Re: [time-nuts] low power divide by 5
To divide by 5 with a '161/'163 counter, connect the 8's bit output to the /preset enable input. Then set the input bits to 12. The counter will count: 12, 13, 14, 15, 0, 12, 13, 14, 15, 0 ... This is the fastest configuration. It avoids external gate delay and the slower carry output. You can only divide by up to 9 this way. I have been doing this for at least 40 years with various logic families du jour. Rick N6RK On 6/29/2020 3:32 PM, ed breya wrote: Looks like the AC161 and AC163 are readily available, so they may be rigged for divide 5. It seems that of the counters surviving into AC, only binary ones are included, and the oddballs like decade are considered unnecessary - apparently nobody divides by 10 anymore, except inside of a processor. Ed ___ 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] 3 Gorges dam slows down Earth's rotation by 60 ns/day
I love the analysis of the Earth! Can you do it for Mars too or is the data not available ? cheers Tim On 30/6/20 3:53 am, Tom Van Baak wrote: [snip] And if you haven't see it before, I have phase, frequency, and ADEV plots of earth here: http://leapsecond.com/museum/earth/ ___ 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] 1pps signal measurement
Am 29.06.20 um 20:48 schrieb Gerhard Hoffmann: eternity, with CMOS being so slow that interoperability with CMOS was not an advantage. ooohps, sorry: substitute / interoperability with CMOS / interoperability with TTL / ___ 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] FEI Nanosync 2
Hi — In a parallel life I work as a broadcast radio engineer. An AM transmitter's hybrid digital control system contains an embedded FEI Nanosync 2 GPS receiver. The GPS time data appears to suffer from a week 1024 rollover problem, causing the control system to believe (and broadcast) a date around 2000 November (if I remember correctly). I can get access to the serial port to the FEI Nanosync 2 card. Does anyone have experience or suggestions as to how to force this receiver to the proper date? Thanks for any help. — Eric p.s.: I apologize if the information requested below is in the archives somewhere. Is there an alternative search other than month-by-month? ___ 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] low power divide by 5
Am 29.06.20 um 18:43 schrieb jimlux: What logic family might be appropriate for a divide by 5 from 50 to 10MHz, low power, running off 3.3 or 5V? In the picture is probably what you need, and maybe more. The left third is a comparator that generates valid CMOS levels from a vaguely defined sine signal. The right third determines if there is a valid reference and tells the PLL (not in the picture) to use or ignore it. If you have a valid CMOS signal, the middle is all that is needed. LVC163 + LVC04. Good enough for 150 MHz+. On terminal count, the inverter forces the counter to load the P0..3 pins on the next clock. The value on P0..3 determines the division ratio, from 2 to 16. Large numbers = few clocks until the next terminal count. The example is divide by 5, which happens to fit your problem. IIRC, the 74AC191 could have done that without the external inverter, but it did not make it into the 74LVC series. That's what I used to lock my DG8SAQ vector network analyzer V2+ to an external 10 MHz reference before that was available in V3. The PLL chip was a 74lvc4046. https://www.digikey.de/product-detail/de/nexperia-usa-inc/74LVC163PW-118/1727-3097-2-ND/946683 Cheers, 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] low power divide by 5
Looks like the AC161 and AC163 are readily available, so they may be rigged for divide 5. It seems that of the counters surviving into AC, only binary ones are included, and the oddballs like decade are considered unnecessary - apparently nobody divides by 10 anymore, except inside of a processor. Ed ___ 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] low power divide by 5
Well, data sheets are out there, but I don't know about the actual
parts. Unfortunately, the 74AC family has far fewer members than the
74HC and others. I think each step in the evolution loses some types
that aren't expected to be high enough in volume for the most modern
applications. For instance, if you look back through the history of TTL
and its descendants, there are a lot of numbers that have gone extinct,
and new ones born.
I know the 74AC parts are plentiful in the high speed bus type stuff
('374, '244, '541, etc) and glue logic. It seems that many counters
should still be around too. Here's a '390 datasheet I found:
https://pdf1.alldatasheet.com/datasheet-pdf/view/106913/TOSHIBA/TC74AC390F.html
So, it must have existed sometime, but maybe it didn't make the
evolutionary cut. In any case, I think there must be some available
somewhere, even if obsolete. 74AC may be available in other counters
like '160 or '190 families. I haven't looked in a while.
