[time-nuts] Dalibor Farny : A New Project : IRIG-B synchronization
Dalibor Farny (Czech) came to clocks and timing five years ago, via Nixie Tubes. He is now a 21st century manufacturer of Nixie Tubes (over 8,000). https://www.daliborfarny.com/ The Bombe Clock Project, by Paul Perry, used Dalibor’s Nixie tubes and original drawings from the Alan Turing Trust (UK). https://www.bad-dog-designs.co.uk/contemporary-clocks/bombe/ == He has now started a project for time source synchronization that uses an IRIG-B signal source for 1 PPS extraction. YouTube video shows the project (with Nixie production interruptions) https://youtu.be/bOJmnx2Q_VQ It appears that his IRIG-B and 1 PPS testing source is a product from Brandywine Communications (Tustin, CA) https://www.brandywinecomm.com/ greg w9gb Sent from iPad Air ___ 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] Lucent KS-24361, aka HP/Symmetricom Z3812A
It has been five years (2014) since the Lucent GPSDO units, used in the cellular industry, appeared on the surplus market. The REF-0 units are still on the surplus market. Lucent KS-24361, aka HP/Symmetricom Z3812A. https://www.prc68.com/I/KS-24361.html Stewart Cobb & Bob Camp characterized the KS-24361 operation (October 2014) https://time-nuts.febo.narkive.com/Rp1KmwVT/lucent-ks-24361-hp-symmetricom-z3809a-z3810a-z3811a-z3812a-gpsdo-system Dan Watson explored modifications (August 2015) for the REF-0 boxes to operate as a stand-alone GPSDO. Including an updated GPS receiver to emulate the Oncore UT+ timing receiver. https://syncchannel.blogspot.com/2015/08/standalone-operation-of-lucent-ks-24361.html Thomas Petig (Germany) built upon Dan’s work and explored the SCPI commands available on this KS-24361. http://www.petig.eu/ref0/ On the EEVBlog list, September 2015, Peter Garde (time-nut Australia) wrote the document: Standalone GPSDO Operation of the Lucent KS-24361 REF-0 https://www.eevblog.com/forum/testgear/economical-option-for-precision-frequency-reference/?action=dlattach;attach=172662 == Has anyone taken “The Next Step”, replacing the Motorola Oncore 8-channel receiver (VP or UT+) with the Synergy Systems’ SSR-M8 Multi-GNSS Precision Timing Receiver? http://synergy-gps.com/synergy-products/ssr-m8-multi-gnss-precision-timing-receiver/ This receiver features u-Blox LEA-M8 series miniature GNSS timing module (72-channel, SBAS enabled); a Motorola binary message emulation; and User Configurable PPS Output Rate. greg w9gb Sent from iPad Air ___ 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] Beginner's Atomic Clock
Hi You probably are not going to find the Nano’s on the used market. The last one I worked with was very much a pre-production unit and that was only a few years back. Indeed if you are simply looking for a lab clock, the miniature Rb’s may not be the best choice. Their stability is generally not as good as that of their bigger cousins. That applies to temperature as well as short term stability. Since you pay a premium for the smaller parts, the “bang for the buck” really isn’t there in a home bench application. If indeed you are trying to build something to go in a drone or put into space, they make a lot of sense. If you are carrying it on your back along with all the batteries to power it, again a very reasonable thing to go with. Lots of fun !!! > On Sep 17, 2019, at 7:18 AM, pisymbol . wrote: > > On Mon, Sep 16, 2019 at 11:00 PM Dana Whitlow wrote: > >> All of the available Rb standards that I've seen have a 10 MHz output, >> Some have a >> 1 PPS output as well. >> original buyer could save a few bucks. My PRS-10 is one of these. >> >> > How does this compare with say a used Accubeat AR133/60 substance? I also > see they have a Nano unit that looks awesome (but I have no idea what the > price is and if they are ever sold used?). > > -aps > ___ > 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] Beginner's Atomic Clock
