Re: [time-nuts] Anybody have suggestions for time related science fair projects?
David.vanhorn wrote:
> Measuring the speed of light (Fizeau or Michelson method? Other ways)
>
>
> I saw a great demo of this at the Exploratorium in SF. They had a long spool
> of fiber optic, a disc with holes, and a light source. When static, if the
> light shines through the hole in the disc into the fiber, then you can see
> the light coming out the other end of the fiber through a different hole.
> When rotating, you increase speed and the fiber output gets dimmer and dimmer
> till it's gone. At that point, the light going into the fiber arrives when
> the other end is blocked, and vice versa. High tech, but simple.
>
My favorite exhibit that we never see anymore. IIRC it was a quarter
mile of fiber and a green laser. And ISTR that the disc had one hole on
one arm and two radially on the other, but I can't remember why. I
thought that the light would pass through the same hole twice, once on
the way in and on the way out when that same hole rotated 180 degrees to
the other end of the fiber. The disk spun somewhere around 50 rps (60
with an AC motor?).
--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Re: [time-nuts] Help Identifying this surplus Timing Module
Thank you bob and Gary for your investigations! I appreciate it! Here are a couple more views: https://imgur.com/a/auWdXvq "This is the picture with sticker removed. The large IC at the back has its label scratched off. ... that was intentional, but he has a note saying it is a member of Motorola DSP56300 family. It was likely purchased in 2010 based on an eBay invoice which has no date on it, but the scanned date was Feb 2011." If anyone else has any more ideas, I would gladly hear them! Thanks again! -Randal (at CubeCentral) -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gary Chatters Sent: Friday, May 11, 2018 19:07 To: time-nuts@febo.com Subject: Re: [time-nuts] Help Identifying this surplus Timing Module A little Googling found a two page datasheet. It doesn't tell you much more than what you already found out, but does have specifications. I can't figure out the correct link to include here, but a Google search with the string "ATiMe-s 38.88" (don't include the quotes) should bring up the link in the first couple of hits. It is a PDF at the www.sbtron.co.kr website. gc On 05/11/2018 07:16 PM, CubeCentral wrote: > Hello All! > > > > I would like to enlist your help in identifying this "surplus Timing > Module": https://imgur.com/a/Psw8gP7 > > > > All the hints I've been given are: > > - Purchased about a decade ago > > - Might use a Motorola DSP as the processor > > > > A quick google search lead me to a possible description: > > "High speed, hitless, ultra low jitter timing module for OC-N line > interfaces: The TF Systems / ATiMe-LC is a timing reference source for OC-N > and STM-N interfaces. It complements TeraSync's central timing modules to > provide a complete and redundant timing solution at the system level." > > > > ...but I'm unsure if that is 100% the same module. If you would like to get > some different photos, please let me know and I will see what I can do. Any > thoughts or ideas would be greatly appreciated! Thanks! > > > > -Randal (at CubeCentral) > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/11/18 7:07 AM, Philip Gladstone wrote: On 11/05/2018 07:23, jimlux wrote: On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. The advice that we got when doing a middle school science project was that you wanted an experiment with only one variable (altitude or temperature etc) and a measurement of a single variable (maybe over time). and with multiple measurements possible - most middle school projects tend to be a "one and done" - you get big kudos if you show even basic statistical analysis - a simple significance test is a big deal, assuming you're not doing it with some cookbook calculator. You'd need to be able to explain what it means to the judges. And something where you show an appreciation of measurement precision and any curve fit. I used to mark down projects where they used Excel to do a regression curve, and then reported the coefficients with 5 digits of precision, on measurements with at most 2 digits. (and no, not thousands of measurements to get a sqrt(N) improvement) AVAR is a kind of sophisticated concept - I think it would be hard for a middle schooler to adequately explain what it is (heck, there's enough trouble for people who do it for a living). ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TruePosition GPSDO Holdover Issues
What antenna are you using and where is it located? I have the TruePosition with a Motorola PCTEL 8508851k66 antenna on a windowsill with a ground plane under the antenna and it generally sees 4-7 sats. I have seen some holdovers but it has been better after running for a while and doing a survey. The TruePosition seems to switch between modes 0 and 1 as new sats come into view. The 10 MHz out does not change that I can see when this happens. Regards, Mark W7MLG On Fri, May 11, 2018 at 10:56 AM, gandalfg8--- via time-nuts < time-nuts@febo.com> wrote: > I've had one of the cheap TruePosition GPSDOs running here for the past > week, this is the earlier version with the Bliley oscillator, and as Mark > reported have been seeing what I consider to be excessive holdover reports > from Lady Heather. > > At 55 degrees north the number of Sats visible can be a bit variable, and > with this running on an indoor antenna probably even more so, but I've run > plenty of other GPSDOs here in similar fashion and have not seen this > before. > > I've not been running Lady H in logging mode, just running in the > background when this PC is on so all a bit hit and miss, but I have been > seeing holdover reports every day and with the time building up as the day > goes by. The time never exceeds 5 or 6 minutes though so if it was just > being used as a reference without monitoring the status this could easily > go unnoticed. > > The LMU300 Location Measurement Unit that this comes from will need to > track four Sats for positioning purposes, and the manual for that does > state that the LMU300 will indicate a holdover alarm when "The LMU cannot > lock on to the minimum number (4) of GPS satellites and the LMU GPS > receiver board has been in holdover for over 15 minutes", and I had started > to wonder if the firmware in the GPSDO might also be treating less than > four Sats tracked as a holdover situation. > > Earlier this afternoon I happened to catch it with between three or four > Sats being tracked and it did seem to be dropping in and out of holdover as > the number varied, once the number of tracked Sats increased again and > stayed there, it's been six for some time now, it settled down again and > hasn't returned to holdover since. > > Hardly the stuff of scientific observation I know, and I need to start > logging what's happening, but it does seem more likely now that these units > could be reporting a holdover event when the number of tracked Sats drops > below four. > > Nigel, GM8PZR > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TruePosition GPSDO Holdover Issues
It definitely works better on a windowsill than under the roof. It also did not work at all with a patch antenna. I can compare it to another GPSDO used as a reference and I see ADEV in the range of 2.5E-10 for low Tau 10-1000s, heading down for larger Tau. I see phase noise of -102 dBc/Hz at 10 Hz offset, getting better from there. Regards, Mark W7MLG On Fri, May 11, 2018 at 12:33 PM, wrote: > Hi Mark, > > The antenna is a Micropulse 1373FW/D, described on the label as an L/W > Survey GPS Antenna, whatever that might mean, Land and Water perhaps?:-) > I did try a small Motorola magnetic patch, I regularly use these with > Thunderbolts etc with no problems, but as Mark Sims predicted the > Trueposition reported an antenna error with that, although I'm not sure why. > This antenna is on top of the metal case of some test gear, just below > ceiling height in a single story building and at the moment the unit is > tracking six sats. > As commented earlier, we're at 55 degrees north so there's a big empty > space between northwest and northeast and the number of sats is a bit > variable. > What I'm seeing though is about par for the course with this setup, this > one is showing six sats at the moment and seven or eight, the max for this > GPSDO, isn't unusual and this is generally much the same as I'd expect > anyway, but this is the only