I can't offhand remember all the HC counters, but I don't think any will
be acceptable for 50 MHz. Gotta go with AC or more modern low-level
families. If worse came to worse, you can definitely get some AC74s and
build your own machine, but it won't be as nice as dropping in a single
AC390 and having dividers to spare.
Ed
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Re: [time-nuts] low power divide by 5
I just looked around for some AC390s - it appears they may have been made only by Toshiba and Hitachi, and have gone obsolete. Looks like you can't just call Mouser to order some up. But, looking at this site, it appears that a lot exist - at least a million pieces floating around out there, if these inventory numbers are true. https://www.digchip.com/datasheets/quote.php?action=search=74AC390 Ed ___ 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] low power divide by 5
You might try the 74AC161, which works to 73MHz at 3.3V or 103 MHz at 5V, -40 to 85C. Set the data inputs to DCBA = 1011 and connect an inverter from the carry output (pin 15) to the Load input (pin 9) to divide by 5. See http://www.techlib.com/electronics/74161Divider.htm On Mon, Jun 29, 2020 at 12:49 PM jimlux wrote: > What logic family might be appropriate for a divide by 5 from 50 to > 10MHz, low power, running off 3.3 or 5V? > > > ___ > 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. > -- --Jim Harman ___ 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] FW: HP-5732A operation with no CRT display.
Hi Lester, I had this problem with the 5372A at work. As others have noted, documentation of the CRT unit is for sure leaving a lot to wish for when comparing how well the rest of the unit is documented. We could however fairly quickly see the problem, and it turned out that a capacitor had let out it's grey smoke. So, we replaced it and it fired up and worked. Took care of a little trimming and it went out the lab again. The CRT unit is fairly standard as for monochrome CRT goes, so nothing very advanced. I usually do not service CRTs but me and my colleague did not found it very challenging in the end. One just needs to be careful with voltages. It was a fair bit of unscrewing to "get to it" as I recall, so both top and bottom lid had to be popped, as well as the side lid which hides screws. Besides the CMOS-battery, the CRT failure is the only other service I've had to do to the 5372As. The "GUI" of the 5372A leaves a few things to desire, but it has it's good points too. The GPIB command structure may be daunting at first, but if one really reads the programming manual, your really get to learn how everything is processed from the hardware bits, because the preferred interface just dumps one of a number of subsets of data register read-outs, and all the processing one needs to do it explained in detail. It also becomes apparent that a sneak-feature is that 100 ps resolution may be possible to support by replacing the interpolator boards. If I had the time, I would do a modern hardware to grab data on the fast-port connectors and dump them out over Ethernet. This would be the way to keep the counter operating continuously with fast data gathering, but without being limited to the 8192 samples long memory, which when full being processed by the 68k processor before another run could be triggered. Offboarding that the existing CPU would be used to set the instrument up, and then all the data is gathered and processed in somewhat more modern hardware. Cheers, Magnus On 2020-06-28 16:22, Lester Veenstra via time-nuts wrote: > > > TimeNuts: > > > > I have a HP 5732A with a defective CRT driver board. Since this (A17) > is undocumented (as no repairable) I am of course trying to work my way > around it to see if the defect is findable. > > > > Any A17 boards loose out there, or even better, documentation? > > I see good H and V sync inputs as well as the ZMod (Video data) into the > board, bur the drive for the two deflection coils is not what I would > expect. > > > > Trace is some where up off crt but with vertical coils disconnected, still > no horizontal line. > > With no drives connected to H & V coils, dim spot in center. Spot moves well > in both axis with low voltage DC applied. > > > > > > However, it occurs to me; Does anyone have HPIB code that allows use of the > instrument without the GUI user interface? > > I seem to recall some discussion of “raw data” dumps turned into useful > measurements. > > > > > > Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y > > les...@veenstras.com > > > > 452 Stable Ln (HC84 RFD USPS Mail) > > Keyser WV 26726 > > > > GPS: 39.336826 N 78.982287 W (Google) > > GPS: 39.33682 N 78.9823741 W (GPSDO) > > > > > > Telephones: > > Home: +1-304-289-6057 > > US cell+1-304-790-9192 > > Jamaica cell: +1-876-456-8898 > > > > > > ___ > 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] FW: HP-5732A operation with no CRT display.
