Re: [time-nuts] WWVB Signal Generator
Wayne very good progress. You can actually feed the loop coild that exists with the cap it should resonate. Thats my plan at least. Regards Paul WB8TSL On Thu, Aug 30, 2018 at 9:44 PM, Wayne Holder wrote: > I've had some luck improving things with my ATTiny85-based WWVB Simulator > design by replacing the crappy, 8 MHz internal oscillator with an 8 MHz > crystal and removing the tweaked timer values I had previously used. In > addition, based on a suggestion from Paul Swed, I tried looping the antenna > wire a few times around the ferrite rod of a WWVB receiver module I > happened to have lying around and this also greatly improved things (see > photo on web page at > https://sites.google.com/site/wayneholder/controlling-time). In fact, > with > the ferrite rod in place, the BALDR clock now syncs even when completely > disconnected from being grounded to the ATTiny85 and the scope. > > I've updated my web page, and the source code at the bottom of the page, > accordingly. BTW, the SYNC output is now moved to pin 7 and the PPS output > is currently disabled in the code. In addition, I've added some additional > info on my web page about how to compile and download the program to an > ATTiny85 using ATTinyCore by Spence Konde. > > I've ordered a 15.36 MHz crystal to try, as that should let the ATTiny85 > generate a true, 60,000 Hz output but, so far, the 8 MHz crystal has helped > improve things quite a bit. In addition, I plan to do more tests on > different types of antennas in order to see if I can make things even more > reliable and stable. > > I still plan on reworking the code so it can also run on a 328-based > Arduino board but, currently, the Arduino IDE has no easy way to work with > boards that don't use a standard, 16 MHz crystal, as this frequency is used > by the serial port and, in turn, by the boot loader, so altering it can > break the ability to upload code. This has actually caused some issues for > some of my other projects, so I'm investigating how this issue might be > handled. > > Also, if anyone is interested in trying out other modulation schemes, I can > easily add a compile option t the code that will let it output a binary > low/high modulation signal instead of the PWM signal. > > Wayne > > On Thu, Aug 30, 2018 at 8:53 AM paul swed wrote: > > > Wayne as I work through the chronverter I do know the good phase tracking > > clocks really demand on frequency behavior. As I measured its +/- .6 Hz > at > > 60 KHz. I believe the cheapy wall clocks are a bit wider, but not sure as > > they are hard to actually measure. They do use a small tuning fork > crystal > > and from experience these are sharp. When I experimented with them they > > were maybe 5 Hz. Indeed the Chinese website had 25 X 60 KHz crystals for > > maybe $2. > > With respect to the antenna. My thinking is a loopstick resonated on 60 > KHz > > and most likely driving it push pull or single ended. Thats 1 transistor > if > > single ended as common collector if I had to guess. The reason is the > > micros put out a fair level of signal so its a case of upping current > into > > the antenna. But it really will be a bit of experimenting. > > I did look at your code and that was so nice it opened up straight into > the > > arduino IDE. > > Regards > > Paul > > WB8TSL > > > > On Thu, Aug 30, 2018 at 5:12 AM, Wayne Holder > > wrote: > > > > > For anyone trying out my ATTiny85 code, I've done some additional tests > > and > > > find that placement of the antenna near the clock is very finicky and, > so > > > far, the only way to get a reliable decode of the time in the clock is > by > > > using a scope to monitor the demodulated output and then moving the > > antenna > > > around until the demodulated signal lines up cleanly with modulated > > carrier > > > and there are no intra bit glitches. This can take a bit of patience, > so > > > clearly a better solution needs to be found. I've found that any type > of > > > glitch in the demodulated signal seems to prevent the clock chip from > > > decoding the time. > > > > > > It's possible the difficultly with locking onto my simulated WWVB > signal > > > may be partially due to the design of the clock (from my location it's > > > never been able to to lock onto the real WWVB signal), but I have no > > > reference to compare it against so, for now, I have conclude that the > > > PWM-based modulation scheme my code uses may also be suboptimal for > this > > > application. To make testing even more frustrating, the BALDR clock > I'm > > > using will only look for a signal for about 6 minutes before it goes to > > > sleep and I have to then power cycle the clock to get it to listen > again. > > > > > > So, keep this in mind if you're going to try and replicate my results. > > > > > > Wayne > > > > > > On Wed, Aug 29, 2018 at 6:03 PM Wayne Holder > > > wrote: > > > > > > > For those that have asked for my to publish the source code for my > > > > ATTiny85-based WWVB
Re: [time-nuts] law and regulation applying to time.. was Re: OOPS on my wwv legal post
On Thu, Aug 30, 2018 at 2:03 PM jimlux wrote: > > On 8/29/18 6:55 PM, John Hawkinson wrote: > > Continuing reference to what is "legal" or "the law" is very confusing to > > me because no one has cited any statues, regulations, or case law. > > > > What's the basis for these claims about legal requirement? Can we please > > cite chapter and verse? Without it, it's hard to distinguish rumor and > > anecdote from fact, or refute anything. > > > > > > This is an interesting point - a year or so ago (probably around the > time of the last leap second) there was all this stuff about UTC and > leap seconds vis a vis electronic trading > > There's a internationally agreed second (defined by vibrations of Cs, > etc.), and I assume that "standard practice" is that everyone adopts > this rate. > As I have read it, the "law" regarding time is about when "something" happened, and as the "something" is usually between two parties an external standard needs to be used, so although the second is defined by the number of transition between the two hyperfine ground states of caesium, UTC is used as the "standard" and so even though a trading entity may have a Cs "clock" it would only be used as a holdover device if time from a directly continuously traceable (to UTC) was unavailable. > > But is it a legal or regulatory *requirement* - or is it just standard > practice, in the same sense that everyone uses the same M2 or 6-32 > threads. There's no *law* that requires me to use a particular pipe > thread or resistor color code. There's a standard that has been > promulgated for these things, and if I buy, and you sell, it's to our > mutual advantage to use the same standard. > As above the "law" usually relates to UTC rather than how you derive a second. > > But if wanted to be "different", (say I was hand crafting English sports > cars :), I could use a completely different series of fasteners and > standard dimensions, and I could even use the positive terminal of the > battery as the chassis common. > While it would be possible to build using a different thread to Whitworth https://en.wikipedia.org/wiki/British_Standard_Whitworth or metric, having to make every single nut and bolt would be a considerable overhead. OT (very) I learnt to drive in a positive earth Morris Minor, and that was only a "few" decades ago (-: > > But is there some International banking agreement that requires UTC? Or > a SEC rule? > MIFID II is a European (not quite International, but when one considers the reach, it is effectively International) law that specifically names UTC and tracebility http://ec.europa.eu/finance/docs/level-2-measures/mifid-rts-25_en.pdf > > I buy lots of things that have requirements that say, in effect > "calibration shall be traceable to NIST or other National Standards > Lab", but that's a *contractual* requirement, not a *legal* requirement. > > There may well be a law in the United States, probably buried in some > enabling or appropriating bill, that says "The Department of Commerce > shall provide national standards for mass, time, voltage, etc." but > that doesn't say "and all residents of the United States shall use only > the standard provided by the Department of Commerce, and no other" > > What about Germany? Notoriously it is "Das Land der Gebote, der > Vorschriften, und der Verbote." (Commandments, regulations, and > prohibitions) > Germany uses UTC > Cheers ___ 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] NIST
On Thu, Aug 30, 2018 at 12:59 PM Bob kb8tq wrote: > There most certainly was a lot of “stuff” in orbit by that time. If there was > a mass die off of satellites, you would not have to look hard to find out > about > it. Probably not as many as there are 3 decades later, but of course. Satellite service (any type of satellite) is much more likely to be human-caued. But here (and in other fora) the concern is that WWV Must Be Maintained in order to save us from being late for coffee if another event on the level of the Carrington Event takes out every single GNSS spacecraft in orbit. But I can't find anything on the effect of that sort of solar event on satellites. Almost as if, maybe, satellite operators were aware of solar physics and planned for this sort of event. And I still haven't seen any coherent argument in favor of keeping WWV that doesn't involve nostalgia or (perhaps) unfounded fear. -- Peter Laws | N5UWY | plaws plaws net | Travel by Train! ___ 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] NIST
Hi The original “we cracked GPS” paper back in the 1980’s (that unlimitedly lead to the end of SA) used a medium sized dish ( think of the good old C-band antennas) to pick out a single sat. Bob > On Aug 30, 2018, at 9:54 PM, Brooke Clarke wrote: > > Hi Gregory: > > I wonder if anyone has tried using a small parabolic dish, like used for Free > To Air satellite TV and aimed it at a GPS satellite track or at a WAAS > geostationary satellite using a feed antenna with reverse polarization from a > normal GPS antenna? > http://www.prc68.com/I/FTA.shtml > > -- > Have Fun, > > Brooke Clarke > https://www.PRC68.com > https://www.end2partygovernment.com/2012Issues.html > axioms: > 1. The extent to which you can fix or improve something will be limited by > how well you understand how it works. > 2. Everybody, with no exceptions, holds false beliefs. > > Original Message >> On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: >>> I would disagree in that ease of jamming/spoofing is strongly related to >>> wavelength. That's because antenna efficiency >>> goes down as the size of the antenna gets smaller than 1/4 wave. >>> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 >>> wavelength is a few inches, something that you can >>> hold in your hand. >> However, the short wavelengths of GPS make beam forming a reasonable >> countermeasure against jamming. >> >> By having a small array of GPS antennas a receiver can digitally form >> beams that both aim directly at the relevant satellites (so even >> reducing intersatellite interference) while also steering a deep null >> in the direction of the jammer. If the jammer is powerful enough to >> overload the front-end then this won't help, but against a >> non-targeted area denying jammer it should be fairly effective. >> >> There are many papers on GNSS beamforming. ( e.g. >> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ >> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) >> >> This kind of anti-jamming solution should even be pretty inexpensive >> -- really no more than the cost of N receivers. Except that it is >> specialized technology and thus very expensive. :) >> >> Seeing some open source software implementing beam-forming was one of >> the things I hoped to see result from the open hardware multi-band >> GNSS receivers like the GNSS firehose project ( >> http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once >> you're going through the trouble of running three coherent receivers >> for three bands, stacking three more of them and locking them to the >> same clock doesn't seem like a big engineering challenge... and the >> rest is just DSP work. >> >> Even absent fancy beam forming, for GNSS timing with a surveyed >> position except at high latitudes it should be possible to use a >> relatively high gain antenna pointed straight up and by doing so blind >> yourself to terrestrial jammers at a cost of fewer SVs being >> available. But I've never tried it. >> >> In an urban area I noticed my own GPSDOs losing signal multiple times >> per week. Monitoring with an SDR showed what appeared to be jammers. >> >> As others have noted intermittent jamming is pretty benign to a GPSDO. >> Spoofing, OTOH, can trivially mess up the timing. It's my view that >> if you need timing for a security critical purpose there isn't really >> any GNSS based solution commercially available to the general public >> right now, the best bet is a local atomic reference with a GPSDO used >> to monitor and initially set it. >> >> ___ >> 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] NIST
