Re: [time-nuts] WWVB format change in 2012
As Tom mentioned I am familiar with the chips. But the bottom line is there are no chips either old style or new around anymore from what I have seen. If you can find the consumer atomic clocks that are pretty rare these days you can get the AM clock receiver from those. The new chips (Literally the die, not even an soic) was supposed to show up in clocks around the new year. They never did or at least its totally not apparent. The intent was not for consumer but embedded in things like stop lights. But this thread shifted from the original request I believe for something that could be used in Singapore. Regards Paul WB8TSL On Tue, Mar 1, 2016 at 7:39 AM, Bob Camp wrote: > Hi > > > On Mar 1, 2016, at 2:44 AM, Sanjeev Gupta wrote: > > > > On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta wrote: > > > >> Are there commercially (or widely-used) receivers for professional use > >> which listen to the WWVB signal? > > > > > > Folks, I am trying to trace down xtendwave. They seem to have released a > > Everset IC, and then renamed themselves to Everset in 2013 or 2014. > > > > Is there *any* commercial gear available for WWVB at all, today? Price > is > > not an issue, just a public product page will do. > > GPS has become so cheap and it’s so accurate under normal conditions that > you rarely see anything else considered for this stuff. That’s not to say > that a > monoculture is a good idea (it isn’t). > > Bob > > > > > > > > -- > > Sanjeev Gupta > > +65 98551208 http://www.linkedin.com/in/ghane > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Hi > On Mar 1, 2016, at 2:44 AM, Sanjeev Gupta wrote: > > On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta wrote: > >> Are there commercially (or widely-used) receivers for professional use >> which listen to the WWVB signal? > > > Folks, I am trying to trace down xtendwave. They seem to have released a > Everset IC, and then renamed themselves to Everset in 2013 or 2014. > > Is there *any* commercial gear available for WWVB at all, today? Price is > not an issue, just a public product page will do. GPS has become so cheap and it’s so accurate under normal conditions that you rarely see anything else considered for this stuff. That’s not to say that a monoculture is a good idea (it isn’t). Bob > > > -- > Sanjeev Gupta > +65 98551208 http://www.linkedin.com/in/ghane > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
gha...@gmail.com said: > Is there *any* commercial gear available for WWVB at all, today? Price is > not an issue, just a public product page will do. I don't know of any gear that is currently available in the US. A few years ago, you used to be able to get a small board and ferrite antenna. I think it was under $20. I just poked around and they are no longer available. https://www.sparkfun.com/products/retired/10060 They have a link to the data sheet if you are curious. It's an old chip that only decodes the AM part of the signal so it doesn't get the advantages of the new modulation. This might be a lead if you are in the UK: http://www.tuxcat.com/benjy/ham/WWVB/ If you are desperate, consider buying a battery powered clock and taking it apart to find the antenna and WWVB chip. The chip will probably be under a blob of epoxy. You will have to hack the board. ... -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Sanjeev Gupta wrote: > Folks, I am trying to trace down xtendwave. They seem to have released a > Everset IC, and then renamed themselves to Everset in 2013 or 2014. Contact Paul Swed or me off-list about this. > Is there *any* commercial gear available for WWVB at all, today? Price is > not an issue, just a public product page will do. Time by radio -- WWVB (and DCF-77, MSF, JJY) -- is still in use. But most of the high-end commercial timing companies have long since switched to GPS. Now that most everyone on the planet has a mobile phone or WiFi or internet, the need for 1-bit-per-second time over LF or SW radio is not as great as it was 20 years ago. But you asked for product pages. Try these: https://www.meinbergglobal.com/english/products/usb-wwvb-clock.htm https://www.lacrossetechnology.com/clocks/atomic-digital/wall/ https://www.lacrossetechnology.com/clocks/atomic-analog/ http://www.casio.com/products/Watches/wave_ceptor/ http://www.jp-watch.com/product/44 http://www.ebay.com/itm/181283274562 /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Tue, Mar 01, 2016 at 03:44:01PM +0800, Sanjeev Gupta wrote: > Folks, I am trying to trace down xtendwave. They seem to have released a > Everset IC, and then renamed themselves to Everset in 2013 or 2014. It's not an IC, exactly, it's a