Thanks Don, but I suspect we both have the same manual. Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y les...@veenstras.com 452 Stable Ln (HC84 RFD USPS Mail) Keyser WV 26726 GPS: 39.336826 N 78.982287 W (Google) GPS: 39.33682 N 78.9823741 W (GPSDO) Telephones: Home: +1-304-289-6057 US cell +1-304-790-9192 Jamaica cell: +1-876-456-8898 -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of DON MURRAY via time-nuts Sent: Sunday, June 28, 2020 9:03 PM To: time-nuts@lists.febo.com Cc: DON MURRAY Subject: Re: [time-nuts] FW: HP-5732A operation with no CRT display. I'll check my 5372A manual to see if I can be of any help. Don W4WJ On Sunday, June 28, 2020 ed breya wrote: I have a 5372A, and way back when I got it, I of course looked for the manual and think I got the pdf. As I recall, this was from the era where HP still provided full "real" manuals with all the schematics etc. The exception sometimes is if the entire display is an OEM unit, treated as a single component, and minimally documented. I don't recall much of the guts, as it's been a lot of years since I saw the inside. Do you have the regular manual? Is the display an OEM unit, or actually HP-made? If it's all HP, then it seems the schematics should be around somewhere, unless maybe accidentally left out of the printing somehow. Ed ___ 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] Vibration isolation of quartz oscillators
Hello Tom, (and thanks everyone for your advice) I want to do the same as you: rack mount the oscillators. Elaborate vibration isolation solutions are not possible in the available space viz 3 to 4 RU. I have the manufacturer’s test data for the oscillators, plus my own test data, so I think I will just make a trial test with the existing isolation system and then see if there any problems when in the rack. Cheers Michael On Tue, 30 Jun 2020 at 2:52 am, Tom Knox wrote: > I am enjoy this Nth degree Vibration Isolation discussion. Countless > amazing tables where I work. > I have been focused on more practical solutions for Vibration isolation of > my rack mount oscillators in my home lab, and I think at that level in some > ways are focused on eliminating resonances as well as trading one frequency > for another taking higher intensity "square waves" and dissipating them > over time. > Any thoughts? > Cheers; > > Tom Knox > > SR Test and Measurement Engineer > > Ascent Concepts and Technology > Much > 4475 Whitney Place > > Boulder Colorado 80305 > > 303-554-0307 > > act...@hotmail.com > > "Peace is not the absence of violence, but the presence of Justice" Both > MLK and Albert Einstein > > > From: time-nuts on behalf of > Poul-Henning Kamp > Sent: Monday, June 29, 2020 12:16 AM > To: Discussion of precise time and frequency measurement < > time-nuts@lists.febo.com>; ed breya > Subject: Re: [time-nuts] Vibration isolation of quartz oscillators > > > ed breya writes: > > > The nicest optical bench I've ever seen in person, was in one of our > > labs many years ago. It was a huge, precisely flat polished granite slab > > about 6-8" thick, about 4x8' or maybe 5x10', mounted on active-leveling > > pneumatic bladders. It was loaded with thousands of threaded inserts, > > uniformly spaced on a grid, for mounting optical devices and equipment. > > It is worth foot-noting here, that at that level of quality they > are usually not made from natural granite, but rather from > "epoxy-granite", which can be designed to have very low temp-co. > > > There are lower-grade type platforms available, commonly called "optical > > breadboards," that are made from thick sheets of aluminum or stainless > > steel, [...] > > and these obviously have a sizeable temp-co, so the money you saved on > your bench you get to spend on your air-con. > > They are a lot easier to move around though. > > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > p...@freebsd.org | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > > ___ > time-nuts mailing list -- time-nuts@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] FW: HP-5732A operation with no CRT display.