I once bought a pair of low power 315 MHz TX/RX modules and was going to try them in a model rocket + GPS. I tested them with a serial port and they had a range of a couple thousand feet at 1200 BPS. But when the transmitter was connected to the GPS, the GPS lost lock... turns out 315 MHz * 5 is the GPS carrier frequency. They would totally jam GPS over around a mile diameter. Also the maker of the modules stopped selling them and actually disavowed that they ever existed! ___ 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] NIST
Hi Gregory: I wonder if anyone has tried using a small parabolic dish, like used for Free To Air satellite TV and aimed it at a GPS satellite track or at a WAAS geostationary satellite using a feed antenna with reverse polarization from a normal GPS antenna? http://www.prc68.com/I/FTA.shtml -- Have Fun, Brooke Clarke https://www.PRC68.com https://www.end2partygovernment.com/2012Issues.html axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency goes down as the size of the antenna gets smaller than 1/4 wave. So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can hold in your hand. However, the short wavelengths of GPS make beam forming a reasonable countermeasure against jamming. By having a small array of GPS antennas a receiver can digitally form beams that both aim directly at the relevant satellites (so even reducing intersatellite interference) while also steering a deep null in the direction of the jammer. If the jammer is powerful enough to overload the front-end then this won't help, but against a non-targeted area denying jammer it should be fairly effective. There are many papers on GNSS beamforming. ( e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) This kind of anti-jamming solution should even be pretty inexpensive -- really no more than the cost of N receivers. Except that it is specialized technology and thus very expensive. :) Seeing some open source software implementing beam-forming was one of the things I hoped to see result from the open hardware multi-band GNSS receivers like the GNSS firehose project ( http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once you're going through the trouble of running three coherent receivers for three bands, stacking three more of them and locking them to the same clock doesn't seem like a big engineering challenge... and the rest is just DSP work. Even absent fancy beam forming, for GNSS timing with a surveyed position except at high latitudes it should be possible to use a relatively high gain antenna pointed straight up and by doing so blind yourself to terrestrial jammers at a cost of fewer SVs being available. But I've never tried it. In an urban area I noticed my own GPSDOs losing signal multiple times per week. Monitoring with an SDR showed what appeared to be jammers. As others have noted intermittent jamming is pretty benign to a GPSDO. Spoofing, OTOH, can trivially mess up the timing. It's my view that if you need timing for a security critical purpose there isn't really any GNSS based solution commercially available to the general public right now, the best bet is a local atomic reference with a GPSDO used to monitor and initially set it. ___ 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] NIST
Hi ….. ok, so you are dealing with city wide jammers that take out all of New York City on a daily basis? Again, that was the original example tossed out. “A cigarette pack sized jammer that takes out an entire city”. A jammer with that sort of range is an easy jammer to spot. Somehow I find that a bit difficult to believe. What I’ve seen and gone after are *far* shorter range than that magic device. A short rang mobile jammer aimed at an ankle bracelet takes out an infrastructure device for minutes. That’s why those devices have holdover capabilities. Indeed at the point they *do* start interfering with major systems over a wide range…. bigger gear gets brought in. Jamming that actually takes utility systems down is very rare. No cell phone service anywhere in New York is something that gets noticed pretty fast. It also fires up meetings that last quite literally for years ….. Bob > On Aug 30, 2018, at 8:43 PM, Scott McGrath wrote: > > Just ask the NY Port authority how ‘easy’ knocking these jammers offline is. > Usually done by vehicle to vehicle inspection with a SA. > > And yes the day job all too frequently searching for and identifying > interference sources. > > One of the more interesting ones was a halogen leak detector wiping out WiFi > at a manufacturing plant. So my opinions on interference location are > informed by leading teams of people doing just that. > > Content by Scott > Typos by Siri > > On Aug 30, 2018, at 8:24 PM, Bob kb8tq wrote: > > Hi > > Since timing receivers are actually going to prefer high angle sats, an > antenna that rejects > close to the horizon is a pretty common thing. Enhancing that sort of > rejection doesn’t take > a lot of effort. > > Bob > >> On Aug 30, 2018, at 7:05 PM, Gregory Maxwell wrote: >> >> On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: >>> I would disagree in that ease of jamming/spoofing is strongly related to >>> wavelength. That's because antenna efficiency >>> goes down as the size of the antenna gets smaller than 1/4 wave. >>> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 >>> wavelength is a few inches, something that you can >>> hold in your hand. >> >> However, the short wavelengths of GPS make beam forming a reasonable >> countermeasure against jamming. >> >> By having a small array of GPS antennas a receiver can digitally form >> beams that both aim directly at the relevant satellites (so even >> reducing intersatellite interference) while also steering a deep null >> in the direction of the jammer. If the jammer is powerful enough to >> overload the front-end then this won't help, but against a >> non-targeted area denying jammer it should be fairly effective. >> >> There are many papers on GNSS beamforming. ( e.g. >> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ >> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) >> >> This kind of anti-jamming solution should even be pretty inexpensive >> -- really no more than the cost of N receivers. Except that it is >> specialized technology and thus very expensive. :) >> >> Seeing some open source software implementing beam-forming was one of >> the things I hoped to see result from the open hardware multi-band >> GNSS receivers like the GNSS firehose project ( >> http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once >> you're going through the trouble of running three coherent receivers >> for three bands, stacking three more of them and locking them to the >> same clock doesn't seem like a big engineering challenge... and the >> rest is just DSP work. >> >> Even absent fancy beam forming, for GNSS timing with a surveyed >> position except at high latitudes it should be possible to use a >> relatively high gain antenna pointed straight up and by doing so blind >> yourself to terrestrial jammers at a cost of fewer SVs being >> available. But I've never tried it. >> >> In an urban area I noticed my own GPSDOs losing signal multiple times >> per week. Monitoring with an SDR showed what appeared to be jammers. >> >> As others have noted intermittent jamming is pretty benign to a GPSDO. >> Spoofing, OTOH, can trivially mess up the timing. It's my view that >> if you need timing for a security critical purpose there isn't really >> any GNSS based solution commercially available to the general public >> right now, the best bet is a local atomic reference with a GPSDO used >> to monitor and initially set it. >> >> ___ >> 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] NIST
Just ask the NY Port authority how ‘easy’ knocking these jammers offline is. Usually done by vehicle to vehicle inspection with a SA. And yes the day job all too frequently searching for and identifying interference sources. One of the more interesting ones was a halogen leak detector wiping out WiFi at a manufacturing plant. So my opinions on interference location are informed by leading teams of people doing just that. Content by Scott Typos by Siri On Aug 30, 2018, at 8:24 PM, Bob kb8tq wrote: Hi Since timing receivers are actually going to prefer high angle sats, an antenna that rejects close to the horizon is a pretty common thing. Enhancing that sort of rejection doesn’t take a lot of effort. Bob > On Aug 30, 2018, at 7:05 PM, Gregory Maxwell wrote: > > On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: >> I would disagree in that ease of jamming/spoofing is strongly related to >> wavelength. That's because antenna efficiency >> goes down as the size of the antenna gets smaller than 1/4 wave. >> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 >> wavelength is a few inches, something that you can >> hold in your hand. > > However, the short wavelengths of GPS make beam forming a reasonable > countermeasure against jamming. > > By having a small array of GPS antennas a receiver can digitally form > beams that both aim directly at the relevant satellites (so even > reducing intersatellite interference) while also steering a deep null > in the direction of the jammer. If the jammer is powerful enough to > overload the front-end then this won't help, but against a > non-targeted area denying jammer it should be fairly effective. > > There are many papers on GNSS beamforming. ( e.g. > https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ > https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) > > This kind of anti-jamming solution should even be pretty inexpensive > -- really no more than the cost of N receivers. Except that it is > specialized technology and thus very expensive. :) > > Seeing some open source software implementing beam-forming was one of > the things I hoped to see result from the open hardware multi-band > GNSS receivers like the GNSS firehose project ( > http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once > you're going through the trouble of running three coherent receivers > for three bands, stacking three more of them and locking them to the > same clock doesn't seem like a big engineering challenge... and the > rest is just DSP work. > > Even absent fancy beam forming, for GNSS timing with a surveyed > position except at high latitudes it should be possible to use a > relatively high gain antenna pointed straight up and by doing so blind > yourself to terrestrial jammers at a cost of fewer SVs being > available. But I've never tried it. > > In an urban area I noticed my own GPSDOs losing signal multiple times > per week. Monitoring with an SDR showed what appeared to be jammers. > > As others have noted intermittent jamming is pretty benign to a GPSDO. > Spoofing, OTOH, can trivially mess up the timing. It's my view that > if you need timing for a security critical purpose there isn't really > any GNSS based solution commercially available to the general public > right now, the best bet is a local atomic reference with a GPSDO used > to monitor and initially set it. > > ___ > 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] NIST
