Re: [time-nuts] EFOS2 Maser acting up :(

2018-08-13 Thread Dana Whitlow
Corby, What's the H flow rate control doing when the IF level goes down, or increases, depending? Prior to retirement, I was the "Keeper of The Clock" at my job, which entailed riding herd on our Symmetricom H-Maser (among other things). At one point about five years ago, the IF amplitude began

Re: [time-nuts] Pressure related rubidium oscillator aging

2018-08-14 Thread Dana Whitlow
in a matter of days due to in-diffusion from the high pressure He atmosphere. They had to order custom vidicon tubes made of special glasses for which He diffusion was much lower. Dana On Tue, Aug 14, 2018 at 4:21 PM, Attila Kinali wrote: > On Tue, 14 Aug 2018 14:23:56 -0500 > Dana Whitlow

Re: [time-nuts] PPS pulse length (was: 1PPS for the beginner)

2018-08-14 Thread Dana Whitlow
Arecibo did a kind of cute trick with their distributed 1PPS. The one second pulses were of one length (100 ns as I recall), but the 10 sec boundaries had the pulses be about twice that length. One could carry this scheme to considerable lengths as desired. Dana On Tue, Aug 14, 2018 at 4:00

Re: [time-nuts] Question about effect of spurious frequency modulation on Allan Deviation

2018-08-06 Thread Dana Whitlow
One might also do some trials based on comparing ADEV results between a clean carrier signal and ones corrupted with varying degrees of FM (for example), to get a feel for the problem. If nothing else, one ought to be able to get some feel for the sensitivities involved. Dana K8YUM On Mon,

Re: [time-nuts] Bicentennial GOES satellite clock

2018-08-12 Thread Dana Whitlow
How exactly does one get submillisecond time of day precision with a sextant? (even if sticks and pebbles are thrown into the mix) I'd say more like ~1 sec precision on a really fine day, it the sextant is wielded by a skilled and practiced operator who has apriori knowledge of his location. And

Re: [time-nuts] NIST

2018-08-13 Thread Dana Whitlow
Note to all; Be cautious about getting time of day from consumer GPS products. All that I have encountered (so far) exhibit T.O.D. errors up to a few tenths of a second, and the error is not repeatable from session to session. Some do have PPS outputs, which are typically claimed to provide

Re: [time-nuts] NIST

2018-08-13 Thread Dana Whitlow
er is reading this and getting the idea to make a GPS to > WWVB timecode radio transmitter, clever gent that he is. :-) > > Best Wishes, > Craig > KI7CRA > > > On Aug 11, 2018, at 7:48 PM, Dana Whitlow wrote: > > > > I fear the worst. The line in the webs

Re: [time-nuts] 1PPS for the beginner

2018-08-14 Thread Dana Whitlow
> may be a few still in production that don’t. > > Without full doc’s on a GPSDO, you really don’t *know* where the PPS is > set to originate. It may > be coming from the disciplined clock on the board. It also *may* be coming > straight from the GPS > module. There are indeed

Re: [time-nuts] NIST

2018-08-11 Thread Dana Whitlow
I fear the worst. The line in the website simply stated something like "shutting down the transmitters in Colorado and Hawaii", which would seem to include the whole enchilada. For the wall clocks, GPS should work well if people are willing to go to battery- backed AC power. But not so good for

Re: [time-nuts] 1PPS for the beginner

2018-08-14 Thread Dana Whitlow
Could someone please define and explain the term 'hanging bridge' in this context? Thanks, Dana On Tue, Aug 14, 2018 at 7:02 AM, Azelio Boriani wrote: > Hanging bridges out of a GPSDO's PPS? Interesting... time to try to > setup a measurement and see the relation between the GPS's PPS

Re: [time-nuts] WWVB and Chronverter update

2018-08-24 Thread Dana Whitlow
that can drive a 1 transistor or diode modulator. > Regards > Paul > WB8TSL > > On Fri, Aug 24, 2018 at 3:14 AM, Dana Whitlow > wrote: > > > Is there a schematic published for the Chronverter? I agree with Didier > > that the > > OOK issue *ought *

Re: [time-nuts] Petition to Maintain WWV, WWVH, WWVB

2018-08-24 Thread Dana Whitlow
Is there more of it? What I see makes no reference to WWVB. Dana On Fri, Aug 24, 2018 at 1:10 PM Graham / KE9H wrote: > Here is the URL of a petition to maintain funding of WWV, WWVH, WWVB. > > Only currently at about 7 percent of the number required for a response > from White House. > > >

Re: [time-nuts] Russian HF Timing Service ?

