Masers but I don't know the cost. pH Maser 1008 https://www.t4science.com/products/phmaser-1008/ On the basis of just a few examples (they are very rare) a used active Maser can be found for 30-40 Thousand dollars. This for a demonstrated working unit less transport costs which won't be cheap! Expect to pay $1000.00 every 4-5 years on ion pump repair, electricity costs for 24/7 operation, air-con costs to keep it happy, cost of a vacuum turbopump station and ion pump controller for the ion pump repairs. (and don't forget a place to park a small refrigerator sized instrument.) The older Masers are more serviceable than some newer vintages, however getting some specialized parts may be impossible. Some newer Masers use getter packages as the main Hydrogen waste pump and make it very difficult to service the vacuum system. Also some do not make provision for easy field replacement of the ion pumps. Hope this helps and good luck on the lottery! If you do win I would suggest the MHM 2010 https://www.microsemi.com/product-directory/active-hydrogen-maser/4123-mh m-2010-active-hydrogen-maser Cheers, Corby ___ 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] GPS frequency uncertainty
Yo Bubba Dudes! In a number of fascinating and highly educational for me were the explanation of accuracy by TVB and others. I learned quite a lot, thank you. Bob mentioned about slight orbital variations in the GPS satellites. IIRC those slight variations meant that you could only reliably get about 1x10^12.accuracy. Would someone please expand on what the practical frequency calibration limit might be? Regards, Perrier ___ 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] verifying synchronization with PPS
> > Folkert van Heusden has a driver for NTP which includes PPS output: > > https://vanheusden.com/time/rpi_gpio_ntp/ > > Perhaps this might help? > > Indeed I did! :-) > > But please note that the jitter is high, iirc around 18ms. > Personally I would use https://github.com/mlichvar/pps-gpio-poll.git and > then patch it toggle an other gpio-pin. It has this functionality, thus no real patching required. You only need to remove the /* around #define GPIO_ECHO in pps-gpio-poll.c and then make/install/reboot (well not literally reboot of course). ___ 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] Used Hydrogen Maser
Asked and answered before I think, but as far as I know a new maser is in the 2-300K euro range, a used one you can perhaps expect to pay about a tenth of that - if you can find one. Not that many around, but some of the older ones on VLBI sites are getting a bit long in the tooth. If you are serious, I would contact the manufacturers and signal interest - perhaps they can broker a deal when they replace an old one. Keep in mind theres usually a reason they get replaced.. Long term cost are not insignificant, ion pumps cost a bit (a few hundred dollars a year, say), and you need some equipment to change them, unless you can borrow it. Ultra high vacuum pumps and high voltage powersupplies. Then there is the cost for electricity, and temperature control etc. Depending on the type, hydrogen cartridges are pricey, ultra pure H2 in a bottlenless so, but still. Probably more I forgot.. Ole On Wednesday, July 10, 2019, Perry Sandeen via time-nuts < time-nuts@lists.febo.com> wrote: > Yo Bubba Dudes!, > OK, I'll finally ask the question that probably a lot of list members > wanted to know but were reticent to ask. > First, what is the price of one of a new Hydrogen Maser? (This is > important if I win the lottery.) > Second, what would be prices for used Hydrogen Maser in *reasonable* > working condition and what might be the long term costs to keep it running? > Thirdly, what are the chances of finding a used one? > Then again, might it be better, money wise just to limp along with used HP > Cs? > Regards, > Perrier > > > > ___ > 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] Used Hydrogen Maser
Tom Van Baak said on Aug 29, 2013: >The pursuit of precision tends to be exponential rather than linear. ... >As a rough example in the ADEV world: >- for 1e-11, you can buy almost any XO, TCXO, or risky OCXO for $10. >- for 1e-12, you can find a reputable OCXO on eBay for under $100. >- for 1e-13, you can find an old but maybe working cesium clock for 1 k$. >- for 1e-14, spend 10 k$ and get a certified working hp 5071A. >- for 1e-15, spend 100 k$ and find a used active H-maser. >- for 1e-16, spend 1 M$ to hire physicists and build a Cs fountain. >- for 1e-17, spend 10 M$ to fund a national research institute to build ion or >optical clocks. Add the 1k USD running cost per year just to keep the active maser running. I think that chances of finding an active H-maser used are near 0. Better to stick with GPSDOs: they bring into your home the stability and accuracy of the USNO UTC (well, close to...). On Wed, Jul 10, 2019 at 2:00 PM Perry Sandeen via time-nuts wrote: > > Yo Bubba Dudes!, > OK, I'll finally ask the question that probably a lot of list members wanted > to know but were reticent to ask. > First, what is the price of one of a new Hydrogen Maser? (This is important > if I win the lottery.) > Second, what would be prices for used Hydrogen Maser in *reasonable* working > condition and what might be the long term costs to keep it running? > Thirdly, what are the chances of finding a used one? > Then again, might it be better, money wise just to limp along with used HP Cs? > Regards, > Perrier > > > > ___ > 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] Used Hydrogen Maser