bare product intended for integration into something else. > Is there *any* commercial gear available for WWVB at all, today? Price is > not an issue, just a public product page will do. There's plenty of older gear out there that did not phase lock, and works just fine. Existing chipsets and receivers work fine for those. Even phase locking receivers can be modified. They changed the simple carrier to a phase keyed one, but they did not change the amplitude coding. I know Meinberg had WWVB modules available for some of their products, you might see what they are up to. --msa ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta wrote: > Are there commercially (or widely-used) receivers for professional use > which listen to the WWVB signal? Folks, I am trying to trace down xtendwave. They seem to have released a Everset IC, and then renamed themselves to Everset in 2013 or 2014. Is there *any* commercial gear available for WWVB at all, today? Price is not an issue, just a public product page will do. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On 2/29/16 5:31 AM, Tim Shoppa wrote: I have observed always less than 1 millisecond offset and skew with the ntpd wwv audio refclock over more than the past decade. Setting up the audio refclocks involves calculating and configuring propagation delay and delays in the receiver and audio chain. As Sanjeev has mentioned, setting up audio drivers for lowlatency by platform specific ioctl's is necessary and that may imply code portability issue. While propagation delay over a several thousand mile path is circa 10ms, the ionospheric changes are way less than a percent of that. I don't think it was you Hal, but someone else here was implying uncertainties in propagation delay on the hundreds of milliseconds, and that is off by 3 orders of magnitude. (Yes I have heard and observed long path, as well as ionospheric changes in short path) the entire transit time around the earth is 150 milliseconds, so you're right "hundreds of milliseconds" must be a typo: "hundreds of microseconds" sounds believable. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Mon, Feb 29, 2016 at 6:35 AM, Hal Murray wrote: > The audio stuff seems particularly ugly. > > Are there any good non-GPS options these days? In this context, "good" is > a > bit hard to pin down. My straw man is either something in production or > something like a TBolt or Z38xx that is available surplus at hobbyist > prices. > On Mon, Feb 29, 2016 at 6:39 AM, Hal Murray wrote: tic-...@bodosom.net said: >> If you can get audio they work. The documented accuracy for WWV is within 1 >> millisecond of the time pulse. >Where is that documented and/or can anybody verify that they get results in >that range? First off this is a bit time-nuts relevant because RF timing propagation is germane but the basic pulse extraction is low accuracy and hence not so much time-nut relevant. That also informs the forest for the trees issue here: the original intent (as in Dr. Mills PDP-11 assembler coded demodulator) is a periodic (i.e. daily) clock update. So despite the predicted 1ms accuracy a .1s system error was probably considered acceptable. The WWV refclock shares this operational sense with the ACTS driver. You phone home maybe once a day and, in the case of the ACTS driver, NTPD won't use it unless you're orphaned. Regarding non-GPS. Do you consider a CDMA receiver non-GPS? How about a disciplined oscillator in hold-over? In consideration of the recent GPS glitch is GLONASS non-GPS or are you speaking more broadly (ie. GPS as a synonym for GNSS). And lastly despite the politics it would seem the folks on the ntp-questions and ntp-hackers are a better resource. Unless they're all here. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On 2/29/16 3:39 AM, Hal Murray wrote: tic-...@bodosom.net said: If you can get audio they work. The documented accuracy for WWV is within 1 millisecond of the time pulse. Where is that documented and/or can anybody verify that they get results in that range? What is the (ballpark) of the day/night shift? http://www.cliftonlaboratories.com/wwv_short_term_jitter.htm has a number of off the air measurements, and a reference to a 1959 HP journal article about the timing uncertainty http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1959-11.pdf ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On 2/29/16 3:39 AM, Hal Murray wrote: tic-...@bodosom.net said: If you can get audio they work. The documented accuracy for WWV is within 1 millisecond of the time pulse. Where is that documented and/or can anybody verify that they get results in that range? What is the (ballpark) of the day/night shift? https://www.febo.com/pages/hf_stability/ shows the "about 1 Hz" variation one sees in various places. That's the apparent variation in frequency which is really the phase shift changing during sunrise/sunset. Looking at the 10 MHz data, it looks like there's a 0.1 Hz change lasting about 2 hours. I think that's a change of 720 cycles, or 72 microseconds at 10 MHz. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