On 9/17/2019 12:33 AM, Dr. David Kirkby wrote: Is there any advantage in using a GPS Rb disciplined oscillator vs a GPS disciplined high quality OCXO like the HP 10811A? I can’t understand why there should be, as a Rb source would use an OCCO in its output stage Therefore in each case * Short term stability depends upon the quality of the OCXO * Long term stability depends upon GPS. Perhaps there’s is period over which the the overall stability can be improved by adding a rubidium oscillator. I would be interested to know if that is the case or not. Dave What I was always told was that Rb has low enough noise coming off the atoms such that it can use a relatively fast loop to lock the OCXO and clean it up. OTOH, the 5071 Cs has to use a very long time constant loop to control the 10811, hence it doesn't clean it up except very close to the carrier. Even the high performance version of the 5071 doesn't compare with Rb. Rick N6RK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Beginner's Atomic Clock
Dr. Kirby, et al, Remember that a GPS-disciplined Rb has two loops, hence two time constants, to consider: a) the loop which locks the Rb's internal OCXO to the atomic transition, and b) the GPS disciplining loop. I surmise that the internal loop (a) is fast enough to thoroughly suppress drifts of the unit's internal OCXO in the face of local temperature variations etc. But the other loop (b) can be, and should be, pretty slow (time constant of hours or more), so as to prevent the disciplined source being jerked around by GPS "noise". This is why the Rb can advantageous over the OCXO- the Rb is inherently stable enough to permit using a very slow loop for disciplining by GPS. In my own experience to date, the one GPSDO I have with user-adjustable loop bandwidth suffers greatly from ambient temperature variations when I make the disciplining loop TC large enough to effectively remove GPS noise. I can easily see HVAC cycling, for example, when I use a long time constant. I've played with numbers ranging from 5 sec up to 500 sec, and think the best compromise is around 40 sec. This with an old Trimble T'Bolt which was apparently built around 2004 or thereabouts. My other GPSDO is a CNS Clock II, purchased new about a year ago. It does *not* have provisions for user adjustment of the disciplining loop, which is fixed at some rather short time constant (I'm estimating roughly 5 sec). So its OCXO is kept pretty honest in the face of ambient temperature variations; however GPS noise jerks it around very considerably. in the short term. I'm finding this device's greatest utility in looking at phase drift in my Rb sources over a period of several hours at a time, mainly for purposes of frequency setting. My two Rb's are an old (telecom-modded) PRS-10 and an old L-PRO, neither of which has GPS disciplining capability. I continue to agonize over whether or not I should buy new (standard-featured) PRS-10- I've been trying to make this decision for about 2.5 years so far :-) I do not have access to the revered HP 10811A, so can't speak to its value for my interests. I'd dearly love to borrow one, as it would undoubtedly provide a good learning experience for me. Dana On Tue, Sep 17, 2019 at 3:11 AM Dr. David Kirkby < drkir...@kirkbymicrowave.co.uk> wrote: > On Tue, 17 Sep 2019 at 04:00, Dana Whitlow wrote: > > > The nice thing about a Rb is that its short term stability (seconds to > > minutes and perhaps > > even longer) is much better than that of a GPS timing receiver. The bad > > news is that Rb > > standards exhibit long term frequency drift in the neighborhood of a few > > parts in 10^11 > > per month. A pretty fair compromise is to use an Rb standard that is > > disciplined by GPS > > PPS pulses with a loop time constant on the order of a day or so. > > > > Dana (K8YUM) > > > Is there any advantage in using a GPS Rb disciplined oscillator vs a GPS > disciplined high quality OCXO like the HP 10811A? I can’t understand why > there should be, as a Rb source would use an OCCO in its output stage > Therefore in each case > > * Short term stability depends upon the quality of the OCXO > * Long term stability depends upon GPS. > > Perhaps there’s is period over which the the overall stability can be > improved by adding a rubidium oscillator. I would be interested to know if > that is the case or not. > > Dave > > > -- > Dr. David Kirkby, > Kirkby Microwave Ltd, > drkir...@kirkbymicrowave.co.uk > https://www.kirkbymicrowave.co.uk/ > Telephone 01621-680100./ +44 1621 680100 > > Registered in England & Wales. > Company number 08914892. > Registered office: > Stokes Hall Lodge, > Burnham Rd, > Althorne, > Chelmsford, > Essex, > CM3 6DT, > United Kingdom > ___ > 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] Capturing NMEA and TICC timestamp data in time-correlated way?