Perry, The only H-maser with which I've had direct experience (the MHM-2010) costs around $250,000 new. But there are some other brands, mostly foreign. The immediate operating cost is that of AC power. IIRC, the '2010 uses about 100W or maybe 125W, *all the time*. The H-maser is *not* the kind of thing one turns on when needed and back off in between uses. The hydrogen supply is usually large enough to last about 15 years or more. A sort of hidden cost is that the unit must be operated in a temperature-controllled environment for best stability- hence there is also the purchase and operating costs of a suitable A/C system. Also note that H-masers *do* drift in frequency over time. The one we had at Arecibo typically needed frequency correction of about 3.5E-14 about every 4 months on average, to keep the observatory's master clock on time within 25-50 nsec as needed for certain types of radio astronomy situations. We used the H-maser because it has the best stability (over the range of seconds to hours) of anything commercially available. The maser operated without difficulty for about the first 8 years before it lost one of its two vacion pumps. We had to pay $12k for an engineer from Symmetricom to bring down a pair of new pumps and oversee the installation. He replaced the failed one on one day while I took notes; then the next day I replaced the 2nd one under his close supervision and scrutiny. Because the maser was well designed with vacuum isolation valves, both pump replacements were accomplished without shutting down the maser and with no disturbance to observations. A few years later the maser's internal log data showed that the hydrogen pressure was oscillating, along with synchronized fluctuations in drive to the Pd Pd "valve", with a period of about 11 days. At this point there was no noticeable effect on timing accuracy. A series of calls to Symmetricom customer service indicated that they had no idea what was going on, and they counseled "watchful waiting". We did that for several more years up until I retired in Dec 2016, with the only change being a very gradual drift in oscillation period and amplitude. The in late Dec 2018, the maser basically died outright, and Symmetricom (then part of Micro-Semi) was unable to provide a definite diagnosis- just a couple of theories. But they advised against trying to fully diagnose and repair the unit, considering its advanced age (approx 15 years at the time). Hope this helps ... Dana On Wed, Jul 10, 2019 at 7:00 AM Perry Sandeen via time-nuts < time-nuts@lists.febo.com> wrote: > Yo Bubba Dudes!, > OK, I'll finally ask the question that probably a lot of list members > wanted to know but were reticent to ask. > First, what is the price of one of a new Hydrogen Maser? (This is > important if I win the lottery.) > Second, what would be prices for used Hydrogen Maser in *reasonable* > working condition and what might be the long term costs to keep it running? > Thirdly, what are the chances of finding a used one? > Then again, might it be better, money wise just to limp along with used HP > Cs? > Regards, > Perrier > > > > ___ > 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] verifying synchronization with PPS
> Folkert van Heusden has a driver for NTP which includes PPS output: > https://vanheusden.com/time/rpi_gpio_ntp/ > Perhaps this might help? Indeed I did! :-) But please note that the jitter is high, iirc around 18ms. Personally I would use https://github.com/mlichvar/pps-gpio-poll.git and then patch it toggle an other gpio-pin. ___ 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] Using the LT3042
Those measurements don't go low enough in frequency to capture the very low frequency noise of the LT3042 which uses a noisy current source to produce a voltage drop in a resistor as the reference. At low enough frequencies the LT3042 is very noisy. Low pass reference filters with milliHz or lower cutoff frequencies are usually impractical. Bruce > On 10 July 2019 at 22:58 Gerhard Hoffmann wrote: > > > > Am 10.07.19 um 11:27 schrieb Bruce Griffiths: > > Like virtually all low dropout regulator ICs the LT3042 is quite noisy at > > frequencies below its reference low pass filter high frequency cutoff. Some > > zener based references are considerably quieter in this region. > > We had that already last year. > > I have delivered measured curves that