I have observed always less than 1 millisecond offset and skew with the ntpd wwv audio refclock over more than the past decade. Setting up the audio refclocks involves calculating and configuring propagation delay and delays in the receiver and audio chain. As Sanjeev has mentioned, setting up audio drivers for lowlatency by platform specific ioctl's is necessary and that may imply code portability issue. While propagation delay over a several thousand mile path is circa 10ms, the ionospheric changes are way less than a percent of that. I don't think it was you Hal, but someone else here was implying uncertainties in propagation delay on the hundreds of milliseconds, and that is off by 3 orders of magnitude. (Yes I have heard and observed long path, as well as ionospheric changes in short path) Tim N3QE On Monday, February 29, 2016, Hal Murray wrote: > > tic-...@bodosom.net said: > > If you can get audio they work. The documented accuracy for WWV is > within 1 > > millisecond of the time pulse. > > Where is that documented and/or can anybody verify that they get results in > that range? > > What is the (ballpark) of the day/night shift? > > > -- > These are my opinions. I hate spam. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Bob Camp wrote: > Hi > > WWVB and WWV (like any radio uncorrected radio system) has fairly predictable > shifts > associated with the day / night ionosphere. One *could* fix that issue with a > table > based on station location. I do not know of any library of code that does > that already. > > The next “layer” of trouble comes from how the low cost receivers are > implemented. The > common issue is local noise. The common solution is a narrowband crystal > filter in front > of the receiver. The bandwidth of that filter (and to some extent it’s > temperature dependance) place > a “best case” limit on performance in the 10’s to 100’s of ms range depending > on the > exact details. There are higher performance receivers (but not a lot of them) > that do get into > the single digit ms range. At that point the propagation issue mentioned > above needs some > work. > > Further complicating things is the distance factor. A user in Denver with > ground wave “view” > of the transmitter will do *much* better than the numbers above. A user in > Miami or Bangor ME > may be very lucky to get close to the numbers above on an intermittent basis. I'm basically familiar with the ground wave / sky wave problem. Quite some time ago I had found a PDF on the 'net with some explanations, measurements, and a U.S. map showing e.g. which regions were mostly affected by temporary cancellation due to interference of the sky and groundwave with the same amplitude. If I remember correctly this was an old publication from NIST or so. Eventually it's hard to find by search machines since it wasn't a generated PDF with text, but just a scan of an old printed article. Unfortunately I hadn't saved a copy, and now I'm unable to find it. Anybody has a hint what this could have been? Thanks, Martin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
m...@latt.net said: > What are you trying to do? Kill the refclocks entirely, or just pare > them > down to essentials? The idea is to drop the ones that aren't being used and/or we can't test. If we dropped one in error, we can recover it. The audio stuff seems particularly ugly. I don't know if that's just because I/we don't understand that area and/or if POSIX didn't get it right and/or if OSes don't implement POSIX audio. Are there any good non-GPS options these days? In this context, "good" is a bit hard to pin down. My straw man is either something in production or something like a TBolt or Z38xx that is available surplus at hobbyist prices. A reasonable candidate for a low cost WWV receiver would be one of the USB receiver modules. I think they are targeted at TV but they cover a wide input frequency range. I think the SDR projects are using them. If anybody has experience with them in a non-Windows environment please poke me off list. A friend gave me one, but I got distracted before I got it working. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