Ed: Like many cards and parts in this unit; Not field repairable, so no schematics or parts list. I do have the "full" maintenance manual. It appears to be a OEM Taiwan "Part", the CRT and driver board. Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y les...@veenstras.com 452 Stable Ln (HC84 RFD USPS Mail) Keyser WV 26726 GPS: 39.336826 N 78.982287 W (Google) GPS: 39.33682 N 78.9823741 W (GPSDO) Telephones: Home: +1-304-289-6057 US cell +1-304-790-9192 Jamaica cell: +1-876-456-8898 -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of ed breya Sent: Sunday, June 28, 2020 5:25 PM To: time-nuts@lists.febo.com Subject: Re: [time-nuts] FW: HP-5732A operation with no CRT display. I have a 5372A, and way back when I got it, I of course looked for the manual and think I got the pdf. As I recall, this was from the era where HP still provided full "real" manuals with all the schematics etc. The exception sometimes is if the entire display is an OEM unit, treated as a single component, and minimally documented. I don't recall much of the guts, as it's been a lot of years since I saw the inside. Do you have the regular manual? Is the display an OEM unit, or actually HP-made? If it's all HP, then it seems the schematics should be around somewhere, unless maybe accidentally left out of the printing somehow. Ed ___ 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] FW: HP-5732A operation with no CRT display.
Dave:I have a "not working, parts only" unit coming. I will see if A17 is working on that unit. If I get one working, I think I can signal trace to the problem unit, using the good one as reference Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y les...@veenstras.com 452 Stable Ln (HC84 RFD USPS Mail) Keyser WV 26726 GPS: 39.336826 N 78.982287 W (Google) GPS: 39.33682 N 78.9823741 W (GPSDO) Telephones: Home: +1-304-289-6057 US cell+1-304-790-9192 Jamaica cell: +1-876-456-8898 -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of VE7HR Sent: Sunday, June 28, 2020 9:01 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FW: HP-5732A operation with no CRT display. Lester, I think looking at the parts list in the Service manual from Artek it’s a bought out all in one unit. If I recall the BOM has one line item. Have you checked with Walter at Sphere? He has the next PN in the sequence which is a Sony Color display. Or check with Newscope for a LCD replacement. My new to me 5372A has a bright screen but I noticed it glitched a few times yesterday. The size changed for an instant a couple of time but other wise is working. Dave Sent from my iPhone > On Jun 28, 2020, at 5:50 PM, ed breya wrote: > > I have a 5372A, and way back when I got it, I of course looked for the > manual and think I got the pdf. As I recall, this was from the era where HP > still provided full "real" manuals with all the schematics etc. The exception > sometimes is if the entire display is an OEM unit, treated as a single > component, and minimally documented. I don't recall much of the guts, as it's > been a lot of years since I saw the inside. > > Do you have the regular manual? Is the display an OEM unit, or actually > HP-made? If it's all HP, then it seems the schematics should be around > somewhere, unless maybe accidentally left out of the printing somehow. > > Ed > > ___ > 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] Vibration isolation of quartz oscillators
Folks, A long time ago I worked for a division of Litton Industries. One day we visited the Litton Guidance and Control Systems Division, which manufactured Optical Gyros. Part of the test facility was a granite slab mounted using isolators on a column in a hole. I was told that the column went down to bedrock to minimize vibration. Francis Grosz ___ 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] 1pps signal measurement
Am 29.06.20 um 19:35 schrieb Mark Spencer: I am also wondering a bit about the possible impact of my 5370B's having a maximum trigger setting of approx 2.18 volts vis a vis the typical specs for 5 volt TTL signals that typically define a logic 1 as having a slightly higher voltage ? Would enabling the 10:1 attenuator on the input to the 5370B make sense ? TTL has nothing to do with 5V, other than that 5V is the intended supply voltage. An input at less than 0.8V is guaranteed to be low, anything higher than 2.4V is guaranteed high, the nominal switching level is about 1V8. The difference between 1V8 and 0V8/2V4 is to provide a minimum noise immunity. It's different for CMOS. CMOS outputs are close to either VDD or GND, and the inputs switch nominally at 1/2 VDD. That went on for a little eternity, with CMOS being so slow that interoperability with CMOS was not an advantage. So people used pullup resistors and were happy. I still hear the voice of the professor saying "Ladies & Gents, now you understand why CMOS will never be fast!". Oh, he was wrong! Then the CMOS steamroller accelerated. Nobody escapes the CMOS steamroller, as they used to say. The 74HC series was as fast as 74LS and switched at 1/2 VDD. The functions were like the TTL series. Then there was the 74HCT series with a switching threshold at 1V8, like TTL. That was implemented by massaging the width/length ratio of the FETs and the intention was to get 74LS sockets. Replacements were a no-brainer, only open inputs would no longer default to "High". With CMOS, they have to be definitely driven to a valid value, bad things happen if not. 74AC / 74ACT is like 74HC/HCT on steroids. Faster but essentially the same. 3.3V CMOS came later with a switching threshold at 1/2 * 3V3, so it is TTL compatible by coincidence. 