2018-08-21 Thread Dana Whitlow
Not having the coordinates in hand, all I can do is suggest using Google Earth (or Maps) and look for suitable antenna farm(s). Dana On Tue, Aug 21, 2018 at 12:05 PM Mark Sims wrote: > Lady Heather v6 has a command (SD) that estimates the propagation delay > (and distance) between your

Re: [time-nuts] WWVB Signal Generator

2018-08-25 Thread Dana Whitlow
With the watch being physically close to the faux WWVB "transmitter", one is in the so-called "near field" regime, where the field strength (V/m) falls as the inverse cube of the distance. If one is putting the watch, say, within a few inches of the transmitter, reliable reception should be

Re: [time-nuts] WWVB Signal Generator

2018-08-29 Thread Dana Whitlow
er, > > > 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 >

Re: [time-nuts] TNS-BUF update

2018-08-19 Thread Dana Whitlow
Be watchful about the black epoxy. It may just be a dyed (otherwise clear) epoxy, and some of the black dyes in common use pass near IR quite readily. This would probably be most troublesome if the ambient light source were of the incandescent persuasion. Also, small diodes in clear packages

Re: [time-nuts] Naked 4046 PLL chip

2018-07-21 Thread Dana Whitlow
Did the original '4046 include the anti-backlash fix? Dana On Saturday, July 21, 2018, Dr. Ulrich L. Rohde via time-nuts < time-nuts@lists.febo.com> wrote: > Obsolet by today’s standard > > Sent from my iPhone > > > On Jul 21, 2018, at 10:44 AM, Poul-Henning Kamp > wrote: > > > > Clearly not

Re: [time-nuts] Effects of Simple GPS jamming on GPSDO's ?

2018-08-31 Thread Dana Whitlow
I'm thinking about if/when "the big one hits" and takes out most or all of the GPS sats, cell phone systems, etc. Then the time required to reboot up to a reasonable level of technology might turn out to be limited by our ability to determine time and freq somewhat accurately. The better we can

Re: [time-nuts] Lost GPS lock or 1PPS recently?

2018-09-04 Thread Dana Whitlow
Scott & John, Do either of you have any activity by "Light Squared" (or whatever it's now called) in your area. Jamming does not always have to be in-band to be effective. Dana On Tue, Sep 4, 2018 at 1:11 PM Scott McGrath wrote: > My TrueTime DC-XL has lost lock since yesterday as has my

Re: [time-nuts] wwvb antenna transmission Well harder then I might think.

2018-09-06 Thread Dana Whitlow
Paul, You really don't want to be building an antenna that radiates energy, which is a far-field concept. In your case, at 30 ft range, you're so far inside the near field that all the antenna articles in the world won't help, since they address radiating into the far field. That's what WWVB

Re: [time-nuts] OOPS on my wwv legal post

2018-08-30 Thread Dana Whitlow
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

Re: [time-nuts] WTS: Efratom PTB-100 Precision Timebase

2018-07-08 Thread Dana Whitlow
Don, I've noticed that in general IEEE retains copyright on most stuff they publish. I've been a member for more than 20 years, and this galls me. For an organization that purports to be for the good of mankind, they seem awfully stingy with the information they gather. But if you do acquire

Re: [time-nuts] How can I measure time-delay of a cable with HP 5370B time-interval counter?

2018-10-28 Thread Dana Whitlow
If you can get access to a 2-channel 'scope, try it instead of a TIC so you can get some clue as to what's happening. I suspect that one component of the problem is that the supposedly Hi-Z input of the counter really isn't but has a stub of unterminated cable between the input connector and

Re: [time-nuts] Tbolt GPS for sale

2018-10-30 Thread Dana Whitlow
Jerry, Please contact me off-list. I have questions, and might be very interested in your T'bolt. Dana k8yumdoo...@gmail.com (830) 896-6712 On Tue, Oct 30, 2018 at 5:05 PM Jerry wrote: > Subject: Tbolt GPS for sale > I am selling my Trimble 10 MHz Thunderbolt GPS disciplined

Re: [time-nuts] Oscilloscope-based measurements of frequency stability

2018-10-02 Thread Dana Whitlow
related to making > repeatable measurements using scopes. I'm gonna see if I can find some of > those. I remember some crazy looking telco standard that required measuring > amplitude noise on time scales measured in weeks. > > Tim N3QE > > On Mon, Oct 1, 2018 at 8:47 AM D