tic-...@bodosom.net said: > If you can get audio they work. The documented accuracy for WWV is within 1 > millisecond of the time pulse. Where is that documented and/or can anybody verify that they get results in that range? What is the (ballpark) of the day/night shift? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 3:09 PM, Sanjeev Gupta wrote: > I am reviewing and expanding and for the NTPSec project < > http://www.ntpsec.org >, a fork of NTP. > Apologies, this should have been: I am reviewing and expanding and documentation for the NTPSec project < http://www.ntpsec.org >, a fork of NTP. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Hi WWVB and WWV (like any radio uncorrected radio system) has fairly predictable shifts associated with the day / night ionosphere. One *could* fix that issue with a table based on station location. I do not know of any library of code that does that already. The next “layer” of trouble comes from how the low cost receivers are implemented. The common issue is local noise. The common solution is a narrowband crystal filter in front of the receiver. The bandwidth of that filter (and to some extent it’s temperature dependance) place a “best case” limit on performance in the 10’s to 100’s of ms range depending on the exact details. There are higher performance receivers (but not a lot of them) that do get into the single digit ms range. At that point the propagation issue mentioned above needs some work. Further complicating things is the distance factor. A user in Denver with ground wave “view” of the transmitter will do *much* better than the numbers above. A user in Miami or Bangor ME may be very lucky to get close to the numbers above on an intermittent basis. For time transfer, you have “carrier phase ambiguity” due to the day night propagation shifts. Simply put the time delay to the transmitter caused the received signal to vary by more than one cycle. That makes it a less than ideal source of time. For precision use, a WWVB system often does a carrier measure at a single time per day. The phase data is averaged over may days to make a precision estimate. This works ok for a frequency based (think GPSDO) type system). For autonomous timing it’s not a practical solution. Bob > On Feb 28, 2016, at 11:15 AM, Sanjeev Gupta wrote: > > On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp wrote: > >> The new WWVB format is troublesome for older gear that looks at carrier >> phase as a source of precision timing. The NTP driver does not do this. >> >> The new WWVB format is fine for any gear that recovers time from the >> AM modulation on the carrier. This is what the NTP driver *does* do. >> > > This is a very clear phrasing, thanks. > > My understanding is that existing commercially-available equipment that > recovers time from the AM carrier provides an accuracy on the order of a > milli-second. Anything better required tracking phase. > > So, what would the (NTP with current WWVB equipment) accuracy and jitter be? > > I appreciate that we seem to be moving towards a GPS-monoculture, but how > close is the (NTP with WWVB AM) to the 50 microseconds number? > > -- > Sanjeev Gupta > +65 98551208 http://www.linkedin.com/in/ghane > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta wrote: > > Among NTPSec's goals are a smaller, auditable, code-base; hence support for > receivers last available in the early-1990s is being removed. > I'm a bit confused by your question and the responses. There are (I believe) three audio drivers supporting WWV, CHU and IRIG. These drivers are receiver agnostic. If you can get audio they work. The documented accuracy for WWV is within 1 millisecond of the time pulse. There are multiple drivers supporting WWV/CHU/DCF. These are for specific families of RF receivers which produce a digital stream of some sort (e.g. ISA bus communication). Presumably the latter are what you're looking at as obsolete (e.g. Truetime, Traconix, Chronolog, Ultralink etc. [and my apologies if any of these are not obsolete]). Perhaps you could clarify your intent. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On 2/28/16 7:07 AM, Sanjeev Gupta wrote: On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa wrote: Support for WWV in ntpd using the wwv_audio refclock is very good and delivers jitters substantially less than a millisecond. I have been using this for over a decade. Thank you. In particular, WWV, as compared to WWVB. What you're looking at (unless you're very close to WWV or WWVH) is the uncertainty in the skywave path through the ionosphere. Is there an on-web reference that I can document, so that the NTPSec developers can decide on if and how to support WWV. A reference to what WWV radiates as a signal? http://www.nist.gov/pml/div688/grp40/wwv.cfm