Hi Since timing receivers are actually going to prefer high angle sats, an antenna that rejects close to the horizon is a pretty common thing. Enhancing that sort of rejection doesn’t take a lot of effort. Bob > On Aug 30, 2018, at 7:05 PM, Gregory Maxwell wrote: > > On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: >> I would disagree in that ease of jamming/spoofing is strongly related to >> wavelength. That's because antenna efficiency >> goes down as the size of the antenna gets smaller than 1/4 wave. >> So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 >> wavelength is a few inches, something that you can >> hold in your hand. > > However, the short wavelengths of GPS make beam forming a reasonable > countermeasure against jamming. > > By having a small array of GPS antennas a receiver can digitally form > beams that both aim directly at the relevant satellites (so even > reducing intersatellite interference) while also steering a deep null > in the direction of the jammer. If the jammer is powerful enough to > overload the front-end then this won't help, but against a > non-targeted area denying jammer it should be fairly effective. > > There are many papers on GNSS beamforming. ( e.g. > https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ > https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) > > This kind of anti-jamming solution should even be pretty inexpensive > -- really no more than the cost of N receivers. Except that it is > specialized technology and thus very expensive. :) > > Seeing some open source software implementing beam-forming was one of > the things I hoped to see result from the open hardware multi-band > GNSS receivers like the GNSS firehose project ( > http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once > you're going through the trouble of running three coherent receivers > for three bands, stacking three more of them and locking them to the > same clock doesn't seem like a big engineering challenge... and the > rest is just DSP work. > > Even absent fancy beam forming, for GNSS timing with a surveyed > position except at high latitudes it should be possible to use a > relatively high gain antenna pointed straight up and by doing so blind > yourself to terrestrial jammers at a cost of fewer SVs being > available. But I've never tried it. > > In an urban area I noticed my own GPSDOs losing signal multiple times > per week. Monitoring with an SDR showed what appeared to be jammers. > > As others have noted intermittent jamming is pretty benign to a GPSDO. > Spoofing, OTOH, can trivially mess up the timing. It's my view that > if you need timing for a security critical purpose there isn't really > any GNSS based solution commercially available to the general public > right now, the best bet is a local atomic reference with a GPSDO used > to monitor and initially set it. > > ___ > 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] NIST
Hi Actually it’s pretty simple to track down that sort of jammer ….. and yes, the gear to do it is out there in quantity. Bob > On Aug 30, 2018, at 6:51 PM, Scott McGrath wrote: > > As Brooke notes while low frequency jammers are possible, practicality is > another matter, All it takes to jam a city scale area is a box the size of > a pack of cigarettes.Because the GPS signal is very, very weak. > > As an intentional denial put a couple hundred on stray animals.Now track > those jammers down. > > I doubt if any agency owns enough DF equipment to find them all in a > reasonable amount of time. > > Thats why we need backup systems and each backup system will have less and > less accuracy as it increases in robustness. The HF systems could provide > adequate syncing for the Market example. > > > > On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp wrote: > > > In message <96e995c4-5ca2-af02-9738-0a6d87a9f...@pacific.net>, Brooke Clarke > writes: > >> But it's extremely hard to make a jammer for WWVB (60 kHz) [...] > > You can do it city-scale with a 18-wheeler sized loop-antenna > and a good size diesel-generator. > > However pedestrians will very likely note metalic items vibrating > as they pass the "mystery white truck". > > Sweden were much more serious about it: > > http://www.antus.org/RT02.html > > Tl;drs: > > They erected 9 200m tall Loran-C class antennas each driven by > a Loran-C transmitter with an advanced degree which could jam > Loran-C or Chayka. > > They even mounted decoy parabolas on the towers them to hide their > true purpose. > > The fact that all the transmitters were on the east coast does drop > a hint that swedens much touted neutrality had a bit of a slant. > > -- > 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] NIST
Before retiring I did some field work on the Tomahawk AGR (https://www.raytheon.com/capabilities/products/gps_anti-jam) Wes N7WS On 8/30/2018 4:05 PM, Gregory Maxwell wrote: However, the short wavelengths of GPS make beam forming a reasonable countermeasure against jamming. ___ 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] NIST
Is there a translation of this anywhere? Don Sweden were much more serious about it: http://www.antus.org/RT02.html Tl;drs: They erected 9 200m tall Loran-C class antennas each driven by a Loran-C transmitter with an advanced degree which could jam Loran-C or Chayka. They even mounted decoy parabolas on the towers them to hide their true purpose. The fact that all the transmitters were on the east coast does drop a hint that swedens much touted neutrality had a bit of a slant. -- Dr. Don Latham PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304 ___ 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] News
Congratulations, Magnus! Fellowship is next. On Thursday, August 30, 2018, Magnus Danielson wrote: > Hi Bob, > > On 08/30/2018 10:33 PM, Bob kb8tq wrote: > > Hi > > > > Magnus … do you have some news you might want to share with the group? > > Oh, well, sure: > > Today I received a nice email from IEEE starting with: > "It is a great pleasure to congratulate you on your elevation to the > grade of IEEE Senior member. IEEE Senior Membership is an honor bestowed > only to those who have made significant contributions to the profession." > > I'm humbled by these words, but proud of the achievement and happy for > the distinction. This has been a process that has been going on since > spring when IEEE approached me and pointed out that I should be able to > become senior member, writing up a modern CV and then being interviewed > by three Senior Members was interesting, sharing the room with very > senior engineers, PhDs and professors all seeking to reach the IEEE > Senior member elevation. > > Cheers, > Magnus > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/ > listinfo/time-nuts_lists.febo.com > and follow the instructions there. > -- Patriotism is supporting your country all the time, and your government when it deserves it. --Mark Twain We may be surprised at the people we find in heaven. God has a soft spot for sinners. His standards are quite low. --Desmond Tutu ___ 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] NIST
On Thu, Aug 30, 2018 at 9:43 PM Brooke Clarke wrote: > I would disagree in that ease of jamming/spoofing is strongly related to > wavelength. That's because antenna efficiency > goes down as the size of the antenna gets smaller than 1/4 wave. > So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength > is a few inches, something that you can > hold in your hand. However, the short wavelengths of GPS make beam forming a reasonable countermeasure against jamming. By having a small array of GPS antennas a receiver can digitally form beams that both aim directly at the relevant satellites (so even reducing intersatellite interference) while also steering a deep null in the direction of the jammer. If the jammer is powerful enough to overload the front-end then this won't help, but against a non-targeted area denying jammer it should be fairly effective. There are many papers on GNSS beamforming. ( e.g. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134596/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5134483/ ) This kind of anti-jamming solution should even be pretty inexpensive -- really no more than the cost of N receivers. Except that it is specialized technology and thus very expensive. :) Seeing some open source software implementing beam-forming was one of the things I hoped to see result from the open hardware multi-band GNSS receivers like the GNSS firehose project ( http://pmonta.com/blog/2017/05/05/gnss-firehose-update/ ) since once you're going through the trouble of running three coherent receivers for three bands, stacking three more of them and locking them to the same clock doesn't seem like a big engineering challenge... and the rest is just DSP work. Even absent fancy beam forming, for GNSS timing with a surveyed position except at high latitudes it should be possible to use a relatively high gain antenna pointed straight up and by doing so blind yourself to terrestrial jammers at a cost of fewer SVs being available. But I've never tried it. In an urban area I noticed my own GPSDOs losing signal multiple times per week. Monitoring with an SDR showed what appeared to be jammers. As others have noted intermittent jamming is pretty benign to a GPSDO. Spoofing, OTOH, can trivially mess up the timing. It's my view that if you need timing for a security critical purpose there isn't really any GNSS based solution commercially available to the general public right now, the best bet is a local atomic reference with a GPSDO used to monitor and initially set it. ___ 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] NIST
As Brooke notes while low frequency jammers are possible, practicality is another matter, All it takes to jam a city scale area is a box the size of a pack of cigarettes.Because the GPS signal is very, very weak. As an intentional denial put a couple hundred on stray animals.Now track those jammers down. I doubt if any agency owns enough DF equipment to find them all in a reasonable amount of time. Thats why we need backup systems and each backup system will have less and less accuracy as it increases in robustness. The HF systems could provide adequate syncing for the Market example. On Aug 30, 2018, at 6:18 PM, Poul-Henning Kamp wrote: In message <96e995c4-5ca2-af02-9738-0a6d87a9f...@pacific.net>, Brooke Clarke writes: > But it's extremely hard to make a jammer for WWVB (60 kHz) [...] You can do it city-scale with a 18-wheeler sized loop-antenna and a good size diesel-generator. However pedestrians will very likely note metalic items vibrating as they pass the "mystery white truck". Sweden were much more serious about it: http://www.antus.org/RT02.html Tl;drs: They erected 9 200m tall Loran-C class antennas each driven by a Loran-C transmitter with an advanced degree which could jam Loran-C or Chayka. They even mounted decoy parabolas on the towers them to hide their true purpose. The fact that all the transmitters were on the east coast does drop a hint that swedens much touted neutrality had a bit of a slant. -- 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] law and regulation applying to time.. was Re: OOPS on my wwv legal post
On Thu, 30 Aug 2018 at 14:03, jimlux wrote: > > There may well be a law in the United States, probably buried in some > enabling or appropriating bill, that says "The Department of Commerce > shall provide national standards for mass, time, voltage, etc." but > that doesn't say "and all residents of the United States shall use only > the standard provided by the Department of Commerce, and no other" > > What about Germany? Notoriously it is "Das Land der Gebote, der > Vorschriften, und der Verbote." (Commandments, regulations, and > prohibitions) > In the UK there are laws requiring metric for most things - beer being one obvious exception I can think of, as I had 3 pints today. https://www.gov.uk/guidance/packaged-goods-weights-and-measures-regulations That said, it references the "1985 Weights and measures Act" http://www.legislation.gov.uk/ukpga/1985/72/contents which refers to "United Kingdom primary standards and authorised copies of the primary standards." The United Kingdom primary standards shall be— (a)in the case of the yard, the bar described in Part I of Schedule 2 to this Act; (b)in the case of the pound, the cylinder described in Part II of that Schedule; (c)in the case of the metre, the bar described in Part III of that Schedule; (d)in the case of the kilogram, the cylinder described in Part IV of that Schedule. Then going to the metre definition, it talks of an X shaped bar http://www.legislation.gov.uk/ukpga/1985/72/schedule/2 I believe that is almost certainly the one held at NPL, and was on display at the recent "NPL Open House". However, it makes no reference to NPL directly. There was a case of a butcher not too far from me who refused to sell meat in kg. http://news.bbc.co.uk/1/hi/uk/629763.stm I believe he died before going to prison, but he was quite adamant he would not sell in kg. It would have been interesting if he priced his meat at £12 / 0.45454545454545454545454545454545454545454545454545454545454545454 kg, which would be £12/pound. When it comes to time (the subject of this list), I'm not sure where the UK stands legally. I will ask on the newgroup uk.legal.moderated https://groups.google.com/forum/#!forum/uk.legal.moderated which is visited by solicitors, students of law, and people wanting legal advice. Dr David Kirkby Ph.D C.Eng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom. Registered in England and Wales as company number 08914892 https://www.kirkbymicrowave.co.uk/ Tel 01621-680100 / +44 1621-680100 ___ 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] News
Congrats Magnus! -- 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.