Re: [time-nuts] XKCD on time :)

2018-09-28 Thread Dana Whitlow
David Van Horn, You're on the right track, but what would you do about those pesky leap seconds? Dana On Fri, Sep 28, 2018 at 2:48 PM Artek Manuals wrote: > H Farce-Book hadn't considered that approach .. some sort > of (ready for this ) > > "subliminal millennial mind control"

Re: [time-nuts] 10 MHz -> 16 MHz

2018-09-30 Thread Dana Whitlow
Tom, Divide the 10 MHz down to 2 MHz in the usual way, then multiply by 8 with a cascade of three analog freq doublers separated by fairly narrow bandpass filters. Caveats: Would need four filters total along the path to get rid of unwanted frequency components, gain distributed along the path

Re: [time-nuts] Oscilloscope-based measurements of frequency stability

2018-10-01 Thread Dana Whitlow
lloscope-based measurements of frequency > stability > > > > This sounds interesting enough and I would appreciate any notes or > insight on doing this. I have a PRS10 and several GPSDOs that I would like > to evaluate for performance on my scope. > > > > Many thanks

[time-nuts] Oscilloscope-based measurements of frequency stability

2018-10-01 Thread Dana Whitlow
I cheered when I saw Dave B's "silly question", for then I realized that I'm not the only one who likes to measure things with an o'scope. I had purchased a GPSDO a few weeks before and had been observing its behavior relative to a free- running Rb by watching 10 MHz sinewaves drift with respect

Re: [time-nuts] 10MHz standard for comms receivers

2018-10-01 Thread Dana Whitlow
Isn't it the case that computer clocks these days are subject to two influences that make them worthless for timing? 1. Deliberate random FM to spectrally spread RFI leakage. and 2, Wild variations of clock speed according to usage needs of the moment, in order to reduce average power

Re: [time-nuts] Frequency over fiber (was WWV and legal issues)

2018-09-02 Thread Dana Whitlow
Question: Supposing you buy a bundle of a couple of dozen fibers inside one outer jacket: Can anyone give me an idea of how well the individual fibers are likely to be matched in delay, and in delay tempco? Dana On Sun, Sep 2, 2018 at 1:46 PM Poul-Henning Kamp wrote: > > > In

Re: [time-nuts] A silly question ...

2018-09-28 Thread Dana Whitlow
my PRS-10, for example, although I've seen no evidence of unstable timing results. But in this arena, it generally pays to be fussy. Dana Whitlow On Fri, Sep 28, 2018 at 7:06 AM Bill Byrom wrote: > On Thu, Sep 27, 2018, at 11:55 AM, Dave B via time-nuts wrote: > > Triggering a dual beam 's

Re: [time-nuts] new op amp for distribution amplifiers

2018-12-15 Thread Dana Whitlow
Has anybody tried the AD8003 (triple video line driver amplifier) for use as distribution amplifiers? It looks to me like this part might be a decent choice. On caveat, however: don't succumb to the temptation to reduce the circuit bandwidth by putting a capacitor across the feedback resistor-

Re: [time-nuts] Modern signal generators

2018-12-11 Thread Dana Whitlow
Ulrich, Is it OK for us to forward the URL for your "Noise" paper to others outside the time-nuts group? Thanks, Dana K8YUM On Tue, Dec 11, 2018 at 9:24 AM Ulrich Rohde via time-nuts < time-nuts@lists.febo.com> wrote: > >

Re: [time-nuts] Scientists Build Atomic Clocks Accurate Enough to Measure Changes in Spacetime Itself

2018-11-30 Thread Dana Whitlow
I wonder if that "insult" was the inspiration for thermometers designed around quartz resonators. For more details on the new "accelerometer", one might want to read:

Re: [time-nuts] VLF time station, cheap sdrs

2018-12-05 Thread Dana Whitlow
I generated a spiral plot of phase and amplitude covering about 3 minutes of WWVB last fall. It's a good-size file, around 2MB as I recall. Should I send it? Dana On Wed, Dec 5, 2018 at 8:56 AM jimlux wrote: > https://www.rtl-sdr.com/tag/vlf/ > > a fair number of examples - > > As I

[time-nuts] Looking for ADEV plot(s) for the SRS model SG384 sig gen

2018-12-08 Thread Dana Whitlow
I'm considering purchasing one of these units, but would like to know just how bad/good is bad/good before I leap. I'd get the most useful info for the case of all modulations OFF, "perfect" external reference, and for a reasonable assortment of RF frequencies (or one frequency plus a statement