one I've seen dropping in and out of holdover. > I did run a survey when I first set it up and it's fine re position. > I haven't got a counter on it at the moment but was monitoring it with a > CNT91 earlier in the week and I couldn't see any change in the output > either, but having said that if it was handling the holdover properly then > there shouldn't be any obvious change in the short time scales we're > talking about anyway. > > I'm happy with the setup, dropping down to just a few sats isn't unusual > here, but again this is the only one I've seen behaving like this so I'm > still inclined to think it's doing what it's supposed to. > I'll try to set up some continuous logging over the weekend and see if I > can get any more definite correlation between number of sats tracked and > indicating holdover. > > Regards, > > Nigel, GM8PZR > > > > -Original Message- > From: Mark Goldberg > To: gandalfg8 ; Discussion of precise time and > frequency measurement > Sent: Fri, 11 May 2018 19:59 > Subject: Re: [time-nuts] TruePosition GPSDO Holdover Issues > > What antenna are you using and where is it located? I have the > TruePosition with a Motorola PCTEL 8508851k66 antenna on a windowsill with > a ground plane under the antenna and it generally sees 4-7 sats. I have > seen some holdovers but it has been better after running for a while and > doing a survey. The TruePosition seems to switch between modes 0 and 1 as > new sats come into view. The 10 MHz out does not change that I can see when > this happens. > > Regards, > > Mark > W7MLG > > > On Fri, May 11, 2018 at 10:56 AM, gandalfg8--- via time-nuts < > time-nuts@febo.com> wrote: > > I've had one of the cheap TruePosition GPSDOs running here for the past > week, this is the earlier version with the Bliley oscillator, and as Mark > reported have been seeing what I consider to be excessive holdover reports > from Lady Heather. > > At 55 degrees north the number of Sats visible can be a bit variable, and > with this running on an indoor antenna probably even more so, but I've run > plenty of other GPSDOs here in similar fashion and have not seen this > before. > > I've not been running Lady H in logging mode, just running in the > background when this PC is on so all a bit hit and miss, but I have been > seeing holdover reports every day and with the time building up as the day > goes by. The time never exceeds 5 or 6 minutes though so if it was just > being used as a reference without monitoring the status this could easily > go unnoticed. > > The LMU300 Location Measurement Unit that this comes from will need to > track four Sats for positioning purposes, and the manual for that does > state that the LMU300 will indicate a holdover alarm when "The LMU cannot > lock on to the minimum number (4) of GPS satellites and the LMU GPS > receiver board has been in holdover for over 15 minutes", and I had started > to wonder if the firmware in the GPSDO might also be treating less than > four Sats tracked as a holdover situation. > > Earlier this afternoon I happened to catch it with between three or four > Sats being tracked and it did seem to be dropping in and out of holdover as > the number varied, once the number of tracked Sats increased again and > stayed there, it's been six for some time now, it settled down again and > hasn't returned to holdover since. > > Hardly the stuff of scientific observation I know, and I need to start > logging what's happening, but it does seem more likely now that these units > could be reporting a holdover event when the number of tracked Sats drops > below four. > > Nigel, GM8PZR
Re: [time-nuts] Ublox Galileo/Beidou PRNs
Mark! On Fri, 11 May 2018 21:02:59 + Mark Sims wrote: > Does anybody know how Ublox maps their reported PRNs for Galileo and > Beidou satellites to the true satellite PRNs. What little there is > on the web appears on the web is rather incorrect. Depends a LOT on your u-blox firmware version, and how it is configured. For example, the NMEA versions are inconsistent on PRNs. Check out this document: https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_%28UBX-13003221%29_Public.pdf 'u-blox8-M8_ReceiverDescrProtSpec_(UBX-13003221).pdf' Appendix A. It's ugly. Have a stiff drink first for courage. The future is gnsid:svid. Someday... RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Help Identifying this surplus Timing Module
A little Googling found a two page datasheet. It doesn't tell you much more than what you already found out, but does have specifications. I can't figure out the correct link to include here, but a Google search with the string "ATiMe-s 38.88" (don't include the quotes) should bring up the link in the first couple of hits. It is a PDF at the www.sbtron.co.kr website. gc On 05/11/2018 07:16 PM, CubeCentral wrote: Hello All! I would like to enlist your help in identifying this "surplus Timing Module": https://imgur.com/a/Psw8gP7 All the hints I've been given are: - Purchased about a decade ago - Might use a Motorola DSP as the processor A quick google search lead me to a possible description: "High speed, hitless, ultra low jitter timing module for OC-N line interfaces: The TF Systems / ATiMe-LC is a timing reference source for OC-N and STM-N interfaces. It complements TeraSync's central timing modules to provide a complete and redundant timing solution at the system level." ...but I'm unsure if that is 100% the same module. If you would like to get some different photos, please let me know and I will see what I can do. Any thoughts or ideas would be greatly appreciated! Thanks! -Randal (at CubeCentral) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Ashtech Z12 question.
The "new" Z12 from Ebay came in today. Works fine (except bad memory backup batteries). So antenna, power supply, cables are OK. Replacing the memory backup batteries is fairly easy, except for the gazillion and three screw to open it up. A pair of memory batteries costs around $15. I need to go over the bad one in more detail and see if I can find any bad caps... I had done a quick in-circuit test before replacing the batteries and did not see anything suspicious. It could also be something on the RF side or oscillator has drifted out of range. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Datametrics SP-100 Time Code Generator
Hello, I'm looking for a schematic and/or service manual for a Datametrics SP-100, a 1970s-era rack-mount IRIG time code generator. According to the Time Nuts archives, Dave Brown (ZL3FJ) was looking for this information back in 2005 but as far as I can see received no reply. I have found references to its use in a timing distribution system but haven't found service information that would allow component level repair. Does anyone have, or know of a source for, technical information on this unit? Thanks! Cheers, Dan --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Help Identifying this surplus Timing Module
Hi The big chip with the sticker on it is an Altera FPGA. A picture of the back side might help a little (if there is anything on the back side …). Simple answer - it’s a nice source of parts …. Bob > On May 11, 2018, at 7:16 PM, CubeCentral wrote: > > Hello All! > > > > I would like to enlist your help in identifying this "surplus Timing > Module": https://imgur.com/a/Psw8gP7 > > > > All the hints I've been given are: > > - Purchased about a decade ago > > - Might use a Motorola DSP as the processor > > > > A quick google search lead me to a possible description: > > "High speed, hitless, ultra low jitter timing module for OC-N line > interfaces: The TF Systems / ATiMe-LC is a timing reference source for OC-N > and STM-N interfaces. It complements TeraSync's central timing modules to > provide a complete and redundant timing solution at the system level." > > > > ...but I'm unsure if that is 100% the same module. If you would like to get > some different photos, please let me know and I will see what I can do. Any > thoughts or ideas would be greatly appreciated! Thanks! > > > >-Randal (at CubeCentral) > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Help Identifying this surplus Timing Module