http://tf.nist.gov/general/pdf/1383.pdf ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Sanjeev Gupta writes: > that as a result of the change, precision equipment may not be able to > recover a usable signal from the new modulation scheme, rendering it > useless for the sub-100 microsec disciplining. In fact, the new scheme may actually help with accurate ON-TIME determination. Currently, I have a proof-of-concept research system running that routinely keeps time to well within the rather broad 100 uS range when compared to GPS. This system does not yet use the phase information, but uses other techniques to extract the ON-TIME information from the signal (which still has to be corrected for propagation delays.) Future work will include using the phase information and I am confident this will only improve the results. > A supplementary question: If you have your own homebrew for these signals, > do you use them as a refclock for NTP? While the proof-of-concept system is not being used for a refclock for NTP, it is able to keep time as described above and FREQUENCY to the under 1 E-10 range. I am still working to improve that and hope to verify it in a way directly traceable to NIST. James Flynn California State University Northridge ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 03:09:32PM +0800, Sanjeev Gupta wrote: > I am reviewing and expanding and for the NTPSec project < > http://www.ntpsec.org >, a fork of NTP. > > Among NTPSec's goals are a smaller, auditable, code-base; hence support for > receivers last available in the early-1990s is being removed. I'm not sure I would make that assumption. Given recent attacks on NTP (that will ultimately require a new protocol to fix), the ability of more upstream references is better than fewer. Stripping things out that would provide more sources of trusted time appears to be at odds with making NTP "more secure." > I have been on this list for some years (thank you), but as I am in > Singapore, I did not pay attention to the WWVB format change. I understand > that as a result of the change, precision equipment may not be able to > recover a usable signal from the new modulation scheme, rendering it > useless for the sub-100 microsec disciplining. So the common, cheaper receivers that just looked at the AM envelope are unaffected. Higher grade, phase tracking receivers were affected, but can be modified to restore the carrier, and thus are still operable. > However, I am not clear if WWV and WWVH are still usable by commercially > available equipment, or of such equipment is also obsolete now. WWV and WWVH have worked pretty much the same way they do now for decades; I have running WWV and WWVH refclocks, even the TrueTime TL_3 (in REFCLOCK_TRUE.) Where this gets sticky is there is support for older receivers (say, OMEGA and the like), in the same refclocks (continuing to use TRUE as an example here.) So, you could safely remove the bits pertaining to OMEGA, but I'd retain the WWV, WWVB, TCU, and XL-DC support.) Since the XL-DC is a GPS, I suppose you could implement support for it in gpsd. Other, older refclocks are in a similar state, where one vendor used more or less the same serial protocol regardless of what the actual reference was. What are you trying to do? Kill the refclocks entirely, or just pare them down to essentials? Cheers, --msa ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 10:57 PM, Bob Camp wrote: > The new WWVB format is troublesome for older gear that looks at carrier > phase as a source of precision timing. The NTP driver does not do this. > > The new WWVB format is fine for any gear that recovers time from the > AM modulation on the carrier. This is what the NTP driver *does* do. > This is a very clear phrasing, thanks. My understanding is that existing commercially-available equipment that recovers time from the AM carrier provides an accuracy on the order of a milli-second. Anything better required tracking phase. So, what would the (NTP with current WWVB equipment) accuracy and jitter be? I appreciate that we seem to be moving towards a GPS-monoculture, but how close is the (NTP with WWVB AM) to the 50 microseconds number? -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