Re: [time-nuts] PRS10 case temperature

2018-11-16 Thread Dana Whitlow
My PRS-10 (a telecom version) runs with a heatsink temp of around 55C of a bit less. But some areas of the case actually run a few deg hotter than that. Dana On Fri, Nov 16, 2018 at 3:49 PM Mark Sims wrote: > My case temp runs around 70C with the SRS heatsink installed. If you > don't have

[time-nuts] RF isolation requirements for multiple GPS receivers

2018-11-27 Thread Dana Whitlow
I want to run about 4 separate GPS units of disparate manufacture from a single antenna. My plan is to provide power for the antenna via a bias tee (power inserter) at the bottom end of the antenna's cable, then use an isolating splitter on the receiver side of the bias tee to split to the

Re: [time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

2019-01-10 Thread Dana Whitlow
I was moved to check on the terms "decimate" and "downsample" to see what their relative meanings are, and was disappointed to see that they are virtually the same. Perhaps Tom would be willing to discuss this point and suggest meanings to be used in this group. Dana On Thu, Jan 10, 2019 at

Re: [time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

2019-01-10 Thread Dana Whitlow
I'm confused... I see two separate cases here: Case A: you simply throw away samples, keeping only every nth sample, without regard for the frequency content of the original signal. Case B: you first perform appropriate anti-aliasing filtering on the original signal, and only then throw away

Re: [time-nuts] Programmable clock for BFO use....noise

2018-09-14 Thread Dana Whitlow
Frequency dividers can be pretty low noise, if you choose the right class of logic. I remember that at one time in the distant past, LSTTL was considered king. Unfortunately I've been out of touch with frequency dividers long enough to be ignorant of what works well today. i'd suggest trying

Re: [time-nuts] Noise of digital frequency circuits (was: Programmable clock for BFO use....noise)

2018-09-16 Thread Dana Whitlow
I'd been thinking, in an admittedly non-rigorous sort of way, about this matter for some years. As I see it, it is certainly true that the phase of an oscillator's output is a continuous funciton of time. It could be described as a continuous ramp, whose slope corresponds to the frequency, and

Re: [time-nuts] Noise of digital frequency circuits (was: Programmable clock for BFO use....noise)

2018-09-16 Thread Dana Whitlow
lot of years. In general faster saturated logic produces lower noise > floors than slower > logic. > > Bob > > > On Sep 16, 2018, at 4:33 PM, Dana Whitlow wrote: > > > > I'd been thinking, in an admittedly non-rigorous sort of way, about this > > matter fo

Re: [time-nuts] 4.19 MHz xtal

2019-03-31 Thread Dana Whitlow
Could it really be 4.194304 MHz (2^22 Hz)? Dana On Sun, Mar 31, 2019 at 5:03 PM Neville Michie wrote: > Hi, > I have a Philips quartz clock that runs on 4.19 MHz. > In spite of the high frequency it still runs for years > on a C cell. > Can any of the quartz crystal gurus explain why this >

Re: [time-nuts] reply re Harrison's timing method - #13 in Vol 176, Issue 44 digest

2019-03-27 Thread Dana Whitlow
Relative to Harrison's method of star position measurement and timing, and the possible effects of diffraction thereof: Hanbury Brown's book "The Intensity Interferometer" may provide some useful insight about various error sources, even though in a different context, that of measurement of a

Re: [time-nuts] HP Stories: An architectural view of the HP 5060/5061 and awkward oscillator adjustments.

2019-02-24 Thread Dana Whitlow
I remember often reading that if you run a 'lyt at a voltage much reduced from its rating, the oxide layer would get thinner over time so that in the end, the effective rating of the capacitor was about what you had been running it at. This would seem to imply that purposely overrating a 'lyt is

Re: [time-nuts] injection locking crystal oscillator

2019-02-28 Thread Dana Whitlow
Hello Thomas, What you ask is possible, but only if the native crystal oscillator frequency is close enough to the signal from the GPSDO. You may have to tune the oscillator yourself to get it to lock, and you may or may not find that the result is predictable from day to day. This would depend

Re: [time-nuts] Bricked Garmin GPS 18x LVC

2019-02-23 Thread Dana Whitlow
If you open it up, then simply connect a load resistor, perhaps in the neighborhood of 100 ohms (but definitely not a direct short!) across the super cap to drain it faster. Dana On Sat, Feb 23, 2019 at 8:00 AM Jason Rabel via time-nuts < time-nuts@lists.febo.com> wrote: > That page you linked