show that it's not true. > > The trick of the LT3042 is that it's reference is not very noisy, > > and there is NO VOLTAGE GAIN after the reference. Zener-based > > reference diodes are _much_ worse, and the LT3042 can hold > > the candle even to 2V7-Zeners and most LEDs. > > You can filter the LT3042 reference quite heavily, and there is > > a startup circuit so you do not have to wait too long for the output voltage > > to become stable. > > > common Regulators: > > < > https://www.flickr.com/photos/137684711@N07/24070698809/in/album-72157662535945536/ > > > > > > Zeners: (Look at that awful super-precision ovenized LM399!) > > < > https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536/ > > > > > > LEDs: > > < > https://www.flickr.com/photos/137684711@N07/24354944411/in/album-72157662535945536/ > > > > > > King of the LEDs is hp/Avago/Broadcom HLMP6600, if it is still alive. > > > I plan to repeat these measurements in the close future with a new > FET-based amplifier that > > is not challenged by that stronger-than-1/f low frequency noise and that > can use cross correlation > > additionally because of its missing noise current. > > > regards, Gerhard. > > > ___ > 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] Used Hydrogen Maser
Yo Bubba Dudes!, OK, I'll finally ask the question that probably a lot of list members wanted to know but were reticent to ask. First, what is the price of one of a new Hydrogen Maser? (This is important if I win the lottery.) Second, what would be prices for used Hydrogen Maser in *reasonable* working condition and what might be the long term costs to keep it running? Thirdly, what are the chances of finding a used one? Then again, might it be better, money wise just to limp along with used HP Cs? Regards, Perrier ___ 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] Neural net to control oven temperature ?
Hi Chase thanks for the email. thanks for the tip on use of logistical classifiers. Agreed the PID (and variations ) is a seemingly perfect fit , at least at the top level.. My guess is that the type of disturbance the 'the system' (affecting, ultimately, the set temperature) (the device) could be classified (in real time) as a cause of different mechanisms, and for a specific mechanism, there might be a more optimal solution to minimize error. My primary intrest in these things looking at new ways to do old things better.. I like systems that predict the error that is coming, before it occurs...so I like adaptive filter driven control systems . I am slowly getting my head around alpha-beta and Kalmans as time permits. The most popular neural net function is of course computers playing games- feed it the history of 10,000 games and as Chase says, it figures out the patterns of Y in a sea of X If anyone is interested in this stuff, you dont need to buy a dev kit. You can do it all in Python. Or C . Once you understand the basics , it is easy enough to program. If you dont understand the basics, you might not be able to acheive a desired outcome. There are quite a few good books on these subjects for Python for those interested. I wish I could go back to school and do a year or two on this stuff... glen On 10/07/2019 12:23 PM, Chase Turner wrote: Hi Glen, This is actually something I know a little about. Neural nets are most useful for feature selection, that is, finding the important x that is a function of y, in a very large sea of x variables. In this case, we already know what's important, which is temperature stability. So, a neural net would be a bit much when we already know what feature is important for function. Additionally, unless I'm mistaken, oven control is probably a linear relationship of some sort or another, and neural nets are much better suited for examining and revealing insights about non-linear data. If you have a method by which you can collect the necessary data that has a bearing on the oven functionality, you'd probably be better off training a logistic classifier, and using it instead. That said, both methods would be overkill, imo- I'd use a PID instead. Best, Chase On Tue, Jul 9, 2019 at 10:00 PM Glen English VK1XX < glenl...@pacificmedia.com.au> wrote: Has anyone tried to use a Neural net to control oven tmep, rather than the ye olde PID ? IE the algorithm learns from previous beheviour and successfully predicts behaviour (or not). I'm sure there are a few out there proficient with machine learning algorithms. Might make a good masters thesis I bet. Given that oven control based on inputs and whatever is not random, unlike say flicker etc. glen ___ 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] Using the LT3042