Hi Given the frequency of the oscillator, it’s some sort of sync module for a telecom system. What data rate and what sort of coding …. who knows … Bob > On May 11, 2018, at 7:16 PM, CubeCentral wrote: > > Hello All! > > > > I would like to enlist your help in identifying this "surplus Timing > Module": https://imgur.com/a/Psw8gP7 > > > > All the hints I've been given are: > > - Purchased about a decade ago > > - Might use a Motorola DSP as the processor > > > > A quick google search lead me to a possible description: > > "High speed, hitless, ultra low jitter timing module for OC-N line > interfaces: The TF Systems / ATiMe-LC is a timing reference source for OC-N > and STM-N interfaces. It complements TeraSync's central timing modules to > provide a complete and redundant timing solution at the system level." > > > > ...but I'm unsure if that is 100% the same module. If you would like to get > some different photos, please let me know and I will see what I can do. Any > thoughts or ideas would be greatly appreciated! Thanks! > > > >-Randal (at CubeCentral) > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Help Identifying this surplus Timing Module
Hello All! I would like to enlist your help in identifying this "surplus Timing Module": https://imgur.com/a/Psw8gP7 All the hints I've been given are: - Purchased about a decade ago - Might use a Motorola DSP as the processor A quick google search lead me to a possible description: "High speed, hitless, ultra low jitter timing module for OC-N line interfaces: The TF Systems / ATiMe-LC is a timing reference source for OC-N and STM-N interfaces. It complements TeraSync's central timing modules to provide a complete and redundant timing solution at the system level." ...but I'm unsure if that is 100% the same module. If you would like to get some different photos, please let me know and I will see what I can do. Any thoughts or ideas would be greatly appreciated! Thanks! -Randal (at CubeCentral) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Ublox Galileo/Beidou PRNs
Does anybody know how Ublox maps their reported PRNs for Galileo and Beidou satellites to the true satellite PRNs. What little there is on the web appears on the web is rather incorrect. For Galileo I have seen Ublox PRNs from 212 to 240. That seems to imply it might be ACTUAL = UBLOX_PRN - 210. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Question about frequency counter testing
Hi, On 05/11/2018 05:35 PM, Bob kb8tq wrote: > Hi > > If you do the weighted average as indicated in the paper *and* compare it to > a “single sample” computation, > the results are different for that time interval. To me that’s a problem. To > the authors, the fact that the rest of > the curve is the same is proof that it works. I certainly agree that once you > get to longer tau, the process > has no detrimental impact. There is still the problem that the first post on > the graph is different depending > on the technique. Check what I did in my paper. I made sure to check that my estimator of phase and frequency is bias-free, that is, when exposed to stable phase or stable frequency, that comes out of the phase and frequency unbiased, but 0 as you switch them, as a good estimator should do. > The other side of all this is that ADEV is really not a very good way to test > a counter. It has it’s quirks and it’s > issues. They are impacted by what is in a counter, but that’s a side effect. > If one is after a general test of > counter hardware, one probably should look at other approaches. Well, you can tell a few things from the ADEV, to give you a hint about what you can expect from that counter when you do ADEV... and measure of frequency. The 1/tau limit is that of the counter. It's... a complex issue of single-shot resolution and noise, but a hint. > If you are trying specifically just to measure ADEV, then there are a lot of > ways to do that by it’s self. It’s not > clear that re-invinting the hardware is required to do this. Going with an > “average down” approach ultimately > *will* have problems for certain signals and noise profiles. The filtering needs to be understood and handled correctly, for sure, and it's not doing anything good for lower true ADEV measures. Filtering helps for improving the frequency reading, as the measures deviation shifts from ADEV to MDEV or PDEV, but let's not confuse that with improving the ADEV, it's a completely different thing. Improving the ADEV takes single-shot resolution, stable hardware and stable reference source. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
HI > On May 11, 2018, at 3:12 PM, Magnus Danielson > wrote: > > Hi Don, > > On 05/10/2018 02:59 PM, Don Murray via time-nuts wrote: >> Hi Magnus... >> >> >> Appreciate any help! >> >> I participate in the ARRL Frequency Measuring Test, >> and I would like to automate the measuring process. >> >> I have two frequencies, A and B... >> >> A is a GPS locked HP 3336B set to 455,000.000 Hz >> >> I use the 3336B instead of the 455,000Hz BFO >> signal from my GPS locked Racal receiver so >> that I can measure AM stations without the >> annoying beat note. ;-) >> >> B is an IF signal which should appear between >> 455,000.000Hz and 455,001.000 Hz >> >> I would like the 5372A to calculate the B minus A >> delta, over a manually started and automatically >> stopped measurement period of 110 seconds. >> >> I would like a delta resolution of 0.001Hz to be >> developed by the box. > > There is no point in using two channels and a generator. > You can do that straight out of the box just by locking it to the GPS, > which you should do anyway. > > Just measure the signal. Using the Math you can subtract or add whatever > frequency you want. You can get A-B or B-A measures in Frequency mode, > it's just not necessary. > > Now, you want to use the single-shot run mode. > > It should be relative trivial to setup a large number of samples with a > suitable distance inbetween them. > > Getting 1 mHz resolution isn't too hard that way, considering you have > 110 s of time to do it. > >> Now, there will be doppler. I want the box >> to analyze and give me a best statistical guess >> for the B minus A delta. > > Now, doppler is tricky, as the HP5372A in all its glory does not have > built-in compensation for it, and besides, you need to figure out where > the true zero is. > > What the box will give you is a frequency estimation assuming doppler > free conditions. If you want to do smarter things, you need to pull the > data off the counter in binary form and post-process it yourself. The > programmers manual for the HP5372A is a great teaching tool for how > these beasts process stuff. > >> BTW the B minus A delta will be added to the >> frequency of my Racal receiver to give me the >> best "guess" as to the correct frequency of the >> target signal. > > For sure. This is BTW something you can do in the Math part of the > HP5372A, so you can have it crunch out the right value straight out. > >> The Racal reads out to the Hz, and I am able to >> accurately determine if the Racal is tuned above >> or below the "target" frequency. >> >> I will be tuned below the "target" and within >> 1 Hz of the "target." >> >> I assume I will be in the one frequency mode. >> >> Can the box give me the desired resolution? > > Sure, assuming the doppler limitation. > >> What sampling period would be the best to use? > > Use one short enough to get as many sample points over the 110 s you want. The 110 seconds is the big gotcha here. What you really want is a unified record of the entire time they are transmitting. If it’s less than 2 minutes, you are fine. If it runs for 5, 10 or 15 minutes that’s not quite so good. Stitching data together gets you back to binary dumps and a lot of post processing. Once you do that, there really is no advantage over a SDR running on the same signal. Bob > >> What statistical result would I use as my delta? > > Mean value on the Statistics display. It's a linear regression result, > which has good processing gain for frequency. > >> Appreciate your help. My head is spinning whenever I >> get into the operating manual! > > It's a beast, for sure. It took some time to master, but it's a lovely > tool when you understand it and accept it's up-front complexity. > > I could maybe take mine for a test-spin somewhat later. > > Cheers, > Magnus > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