Re: [time-nuts] NIST
Hi Well, designing jammers on a public forum is an “interesting” thing to do….. With WWVB, you are fine with a “near field” solution. You don’t need something that propagates for miles and miles. The other thing you have in your favor is that coming up with a KW at 60 KHz is quite easy. All those 60 KHz switchers we complain about … there’s your dirt cheap source of parts. The next part of the “solution” is to feed your signal into the local power grid. Your switcher is happy with a low impedance load. The power line looks fairly low impedance at 60 KHz. It goes the RF and out and about it flows. Indeed it works pretty well over a good chunk of ground. At least as good as your typical GPS jammer and no more expensive. Been there end done all that, though not for a WWVB jammer. Bob > On Aug 30, 2018, at 5:20 PM, Brooke Clarke wrote: > > Hi Bob: > > I would disagree in that ease of jamming/spoofing is strongly related to > wavelength. That's because antenna efficiency goes down as the size of the > antenna gets smaller than 1/4 wave. > So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength > is a few inches, something that you can hold in your hand. > It's harder to make a WWV jammer (.5, 5, 10, 15, 20 MHz) since a 1/4 > wavelength in in the range of 500 to 12 feet, something that can be mounted > on a vehicle for the higher frequencies. > But it's extremely hard to make a jammer for WWVB (60 kHz) where a > 1/4wavelength is over 4,000 feet. This means an antenna that can be vehicle > mounted will be very inefficient. Note this also means that it's extremely > hard to make a Loran-C jammer. Note that the WWVB and LORAN-C transmitters > run very high power and the antennas are massive. > > This also means that if someone makes a WWVB simulator for their house the > signal at the next door neighbor's house is probably going to be too small to > effect their clocks. > > PS. Some decades ago I maintained a beacon transmitter "LAH" on 175 kHz where > the rules for unlicensed operation limited the input power to 1 Watt and > total antenna length to 50 feet. Under these conditions the effective > radiated power might be 2 milliwatts, orders of magnitude less if a portable > system. > http://www.auroralchorus.com/pli/1750meter_antennas.pdf > > -- > Have Fun, > > Brooke Clarke, N6GCE > https://www.PRC68.com > https://www.end2partygovernment.com/2012Issues.html > axioms: > 1. The extent to which you can fix or improve something will be limited by > how well you understand how it works. > 2. Everybody, with no exceptions, holds false beliefs. > > Original Message >> Hi >> >> When infastructure GPS *does* get jammed these days that source gets tracked >> down a lot faster >> than a month or so. Anything that goes on for more than a day gets booted up >> pretty high >> pretty fast. Indeed I’ve been in the middle of that more than I would have >> wished to be ….. >> >> The same sort of RFI issues that take out GPS from a TV preamp can equally >> well take out WWVB or WWV. >> With WWVB, there are a *lot* of 60KHz switching power supplies out there to >> create problems. There is nothing >> unique about any of these services in terms of being jam immune. >> >> The bigger issue with any of them is spoofing. A proper GPSDO will go into >> holdover when RFI jammed. I would >> *assume* the same would be true of a fancy WWVB device. I’m not at all sure >> that’s true of a real WWVB standard, >> they haven’t been for sale new for a really long time. If your time source >> is in holdover, you can go out and track down >> the issue. If it simply locks to the new signal …. not so much. >> >> There is a subtle distinction in some of this. Newer systems do indeed want >> time. Older systems were generally after >> frequency. The only WWVB standards I’ve seen were aimed at frequency (and >> frequency holdover) rather than time and >> time holdover. Getting reasonable (1 to 10 ppb) frequency from WWVB is a >> very different task than getting the sort of time >> that modern systems are after. >> >> Bob >> >>> On Aug 30, 2018, at 2:46 PM, Scott McGrath wrote: >>> >>> The port of Long Beach CA was jammed wrt GPS for several months by a >>> malfunctioning 29.95 TV preamplifier on a boat. >>> >>> GPS was completely unusable when this unsuspecting guy was watching TV on >>> his boat. >>> >>> He had quite the surprise when the coasties with guns showed up. >>> >>> The fact is civillian GPS Is trivial to jam and jammers can be bought >>> ‘under the counter’ at any truckstop along with illlegal linear amplifiers. >>> >>> >>> >>> On Aug 30, 2018, at 12:58 PM, Peter Laws wrote: >>> >>> On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: >>> >>> I have yet to hear anyone make a case for retaining the HF system that isn't backed by nostalgia. >>> Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS >>>
Re: [time-nuts] NIST
Hi Bob: I would disagree in that ease of jamming/spoofing is strongly related to wavelength. That's because antenna efficiency goes down as the size of the antenna gets smaller than 1/4 wave. So, it's easy to make a GPS jammer (1,100 to 1,600MHz) since a 1/4 wavelength is a few inches, something that you can hold in your hand. It's harder to make a WWV jammer (.5, 5, 10, 15, 20 MHz) since a 1/4 wavelength in in the range of 500 to 12 feet, something that can be mounted on a vehicle for the higher frequencies. But it's extremely hard to make a jammer for WWVB (60 kHz) where a 1/4wavelength is over 4,000 feet. This means an antenna that can be vehicle mounted will be very inefficient. Note this also means that it's extremely hard to make a Loran-C jammer. Note that the WWVB and LORAN-C transmitters run very high power and the antennas are massive. This also means that if someone makes a WWVB simulator for their house the signal at the next door neighbor's house is probably going to be too small to effect their clocks. PS. Some decades ago I maintained a beacon transmitter "LAH" on 175 kHz where the rules for unlicensed operation limited the input power to 1 Watt and total antenna length to 50 feet. Under these conditions the effective radiated power might be 2 milliwatts, orders of magnitude less if a portable system. http://www.auroralchorus.com/pli/1750meter_antennas.pdf -- Have Fun, Brooke Clarke, N6GCE https://www.PRC68.com https://www.end2partygovernment.com/2012Issues.html axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. Original Message Hi When infastructure GPS *does* get jammed these days that source gets tracked down a lot faster than a month or so. Anything that goes on for more than a day gets booted up pretty high pretty fast. Indeed I’ve been in the middle of that more than I would have wished to be ….. The same sort of RFI issues that take out GPS from a TV preamp can equally well take out WWVB or WWV. With WWVB, there are a *lot* of 60KHz switching power supplies out there to create problems. There is nothing unique about any of these services in terms of being jam immune. The bigger issue with any of them is spoofing. A proper GPSDO will go into holdover when RFI jammed. I would *assume* the same would be true of a fancy WWVB device. I’m not at all sure that’s true of a real WWVB standard, they haven’t been for sale new for a really long time. If your time source is in holdover, you can go out and track down the issue. If it simply locks to the new signal …. not so much. There is a subtle distinction in some of this. Newer systems do indeed want time. Older systems were generally after frequency. The only WWVB standards I’ve seen were aimed at frequency (and frequency holdover) rather than time and time holdover. Getting reasonable (1 to 10 ppb) frequency from WWVB is a very different task than getting the sort of time that modern systems are after. Bob On Aug 30, 2018, at 2:46 PM, Scott McGrath wrote: The port of Long Beach CA was jammed wrt GPS for several months by a malfunctioning 29.95 TV preamplifier on a boat. GPS was completely unusable when this unsuspecting guy was watching TV on his boat. He had quite the surprise when the coasties with guns showed up. The fact is civillian GPS Is trivial to jam and jammers can be bought ‘under the counter’ at any truckstop along with illlegal linear amplifiers. On Aug 30, 2018, at 12:58 PM, Peter Laws wrote: On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: I have yet to hear anyone make a case for retaining the HF system that isn't backed by nostalgia. Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS WILL DIE" posts (elsewhere, not here ... quite ...) are the type of hysteria that is usually reserved for, I don't know, the EMP folks. :-) As for solar flares taking out the various GNSSs ... wouldn't a solar flare only take out the vehicles that were on the "sunny" side of the Earth? Wouldn't the (approximately) half of the SVs that are in the Earth's shadow be unaffected? Serious technical question - I have no idea. One of the responses to my initial message pointed out that the effects of solar flares and CMEs take a while to get from Sol to Sol III and don't arrive all at once, so potentially all GNSS spacecraft could be affected. Since then, I've been poking around for papers on the effect (observed, potential, theoretical) of these events on the Navstar or other GNSS constellations but am not having much luck. I assume it's because I'm not putting the right magic incantation into the google machine. Anyone got some cites? Looking for the effect of solar flares and CMEs on the spacecraft themselves and not how the GNSSs can be used to measure the effects on the ionosphere, etc (those seem plentiful). IOW, I'm
[time-nuts] News
Hi Magnus … do you have some news you might want to share with the group? Bob ___ 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] NIST
Hi When infastructure GPS *does* get jammed these days that source gets tracked down a lot faster than a month or so. Anything that goes on for more than a day gets booted up pretty high pretty fast. Indeed I’ve been in the middle of that more than I would have wished to be ….. The same sort of RFI issues that take out GPS from a TV preamp can equally well take out WWVB or WWV. With WWVB, there are a *lot* of 60KHz switching power supplies out there to create problems. There is nothing unique about any of these services in terms of being jam immune. The bigger issue with any of them is spoofing. A proper GPSDO will go into holdover when RFI jammed. I would *assume* the same would be true of a fancy WWVB device. I’m not at all sure that’s true of a real WWVB standard, they haven’t been for sale new for a really long time. If your time source is in holdover, you can go out and track down the issue. If it simply locks to the new signal …. not so much. There is a subtle distinction in some of this. Newer systems do indeed want time. Older systems were generally after frequency. The only WWVB standards I’ve seen were aimed at frequency (and frequency holdover) rather than time and time holdover. Getting reasonable (1 to 10 ppb) frequency from WWVB is a very different task than getting the sort of time that modern systems are after. Bob > On Aug 30, 2018, at 2:46 PM, Scott McGrath wrote: > > The port of Long Beach CA was jammed wrt GPS for several months by a > malfunctioning 29.95 TV preamplifier on a boat. > > GPS was completely unusable when this unsuspecting guy was watching TV on his > boat. > > He had quite the surprise when the coasties with guns showed up. > > The fact is civillian GPS Is trivial to jam and jammers can be bought ‘under > the counter’ at any truckstop along with illlegal linear amplifiers. > > > > On Aug 30, 2018, at 12:58 PM, Peter Laws wrote: > > On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: > > >> I have yet to hear anyone make a case for retaining the HF system that >> isn't backed by nostalgia. > > Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS > WILL DIE" posts (elsewhere, not here ... quite ...) are the type of > hysteria that is usually reserved for, I don't know, the EMP folks. > :-) > > >> As for solar flares taking out the various GNSSs ... wouldn't a solar >> flare only take out the vehicles that were on the "sunny" side of the >> Earth? Wouldn't the (approximately) half of the SVs that are in the >> Earth's shadow be unaffected? Serious technical question - I have no >> idea. > > One of the responses to my initial message pointed out that the > effects of solar flares and CMEs take a while to get from Sol to Sol > III and don't arrive all at once, so potentially all GNSS spacecraft > could be affected. > > Since then, I've been poking around for papers on the effect > (observed, potential, theoretical) of these events on the Navstar or > other GNSS constellations but am not having much luck. I assume it's > because I'm not putting the right magic incantation into the google > machine. > > Anyone got some cites? Looking for the effect of solar flares and > CMEs on the spacecraft themselves and not how the GNSSs can be used to > measure the effects on the ionosphere, etc (those seem plentiful). > IOW, I'm curious about the resiliency of the systems to solar events. > > I did note that at the time of the 1989 solar event that took out a > lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs" > were in orbit. Well, maybe a couple of the later ones - the > operational constellation started launching about a month before that > flare. > > As I said initially, I'll be sad if WWV* goes away but it won't affect > my life in any measurable way that I can see. I mean, other than the > mantle clock slowly losing time. > > -- > Peter Laws | N5UWY | plaws plaws net | Travel by Train! > > ___ > 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] WWVB Chronverter update progress