> I can capture the NMEA data and the TICC data - this is not a problem. > But I'd really like to be able to capture both datasets in some sort of > time-correlated way, so I can easily post-process the TICC data using the > quantization error data. I can probably throw something together in Python > or C to do this, but before I went through the effort, I figured I would ask > if there is a standard tool I haven't been able to find yet which is in > common use. How accurately do you want to stamp the NMEA data? If the time on your PC is good enough, then software will work. If you can feed a PPS to both the TICC and your PC, then you can get accurate timings on a second signal to the TICC. With a good PPS, ntpd should hold the time on a PC better than a ms. You don't actually need good time on the PC, or a good PPS. All you need is a signal that is ballpark of once a second that you can feed to both the PC and TICC. You can use the PPS capture on the PC to tell you when it arrives without using it to control the time. If you want more accurate timings on the NMEA data, I think you will need to build something to indicate the start of the NMEA data clump and feed that signal to the TICC. The idea is to turn a long burst of transitions into a single pulse so you don't swamp the TICC. [It might just work. I'm assuming the TICC will be overloaded by the NMEA bit stream, but it will probably get the first bit and lots of others. You can throw away the others. Has anybody tried something like this?] You could do it in hardware with a retrigerable one-shot. This assumes that the characters come out back-to-back, no extra time between them due to software being busy doing something else. Set the one-shot for a bit longer than a character time and trigger it from the serial data stream. That will give you an output pulse a bit longer than the NMEA burst. You can feed that to the TICC. If your geek hat is on, you will have to subtract off the delay through the one-shot. (I'm thinking of one-shots because I was working with a FatPPS recently. 74LS123 Thanks John.) If you prefer software, you can do it with your favorite tiny PIC or AVR size chip. That will probably add several cycles of jitter. I'd have to look at the data sheets carefully to work out the details. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Beginner's Atomic Clock
On 9/17/19 3:33 AM, Dr. David Kirkby wrote: > On Tue, 17 Sep 2019 at 04:00, Dana Whitlow wrote: > >> The nice thing about a Rb is that its short term stability (seconds to >> minutes and perhaps >> even longer) is much better than that of a GPS timing receiver. The bad >> news is that Rb >> standards exhibit long term frequency drift in the neighborhood of a few >> parts in 10^11 >> per month. A pretty fair compromise is to use an Rb standard that is >> disciplined by GPS >> PPS pulses with a loop time constant on the order of a day or so. >> >> Dana (K8YUM) > > > Is there any advantage in using a GPS Rb disciplined oscillator vs a GPS > disciplined high quality OCXO like the HP 10811A? I can’t understand why > there should be, as a Rb source would use an OCCO in its output stage > Therefore in each case > > * Short term stability depends upon the quality of the OCXO > * Long term stability depends upon GPS. > > Perhaps there’s is period over which the the overall stability can be > improved by adding a rubidium oscillator. I would be interested to know if > that is the case or not. There are a bunch of interesting tradeoffs in choosing a frequency reference. Any Rb (except the HP 5065A which is in a different class as a lab instrument vs. the small telecom units) will be worse at short tau than a good OCXO, and is also likely to have much worse phase noise. A typical telecom Rb will be around 1e-11 at 1 second while a good OCXO can be one or even two orders of magnitude better. At medium tau (say a few thousand seconds) the Rb will likely be in the mid to upper 13s, which is better than any but a very good OCXO. At long tau, the Rb should show at least an order of magnitude less drift than even a very good OCXO. A Cesium at short tau will typically be worse than either an OCXO or an Rb. The Cs only wins (a) at long tau since there is zero drift; and (b) for absolute accuracy. But at anything shorter than around 10K seconds, it's not the best choice. A good GPSDO is really the overall performance winner -- short term stability and phase noise limited only by the quality of the OCXO, and very good long term stability and accuracy due to the GPS lock. It's only in the mid range of a few hundred to to a couple of thousand seconds, where the OCXO drift kicks in before the GPS discipline takes over, that a GPSDO will underperform a telecom Rb. In short, the GPSDO takes much of the fun out of time-nuttery. :-\ John ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Beginner's Atomic Clock
On Mon, Sep 16, 2019 at 11:00 PM Dana Whitlow wrote: > All of the available Rb standards that I've seen have a 10 MHz output, > Some have a > 1 PPS output as well. > original buyer could save a few bucks. My PRS-10 is one of these. > > How does this compare with say a used Accubeat AR133/60 substance? I also see they have a Nano unit that looks awesome (but I have no idea what the price is and if they are ever sold used?). -aps ___ 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] Beginner's Atomic Clock
On Tue, 17 Sep 2019 at 04:00, Dana Whitlow wrote: > The nice thing about a Rb is that its short term stability (seconds to > minutes and perhaps > even longer) is much better than that of a GPS timing receiver. The bad > news is that Rb > standards exhibit long term frequency drift in the neighborhood of a few > parts in 10^11 > per month. A pretty fair compromise is to use an Rb standard that is > disciplined by GPS > PPS pulses with a loop time constant on the order of a day or so. > > Dana (K8YUM) Is there any advantage in using a GPS Rb disciplined oscillator vs a GPS disciplined high quality OCXO like the HP 10811A? I can’t understand why there should be, as a Rb source would use an OCCO in its output stage Therefore in each case * Short term stability depends upon the quality of the OCXO * Long term stability depends upon GPS. Perhaps there’s is period over which the the overall stability can be improved by adding a rubidium oscillator. I would be interested to know if that is the case or not. Dave > -- Dr. David Kirkby, Kirkby Microwave Ltd, drkir...@kirkbymicrowave.co.uk https://www.kirkbymicrowave.co.uk/ Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales. Company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom ___ 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.