Hi Don, On 05/10/2018 02:59 PM, Don Murray via time-nuts wrote: > Hi Magnus... > > > Appreciate any help! > > I participate in the ARRL Frequency Measuring Test, > and I would like to automate the measuring process. > > I have two frequencies, A and B... > > A is a GPS locked HP 3336B set to 455,000.000 Hz > > I use the 3336B instead of the 455,000Hz BFO > signal from my GPS locked Racal receiver so > that I can measure AM stations without the > annoying beat note. ;-) > > B is an IF signal which should appear between > 455,000.000Hz and 455,001.000 Hz > > I would like the 5372A to calculate the B minus A > delta, over a manually started and automatically > stopped measurement period of 110 seconds. > > I would like a delta resolution of 0.001Hz to be > developed by the box. There is no point in using two channels and a generator. You can do that straight out of the box just by locking it to the GPS, which you should do anyway. Just measure the signal. Using the Math you can subtract or add whatever frequency you want. You can get A-B or B-A measures in Frequency mode, it's just not necessary. Now, you want to use the single-shot run mode. It should be relative trivial to setup a large number of samples with a suitable distance inbetween them. Getting 1 mHz resolution isn't too hard that way, considering you have 110 s of time to do it. > Now, there will be doppler. I want the box > to analyze and give me a best statistical guess > for the B minus A delta. Now, doppler is tricky, as the HP5372A in all its glory does not have built-in compensation for it, and besides, you need to figure out where the true zero is. What the box will give you is a frequency estimation assuming doppler free conditions. If you want to do smarter things, you need to pull the data off the counter in binary form and post-process it yourself. The programmers manual for the HP5372A is a great teaching tool for how these beasts process stuff. > BTW the B minus A delta will be added to the > frequency of my Racal receiver to give me the > best "guess" as to the correct frequency of the > target signal. For sure. This is BTW something you can do in the Math part of the HP5372A, so you can have it crunch out the right value straight out. > The Racal reads out to the Hz, and I am able to > accurately determine if the Racal is tuned above > or below the "target" frequency. > > I will be tuned below the "target" and within > 1 Hz of the "target." > > I assume I will be in the one frequency mode. > > Can the box give me the desired resolution? Sure, assuming the doppler limitation. > What sampling period would be the best to use? Use one short enough to get as many sample points over the 110 s you want. > What statistical result would I use as my delta? Mean value on the Statistics display. It's a linear regression result, which has good processing gain for frequency. > Appreciate your help. My head is spinning whenever I > get into the operating manual! It's a beast, for sure. It took some time to master, but it's a lovely tool when you understand it and accept it's up-front complexity. I could maybe take mine for a test-spin somewhat later. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
If want to exploit what the 5372A can do in FMT-context, you should feed it the amplified and band-pass filtered RF (rather than some down-converted and otherwise mangled version of the signal) and capture timing of the actual zero-crossings and post-process that. -- 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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Question about frequency counter testing
Oleg, On 05/11/2018 04:42 PM, Oleg Skydan wrote: > Hi > > -- > From: "Bob kb8tq" >> The most accurate answer is always “that depends”. The simple answer >> is no. > > I have spent the yesterday evening and quite a bit of the night :) > reading many interesting papers and several related discussions in the > time-nuts archive (the Magnus Danielson posts in "Modified Allan > Deviation and counter averaging" and "Omega counters and Parabolic > Variance (PVAR)" topics were very informative and helpful, thanks!). You are welcome. Good that people have use for them. > It looks like the trick to combine averaging with the possibility of > correct ADEV calculation in the post processing exists. There is a nice > presentation made by prof. Rubiola [1]. There is a suitable solution on > page 54 (at least I understood it so, maybe I am wrong). I can switch to > usual averaging (Lambda/Delta counter) instead of LR calculation (Omega > counter), the losses should be very small I my case. With such averaging > the MDEV can be correctly computed. If fact, you can do a Omega-style counter you can use for PDEV, you just need to use the right approach to be able to decimate the data. Oh, there's a draft paper on that: https://arxiv.org/abs/1604.01004 Need to update that one. > If ADEV is needed, the averaging > interval can be reduced and several measurements (more then eight) can > be combined into one point (creating the new weighting function which > resembles the usual Pi one, as shown in the [1] p.54), it should be > possible to calculate usual ADEV using such data. As far as I > understand, the filter which is formed by the resulting weighting > function will have wider bandwidth, so the impact on ADEV will be > smaller and it can be computed correctly. Am I missing something? Well, you can reduce averaging interval to 1 and then you compute the ADEV, but it does not behave as the MDEV any longer. What you can do is that you can calculate MDEV or PDEV, and then apply the suitable bias function to convert the level to that of ADEV. > I have made the necessary changes in code, now firmware computes the > Delta averaging, also it computes combined Delta averaged measurements > (resulting in trapezoidal weighting function), both numbers are computed > with continuous stamping and optimal overlapping. Everything is done in > real time. I did some tests. The results are very similar to the ones > made with LR counting. Yes, they give relatively close values of deviation, where PDEV goes somewhat lower, indicating that there is a slight advantage of the LR/LS frequency estimation measure over that of the Delta counter, as given by it's MDEV. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
When I was working at the Arecibo Observatory and we were running the ionospheric heater at 5.1 MHz (think Mini-HAARP), I'd sometimes go home (about 3 miles away) and listen to the signal there.There was frequently substantial random fading of the signal, suggesting that I was hearing the vector sum of an NVIS signal off the ionosphere and the usual sidelobe leakage from the dish. Said fading could be said to have a characteristic period of around 1 or 2 seconds, and was occasionally quite deep. So, I'm definitely a believer in short path propagation variations. Dana K8YUM On Fri, May 11, 2018 at 1:09 PM, Bob kb8tq wrote: > Hi > > Well, having actually run FMT virtually “in the back yard” of the > transmitting station …. it’s surprising > what 70 miles will do. In this case, back yard really does mean on the > premises. There is a lot that > gets into even fairly sort distance propagation. > > Bob > > > On May 11, 2018, at 1:52 PM, Jerry Hancock wrote: > > > > If you were in Connie’s back yard or had a very stable ground wave, then > yes, you could automate the testing. > > > > There are a number of challenges with this method as looking at the data > with a simple graph will tell. You might have large fluctuations on the > high frequency side only, for instance, that any averaging or algorithm > would assume to be valid data. > > > > The next issue is the length of the dataset as the key-down time is only > a few minutes so you end-up with not that many samples. > > > > Regards, > > > > Jerry > > > >> On May 10, 2018, at 5:59 AM, Don Murray via time-nuts < > time-nuts@febo.com> wrote: > >> > >> Hi Magnus... > >> > >> > >> Appreciate any help! > >> > >> I participate in the ARRL Frequency Measuring Test, > >> and I would like to automate the measuring process. > >> > >> I have two frequencies, A and B... > >> > >> A is a GPS locked HP 3336B set to 455,000.000 Hz > >> > >> I use the 3336B instead of the 455,000Hz BFO > >> signal from my GPS locked Racal receiver so > >> that I can measure AM stations without the > >> annoying beat note. ;-) > >> > >> B is an IF signal which should appear between > >> 455,000.000Hz and 455,001.000 Hz > >> > >> I would like the 5372A to calculate the B minus A > >> delta, over a manually started and automatically > >> stopped measurement period of 110 seconds. > >> > >> I would like a delta resolution of 0.001Hz to be > >> developed by the box. > >> > >> Now, there will be doppler. I want the box > >> to analyze and give me a best statistical guess > >> for the B minus A delta. > >> > >> BTW the B minus A delta will be added to the > >> frequency of my Racal receiver to give me the > >> best "guess" as to the correct frequency of the > >> target signal. > >> > >> The Racal reads out to the Hz, and I am able to > >> accurately determine if the Racal is tuned above > >> or below the "target" frequency. > >> > >> I will be tuned below the "target" and within > >> 1 Hz of the "target." > >> > >> I assume I will be in the one frequency mode. > >> > >> Can the box give me the desired resolution? > >> > >> What sampling period would be the best to use? > >> > >> What statistical result would I use as my delta? > >> > >> Appreciate your help. My head is spinning whenever I > >> get into the operating manual! > >> > >> TNX... > >> > >> > >> 73 > >> Don > >> W4WJ > >> > >> In a message dated 5/10/2018 2:19:49 AM Central Standard Time, > mag...