On Sun, Feb 28, 2016 at 9:45 PM, Tim Shoppa wrote: > Support for WWV in ntpd using the wwv_audio refclock is very good and > delivers jitters substantially less than a millisecond. I have been using > this for over a decade. > Thank you. In particular, WWV, as compared to WWVB. Is there an on-web reference that I can document, so that the NTPSec developers can decide on if and how to support WWV. -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Hi Ok, I think we have a bit of a terminology issue here. The new WWVB format is troublesome for older gear that looks at carrier phase as a source of precision timing. The NTP driver does not do this. The new WWVB format is fine for any gear that recovers time from the AM modulation on the carrier. This is what the NTP driver *does* do. Simply put - WWVB and NTP work just as well today as they did 20 years ago. As a “future project”, adding a driver to NTP to work with the bitstream from the new phase modulation would be a nice thing. At the moment the number of receivers capable of handling this modulation is pretty small. I would wait until there is at least one commercial product on the market before a driver is written. Bob > On Feb 28, 2016, at 2:09 AM, Sanjeev Gupta wrote: > > Hi, > > I am reviewing and expanding and for the NTPSec project < > http://www.ntpsec.org >, a fork of NTP. > > Among NTPSec's goals are a smaller, auditable, code-base; hence support for > receivers last available in the early-1990s is being removed. > > I have been on this list for some years (thank you), but as I am in > Singapore, I did not pay attention to the WWVB format change. I understand > that as a result of the change, precision equipment may not be able to > recover a usable signal from the new modulation scheme, rendering it > useless for the sub-100 microsec disciplining. > > However, I am not clear if WWV and WWVH are still usable by commercially > available equipment, or of such equipment is also obsolete now. > > I have read Wikipedia, the NIST pages, etc, and am still confused. Could > someone summarise current state: > > > 1. Are there commercially (or widely-used) receivers for professional > use which listen to the WWVB signal? > 2. Are there commercially (or widely-used) receivers for professional > use which listen to the WWV(H) signal? > > A supplementary question: If you have your own homebrew for these signals, > do you use them as a refclock for NTP? > > Thank you > > > -- > Sanjeev Gupta > +65 98551208 http://www.linkedin.com/in/ghane > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format change in 2012
Having a diversity of refclocks is important for any real NTP implementation. There is a strong tendency towards a GPS monoculture and the implementers must work against it. Support for WWV in ntpd using the wwv_audio refclock is very good and delivers jitters substantially less than a millisecond. I have been using this for over a decade. ntpd also supports CHU. Here is a recent article showing how to use the BPSK format of WWVB: http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/Magliacane.pdf Tim N3QE On Sun, Feb 28, 2016 at 2:09 AM, Sanjeev Gupta wrote: > Hi, > > I am reviewing and expanding and for the NTPSec project < > http://www.ntpsec.org >, a fork of NTP. > > Among NTPSec's goals are a smaller, auditable, code-base; hence support for > receivers last available in the early-1990s is being removed. > > I have been on this list for some years (thank you), but as I am in > Singapore, I did not pay attention to the WWVB format change. I understand > that as a result of the change, precision equipment may not be able to > recover a usable signal from the new modulation scheme, rendering it > useless for the sub-100 microsec disciplining. > > However, I am not clear if WWV and WWVH are still usable by commercially > available equipment, or of such equipment is also obsolete now. > > I have read Wikipedia, the NIST pages, etc, and am still confused. Could > someone summarise current state: > > >1. Are there commercially (or widely-used) receivers for professional >use which listen to the WWVB signal? >2. Are there commercially (or widely-used) receivers for professional >use which listen to the WWV(H) signal? > > A supplementary question: If you have your own homebrew for these signals, > do you use them as a refclock for NTP? > > Thank you > > > -- > Sanjeev Gupta > +65 98551208 http://www.linkedin.com/in/ghane > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB format change in 2012
Hi, I am reviewing and expanding and for the NTPSec project < http://www.ntpsec.org >, a fork of NTP. Among NTPSec's goals are a smaller, auditable, code-base; hence support for receivers last available in the early-1990s is being removed. I have been on this list for some years (thank you), but as I am in Singapore, I did not pay attention to the WWVB format change. I understand that as a result of the change, precision equipment may not be able to recover a usable signal from the new modulation scheme, rendering it useless for the sub-100 microsec disciplining. However, I am not clear if WWV and WWVH are still usable by commercially available equipment, or of such equipment is also obsolete now. I have read Wikipedia, the NIST pages, etc, and am still confused. Could someone summarise current state: 1. Are there commercially (or widely-used) receivers for professional use which listen to the WWVB signal? 2. Are there commercially (or widely-used) receivers for professional use which listen to the WWV(H) signal? A supplementary question: If you have your own homebrew for these signals, do you use them as a refclock for NTP? Thank you -- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format