The UnusualElectronics Chronverter with NEO 6 GPS, 9.6 MHz oscillator. dividers and such are all up and working. Watching GPS time, Spectracoms and Truetime clocks all tick at the same time while listening to WWV. exactly as they should. Now I have a alternate for wall clocks should WWVB be turned off. Though that said the next step is to test those out by setting up an antenna. Then time to mount everything in a case. If anyone else follows this path let me know offline happy to help you. Regards Paul WB8TSL On Wed, Aug 29, 2018 at 11:36 AM, paul swed wrote: > Its a LPF and its not effecting anything. Square waves worked fine > actually. But do want to be able to feed an antenna so a bit of filtering > plus the loops stick should do the job. > > On Wed, Aug 29, 2018 at 9:16 AM, Bob kb8tq wrote: > >> HI >> >> If you are feeding “Time Nuts” gear, a fancy filter on the output of the >> WWVB gizmo may be an issue. Temperature impacts the value of the >> components and that value change impacts the phase of the signal…. >> >> Bob >> >> > On Aug 28, 2018, at 9:33 PM, paul swed wrote: >> > >> > LPF filter added 2.2mH choke to a .0022uf cap 1K R pretty simple and >> > anttenuators and isolation to drive up to 4 receivers. >> > Have not looked at the power amp and loops stick antenna yet. But it >> really >> > is time for GPS a neo. >> > Looking very good. >> > >> > On Tue, Aug 28, 2018 at 7:29 PM, paul swed wrote: >> > >> >> Ed appreciate the details but no intent to generally run a GPSDO in >> fact >> >> the 5 V @ 50 ma is a serious power pig. The chronverter draws 5 ma. >> Clearly >> >> the TTL is a heater. Chuckle. I do want to drive the chronverter with >> GPS >> >> as its designed for. >> >> Whats pretty interesting is you can adjust its offset. I just jammed >> time >> >> into it several days and its been fairly good with power ups and down. >> Its >> >> impressive. Though not in an ultimate time-nuts way. >> >> GPS just assures it is accurate. But there is a lot of flexibility. >> >> Main goal of this whole project is to replace wwvb if it goes away. If >> it >> >> does the project doesn't even have to run 24/7. Fire up at 10 pm to 3 >> am >> >> and power down. Thats enough to set my wall clocks for a day. Its just >> nice >> >> to know it can also set the spectracoms and Truetimes. Icing on the >> cake. >> >> I am impressed with what Dave did with the 8 pin pic. He has all of >> the LF >> >> time signals in there. (No wwvb BPSK though) DSTs settings, zone >> offsets, >> >> half zones, etc. >> >> Just looking at low pass filters for the 60 KHz ttl out right now. >> Simple >> >> LR or RC. Since this particular output feeds coax to the quality >> receivers >> >> I don't need to be that careful. Its working great without any >> filtering. >> >> Reality if it draws little power I will let it run 24/7 but then you >> just >> >> have to stick a display on at that point. >> >> Regards >> >> Paul >> >> >> >> On Tue, Aug 28, 2018 at 7:11 PM, ed breya wrote: >> >> >> >>> Paul, >> >>> If you're going to reference it from a GPSDO anyway, why worry about a >> >>> TCXO reference (and power too, for that matter). You can easily make >> the 60 >> >>> kHz from the 10 MHz. >> >>> >> >>> For example, with two 74HC390s and a 74HC86 you can make 50 kHz and 10 >> >>> kHz and mix them with one EXOR section of the '86 to have 60 kHz >> available. >> >>> Some fairly simple bandpass filtering should select and clean it up >> >>> sufficiently. Two other sections of the '86 can be set up as >> inverters and >> >>> self-biased as amplifiers - one to convert the 10 MHz sine reference >> to >> >>> logic, and the other from the filter output to logic, if needed. And, >> you'd >> >>> still have a divide by 5 and an EXOR left over to fool around with. >> >>> >> >>> The same parts and process can be done at a higher frequency and then >> >>> divided down afterward. (5+1) MHz/100, and (500+100) kHz/10 would >> work too. >> >>> It depends on what frequency you prefer for the BPF. If you go high >> at 6 >> >>> MHz, you then have the option to make a crystal filter from readily >> >>> available parts. >> >>> >> >>> Going the high way also provides for higher logic frequencies that are >> >>> more or less in sync, in case you want to do any I-Q modulation type >> stuff >> >>> - you can even use synchronous counters instead, to really make sure. >> >>> >> >>> Overall, I think I'd recommend going at 5+1= 6 MHz, filtering with 6 >> MHz >> >>> crystals, then dividing down to 60 kHz, with 2f and 4f clocks >> available for >> >>> I-Q use. I sketched out a quickie circuit that's quite simple and I >> think >> >>> would do. It would take two HC390s for the dividing, as before. Each >> HC390 >> >>> is two divide by 10 counters, including a 1/2 and 1/5 in each, usable >> >>> separately. So, with two parts, there are four 1/5s and four 1/2s >> available. >> >>> >> >>> Here's a verbal process description: 10 MHz sine convert to logic with >> >>>
Re: [time-nuts] NIST
The port of Long Beach CA was jammed wrt GPS for several months by a malfunctioning 29.95 TV preamplifier on a boat. GPS was completely unusable when this unsuspecting guy was watching TV on his boat. He had quite the surprise when the coasties with guns showed up. The fact is civillian GPS Is trivial to jam and jammers can be bought ‘under the counter’ at any truckstop along with illlegal linear amplifiers. On Aug 30, 2018, at 12:58 PM, Peter Laws wrote: On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: > I have yet to hear anyone make a case for retaining the HF system that > isn't backed by nostalgia. Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS WILL DIE" posts (elsewhere, not here ... quite ...) are the type of hysteria that is usually reserved for, I don't know, the EMP folks. :-) > As for solar flares taking out the various GNSSs ... wouldn't a solar > flare only take out the vehicles that were on the "sunny" side of the > Earth? Wouldn't the (approximately) half of the SVs that are in the > Earth's shadow be unaffected? Serious technical question - I have no > idea. One of the responses to my initial message pointed out that the effects of solar flares and CMEs take a while to get from Sol to Sol III and don't arrive all at once, so potentially all GNSS spacecraft could be affected. Since then, I've been poking around for papers on the effect (observed, potential, theoretical) of these events on the Navstar or other GNSS constellations but am not having much luck. I assume it's because I'm not putting the right magic incantation into the google machine. Anyone got some cites? Looking for the effect of solar flares and CMEs on the spacecraft themselves and not how the GNSSs can be used to measure the effects on the ionosphere, etc (those seem plentiful). IOW, I'm curious about the resiliency of the systems to solar events. I did note that at the time of the 1989 solar event that took out a lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs" were in orbit. Well, maybe a couple of the later ones - the operational constellation started launching about a month before that flare. As I said initially, I'll be sad if WWV* goes away but it won't affect my life in any measurable way that I can see. I mean, other than the mantle clock slowly losing time. -- Peter Laws | N5UWY | plaws plaws net | Travel by Train! ___ 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] WWV and legal issues
Hi Same basic problem with WWVB. If you were using it as a reference, you timed your data collection to avoid the transition periods. You got both phase shifting and the amplitude took a dive. Neither one was going to help you make a precision measurement. In addition there are various weather events (terrestrial and solar) that can get into the mix. You can see blips here and there that do not correlate with the sunrise / sunset stuff. Again, not a big deal if you are manual evaluating the data to check your local Rb standard or super duper OCXO. Not a good thing for disciplining a system 24 hours a day 365 days a year. Bob > On Aug 30, 2018, at 1:54 PM, Attila Kinali wrote: > > On Thu, 30 Aug 2018 12:27:12 -0400 > Bob kb8tq wrote: > >> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully >> stable signal. As soon as >> that signal hits the real world things start to degrade. Propagation between >> transmit and receive sites >> is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade >> noise at 60 KHz. The receive >> signal to noise will never be as good as you might like it to be …. > > I don't know about WWVB, but for DCF77 it's known that sunrise/sunset > causes a phase shift of several 100µs at even moderate distances > (like ~500km). Unfortunately I don't have any measurements at hand. > > > Attila Kinali > > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neal Stephenson > > ___ > 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] NIST
Hi > On Aug 30, 2018, at 12:58 PM, Peter Laws wrote: > > On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: > > >> I have yet to hear anyone make a case for retaining the HF system that >> isn't backed by nostalgia. > > Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS > WILL DIE" posts (elsewhere, not here ... quite ...) are the type of > hysteria that is usually reserved for, I don't know, the EMP folks. > :-) > > >> As for solar flares taking out the various GNSSs ... wouldn't a solar >> flare only take out the vehicles that were on the "sunny" side of the >> Earth? Wouldn't the (approximately) half of the SVs that are in the >> Earth's shadow be unaffected? Serious technical question - I have no >> idea. > > One of the responses to my initial message pointed out that the > effects of solar flares and CMEs take a while to get from Sol to Sol > III and don't arrive all at once, so potentially all GNSS spacecraft > could be affected. > > Since then, I've been poking around for papers on the effect > (observed, potential, theoretical) of these events on the Navstar or > other GNSS constellations but am not having much luck. I assume it's > because I'm not putting the right magic incantation into the google > machine. > > Anyone got some cites? Looking for the effect of solar flares and > CMEs on the spacecraft themselves and not how the GNSSs can be used to > measure the effects on the ionosphere, etc (those seem plentiful). > IOW, I'm curious about the resiliency of the systems to solar events. > > I did note that at the time of the 1989 solar event that took out a > lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs" > were in orbit. Well, maybe a couple of the later ones - the > operational constellation started launching about a month before that > flare. > There most certainly was a lot of “stuff” in orbit by that time. If there was a mass die off of satellites, you would not have to look hard to find out about it. Bob > As I said initially, I'll be sad if WWV* goes away but it won't affect > my life in any measurable way that I can see. I mean, other than the > mantle clock slowly losing time. > > -- > Peter Laws | N5UWY | plaws plaws net | Travel by Train! > > ___ > 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] WWV and legal issues
Hi With the Loran boxes, you were doing well to get down to the 100 ns level. When you did, it always was a questionable sort of reading. More or less - is this real??? I spent a *lot* of time watching that data …. Estimating what WWVB is doing over long baselines as the weather changes is not at all easy. To keep things in sync you need solid data all the time. Guessing at your time source and then trying to discipline against it does not make for a rational disciplining system. Again … I spent a lot of years looking at those phase plots. Could you do pretty well for a few days with either one? Sure you could. For a system time source you are looking at 24 hours a day / 365 days a year sort of performance. We are going round and round talking about the sort of solar flares that haven’t happened in many decades (if ever …). The sort of stuff that disrupts WWVB or Loran (at the 10’s or 100’s of nanoseconds level) happens many times a year, even in a good year. Ramp up the sun spots and it can get really interesting. Is it better if I can toss rocks and hit the transmit antenna? Sure it is. Not everybody was / is within a hundred miles of a master for Loran-C or of Ft. Colins for WWVB. If you are going to use WWVB, it’s got to work in Miami, Florida and in Bangor, Maine. Working out carrier phase on WWVB as MSF comes in at equal strength in New England … yikes …. There are good sound reasons why the WWVB disciplined systems gear got dumped a long time ago and replaced with GPS. The GPS based gear performs better and is more reliable. Bob > On Aug 30, 2018, at 12:46 PM, Scott McGrath wrote: > > One does not get the same instantaneous accuracy that one gets from GPS but > with a long baseline the offsets to your site can be determined.With > eLoran you can get similar levels of accuracy as the old Austron monitors > used to prove > > Content by Scott > Typos by Siri > > On Aug 30, 2018, at 12:27 PM, Bob kb8tq wrote: > > Hi > > WWVB as transmitted ( = right at the input to the antenna) is a wonderfully > stable signal. As soon as > that signal hits the real world things start to degrade. Propagation between > transmit and receive sites > is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade > noise at 60 KHz. The receive > signal to noise will never be as good as you might like it to be …. > > 60 KHz has a period of 16.667 us. GPS gives you ~10 ns sort of time quite > quickly. Resolving the WWVB > carrier to that level is a major challenge. Identifying a single “cycle edge” > as the magic timing ID with either > the old or new modulation formats …. yet another significant challenge. Net > result is that you just can’t > get the same sort of timing out of WWVB. > > Bob > >> On Aug 30, 2018, at 11:15 AM, Mike Bafaro wrote: >> >> According to what I have heard the 60KHz WWVB carrier is guaranteed accurate >> to the atomic standard and is considered traceable. I remember when I was >> in the Navy years ago I remember taking our unit's HP5245L for calibration >> and they used a VLF tracking receiver at 60KHz to do the calibration. If >> WWVB goes off the air what is the replacement for the 60KHz standard? >> >> Mike >> >> -Original Message- >> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Perry >> Sandeen via time-nuts >> Sent: Wednesday, August 29, 2018 6:34 PM >> To: time-nuts@lists.febo.com >> Cc: Perry Sandeen >> Subject: [time-nuts] WWV and legal issues >> >> Yo Dudes!