@rubidium.dyndns.org writes: > >> > >> > >> Hi, > >> > >> What issues do you have? > >> > >> Cheers, > >> Magnus > >> > >> On 05/08/2018 02:32 AM, Don Murray via time-nuts wrote: > >>> Hello Time Nuts... > >>> > >>> > >>> > >>> Who is the resident expert on the HP5372A? > >>> > >>> I have some operational questions. ;-) > >>> > >>> email off list please. w4wj at aol.com > >>> > >>> TNX all... > >>> > >>> 73 > >>> Don > >>> W4WJ > >>> > >>> > >>> ___ > >>> time-nuts mailing list -- time-nuts@febo.com > >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > >>> and follow the instructions there. > >>> > >> ___ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > >> and follow the instructions there. > >> ___ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > >> and follow the instructions there. > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts >
Re: [time-nuts] HP 5372A
Hi Well, having actually run FMT virtually “in the back yard” of the transmitting station …. it’s surprising what 70 miles will do. In this case, back yard really does mean on the premises. There is a lot that gets into even fairly sort distance propagation. Bob > On May 11, 2018, at 1:52 PM, Jerry Hancock wrote: > > If you were in Connie’s back yard or had a very stable ground wave, then yes, > you could automate the testing. > > There are a number of challenges with this method as looking at the data with > a simple graph will tell. You might have large fluctuations on the high > frequency side only, for instance, that any averaging or algorithm would > assume to be valid data. > > The next issue is the length of the dataset as the key-down time is only a > few minutes so you end-up with not that many samples. > > Regards, > > Jerry > >> On May 10, 2018, at 5:59 AM, Don Murray via time-nuts >> wrote: >> >> Hi Magnus... >> >> >> Appreciate any help! >> >> I participate in the ARRL Frequency Measuring Test, >> and I would like to automate the measuring process. >> >> I have two frequencies, A and B... >> >> A is a GPS locked HP 3336B set to 455,000.000 Hz >> >> I use the 3336B instead of the 455,000Hz BFO >> signal from my GPS locked Racal receiver so >> that I can measure AM stations without the >> annoying beat note. ;-) >> >> B is an IF signal which should appear between >> 455,000.000Hz and 455,001.000 Hz >> >> I would like the 5372A to calculate the B minus A >> delta, over a manually started and automatically >> stopped measurement period of 110 seconds. >> >> I would like a delta resolution of 0.001Hz to be >> developed by the box. >> >> Now, there will be doppler. I want the box >> to analyze and give me a best statistical guess >> for the B minus A delta. >> >> BTW the B minus A delta will be added to the >> frequency of my Racal receiver to give me the >> best "guess" as to the correct frequency of the >> target signal. >> >> The Racal reads out to the Hz, and I am able to >> accurately determine if the Racal is tuned above >> or below the "target" frequency. >> >> I will be tuned below the "target" and within >> 1 Hz of the "target." >> >> I assume I will be in the one frequency mode. >> >> Can the box give me the desired resolution? >> >> What sampling period would be the best to use? >> >> What statistical result would I use as my delta? >> >> Appreciate your help. My head is spinning whenever I >> get into the operating manual! >> >> TNX... >> >> >> 73 >> Don >> W4WJ >> >> In a message dated 5/10/2018 2:19:49 AM Central Standard Time, >> mag...@rubidium.dyndns.org writes: >> >> >> Hi, >> >> What issues do you have? >> >> Cheers, >> Magnus >> >> On 05/08/2018 02:32 AM, Don Murray via time-nuts wrote: >>> Hello Time Nuts... >>> >>> >>> >>> Who is the resident expert on the HP5372A? >>> >>> I have some operational questions. ;-) >>> >>> email off list please. w4wj at aol.com >>> >>> TNX all... >>> >>> 73 >>> Don >>> W4WJ >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
By the way, if you would like some data captured during the last run, let me know. I have an excel sheet of the peak data from spectrum lab centered on 1850hz as I use the 3586B receiver. Regards, Jerry Jerry Hancock je...@hanler.com (415) 215-3779 > On May 11, 2018, at 10:52 AM, Jerry Hancock wrote: > > If you were in Connie’s back yard or had a very stable ground wave, then yes, > you could automate the testing. > > There are a number of challenges with this method as looking at the data with > a simple graph will tell. You might have large fluctuations on the high > frequency side only, for instance, that any averaging or algorithm would > assume to be valid data. > > The next issue is the length of the dataset as the key-down time is only a > few minutes so you end-up with not that many samples. > > Regards, > > Jerry > >> On May 10, 2018, at 5:59 AM, Don Murray via time-nuts >> wrote: >> >> Hi Magnus... >> >> >> Appreciate any help! >> >> I participate in the ARRL Frequency Measuring Test, >> and I would like to automate the measuring process. >> >> I have two frequencies, A and B... >> >> A is a GPS locked HP 3336B set to 455,000.000 Hz >> >> I use the 3336B instead of the 455,000Hz BFO >> signal from my GPS locked Racal receiver so >> that I can measure AM stations without the >> annoying beat note. ;-) >> >> B is an IF signal which should appear between >> 455,000.000Hz and 455,001.000 Hz >> >> I would like the 5372A to calculate the B minus A >> delta, over a manually started and automatically >> stopped measurement period of 110 seconds. >> >> I would like a delta resolution of 0.001Hz to be >> developed by the box. >> >> Now, there will be doppler. I want the box >> to analyze and give me a best statistical guess >> for the B minus A delta. >> >> BTW the B minus A delta will be added to the >> frequency of my Racal receiver to give me the >> best "guess" as to the correct frequency of the >> target signal. >> >> The Racal reads out to the Hz, and I am able to >> accurately determine if the Racal is tuned above >> or below the "target" frequency. >> >> I will be tuned below the "target" and within >> 1 Hz of the "target." >> >> I assume I will be in the one frequency mode. >> >> Can the box give me the desired resolution? >> >> What sampling period would be the best to use? >> >> What statistical result would I use as my delta? >> >> Appreciate your help. My head is spinning whenever I >> get into the operating manual! >> >> TNX... >> >> >> 73 >> Don >> W4WJ >> >> In a message dated 5/10/2018 2:19:49 AM Central Standard Time, >> mag...@rubidium.dyndns.org writes: >> >> >> Hi, >> >> What issues do you have? >> >> Cheers, >> Magnus >> >> On 05/08/2018 02:32 AM, Don Murray via time-nuts wrote: >>> Hello Time Nuts... >>> >>> >>> >>> Who is the resident expert on the HP5372A? >>> >>> I have some operational questions. ;-) >>> >>> email off list please. w4wj at aol.com >>> >>> TNX all... >>> >>> 73 >>> Don >>> W4WJ >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] TruePosition GPSDO Holdover Issues