74LV, 74LVC... etc, depending on who makes them. 74LVC may operate at less than 3V3, then the switching thresholds are lower in proportion. These chips may not like input voltages higher than their 2V5 or 3V3 supply, such as 5V. Some families are designed to accept that abuse, some will die. Caveat emptor. To make it short, you have no problem with your counter. The magic voltage for TTL is 1.8V. Cheers, 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] low power divide by 5
On 6/29/20 10:41 AM, ed breya wrote: 74AC logic would do it just fine, but needs 5V nominal for full-speed specs. Lower supply voltage should work, but probably not all the way down to 3.3V with 50 MHz clocking. The spec sheets should indicate the possible range. The 74AC390 can provide divide by 5 directly, with another divide 5 and two divide 2 sections left over - lots of capability. Ed Couldn't find the AC390 - did find HC390, but it only goes to 35 MHz (at room temp, less over temp) However, you got me started hunting for decade counters, and there's things like the 74HC4017 which claims fmax=60 MHz on the data sheet front page, but only claims 35 MHz down in the AC specs ___ 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] Precise Pendulum
John, Everything I've read on the subject says that "spooky action at a distance" does *not* provide for FTL communications. Sorry to disappoint- I'd like to see it, too. Dana On Sun, Jun 28, 2020 at 7:47 AM John Moran, Scawby Design < j...@scawbydesign.co.uk> wrote: > Interesting ... > > They quote - “At the other end of the scale, gravity dominates over very > long distances, while quantum effects vanish entirely at these distances.” > > I thought quantum entanglement was valid over any distance - Einstein’s > “spooky action at a distance”. Thus offering the possibility of > instantaneous transfer of information over stellar distances. > > This is one of the problems they are trying to sort out with the > incompatibility of the two conflicting hypothesis. > > To then dismiss one of the ‘strange’ properties of quantum mechanics where > there is an apparent overlap, right at the beginning, seems a bit strange. > > John > ___ > 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] Precise Pendulum
On Sun, 28 Jun 2020 12:45:05 + "John Moran, Scawby Design" wrote: > They quote - “At the other end of the scale, gravity dominates over very long > distances, > while quantum effects vanish entirely at these distances.” > > I thought quantum entanglement was valid over any distance - Einstein’s > “spooky action at a > distance”. Thus offering the possibility of instantaneous transfer of > information over > stellar distances. I guess you are refering to the Einstein-Podolsky-Rosen (thought) experiment. The EPR experiment is based on entanglement, which is not a force. You create two particles that share a "property". And this property does not change, no matter how far the particles are appart. But, while it is true that this "affects" particles at a distance, it does not mean one can transfer information at superluminal speeds. The whole thing is very weird and my understanding of it is limited, so please excuse me for not explaining it. > This is one of the problems they are trying to sort out with the > incompatibility of > the two conflicting hypothesis. They are not conflicting[1]. Both quantum theory and general relativity are proven and well working theories. The problem with them is that they apply to different scales of size. I.e. we have one theory that works well for large objects and one that works well for small objects, but none that works well for all objects. The "Grand Unified Theory" is the one that suppowed to bridge the gap between the two. With the discovery (or rather verification of existence) of the Higgs boson, we are a large step closer to that lofty goal, but by far not finished. There are still a lot of corner cases that could be explained differently. And that's why physicists come up with new experiments to see what happens when... and see whether they can find a "problem" with a theory. In this sense, the run of the LHC, although generally regarded as a great success, has also been quite boring. Every experiment returned results that were in accordance to current theories. For a lot of phenomena we now have better data, but nothing out of the ordinary that would require new explanations. > To then dismiss one of the ‘strange’ properties of quantum mechanics where > there is an > apparent overlap, right at the beginning, seems a bit strange. No not really. Quantum-gravity experiments have been quite common in the last decades. You have to imagine scientists like sitting in a large and dark room with lots of stuff in it. They don't see anything but what their tiny candle illuminates. So they slowly walk from one object to