Am 10.07.19 um 11:27 schrieb Bruce Griffiths: Like virtually all low dropout regulator ICs the LT3042 is quite noisy at frequencies below its reference low pass filter high frequency cutoff. Some zener based references are considerably quieter in this region. We had that already last year. I have delivered measured curves that show that it's not true. The trick of the LT3042 is that it's reference is not very noisy, and there is NO VOLTAGE GAIN after the reference. Zener-based reference diodes are _much_ worse, and the LT3042 can hold the candle even to 2V7-Zeners and most LEDs. You can filter the LT3042 reference quite heavily, and there is a startup circuit so you do not have to wait too long for the output voltage to become stable. common Regulators: < https://www.flickr.com/photos/137684711@N07/24070698809/in/album-72157662535945536/ > Zeners: (Look at that awful super-precision ovenized LM399!) < https://www.flickr.com/photos/137684711@N07/24411798996/in/album-72157662535945536/ > LEDs: < https://www.flickr.com/photos/137684711@N07/24354944411/in/album-72157662535945536/ > King of the LEDs is hp/Avago/Broadcom HLMP6600, if it is still alive. I plan to repeat these measurements in the close future with a new FET-based amplifier that is not challenged by that stronger-than-1/f low frequency noise and that can use cross correlation additionally because of its missing noise current. regards, Gerhard. ___ 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] Recommendations for time beginner?
From: Frank O'Donnell Forrest, Thanks very much for the extensive comments, they're greatly helpful. [] I have very poor view of the sky immediately outside the room my gear is located in, so for the Trimble I've been using a run of about 50 feet of coax to an active GPS antenna. If I run multiple GPSDOs I hope I can use an antenna splitter rather than putting up multiple antennas. [] If I have anything wrong, or if any of the above suggests any further comments or suggestions (from any one on the list), I'll be very interested. Thanks again, Frank === Frank, Only one comment on that - an antenna splitter is fine for this task. There are splitters designed for GPS use which will pass the receiver output DC through to the antenna, usually taking the highest voltage, but leaving the remaining feeds DC terminated so that the receiver thinks the antenna is still there. Not sure I explained that very well! Alternatively, use a satellite TV splitter and a DC isolator in one of the outputs - if that is needed. I've not used a Trimble so I don't know how sensitive to DC conditions it is. 73, David GM8ARV -- SatSignal Software - Quality software for you Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Using the LT3042
FWIW for the 10MHz distribution amplifier I have been using LT1963 (40 uVrms in 10Hz to 100kHz) which is about 40x worse than the LT3042 spec of 0.8 uVrms in 10Hz to 100kHz. With decent op-amps I think the distribution-amp performance is limited by the op-amp noise and thermal noise in the resistors - I wouldn't expect the residual phase/amplitude noise to improve at all with a better LDO like the LT3042 - but ofcourse I haven't tried this :) The LT3042 spot noise spec of 2nV/sqrt(Hz) corresponds to Johnson noise of a 250 Ohm resistor at room-temperature (if my spreadsheet-calc is right..) - so I guess if one has circuits that are already optimized/limited by supply voltage noise at that level then moving to the LT3042 makes sense. AW On Wed, Jul 10, 2019 at 12:02 PM Perry Sandeen via time-nuts < time-nuts@lists.febo.com> wrote: > Yo Bubba Dudes!, > The LT3042 seems to be a wonderful part. But having learned a long time > ago the it wasn't wise to gold plate a Yugo, so when are there diminishing > returns? > For example I have several HP 10811 oscillators. one is in a HP5335a > counter that I'd like to make as stable as reasonably possible. Another > HP10811 needs a power supply. Also several Lucent XO OCXO's. > So where is it practical to hack for better results and when do you use > some not -as -wonderful regulator chips that come in a much easier to use > dip package for a power supply upgrade? > Regards, > Perrier > > > > > > ___ > 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] Using the LT3042
Like virtually all low dropout regulator ICs the LT3042 is quite noisy at frequencies below its reference low pass filter high frequency cutoff. Some zener based references are considerably quieter in this region. Bruce > On 10 July 2019 at 18:18 Perry Sandeen via time-nuts > wrote: > > > Yo Bubba Dudes!, > The LT3042 seems to be a wonderful part. But having learned a long time ago > the it wasn't wise to gold plate a Yugo, so when are there diminishing > returns? > For example I have several HP 10811 oscillators. one is in a HP5335a counter > that I'd like to make as stable as reasonably possible. Another HP10811 needs > a power supply. Also several Lucent XO OCXO's. > So where is it practical to hack for better results and when do you use some > not -as -wonderful regulator chips that come in a much easier to use dip > package for a power supply upgrade? > Regards, > Perrier > > > > > > ___ > 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] Neural net to control oven temperature ?