I've had one of the cheap TruePosition GPSDOs running here for the past week, this is the earlier version with the Bliley oscillator, and as Mark reported have been seeing what I consider to be excessive holdover reports from Lady Heather. At 55 degrees north the number of Sats visible can be a bit variable, and with this running on an indoor antenna probably even more so, but I've run plenty of other GPSDOs here in similar fashion and have not seen this before. I've not been running Lady H in logging mode, just running in the background when this PC is on so all a bit hit and miss, but I have been seeing holdover reports every day and with the time building up as the day goes by. The time never exceeds 5 or 6 minutes though so if it was just being used as a reference without monitoring the status this could easily go unnoticed. The LMU300 Location Measurement Unit that this comes from will need to track four Sats for positioning purposes, and the manual for that does state that the LMU300 will indicate a holdover alarm when "The LMU cannot lock on to the minimum number (4) of GPS satellites and the LMU GPS receiver board has been in holdover for over 15 minutes", and I had started to wonder if the firmware in the GPSDO might also be treating less than four Sats tracked as a holdover situation. Earlier this afternoon I happened to catch it with between three or four Sats being tracked and it did seem to be dropping in and out of holdover as the number varied, once the number of tracked Sats increased again and stayed there, it's been six for some time now, it settled down again and hasn't returned to holdover since. Hardly the stuff of scientific observation I know, and I need to start logging what's happening, but it does seem more likely now that these units could be reporting a holdover event when the number of tracked Sats drops below four. Nigel, GM8PZR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 5372A
If you were in Connie’s back yard or had a very stable ground wave, then yes, you could automate the testing. There are a number of challenges with this method as looking at the data with a simple graph will tell. You might have large fluctuations on the high frequency side only, for instance, that any averaging or algorithm would assume to be valid data. The next issue is the length of the dataset as the key-down time is only a few minutes so you end-up with not that many samples. Regards, Jerry > On May 10, 2018, at 5:59 AM, Don Murray via time-nuts > wrote: > > Hi Magnus... > > > Appreciate any help! > > I participate in the ARRL Frequency Measuring Test, > and I would like to automate the measuring process. > > I have two frequencies, A and B... > > A is a GPS locked HP 3336B set to 455,000.000 Hz > > I use the 3336B instead of the 455,000Hz BFO > signal from my GPS locked Racal receiver so > that I can measure AM stations without the > annoying beat note. ;-) > > B is an IF signal which should appear between > 455,000.000Hz and 455,001.000 Hz > > I would like the 5372A to calculate the B minus A > delta, over a manually started and automatically > stopped measurement period of 110 seconds. > > I would like a delta resolution of 0.001Hz to be > developed by the box. > > Now, there will be doppler. I want the box > to analyze and give me a best statistical guess > for the B minus A delta. > > BTW the B minus A delta will be added to the > frequency of my Racal receiver to give me the > best "guess" as to the correct frequency of the > target signal. > > The Racal reads out to the Hz, and I am able to > accurately determine if the Racal is tuned above > or below the "target" frequency. > > I will be tuned below the "target" and within > 1 Hz of the "target." > > I assume I will be in the one frequency mode. > > Can the box give me the desired resolution? > > What sampling period would be the best to use? > > What statistical result would I use as my delta? > > Appreciate your help. My head is spinning whenever I > get into the operating manual! > > TNX... > > > 73 > Don > W4WJ > > In a message dated 5/10/2018 2:19:49 AM Central Standard Time, > mag...@rubidium.dyndns.org writes: > > > Hi, > > What issues do you have? > > Cheers, > Magnus > > On 05/08/2018 02:32 AM, Don Murray via time-nuts wrote: >> Hello Time Nuts... >> >> >> >> Who is the resident expert on the HP5372A? >> >> I have some operational questions. ;-) >> >> email off list please. w4wj at aol.com >> >> TNX all... >> >> 73 >> Don >> W4WJ >> >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] (UK) NPL open house
On Fri, May 11, 2018 at 12:57 PM, Adrian Godwin wrote: > Next thursday : > > https://www.eventbrite.co.uk/e/national-physical-laboratory-open-house-2018-prepare-to-be-amazed-tickets-42330306085 If any other Time Nuts are going, it might be amusing to meet up. Cheers ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ashtech Z12 question.
Hi Mark: I've found there are two main reasons older equipment stops working. 1. A metal to metal joint that's supposed to be conductive is not. See Hints & Tips: What Goes Wrong: http://www.prc68.com/I/HaT.shtml#Wgw The fix is simply to disassemble, cycle all joints a few times and reassemble. I have a gut feeling that applying oxygen free silicon grease before reassembly might be a real fix, but don't have enough data to make the claim. 2. Capacitors go bad. Electrolytic caps essentially become open circuits and can do that without any indication of a problem. Other times caps fail and cause very noticeable problems for adjacent components. So a visual and nasal inspection is the fist step. An ESR meter is the second step. http://www.prc68.com/I/HaT.shtml#CF -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message Antenna is good... it is feeding an HP amplified splitter which goes to 7 other receivers. And yes, it died in the middle of a run. I have another Z12 coming from Ebay... -- Rats. Is the antenna known to be good? Is the Z12 providing bias on the antenna cable? Did the Z12 stop tracking right in the middle of the session with no nearby events or configuration changes? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3816A RS-232 interface
Check TWO things. 1.) Has the RS-232 level converter (1488/1489, MAX232, etc.) failed? 2.) What MODE is your Z3816A, SCPI? The GPSCon software places Z3816A into SCPI. This is discussed in K8CU’s notes, below: K8CU Notes - HP Z3816A GPS Frequency Standard Receiver https://www.realhamradio.com/GPS_Z3816A_Receiver.htm greg, w9gb === I am getting some very peculiar behavior with the serial interface on my GPS rcvr (Z3816A). To date, the only thing that works is Sat Stat on a windows 2000 computer. I am using a Null modem and set the monitor computer to 9600-8N1. Other computers and/or utilities seem to give irregular behavior. I have looked at the signals with a scope and they seem borderline OK. The signals (Rx and Tx) swing a bit more than +/- 7 V. There is also some digital noise riding on the lines. I also notice that the -15 Vdc line on the internal power supply is not working (it reads about + 1.2 V). Someone on the web I found a posting claiming that the -15 Vdc line is not needed for the Z3816A. Any help would be appreciated. 1. Is 9600-8N1 correct? 2. Could the lack of the -15 Vdc line be the root cause? 3. Has anyone managed to use GpsCon with a Z3816A? — Thanks much for any input! ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Question about frequency counter testing
Hi Dana, On 05/10/2018 06:17 PM, Dana Whitlow wrote: > I'm a bit fuzzy, then, on the definition of ADEV. I was under the > impression that one measured a series of > "phase samples" at the desired spacing, then took the RMS value of that > series, not just a single sample, > as the ADEV value. You cannot use RMS here, as the noise does not converge as you build the average. This was a huge issue before the Allan processing approach essentially went for combining the average of 2-point RMS measurements, which ends up being a subtraction of two frequency measure. > Can anybody say which it is? The RMS approach seems to make better sense > as it provides some measure > of defense against taking a sample that happens to be an outlier, yet > avoids the flaw of tending to average > the reported ADEV towards zero. Forget about RMS here. Cheers, Magnus > Dana (K8YUM) > > > On Thu, May 10, 2018 at 9:21 AM, Bob kb8tq wrote: > >> Hi >> >> If you collect data over the entire second and average that down for a >> single point, then no, your ADEV will not be correct. >> There are a number of papers on this. What ADEV wants to see is a single >> phase “sample” at one second spacing. This is >> also at the root of how you get 10 second ADEV. You don’t average the ten >> 1 second data points. You throw nine data points >> away and use one of them ( = you decimate the data ). >> >> What happens if you ignore this? Your curve looks “to good”. The resultant >> curve is *below* the real curve when plotted. >> >> A quick way to demonstrate this is to do ADEV with averaged vs decimated >> data …. >> >> Bob >> >>> On May 10, 2018, at 4:46 AM, Oleg Skydan wrote: >>> >>> Hi >>> >>> I have got a pair of not so bad OCXOs (Morion GK85). I did some >> measurements, the results may be interested to others (sorry if not), so I >> decided to post them. >>> >>> I ran a set of 5minutes long counter runs (two OCXOs were measured >> against each other), each point is 1sec gate frequency measurement with >> different number of