another, drawing a map of things and try to see whether there is a pattern somewhere. Whenever there is something that is not explaint to everyones satisfaction, you'll find someone that looks at it from a different direction, from a different angle, to see whether he can gleam new insights. Attila Kinali [1] If two theories have contradicting predictions for something, the whole world usually gears up and tries to find an experiment that shows which one is the right theory. Once, this question has been answered, the one theory that got disproven is either completely discarded or changed to account for that experiment. -- Science is made up of so many things that appear obvious after they are explained. -- Pardot Kynes ___ 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] 3 Gorges dam slows down Earth's rotation by 60 ns/day
Rick, See also the NASA press release from 2005: https://www.jpl.nasa.gov/news/news.php?release=2005-009 The formal paper about the 3 Gorges calculation is here (4 pages, PDF): "Time-variable gravity signal during the water impoundment of China’s Three-Gorges Reservoir" https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2002GL016457 For many more like it google for: Richard Gross rotation day It's worth a minute to look through the search results. What you'll find is that anytime there's a large earth deformation event (e.g., earthquake, tsunami) Richard Gross and Benjamin Fong Chao at NASA Goddard make a *theoretical* prediction about earth rotation. They are legitimate scientists but unfortunately the popular press often distorts or sensationalizes their modest findings. The link you quoted was particularly poor in this respect. Some technical discussion here: https://skeptics.stackexchange.com/questions/45370/will-chinas-three-gorges-dam-slow-down-earths-rotation A long list of resources: https://physics.info/rotational-momentum/resources.shtml And if you haven't see it before, I have phase, frequency, and ADEV plots of earth here: http://leapsecond.com/museum/earth/ /tvb On 6/29/2020 9:39 AM, Richard (Rick) Karlquist wrote: See: https://futurism.com/how-infamous-hydroelectric-dam-changed-earths-rotation Of course, readers of this list know that the earth isn't stable to 60 ns/day in the first place. But this is an interesting calculation, at least to time nuts. 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. ___ 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] low power divide by 5
I just looked at the 74AC390 sheet - it does say it will run to 60 MHz clocking with 3.3V supply, but that's at 25 deg C Tj. So, it looks doable, but depends on your desired operating temperature range. Ed ___ 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] 1pps signal measurement
Hi: After a long break I am spending a bit of time looking at my time nuts gear. I have started looking at the properties of the various 1 pps signals I have access to. Other than routing the signals via Coaxial cable into instruments with a high impedance input (the documentation for some my signal sources caution against terminating the outputs with 50 ohms) setting the trigger point to trigger on the appropriate part of the wave form (typically the leading edge of the pulse) are there any "best practices" I should be aware of ? I am also wondering a bit about the possible impact of my 5370B's having a maximum trigger setting of approx 2.18 volts vis a vis the typical specs for 5 volt TTL signals that typically define a logic 1 as having a slightly higher voltage ? Would enabling the 10:1 attenuator on the input to the 5370B make sense ? Any comments would be appreciated. Thanks Mark S ___ 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] low power divide by 5
74AC logic would do it just fine, but needs 5V nominal for full-speed specs. Lower supply voltage should work, but probably not all the way down to 3.3V with 50 MHz clocking. The spec sheets should indicate the possible range. The 74AC390 can provide divide by 5 directly, with another divide 5 and two divide 2 sections left over - lots of capability. Ed ___ 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] Vibration isolation of quartz oscillators
I am enjoy this Nth degree Vibration Isolation discussion. Countless amazing tables where I work. I have been focused on more practical solutions for Vibration isolation of my rack mount oscillators in my home lab, and I think at that level in some ways are focused on eliminating resonances as well as trading one frequency for another taking higher intensity "square waves" and dissipating them over time. Any thoughts? Cheers; Tom Knox SR Test and Measurement Engineer Ascent Concepts and Technology 4475 Whitney Place Boulder Colorado 80305 303-554-0307 act...