https://www.electronicdesign.com/analog/whats-all-p-i-d-stuff-anyhow For all Bob Pease fans: there's a fabulous 9 volume ~1200 page scan of his columns here: https://archive.org/details/Bob_Pease_Lab_Notes The P-I-D article Ben mentions appears in volume 2, starting on page 167. /tvb ___ 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] Using the LT3042
Yo Bubba Dudes!, The LT3042 seems to be a wonderful part. But having learned a long time ago the it wasn't wise to gold plate a Yugo, so when are there diminishing returns? For example I have several HP 10811 oscillators. one is in a HP5335a counter that I'd like to make as stable as reasonably possible. Another HP10811 needs a power supply. Also several Lucent XO OCXO's. So where is it practical to hack for better results and when do you use some not -as -wonderful regulator chips that come in a much easier to use dip package for a power supply upgrade? Regards, Perrier ___ 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] Advantages of GNSS ???
I did, sorry, - it was a finger slip. Now, what I find kind of funny is that one of the meanings of "monotonous" is "repetitious or periodic" which is almost exactly the opposite of monotonic. Leo > From: "David G. McGaw" > Leo - > I do believe you mean non-monotonic, rather than non-monotonous. Not > being monotonous is a good thing.? :-) > David N1HAC ___ 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] Advantages of GNSS ???
> From: Bob kb8tq > Drive power on an OCXO will pretty much always be below a milli-watt. A > typical design will be in > the range of 1/10 to 1/100 of that power level. It depends whether OCXO is designed for long term stability and low ageing or low phase noise. Low ageing requires low drive but low phase noise needs as much drive as humanely possible - often approaching mW levels. Leo ___ 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] Neural net to control oven temperature ?
The article link in my post doesn't have valid links to the figures (Pease hand-drawn schematics), but these links work: https://web.archive.org/web/20121113202641/https://www.electronicdesign.com/files/29/6131/figure_01.gif https://web.archive.org/web/20121113202709/https://www.electronicdesign.com/files/29/6131/figure_02.gif https://web.archive.org/web/20121113202731/https://www.electronicdesign.com/files/29/6131/figure_03.gif On Wed, Jul 10, 2019 at 1:06 AM Ben Bradley wrote: > > I recall Bob Pease in one of his many "What's all this ...stuff" > columns made a small oven and PID temperature controller that he > claimed kept the temperature within 0.001 degrees or something like > that. This would make machine learning severe overkill. Temp control > is slow enough (and generates/uses a small enough data set) that for > ML or any other method, an ARM or even AVR microcontroller might be > enough to do it. > > I did a quick Google search, this column makes no such claim (it's > about temp controllers in general), but he surely wrote several times > about PID and/or temperature control. He has a lot of hints and ideas > in this column, like having different sensors for the P and I, placed > strategically for better operation: > > https://www.electronicdesign.com/analog/whats-all-p-i-d-stuff-anyhow > > On Wed, Jul 10, 2019 at 12:05 AM paul swed wrote: > > > > I will mention that TI has a neural net chip/eval board now for as I recall > > $99. > > Like so many things maybe it makes sense. > > Regards > > Paul > > WB8TSL > > > > On Tue, Jul 9, 2019 at 11:02 PM Chase Turner wrote: > > > > > Hi Glen, > > > > > > This is actually something I know a little about. > > > > > > Neural nets are most useful for feature selection, that is, finding the > > > important x that is a function of y, in a very large sea of x variables. > > > In > > > this case, we already know what's important, which is temperature > > > stability. So, a neural net would be a bit much when we already know what > > > feature is important for function. Additionally, unless