� >> WWV and all its variations distribute what in the USA is the legal standard >> of time (from USNO) and frequency (NIST). >> �If one is running a freq cal service IIRC it is a legal requirement to be >> able to have traceability to WWV. >> >> If one was to rely on other sources, one has no guarantee that it 1. It is >> as accurate as claimed and 2. It can't be *diddled* with accidentally or >> deliberately. >> Although GPSDO's are very good and popular, they come from satellites that >> are vulnerable to damage from earth based resources. >> When your time and frequency standard(s) is under control on your own >> physical territory then they stand or fail on their own.� >> After the atom bombing of Hiroshima and Nagasaki, one of the major inventors >> of the bomb (I don't remember who) went to see US president Harry Truman and >> essentially told him that the scientists who developed the bomb should have >> a say of how or when it should be used. >> Truman is reported to have said for him to leave his office and told an aid >> that was responsible for his schedule to "never in hell let that (or any >> other) scientist� come to his office to influence American defense policy." >> Considering its status from both a scientific and political perspective, >> IMNSHO it will go on as before. >> To explain the political. No government official wants to see China or the >> Russian federation tell the world quote: See,
Re: [time-nuts] NIST
On Mon, Aug 13, 2018 at 8:52 AM Peter Laws wrote: > I have yet to hear anyone make a case for retaining the HF system that > isn't backed by nostalgia. Still looking for this. Most of the "OMG IF WWV GOES AWAY MILLIONS WILL DIE" posts (elsewhere, not here ... quite ...) are the type of hysteria that is usually reserved for, I don't know, the EMP folks. :-) > As for solar flares taking out the various GNSSs ... wouldn't a solar > flare only take out the vehicles that were on the "sunny" side of the > Earth? Wouldn't the (approximately) half of the SVs that are in the > Earth's shadow be unaffected? Serious technical question - I have no > idea. One of the responses to my initial message pointed out that the effects of solar flares and CMEs take a while to get from Sol to Sol III and don't arrive all at once, so potentially all GNSS spacecraft could be affected. Since then, I've been poking around for papers on the effect (observed, potential, theoretical) of these events on the Navstar or other GNSS constellations but am not having much luck. I assume it's because I'm not putting the right magic incantation into the google machine. Anyone got some cites? Looking for the effect of solar flares and CMEs on the spacecraft themselves and not how the GNSSs can be used to measure the effects on the ionosphere, etc (those seem plentiful). IOW, I'm curious about the resiliency of the systems to solar events. I did note that at the time of the 1989 solar event that took out a lot of Hydro Quebec's grid, only the "Block I" experimental GPS "SVs" were in orbit. Well, maybe a couple of the later ones - the operational constellation started launching about a month before that flare. As I said initially, I'll be sad if WWV* goes away but it won't affect my life in any measurable way that I can see. I mean, other than the mantle clock slowly losing time. -- Peter Laws | N5UWY | plaws plaws net | Travel by Train! ___ 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] time-nuts Digest, Vol 169, Issue 40 SRD ideas
Hi, Gunn diodes idea sound like an interesting experiment. For the moment I won't be able to as I don't have the time, but I'll definitely keep this idea in mind. Thanks for sharing it! Dan PS. Always too busy, never enough time. Perhaps it's why messing with clocks..? -Chickens are more obsessed with time than Humans. Proof: Clock Clock clock From: time-nuts on behalf of Andre Sent: Thursday, August 30, 2018 3:27 AM To: time-nuts@lists.febo.com Subject: Re: [time-nuts] time-nuts Digest, Vol 169, Issue 40 SRD ideas Hi, if its of any help I (still) have a box of goodies including some 10 and 22 GHz Gunnplexers. would the diodes be of any use? The RX (IIRC its a varactor) diode is structurally very similar to an SRD, maybe possible to adapt it if as I expect the resonance is tuned to near 6 GHz by "cooking" it under controlled conditions. If its a close harmonic the diode might pull fine. I think the parameters would need tuning but I have four (!) of them and some other bits which you are welcome to test. Joe Gwinn > Regards > Paul > WB8TSL > > On Mon, Aug 27, 2018 at 8:03 PM, ed breya wrote: > >> I forgot to mention: >> >> If you've been diagnosing by swapping parts, be aware that changing the A3 >> is the same as changing the SRD - they won't necessarily match anymore, so >> would need adjustment. >> >> Maybe your original SRD was just fine, but the whole set needed >> adjustment. Who knows what may have been tweaked or mis-tweaked by >> individuals working on it previously. If the original SRD is intact, just >> check to see if it's still a diode (should look the same as a regular Si >> diode, with maybe a little higher forward voltage drop). If so, it's >> probably OK and can be returned to service. >> ___ 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] Cal standards, WWVB, etc. was Re: WWV and legal issues
On 8/30/18 8:15 AM, Mike Bafaro wrote: According to what I have heard the 60KHz WWVB carrier is guaranteed accurate to the atomic standard and is considered traceable. I remember when I was in the Navy years ago I remember taking our unit's HP5245L for calibration and they used a VLF tracking receiver at 60KHz to do the calibration. If WWVB goes off the air what is the replacement for the 60KHz standard? Mike The 5245L is a 1960,70s vintage thing so I assume you were doing those cals 40 years ago when inexpensive atomic standards like the SRS FS725 didn't exist. These days, I suspect that a $3000 Rb box or a GPSDO would have sufficient accuracy for this sort of thing as a transfer standard, and would be traceable. I can't imagine that a "over the air" signal recovered from WWVB would be better than either of those two. ___ 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] WWV and legal issues
One does not get the same instantaneous accuracy that one gets from GPS but with a long baseline the offsets to your site can be determined.With eLoran you can get similar levels of accuracy as the old Austron monitors used to prove Content by Scott Typos by Siri On Aug 30, 2018, at 12:27 PM, Bob kb8tq wrote: Hi WWVB as transmitted ( = right at the input to the antenna) is a wonderfully stable signal. As soon as that signal hits the real world things start to degrade. Propagation between transmit and receive sites is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade noise at 60 KHz. The receive signal to noise will never be as good as you might like it to be …. 60 KHz has a period of 16.667 us. GPS gives you ~10 ns sort of time quite quickly. Resolving the WWVB carrier to that level is a major challenge. Identifying a single “cycle edge” as the magic timing ID with either the old or new modulation formats …. yet another significant challenge. Net result is that you just can’t get the same sort of timing out of WWVB. Bob > On Aug 30, 2018, at 11:15 AM, Mike Bafaro wrote: > > According to what I have heard the 60KHz WWVB carrier is guaranteed accurate > to the atomic standard and is considered traceable. I remember when I was in > the Navy years ago I remember taking our unit's HP5245L for calibration and > they used a VLF tracking receiver at 60KHz to do the calibration. If WWVB > goes off the air what is the replacement for the 60KHz standard? > > Mike > > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Perry > Sandeen via time-nuts > Sent: Wednesday, August 29, 2018 6:34 PM > To: time-nuts@lists.febo.com > Cc: Perry Sandeen > Subject: [time-nuts] WWV and legal issues > > Yo Dudes!� > WWV and all its variations distribute what in the USA is the legal standard > of time (from USNO) and frequency (NIST). > �If one is running a freq cal service IIRC it is a legal requirement to be > able to have traceability to WWV. > > If one was to rely on other sources, one has no guarantee that it 1. It is as > accurate as claimed and 2. It can't be *diddled* with accidentally or > deliberately. > Although GPSDO's are very good and popular, they come from satellites that > are vulnerable to damage from earth based resources. > When your time and frequency standard(s) is under control on your own > physical territory then they stand or fail on their own.� > After the atom bombing of Hiroshima and Nagasaki, one of the major inventors > of the bomb (I don't remember who) went to see US president Harry Truman and > essentially told him that the scientists who developed the bomb should have a > say of how or when it should be used. > Truman is reported to have said for him to leave his office and told an aid > that was responsible for his schedule to "never in hell let that (or any > other) scientist� come to his office to influence American defense policy." > Considering its status from both a scientific and political perspective, > IMNSHO it will go on as before. > To explain the political. No government official wants to see China or the > Russian federation tell the world quote: See, the USA can't be trusted for > something as important and simple as frequency and time.� However we are your > friends who you can trust. Unquote. > Regards, > > > > > > This is a case of practical use of WWV albeit over 50 years a go the > fundamentals are still valid today. > At Karamursel Air station TUSLOG 234 I was assigned to the base receiver > site.� Our base had to purposes.� to� � > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWV and legal issues
Hi WWVB as transmitted ( = right at the input to the antenna) is a wonderfully stable signal. As soon as that signal hits the real world things start to degrade. Propagation between transmit and receive sites is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade noise at 60 KHz. The receive signal to noise will never be as good as you might like it to be …. 60 KHz has a period of 16.667 us. GPS gives you ~10 ns sort of time quite quickly. Resolving the WWVB carrier to that level is a major challenge. Identifying a single “cycle edge” as the magic timing ID with either the old or new modulation formats …. yet another significant challenge. Net result is that you just can’t get the same sort of timing out of WWVB. Bob > On Aug 30, 2018, at 11:15 AM, Mike Bafaro wrote: > > According to what I have heard the 60KHz WWVB carrier is guaranteed accurate > to the atomic standard and is considered traceable. I remember when I was in > the Navy years ago I remember taking our unit's HP5245L for calibration and > they used a VLF tracking receiver at 60KHz to do the calibration. If WWVB > goes off the air what is the replacement for the 60KHz standard? > > Mike > > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Perry > Sandeen via time-nuts > Sent: Wednesday, August 29, 2018 6:34 PM > To: time-nuts@lists.febo.com > Cc: Perry Sandeen > Subject: [time-nuts] WWV and legal issues > > Yo Dudes!� > WWV and all its variations distribute what in the USA is the legal standard > of time (from USNO) and frequency (NIST). > �If one is running a freq cal service IIRC it is a legal requirement to be > able to have traceability to WWV. > > If one was to rely on other sources, one has no guarantee that it 1. It is as > accurate as claimed and 2. It can't be *diddled* with accidentally or > deliberately. > Although GPSDO's are very good and popular, they come from satellites that > are vulnerable to damage from earth based resources. > When your time and frequency standard(s) is under control on your own > physical territory then they stand or fail on their own.� > After the atom bombing of Hiroshima and Nagasaki, one of the major inventors > of the bomb (I don't remember who) went to see US president Harry Truman and > essentially told him that the scientists who developed the bomb should have a > say of how or when it should be used. > Truman is reported to have said for him to leave his office and told an aid > that was responsible for his schedule to "never in hell let that (or any > other) scientist� come to his office to influence American defense policy." > Considering its status from both a scientific and political perspective, > IMNSHO it will go on as before. > To explain the political. No government official wants to see China or the > Russian federation tell the world quote: See, the USA can't be trusted for > something as important and simple as frequency and time.� However we are your > friends who you can trust. Unquote. > Regards, > > > > > > This is a case of practical use of WWV albeit over 50 years a go the > fundamentals are still valid today. > At Karamursel Air station TUSLOG 234 I was assigned to the base receiver > site.� Our base had to purposes.� to� � > > > > > ___ > 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] time-nuts Digest, Vol 169, Issue 40 SRD ideas