@hotmail.com "Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein From: time-nuts on behalf of Poul-Henning Kamp Sent: Monday, June 29, 2020 12:16 AM To: Discussion of precise time and frequency measurement ; ed breya Subject: Re: [time-nuts] Vibration isolation of quartz oscillators ed breya writes: > The nicest optical bench I've ever seen in person, was in one of our > labs many years ago. It was a huge, precisely flat polished granite slab > about 6-8" thick, about 4x8' or maybe 5x10', mounted on active-leveling > pneumatic bladders. It was loaded with thousands of threaded inserts, > uniformly spaced on a grid, for mounting optical devices and equipment. It is worth foot-noting here, that at that level of quality they are usually not made from natural granite, but rather from "epoxy-granite", which can be designed to have very low temp-co. > There are lower-grade type platforms available, commonly called "optical > breadboards," that are made from thick sheets of aluminum or stainless > steel, [...] and these obviously have a sizeable temp-co, so the money you saved on your bench you get to spend on your air-con. They are a lot easier to move around though. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@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] low power divide by 5
What logic family might be appropriate for a divide by 5 from 50 to 10MHz, low power, running off 3.3 or 5V? ___ 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] 3 Gorges dam slows down Earth's rotation by 60 ns/day
See: https://futurism.com/how-infamous-hydroelectric-dam-changed-earths-rotation Of course, readers of this list know that the earth isn't stable to 60 ns/day in the first place. But this is an interesting calculation, at least to time nuts. 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] Microstepper
On Tue, 02 Jun 2020 05:52:13 + "Poul-Henning Kamp" wrote: > I have played with this one: > > http://www.rudius.net/oz2m/ngnb/dds.htm > > as a synthesizer replacement in the HP5065, but your "dual" configuration > and the integrated 1GHz "pre-oscillator" would fit that purpose better, > so sign me up as interested buyer. As a synthesizer for a Rb vapor cell standard, I would recommend going the same way as INRIM did in [1]. It is by far the lowest noise synthesizer I have seen for the relevant offset frequency range. Yes, it is a quite high effort system. But it's also worth it. With this, you are sure that the short term noise limit will not be the synthesiser anymore, but the lamp noise. In a discussion, Claudio Calosso told me that the difficult part of the whole system is getting to 1.6GHz. That part determines most of the perfomrance. The rest was "quiet easy". Attila Kinali [1] "Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks", by François, Calosso, Abdel Hafiz, Micalizio, Boudot. -- Science is made up of so many things that appear obvious after they are explained. -- Pardot Kynes ___ 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] Vibration isolation of quartz oscillators
If passive vibration isolation is not good enough active dampening is an option with a rig like https://www.herzan.com/products/active-vibration-control/TS-series.html I was not directly involved, but a team that I shared a lab with bought a gizmo like that one and it really helped some very sensitive optical measurements. It does not take up much room, so it might address the "Space is tight" constraint. It won't meet a "budget is tight" constraint though. -Joe Fitzgerald From: time-nuts on behalf of Poul-Henning Kamp Sent: Monday, June 29, 2020 2:16 AM To: Discussion of precise time and frequency measurement; ed breya Subject: Re: [time-nuts] Vibration isolation of quartz oscillators ed breya writes: > The nicest optical bench I've ever seen in person, was in one of our > labs many years ago. It was a huge, precisely flat polished granite slab > about 6-8" thick, about 4x8' or maybe 5x10', mounted on active-leveling > pneumatic bladders. It was loaded with thousands of threaded inserts, > uniformly spaced on a grid, for mounting optical devices and equipment. It is worth foot-noting here, that at that level of quality they are usually not made from natural granite, but rather from "epoxy-granite", which can be designed to have very low temp-co. > There are lower-grade type platforms available, commonly called "optical > breadboards," that are made from thick sheets of aluminum or stainless > steel, [...] and these obviously have a sizeable temp-co, so the money you saved on your bench you get to spend on your air-con. They are a lot easier to move around though. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@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] Vibration isolation of quartz oscillators
ed breya writes: > The nicest optical bench I've ever seen in person, was in one of our > labs many years ago. It was a huge, precisely flat polished granite slab > about 6-8" thick, about 4x8' or maybe 5x10', mounted on active-leveling > pneumatic bladders. It was loaded with thousands of threaded inserts, > uniformly spaced on a grid, for mounting optical devices and equipment. It is worth foot-noting here, that at that level of quality they are usually not made from natural granite, but rather from "epoxy-granite", which can be designed to have very low temp-co. > There are lower-grade type platforms available, commonly called "optical > breadboards," that are made from thick sheets of aluminum or stainless > steel, [...] and these obviously have a sizeable temp-co, so the money you saved on your bench you get to spend on your air-con. They are a lot easier to move around though. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