I'm mistaken, oven > > > control is probably a linear relationship of some sort or another, and > > > neural nets are much better suited for examining and revealing insights > > > about non-linear data. > > > > > > If you have a method by which you can collect the necessary data that has > > > a > > > bearing on the oven functionality, you'd probably be better off training a > > > logistic classifier, and using it instead. That said, both methods would > > > be > > > overkill, imo- I'd use a PID instead. > > > > > > Best, > > > Chase > > > > > > On Tue, Jul 9, 2019 at 10:00 PM Glen English VK1XX < > > > glenl...@pacificmedia.com.au> wrote: > > > > > > > Has anyone tried to use a Neural net to control oven tmep, rather than > > > > the ye olde PID ? > > > > > > > > IE the algorithm learns from previous beheviour and successfully > > > > predicts behaviour (or not). > > > > > > > > I'm sure there are a few out there proficient with machine learning > > > > algorithms. > > > > > > > > Might make a good masters thesis I bet. > > > > > > > > Given that oven control based on inputs and whatever is not random, > > > > unlike say flicker etc. > > > > > > > > glen > > > > > > > > > > > > > > > > ___ > > > > 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] Neural net to control oven temperature ?
I recall Bob Pease in one of his many "What's all this ...stuff" columns made a small oven and PID temperature controller that he claimed kept the temperature within 0.001 degrees or something like that. This would make machine learning severe overkill. Temp control is slow enough (and generates/uses a small enough data set) that for ML or any other method, an ARM or even AVR microcontroller might be enough to do it. I did a quick Google search, this column makes no such claim (it's about temp controllers in general), but he surely wrote several times about PID and/or temperature control. He has a lot of hints and ideas in this column, like having different sensors for the P and I, placed strategically for better operation: https://www.electronicdesign.com/analog/whats-all-p-i-d-stuff-anyhow On Wed, Jul 10, 2019 at 12:05 AM paul swed wrote: > > I will mention that TI has a neural net chip/eval board now for as I recall > $99. > Like so many things maybe it makes sense. > Regards > Paul > WB8TSL > > On Tue, Jul 9, 2019 at 11:02 PM Chase Turner wrote: > > > Hi Glen, > > > > This is actually something I know a little about. > > > > Neural nets are most useful for feature selection, that is, finding the > > important x that is a function of y, in a very large sea of x variables. In > > this case, we already know what's important, which is temperature > > stability. So, a neural net would be a bit much when we already know what > > feature is important for function. Additionally, unless I'm mistaken, oven > > control is probably a linear relationship of some sort or another, and > > neural nets are much better suited for examining and revealing insights > > about non-linear data. > > > > If you have a method by which you can collect the necessary data that has a > > bearing on the oven functionality, you'd probably be better off training a > > logistic classifier, and using it instead. That said, both methods would be > > overkill, imo- I'd use a PID instead. > > > > Best, > > Chase > > > > On Tue, Jul 9, 2019 at 10:00 PM Glen English VK1XX < > > glenl...@pacificmedia.com.au> wrote: > > > > > Has anyone tried to use a Neural net to control oven tmep, rather than > > > the ye olde PID ? > > > > > > IE the algorithm learns from previous beheviour and successfully > > > predicts behaviour (or not). > > > > > > I'm sure there are a few out there proficient with machine learning > > > algorithms. > > > > > > Might make a good masters thesis I bet. > > > > > > Given that oven control based on inputs and whatever is not random, > > > unlike say flicker etc. > > > > > > glen > > > > > > > > > > > > ___ > > > 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.