Hi, if its of any help I (still) have a box of goodies including some 10 and 22 GHz Gunnplexers. would the diodes be of any use? The RX (IIRC its a varactor) diode is structurally very similar to an SRD, maybe possible to adapt it if as I expect the resonance is tuned to near 6 GHz by "cooking" it under controlled conditions. If its a close harmonic the diode might pull fine. I think the parameters would need tuning but I have four (!) of them and some other bits which you are welcome to test. Joe Gwinn > Regards > Paul > WB8TSL > > On Mon, Aug 27, 2018 at 8:03 PM, ed breya wrote: > >> I forgot to mention: >> >> If you've been diagnosing by swapping parts, be aware that changing the A3 >> is the same as changing the SRD - they won't necessarily match anymore, so >> would need adjustment. >> >> Maybe your original SRD was just fine, but the whole set needed >> adjustment. Who knows what may have been tweaked or mis-tweaked by >> individuals working on it previously. If the original SRD is intact, just >> check to see if it's still a diode (should look the same as a regular Si >> diode, with maybe a little higher forward voltage drop). If so, it's >> probably OK and can be returned to service. >> ___ 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] WWV and legal issues
Management signed a PO for the previously "unneeded" Symmetricom units that had been requested a year earlier the next day... Jim From: time-nuts on behalf of Scott McGrath Sent: Thursday, August 30, 2018 11:24:03 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWV and legal issues Bingo - we have a a Winner!!! In a prior life as an architect at a northeastern we had Cs clocks, multiple GPS based NTP servers and CDMA NTP servers as TIME was the public key for all the crypto systems the Cs clocks were there in case GPS ‘went away’ for any reason and with service reliability as the primary goal instead of ‘maximizing shareholder value’ we made sure that precision timing could survive anything short of total destruction of the campus and our backup sites. On Aug 30, 2018, at 11:04 AM, James C Cotton wrote: Time is the public key for a lot of the crypto that runs on networks. Any large university or corporation has multiple GPS based time sources and compares them to others... Back in the mid-1980's a fire in a CO in East Lansing, MI and a backhoe in Jackson, MI took out the Internet connections at the university I work at. A couple of routers using time as the public key and exchanging encrypted routing packets were isolated. Jim Cotton From: time-nuts on behalf of Scott McGrath Sent: Thursday, August 30, 2018 10:42:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWV and legal issues Um no Will the internet continue to route packets without precision timing yes it will, Yes the lambdas will stay lit on fiber but the ATM transport that runs on the lambdas will fail (note DSL is simply an ATM VC over copper). and other timing dependent services will fail Will many services like authentication continue especially those based on multimaster replication continue to function? No they will not, they are totally dependent on precision timing to ensure proper replication sourcing. (Microsoft Active Directory) Banking transactions in the same boat. Unless you’ve actually run a large network you dont realize just how dependent on precision timing the services running over the network have become especially authentication And one reason for this is increased security for the overall network. On Aug 30, 2018, at 8:45 AM, Brian Lloyd wrote: On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath wrote: > > > > Without precision timing there is no telephone network, cell phones or > internet. And that only became true in the last 20 years or so as long > haul networks went from FDM on coaxial cable to TDM on fibre. > The Internet is largely asynchronous due to the store-and-forward nature of the routers. Fiber capacity is increased through the use of wavelength division multiplexing (WDM) which is itself a form of FDM. The Internet functions without any sort of central synchronization. Yes, there are portions that run over the synchronized telco services but that is by convenience, not necessity. -- Brian Lloyd 706 Flightline Spring Branch, TX 78070 br...@lloyd.aero +1.210.802-8FLY (1.210.802-8359) ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ 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] WWV and legal issues
Bingo - we have a a Winner!!! In a prior life as an architect at a northeastern we had Cs clocks, multiple GPS based NTP servers and CDMA NTP servers as TIME was the public key for all the crypto systems the Cs clocks were there in case GPS ‘went away’ for any reason and with service reliability as the primary goal instead of ‘maximizing shareholder value’ we made sure that precision timing could survive anything short of total destruction of the campus and our backup sites. On Aug 30, 2018, at 11:04 AM, James C Cotton wrote: Time is the public key for a lot of the crypto that runs on networks. Any large university or corporation has multiple GPS based time sources and compares them to others... Back in the mid-1980's a fire in a CO in East Lansing, MI and a backhoe in Jackson, MI took out the Internet connections at the university I work at. A couple of routers using time as the public key and exchanging encrypted routing packets were isolated. Jim Cotton From: time-nuts on behalf of Scott McGrath Sent: Thursday, August 30, 2018 10:42:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWV and legal issues Um no Will the internet continue to route packets without precision timing yes it will, Yes the lambdas will stay lit on fiber but the ATM transport that runs on the lambdas will fail (note DSL is simply an ATM VC over copper). and other timing dependent services will fail Will many services like authentication continue especially those based on multimaster replication continue to function? No they will not, they are totally dependent on precision timing to ensure proper replication sourcing. (Microsoft Active Directory) Banking transactions in the same boat. Unless you’ve actually run a large network you dont realize just how dependent on precision timing the services running over the network have become especially authentication And one reason for this is increased security for the overall network. On Aug 30, 2018, at 8:45 AM, Brian Lloyd wrote: On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath wrote: > > > > Without precision timing there is no telephone network, cell phones or > internet. And that only became true in the last 20 years or so as long > haul networks went from FDM on coaxial cable to TDM on fibre. > The Internet is largely asynchronous due to the store-and-forward nature of the routers. Fiber capacity is increased through the use of wavelength division multiplexing (WDM) which is itself a form of FDM. The Internet functions without any sort of central synchronization. Yes, there are portions that run over the synchronized telco services but that is by convenience, not necessity. -- Brian Lloyd 706 Flightline Spring Branch, TX 78070 br...@lloyd.aero +1.210.802-8FLY (1.210.802-8359) ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWV and legal issues
Hi This is not so much a GPS issue as a system design issue. GPSDO’s are used to “smooth over” bumps in a lot of systems out there. At the timing levels required by ATM or authentication setups, you can go a *long* time running on a GPSDO. It’s not a matter of GPS, it’s a matter of doing things on the cheap …. Bob > On Aug 30, 2018, at 10:42 AM, Scott McGrath wrote: > > Um no > > Will the internet continue to route packets without precision timing yes it > will, Yes the lambdas will stay lit on fiber but the ATM transport that runs > on the lambdas will fail (note DSL is simply an ATM VC over copper). and > other timing dependent services will fail > > Will many services like authentication continue especially those based on > multimaster replication continue to function? > > No they will not, they are totally dependent on precision timing to ensure > proper replication sourcing. (Microsoft Active Directory) > > Banking transactions in the same boat. > > Unless you’ve actually run a large network you dont realize just how > dependent on precision timing the services running over the network have > become especially authentication And one reason for this is increased > security for the overall network. > > On Aug 30, 2018, at 8:45 AM, Brian Lloyd wrote: > > On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath wrote: > >> >> >> >> Without precision timing there is no telephone network, cell phones or >> internet. And that only became true in the last 20 years or so as long >> haul networks went from FDM on coaxial cable to TDM on fibre. >> > > The Internet is largely asynchronous due to the store-and-forward nature of > the routers. Fiber capacity is increased through the use of wavelength > division multiplexing (WDM) which is itself a form of FDM. The Internet > functions without any sort of central synchronization. > > Yes, there are portions that run over the synchronized telco services but > that is by convenience, not necessity. > > -- > > > > Brian Lloyd > 706 Flightline > Spring Branch, TX 78070 > br...@lloyd.aero > +1.210.802-8FLY (1.210.802-8359) > ___ > 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] WWV and legal issues
Time is the public key for a lot of the crypto that runs on networks. Any large university or corporation has multiple GPS based time sources and compares them to others... Back in the mid-1980's a fire in a CO in East Lansing, MI and a backhoe in Jackson, MI took out the Internet connections at the university I work at. A couple of routers using time as the public key and exchanging encrypted routing packets were isolated. Jim Cotton From: time-nuts on behalf of Scott McGrath Sent: Thursday, August 30, 2018 10:42:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWV and legal issues Um no Will the internet continue to route packets without precision timing yes it will, Yes the lambdas will stay lit on fiber but the ATM transport that runs on the lambdas will fail (note DSL is simply an ATM VC over copper). and other timing dependent services will fail Will many services like authentication continue especially those based on multimaster replication continue to function? No they will not, they are totally dependent on precision timing to ensure proper replication sourcing. (Microsoft Active Directory) Banking transactions in the same boat. Unless you’ve actually run a large network you dont realize just how dependent on precision timing the services running over the network have become especially authentication And one reason for this is increased security for the overall network. On Aug 30, 2018, at 8:45 AM, Brian Lloyd wrote: On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath wrote: > > > > Without precision timing there is no telephone network, cell phones or > internet. And that only became true in the last 20 years or so as long > haul networks went from FDM on coaxial cable to TDM on fibre. > The Internet is largely asynchronous due to the store-and-forward nature of the routers. Fiber capacity is increased through the use of wavelength division multiplexing (WDM) which is itself a form of FDM. The Internet functions without any sort of central synchronization. Yes, there are portions that run over the synchronized telco services but that is by convenience, not necessity. -- Brian Lloyd 706 Flightline Spring Branch, TX 78070 br...@lloyd.aero +1.210.802-8FLY (1.210.802-8359) ___ 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] 5065 SRD's - Some notes about A3 Multiplier Ass:y
Gentlemen, Some days after I fired up my 5065 after initial repair of the RV Cavity,it became unstable and lost lock. No output signal from the A3 Multiplier Assembly. Q9 (final) was dead and was replaced with a 2N5109to which I added a thermal pad between the case and the PCB. Q5 had also failedand was replaced with 2N4416. (can to GND-plane) Q7 was replaced with BC557. (Long shot - RF PNP are hard to find today...)and it worked. Q3 identified as 3N128 in my schamatic drawing commentsbut I don't remember if I ever replaced that one too. And while the module was opened, I also replaced C37 I noticed some stability problems while trouble-shootingand the cause of this was loose screwsbetween the "Front panel" and the circuit board/screen walls. All the Best Ulf KylenfallSM6GXV ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWV and legal issues