Hi Paul, the phase modulation would interfere with the AM, since during the phase change the narrow band crystal filter's output will sink down as the filter is following the phase change, and the time needed for the filter to "swing in " to the new phase it depend on the angle of the phase change angle, for 180 degree it is 2 x [1/f] x Q , [1/f] x Q needed to "swing on" and the same time to swing down from the old phase. [[Rohde&Schwarz's old Q meter is based on that, it counts the zero crossings until the level of the signal sinks to ]] and that causes an additional AM modulation, if the quartz filter of the clock is not so good, the [1/f] x Q time is shorter and the filter after the demodulator does not let it pass the amplitude change, thus the cheaper clock works better, until one switching mode power supply takes over the control from the WWVB 73 Alex On 11/21/2014 7:17 AM, paul swed wrote: Glenn I want to say that my simple wwvb clocks are working. However my most finicky one is not locked as I just noted. But then its always a problemed child. The format contains bpsk but that was not supposed to interfere with the traditional AM modulation these clocks detect. I might strongley believe that the various electronic lights that are becoming pervasive is seriously deteriorating the ability to detect the signal. I am near Boston so thats fringe. Regards Paul WB8TSL On Fri, Nov 21, 2014 at 12:06 AM, Glenn Little wrote: Are there any "atomic" clocks that do not properly decode the current WWVB format. I have two that will not auto update the time and will troubleshoot if this is not a format issue. Thanks for any help. 73 Glenn WB4UIV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB format
Glenn I want to say that my simple wwvb clocks are working. However my most finicky one is not locked as I just noted. But then its always a problemed child. The format contains bpsk but that was not supposed to interfere with the traditional AM modulation these clocks detect. I might strongley believe that the various electronic lights that are becoming pervasive is seriously deteriorating the ability to detect the signal. I am near Boston so thats fringe. Regards Paul WB8TSL On Fri, Nov 21, 2014 at 12:06 AM, Glenn Little wrote: > Are there any "atomic" clocks that do not properly decode the current WWVB > format. > I have two that will not auto update the time and will troubleshoot if > this is not a format issue. > > Thanks for any help. > 73 > Glenn > WB4UIV > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB format
Are there any "atomic" clocks that do not properly decode the current WWVB format. I have two that will not auto update the time and will troubleshoot if this is not a format issue. Thanks for any help. 73 Glenn WB4UIV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB Format Ownership
On Thu, Sep 27, 2012 at 7:15 PM, Peter Gottlieb wrote: > Not quite sure about the analog to health care, but certainly a > transmission being public domain doesn't mean much if the only possible way > to use it is proprietary. Sounds like something Microsoft would strive for. > I think Apple and the iPhone would be a better example... they are already there. Yes, Microsoft are trying to jump on that bandwagon with the used-to-be-named-Metro interface on Windows 8, but IMO, are shooting themselves in the foot*. Back to the patents. The more ideas we get here, the less defensible the patents will be if they use an idea suggested here (not only this present thread; there were previous threads back in March) - after all, we have many engineers experienced in the field on the list... Orin. *too OT to go into here. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB Format Ownership