timestamps used in LR calculation (from 10 till 5e6). >> The counter provides continuous counting. As you can see I reach the HW >> limitations at 5..6e-12 ADEV (1s tau) with only 1e5 timestamps. The results >> looks reasonable, the theory predicts 27ps equivalent resolution with 1e5 >> timestamps, also the sqrt(N) law is clearly seen on the plots. I do not >> know what is the limiting factor, if it is OCXOs or some counter HW. >>> >>> I know there are HW problems, some of them were identified during this >> experiment. They were expectable, cause HW is still just an ugly >> construction made from the boards left in the "radio junk box" from the >> other projects/experiments. I am going to move to the well designed PCB >> with some improvements in HW (and more or less "normal" analog frontend >> with good comparator, ADCMP604 or something similar, for the "low >> frequency" input). But I want to finish my initial tests, it should help >> with the HW design. >>> >>> Now I have some questions. As you know I am experimenting with the >> counter that uses LR calculations to improve its resolution. The LR data >> for each measurement is collected during the gate time only, also >> measurements are continuous. Will the ADEV be calculated correctly from >> such measurements? I understand that any averaging for the time window >> larger then single measurement time will spoil the ADEV plot. Also I >> understand that using LR can result in incorrect frequency estimate for the >> signal with large drift (should not be a problem for the discussed >> measurements, at least for the numbers we are talking about). >>> >>> Does the ADEV plots I got looks reasonable for the used "mid range" >> OCXOs (see the second plot for the long run test)? >>> >>> BTW, I see I can interface GPS module to my counter without additional >> HW (except the module itself, do not worry it will not be another DIY >> GPSDO, probably :-) ). I will try to do it. The initial idea is not try to >> lock the reference OCXO to GPS, instead I will just measure GPS against REF >> and will make corrections using pure math in SW. I see some advantages with >> such design - no hi resolution DAC, reference for DAC, no loop, no >> additional hardware at all - only the GPS module and software :) (it is in >> the spirit of this project)... Of cause I will not have reference signal >> that can be used outside the counter, I think I can live with it. It worth >> to do some experiments. >>> >>> Best! >>> Oleg UR3IQO >>> <Снимок экрана (1148).png><Снимок экрана (1150).png><Снимок экрана >> (1149).png>___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com
Re: [time-nuts] Question about frequency counter testing
Oleg, On 05/10/2018 10:46 AM, Oleg Skydan wrote: > Hi > > Now I have some questions. As you know I am experimenting with the > counter that uses LR calculations to improve its resolution. The LR data > for each measurement is collected during the gate time only, also > measurements are continuous. Will the ADEV be calculated correctly from > such measurements? Many assume yes, actual answer is no or well, it depends. ADEV assumes brick-wall filtering up to the Nyquist frequency as result of the sample-rate. When you filter the data as you do a Linear Regression / Least Square estimation, the actual bandwidth will be much less, so the ADEV measures will be biased for lower taus, but for higher taus less of the kernel of the ADEV will be affected by the filter and thus the bias will reduce. It was when investigating this that Prof Enrico Rubiola and Prof Francois Vernotte invented the parabolic deviation PDEV. > I understand that any averaging for the time window > larger then single measurement time will spoil the ADEV plot. Correct. > Also I understand that using LR can result in incorrect frequency estimate for > the signal with large drift (should not be a problem for the discussed > measurements, at least for the numbers we are talking about). That is a result of not using a LR/LS method supporting drift, at which time its effect on frequency estimation is greatly reduced. LR only for phase and frequency model, i.e. only linear components, is unable to correctly handle the quadratic nature of linear drift. Thus, by using a LR model that supports it, the quadratic terms influence on frequency estimation can be reduced. > Does the ADEV plots I got looks reasonable for the used "mid range" > OCXOs (see the second plot for the long run test)? You probably want to find the source of the wavy response as the orange and red trace. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Ashtech Z12 question.
Antenna is good... it is feeding an HP amplified splitter which goes to 7 other receivers. And yes, it died in the middle of a run. I have another Z12 coming from Ebay... -- > Rats. Is the antenna known to be good? Is the Z12 providing bias on the antenna cable? Did the Z12 stop tracking right in the middle of the session with no nearby events or configuration changes? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Question about frequency counter testing
Hi If you do the weighted average as indicated in the paper *and* compare it to a “single sample” computation, the results are different for that time interval. To me that’s a problem. To the authors, the fact that the rest of the curve is the same is proof that it works. I certainly agree that once you get to longer tau, the process has no detrimental impact. There is still the problem that the first post on the graph is different depending on the technique. The other side of all this is that ADEV is really not a very good way to test a counter. It has it’s quirks and it’s issues. They are impacted by what is in a counter, but that’s a side effect. If one is after a general test of counter hardware, one probably should look at other approaches. If you are trying specifically just to measure ADEV, then there are a lot of ways to do that by it’s self. It’s not clear that re-invinting the hardware is required to do this. Going with an “average down” approach ultimately *will* have problems for certain signals and noise profiles. Bob > On May 11, 2018, at 10:42 AM, Oleg Skydan wrote: > > Hi > > -- > From: "Bob kb8tq" >> The most accurate answer is always “that depends”. The simple answer is no. > > I have spent the yesterday evening and quite a bit of the night :) reading > many interesting papers and several related discussions in the time-nuts > archive (the Magnus Danielson posts in "Modified Allan Deviation and counter > averaging" and "Omega counters and Parabolic Variance (PVAR)" topics were > very informative and helpful, thanks!). > > It looks like the trick to combine averaging with the possibility of correct > ADEV calculation in the post processing exists. There is a nice presentation > made by prof. Rubiola [1]. There is a suitable solution on page 54 (at least > I understood it so, maybe I am wrong). I can switch to usual averaging > (Lambda/Delta counter) instead of LR calculation (Omega counter), the losses > should be very small I my case. With such averaging the MDEV can be correctly > computed. If ADEV is needed, the averaging interval can be reduced and > several measurements (more then eight) can be combined into one point > (creating the new weighting function which resembles the usual Pi one, as > shown in the [1] p.54), it should be possible to calculate usual ADEV using > such data. As far as I understand, the filter which is formed by the > resulting weighting function will have wider bandwidth, so the impact on ADEV > will be smaller and it can be computed correctly. Am I missing something? > > I have made the necessary changes in code, now firmware computes the Delta > averaging, also it computes combined Delta averaged measurements (resulting > in trapezoidal weighting function), both numbers are computed with continuous > stamping and optimal overlapping. Everything is done in real time. I did some > tests. The results are very similar to the ones made with LR counting. > > [1] http://www.rubiola.org/pdf-slides/2012T-IFCS-Counters.pdf > E. Rubiola, High resolution time and frequency counters, updated version. > > All the best! > Oleg UR3IQO > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