On Thu, Aug 30, 2018 at 9:42 AM, Scott McGrath wrote: > Um no > > Will the internet continue to route packets without precision timing yes > it will, Yes the lambdas will stay lit on fiber but the ATM transport that > runs on the lambdas will fail (note DSL is simply an ATM VC over copper). > and other timing dependent services will fail > You may find less ATM on the fast links than you think. > > Will many services like authentication continue especially those based on > multimaster replication continue to function? > > No they will not, they are totally dependent on precision timing to > ensure proper replication sourcing. (Microsoft Active Directory) Precision timing better than NTP? Are you sure? I guess there are some using Microsoft stuff but the fabric of the Internet sure doesn't depend on it. > > Banking transactions in the same boat. > Same question. > > Unless you’ve actually run a large network you dont realize just how > dependent on precision timing the services running over the network have > become especially authentication And one reason for this is increased > security for the overall network. > Yeah, I have some experience with running a large net. I have a little experience with how the Internet runs. ;-) -- Brian Lloyd 706 Flightline Spring Branch, TX 78070 br...@lloyd.aero +1.210.802-8FLY (1.210.802-8359) ___ 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] WWV and legal issues
Um no Will the internet continue to route packets without precision timing yes it will, Yes the lambdas will stay lit on fiber but the ATM transport that runs on the lambdas will fail (note DSL is simply an ATM VC over copper). and other timing dependent services will fail Will many services like authentication continue especially those based on multimaster replication continue to function? No they will not, they are totally dependent on precision timing to ensure proper replication sourcing. (Microsoft Active Directory) Banking transactions in the same boat. Unless you’ve actually run a large network you dont realize just how dependent on precision timing the services running over the network have become especially authentication And one reason for this is increased security for the overall network. On Aug 30, 2018, at 8:45 AM, Brian Lloyd wrote: On Thu, Aug 30, 2018 at 7:01 AM, Scott McGrath wrote: > > > > Without precision timing there is no telephone network, cell phones or > internet. And that only became true in the last 20 years or so as long > haul networks went from FDM on coaxial cable to TDM on fibre. > The Internet is largely asynchronous due to the store-and-forward nature of the routers. Fiber capacity is increased through the use of wavelength division multiplexing (WDM) which is itself a form of FDM. The Internet functions without any sort of central synchronization. Yes, there are portions that run over the synchronized telco services but that is by convenience, not necessity. -- Brian Lloyd 706 Flightline Spring Branch, TX 78070 br...@lloyd.aero +1.210.802-8FLY (1.210.802-8359) ___ 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] OOPS on my wwv legal post
Since propagation issues quickly degrade both frequency stability and time accuracy, I see little point in worrying about the difference between UTC and UTC(NIST). Of greater interest should be the meaningfulness of time transfer obtained with NIST's TMAS service. It is apparently referred to UTC(NIST). See: https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas It's an interesting service; it has been in use at the Arecibo Observatory since soon after its inception (~5 years ago IIRC) to provide information relevant to decisions for tweaking the observatory's H-maser's frequency. TMAS revolves around "Common View GPS measurements". A major down side (for most time-nuts, anyway) is the cost of the service, which is presently in the neighborhood of $10k per year. I have made inquiry regarding whether or not TMAS is also on the chopping block; nothing heard back so far. Dana Dana On Thu, Aug 30, 2018 at 2:05 AM John Marvin wrote: > I was under the mistaken impression that WWV/WWVB had some type of > direct line to NIST in Boulder. However, when I toured the facility in > Fort Collins earlier this year, I learned otherwise. The signals and > carriers are derived/synced from "ordinary" HP (possibly some more > recent Symmetricom's) cesium beam atomic clocks. I wish I remembered > the details, but I asked how they synced them with NIST. I believe the > answer was that at one time they had some type of connection to Boulder, > but now just use a GPS based solution. > > The WWV and WWVB stations in Fort Collins are old, and run on a fairly > tight budget, with a very small (but dedicated) staff. They are not on > the cutting edge of timekeeping technology. I'm not trying to imply > that WWV/WWVB is "inaccurate", but there is nothing special there. Many > of the participants on this list, if they were determined, could put out > a signal every bit as accurate as WWV or WWVB, they just wouldn't be > able to do it at the power levels (especially WWVB) that WWV and WWVB > signals are transmitted at. The antenna's and transmitter's are some of > the most impressive parts of the WWV / WWVB facilities. > > Regards, > > John > > P.S. I was also impressed with their backup generator, although I now > can't remember if that only provided power for the WWVB station, or for > both WWVB and WWV (they are separate facilities, although in easy > walking distance of each other on the same property). > > > On 8/29/2018 7:24 PM, Steve Allen wrote: > > On Wed 2018-08-29T19:49:59-0400 Bob kb8tq hath writ: > >> A few more details about “traceability”. USNO is by statute the > official source of time for the US. > > I suggest reading Matsakis, Levine, and Lombardi from this year's PTTI > meeting. > > USNO and NIST are both legal sources for the US. > > The USNO site currently has a broken SSL cert, but the paper is also here > > > https://www.researchgate.net/publication/323600621_Metrological_and_legal_traceability_of_time_signals > > > > -- > > Steve Allen WGS-84 > (GPS) > > UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat > +36.99855 > > 1156 High Street Voice: +1 831 459 3046 Lng > -122.06015 > > Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > ___ > 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] WWVB Signal Generator
For anyone trying out my ATTiny85 code, I've done some additional tests and find that placement of the antenna near the clock is very finicky and, so far, the only way to get a reliable decode of the time in the clock is by using a scope to monitor the demodulated output and then moving the antenna around until the demodulated signal lines up cleanly with modulated carrier and there are no intra bit glitches. This can take a bit of patience, so clearly a better solution needs to be found. I've found that any type of glitch in the demodulated signal seems to prevent the clock chip from decoding the time. It's possible the difficultly with locking onto my simulated WWVB signal may be partially due to the design of the clock (from my location it's never been able to to lock onto the real WWVB signal), but I have no reference to compare it against so, for now, I have conclude that the PWM-based modulation scheme my code uses may also be suboptimal for this application. To make testing even more frustrating, the BALDR clock I'm using will only look for a signal for about 6 minutes before it goes to sleep and I have to then power cycle the clock to get it to listen again. So, keep this in mind if you're going to try and replicate my results. Wayne On Wed, Aug 29, 2018 at 6:03 PM Wayne Holder wrote: > For those that have asked for my to publish the source code for my > ATTiny85-based WWVB simulator, I have put up a somewhat hurriedly written > page on my google site at: > > https://sites.google.com/site/wayneholder/controlling-time > > that describes a bit about how the code works, how to compile it using the > Arduino IDE, how I tested it, some issues I have observed in testing it > and, at the bottom of the page, a downloadable zip file that contains the > complete source code. > > Note: as mentioned at the top of this page, this is currently a work in > process, so I'm not yet going to link the article to my main website page, > so you'll need to link in this post to find it. Also, as draft, I'm going > to continue to revise the page until I feel the project is complete enough > to publish. That means the source code zip file is going to potentially > change from time to time, too. > > Wayne > > On Wed, Aug 29, 2018 at 1:35 AM Wayne Holder > wrote: > >> As a follow up, I now have a simple WWVB simulator written in C that's >> now running an an ATTiny85 using nothing more than the internal, 8 >> mHz oscillator and about a 6 inch length of wire connected to one of the >> pins as an antenna. It generates an approximate 60 kHz signal using PWM on >> timer 1. I tweaked the timer value a bit to correct for some variance in >> the internal oscillator, but I' not even sure that was necessary, as my >> target is just a BALDR Model B0114ST, consumer grade "Atomic" clock. >> Modulation is done by varying the duty cycle of the PWM to approximate the >> -17 dBr drop on the carrier. But, again, I don't think this value is >> critical with a consumer clock chip. I tapped the demodulated output >> inside the clock and displayed it on my scope along with the generated >> signal and I got good, steady demodulation with the wire antenna just >> placed near clock. The next step is to connect up a GPS module and add >> code to use it to set the time. I'm also going to change the code to use >> the PPS signal from the GPS to drive the output timing rather than the test >> code I have now that uses timer 0 to generate the PPS interrupt. I'm happy >> to share details if anyone is interested. >> >> Wayne >> >> >> >> On Sun, Aug 26, 2018 at 2:51 PM, paul swed wrote: >> >>> That would be a great neighbor to have but I can tell you around here its >>> the phone. Not to concerned about someone putting up a wwvb replacement. >>> And I can always up the power. Chickle. >>> Regards >>> Paul >>> >>> On Sun, Aug 26, 2018 at 2:34 PM, Bob kb8tq wrote: >>> >>> > Hi >>> > >>> > The gotcha is if you have neighbors two or three doors away that *also* >>> > put up one of >>> > these devices. You then have a real problem with the neighbor(s) in the >>> > middle. The >>> > wavelength is long enough that Raleigh issues won’t get you. You still >>> > have the two >>> > signals ( at slightly different frequencies) beating against each >>> other. >>> > The result is >>> > going to show up as who knows what to this or that receiver. With a >>> > precision receiver, >>> > you might even have issues from the guy two houses away …... >>> > >>> > Bob >>> > >>> > > On Aug 26, 2018, at 1:08 PM, paul swed wrote: >>> > > >>> > > Agree with the conversation. With respect to neighbors when the day >>> comes >>> > > they may ask you to boost your signal. :-) >>> > > Granted maybe the day won't come but at least having your local >>> clocks >>> > work >>> > > is nice. >>> > > Regards >>> > > Paul >>> > > WB8TSL >>> > > >>> > > On Sat, Aug 25, 2018 at 10:29 PM, Dana Whitlow < >>> k8yumdoo...@gmail.com> >>> > > wrote: >>> > > >>> > >> With the
Re: [time-nuts] OOPS on my wwv legal post
I was under the mistaken impression that WWV/WWVB had some type of direct line to NIST in Boulder. However, when I toured the facility in Fort Collins earlier this year, I learned otherwise. The signals and carriers are derived/synced from "ordinary" HP (possibly some more recent Symmetricom's) cesium beam atomic clocks. I wish I remembered the details, but I asked how they synced them with NIST. I believe the answer was that at one time they had some type of connection to Boulder, but now just use a GPS based solution. The WWV and WWVB stations in Fort Collins are old, and run on a fairly tight budget, with a very small (but dedicated) staff. They are not on the cutting edge of timekeeping technology. I'm not trying to imply that WWV/WWVB is "inaccurate", but there is nothing special there. Many of the participants on this list, if they were determined, could put out a signal every bit as accurate as WWV or WWVB, they just wouldn't be able to do it at the power levels (especially WWVB) that WWV and WWVB signals are transmitted at. The antenna's and transmitter's are some of the most impressive parts of the WWV / WWVB facilities. Regards, John P.S. I was also impressed with their backup generator, although I now can't remember if that only provided power for the WWVB station, or for both WWVB and WWV (they are separate facilities, although in easy walking distance of each other on the same property). On 8/29/2018 7:24 PM, Steve Allen wrote: On Wed 2018-08-29T19:49:59-0400 Bob kb8tq hath writ: A few more details about “traceability”. USNO is by statute the official source of time for the US. I suggest reading Matsakis, Levine, and Lombardi from this year's PTTI meeting. USNO and NIST are both legal sources for the US. The USNO site currently has a broken SSL cert, but the paper is also here https://www.researchgate.net/publication/323600621_Metrological_and_legal_traceability_of_time_signals -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ 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.