Not quite sure about the analog to health care, but certainly a transmission being public domain doesn't mean much if the only possible way to use it is proprietary. Sounds like something Microsoft would strive for. On 9/27/2012 9:57 PM, WB6BNQ wrote: The transmitted format on WWVB (and for that matter on the WWV HF stations) is owned by the government and thus the "PEOPLE." As stated to me, John Lowe (WWVB Broadcast Manager) claims he is the person who has designed and is implementing this new broadcast format. Because he is a paid employee of the government (i.e., us PEOPLE) his new protocol is thus, presumably, unencumbered and free to use by anyone. What I find interesting is how a functional system is completely shit canned in favor of a new and yet proven process; particularly seeing as how no means of utilizing said new (and still being tweaked) modulation existed at the beginning of the design process. Obviously, the process was driven by external forces for the total benefit of those external forces. In other words, the benefit was not for "we the people" per se even though that is the stated reason. Conceptually, what Xtendwave seems to be doing is designing a "detection & demodulation" process that they feel is unique and thus eligible for a patent. If that is the whole truth and nothing but the truth, then more power to them. However, if they are attempting to construct their patent verbiage to exclude others from creating or using any other means and thus having sole use of the WWVB format, then one should question the propriety of the whole process including the WWVB staff. If the previous paragraph is the aim, then it is a parallel to a certain medical program where non participation is met with a hefty penalty. Here the hefty penalty would be having to buy the Xtendwave receiving apparatus in order to use said modulation process. Xtendwave would be hard pressed to go after all the "John Doe" hobbyists from both a monetary and political point of view. In the commercial market that would be a different case. Someone on the list posed the question of a "Public" comment period. YES, that would have been nice. BUT, such an action would have been disastrous for the project, if it really made a difference, because those who would bother to respond would likely be negative to the concept. That certainly wouldn't do, so instead it is done in quasi secret and sprung on the unsuspecting as a done deal. Clearly, DO IT and ask for forgiveness afterwards. So much for government transparency ! BillWB6BNQ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2441/5295 - Release Date: 09/27/12 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB Format Ownership
The transmitted format on WWVB (and for that matter on the WWV HF stations) is owned by the government and thus the "PEOPLE." As stated to me, John Lowe (WWVB Broadcast Manager) claims he is the person who has designed and is implementing this new broadcast format. Because he is a paid employee of the government (i.e., us PEOPLE) his new protocol is thus, presumably, unencumbered and free to use by anyone. What I find interesting is how a functional system is completely shit canned in favor of a new and yet proven process; particularly seeing as how no means of utilizing said new (and still being tweaked) modulation existed at the beginning of the design process. Obviously, the process was driven by external forces for the total benefit of those external forces. In other words, the benefit was not for "we the people" per se even though that is the stated reason. Conceptually, what Xtendwave seems to be doing is designing a "detection & demodulation" process that they feel is unique and thus eligible for a patent. If that is the whole truth and nothing but the truth, then more power to them. However, if they are attempting to construct their patent verbiage to exclude others from creating or using any other means and thus having sole use of the WWVB format, then one should question the propriety of the whole process including the WWVB staff. If the previous paragraph is the aim, then it is a parallel to a certain medical program where non participation is met with a hefty penalty. Here the hefty penalty would be having to buy the Xtendwave receiving apparatus in order to use said modulation process. Xtendwave would be hard pressed to go after all the "John Doe" hobbyists from both a monetary and political point of view. In the commercial market that would be a different case. Someone on the list posed the question of a "Public" comment period. YES, that would have been nice. BUT, such an action would have been disastrous for the project, if it really made a difference, because those who would bother to respond would likely be negative to the concept. That certainly wouldn't do, so instead it is done in quasi secret and sprung on the unsuspecting as a done deal. Clearly, DO IT and ask for forgiveness afterwards. So much for government transparency ! BillWB6BNQ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