How about measuring variations in propagation delay for WWV on various frequencies, or WWVB, using GPS ticks as a reference. DanaK8YUM On Fri, May 11, 2018 at 9:41 AM, Van Horn, David < david.vanh...@backcountryaccess.com> wrote: > > Measuring the speed of light (Fizeau or Michelson method? Other ways) > > > I saw a great demo of this at the Exploratorium in SF. They had a long > spool of fiber optic, a disc with holes, and a light source. When static, > if the light shines through the hole in the disc into the fiber, then you > can see the light coming out the other end of the fiber through a different > hole. When rotating, you increase speed and the fiber output gets dimmer > and dimmer till it's gone. At that point, the light going into the fiber > arrives when the other end is blocked, and vice versa. High tech, but > simple. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Question about frequency counter testing
Hi -- From: "Bob kb8tq" The most accurate answer is always “that depends”. The simple answer is no. I have spent the yesterday evening and quite a bit of the night :) reading many interesting papers and several related discussions in the time-nuts archive (the Magnus Danielson posts in "Modified Allan Deviation and counter averaging" and "Omega counters and Parabolic Variance (PVAR)" topics were very informative and helpful, thanks!). It looks like the trick to combine averaging with the possibility of correct ADEV calculation in the post processing exists. There is a nice presentation made by prof. Rubiola [1]. There is a suitable solution on page 54 (at least I understood it so, maybe I am wrong). I can switch to usual averaging (Lambda/Delta counter) instead of LR calculation (Omega counter), the losses should be very small I my case. With such averaging the MDEV can be correctly computed. If ADEV is needed, the averaging interval can be reduced and several measurements (more then eight) can be combined into one point (creating the new weighting function which resembles the usual Pi one, as shown in the [1] p.54), it should be possible to calculate usual ADEV using such data. As far as I understand, the filter which is formed by the resulting weighting function will have wider bandwidth, so the impact on ADEV will be smaller and it can be computed correctly. Am I missing something? I have made the necessary changes in code, now firmware computes the Delta averaging, also it computes combined Delta averaged measurements (resulting in trapezoidal weighting function), both numbers are computed with continuous stamping and optimal overlapping. Everything is done in real time. I did some tests. The results are very similar to the ones made with LR counting. [1] http://www.rubiola.org/pdf-slides/2012T-IFCS-Counters.pdf E. Rubiola, High resolution time and frequency counters, updated version. All the best! Oleg UR3IQO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Measuring the speed of light (Fizeau or Michelson method? Other ways) I saw a great demo of this at the Exploratorium in SF. They had a long spool of fiber optic, a disc with holes, and a light source. When static, if the light shines through the hole in the disc into the fiber, then you can see the light coming out the other end of the fiber through a different hole. When rotating, you increase speed and the fiber output gets dimmer and dimmer till it's gone. At that point, the light going into the fiber arrives when the other end is blocked, and vice versa. High tech, but simple. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 11/05/2018 07:23, jimlux wrote: On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. The advice that we got when doing a middle school science project was that you wanted an experiment with only one variable (altitude or temperature etc) and a measurement of a single variable (maybe over time). Philip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
Hi NTP time offsets through various phases of the distribution process ….. Bob > On May 11, 2018, at 12:55 AM, Hal Murray wrote: > > > A few months ago, I was a judge for the county level middle school science > fair. (I'm not very good at what they wanted, but that's a different > problem.) > > What sort of interesting time related experiments can a middle school geek do? > > Borrowing serious gear may not be off scale as long as a youngster can run it. > > - > > An alternat meaning to the "nut" part of time-nuts: ") > https://www.snopes.com/fact-check/schools-removing-analog-clocks/ > > > -- > These are my opinions. I hate spam. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related sciencefairprojects?
Hi how about frequency difference /temperature of a oved'ed Xtal oscillator -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Hawkins Sent: 11 May 2018 06:40 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Anybody have suggestions for time related sciencefairprojects? Well, how about the frequency drift between a pendulum, a tuning fork, and a crystal. Atomic standards could be added depending on availability. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Thursday, May 10, 2018 11:56 PM To: time-nuts@febo.com Cc: Hal Murray Subject: [time-nuts] Anybody have suggestions for time related science fairprojects? A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. - An alternat meaning to the "nut" part of time-nuts: ") https://www.snopes.com/fact-check/schools-removing-analog-clocks/ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. - No virus found in this message. Checked by AVG - www.avg.com Version: 2016.0.8048 / Virus Database: 4793/15646 - Release Date: 05/11/18 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Z3816A rs-232 interface
I am getting some very peculiar behavior with the serial interface on my GPS rcvr (Z3816A). I have tried several computers and several different GPS utilities (GPS-DOS2, Sat Stat, GpsCon, etc.). To date, the only thing that works is Sat Stat on a windows 2000 computer. I am using a Null modem and set the monitor computer to 9600-8N1. Other computers and/or utilities seem to give irregular behavior. I have looked at the signals with a scope and they seem borderline OK. The signals (Rx and Tx) swing a bit more than +/- 7 V. There is also some digital noise riding on the lines. I also notice that the -15 Vdc line on the internal power supply is not working (it reads about + 1.2 V). Someone on the web I found a posting claiming that the -15 Vdc line is not needed for the Z3816A. So: Any help would be appreciated. 1. Is 9600-8N1 correct? 2. Could the lack of the -15 Vdc line be the root cause? 3. Has anyone managed to use GpsCon with a Z3816A? Thanks much for any input! ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] (UK) NPL open house
Next thursday : https://www.eventbrite.co.uk/e/national-physical-laboratory-open-house-2018-prepare-to-be-amazed-tickets-42330306085 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fair projects?
On 5/10/18 9:55 PM, Hal Murray wrote: A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. The whole area of celestial nav is time related and uses very simple equipment - Telling time by measuring the sun in some way. Occultation of stars by the moon. Positions of jupiter's big 4 moons. Pendulum experiments. If the student has a way to change their altitude, can they measure changes in g. Driving a pendulum. Coupled resonators (spring/mass, pendulum, vibrating rods) Measuring the speed of light (Fizeau or Michelson method? Other ways) Water clock, sand hour glass, etc. Measuring performance variation over environmental variations. the trick with good science projects is finding something that's not just a "lab demo" - where there's some engineering component to figuring out how to execute the demo with unusual or improvised equipment, or where you're measuring something that's not been done before. For instance, measuring time with Jupiter's moons has been done for centuries, but has it been done by taking cell phone pictures through a telescope and then measuring the distances on the resulting images? Can you make a sundial with a webcam pointed at a spherical reflector (to make an "all-sky camera") Other experiments play off a old joke - there's one about "how to you tell how tall a building is using a barometer" - take it to the top of the building drop it, and time how long it takes til it hits the ground. Build a pendulum the height of the building, using the barometer as a pendulum bob. Characterizing a clock is a good one - a) there's well developed analytical tools for doing the data reduction (AVAR, etc.) b) the experiment lends itself to collecting multiple data sets from multiple instances of the clock in question c) clock performance is affected by environment, so there's lots of potential experiments. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