Re: [time-nuts] PRS-10 Warm-up Time, Calibrating/Adjusting, and long-term poweron

2019-03-08 Thread Dana Whitlow
Keep in mind that the 7 min "warmup time" of the PRS-10 is jut the time for the unit to get the physics package close enough to final temperature for the dithering loop to lock to the atomic transition. But based on measurements of current drawn by the oven(s), it takes more like an hour for the

Re: [time-nuts] Examples of noise processes

2019-03-15 Thread Dana Whitlow
Folks, Please be careful about definitions in this discussion. To some people, "phase noise" refers to sideband noise, away from the carrier, arising from some form of random phase modulation of the carrier. To others, the same term refers to the underlying phase modulation itself. While

Re: [time-nuts] OCXO PLL gains?

2019-02-02 Thread Dana Whitlow
I learned a useful rule of thumb design procedure for 2nd degree PLLs some time ago (I'll speak in the context of using an inverting op-amp in the loop gain/filter stage): Step 1: Short the capacitor in the opamp's FB loop, then set the resistor so that the PLL has the desired loop bandwidth.

Re: [time-nuts] Rollover : Thunderbolt

2019-04-06 Thread Dana Whitlow
My ancient T'bolt (purchased well-used several months ago) also went from 1023 to 1024. A quick look at IQ phase data I was recording (referred to a free-running PRS-10) shows no discernible glitch at the moment of rollover. This old T'bolt has been living in 1999 for as long as I've had it. So

Re: [time-nuts] Updating the unit of,time: the second.

2019-05-27 Thread Dana Whitlow
Well, I once had a nutty idea which was to detect earthquakes by looking for the phase variation of DTV station pilot carriers due to seismic waves propagating around, thereby changing the physical distance between transmitter and receiver in a cyclic manner until the 'quake calmed down. Doing

Re: [time-nuts] The forbidden question

2019-06-04 Thread Dana Whitlow
In answer to the question about radio astronomers, consider VLBI (Very Long Baseline Interferometry). VLBI is a mapping (imaging) process in which signals are *simultaneously* received from a small sky region of interest by a collection of radio telescopes scattered about the world. In order for

Re: [time-nuts] Si5351A harmonics question

2019-06-05 Thread Dana Whitlow
Chris, In general I'd say that the rather high level sidebands on your signal are not reasonable at all, but I think I see what's *really* wrong: your SA settings. It looks to me like the tall signal is the DC spur, (a.k.a. "start spur") of you analyzer, and the signal very near center screen is

Re: [time-nuts] Updating the unit of,time: the second.

2019-05-29 Thread Dana Whitlow
Ole, Is it when all 5 conditions are met, or just any one of them? Thanks, Dana On Wed, May 29, 2019 at 11:00 AM Ole Petter Rønningen wrote: > As supporting material; BIPM is considering when a redefinition would be > appropriate: >

Re: [time-nuts] Truetime XLi sat signal levels (dBW to dBc/SNR conversion question)

2019-06-15 Thread Dana Whitlow
Mark, When you refer to "30 dBc", what is that? Is it the eb/n0 value? If so, with the XLi's behavior as you report it, your scheme would fail over most of the useful signal range. And, it will probably differ from setup to setup of the HW, depending on all the parameters that have already

Re: [time-nuts] GPSDO 10MHZ Splitter

2019-06-21 Thread Dana Whitlow
One can reduce the gulp factor mentioned by Scott quite a bit by buying one of the non-connectorized versions from Mini-Circuits and wiring up one's own BNC connectors. One thing to keep in mind with these isolating splitters is that the isolation between outputs is good only if the impedance of

Re: [time-nuts] Subject: Re: GPS 1PPS, phase lock vs frequency lock, design

2019-06-23 Thread Dana Whitlow
Correction from Dana: I meant "... without accumulation of phase error during normal times ...". Sorry about that. Dana On Sun, Jun 23, 2019 at 11:45 AM Dana Whitlow wrote: > Leo, > > Are you saying that you want to abandon phase lock altogether in favor of > freq &

Re: [time-nuts] Subject: Re: GPS 1PPS, phase lock vs frequency lock, design

2019-06-23 Thread Dana Whitlow
Leo, Are you saying that you want to abandon phase lock altogether in favor of freq lock? Or just during the reacquisition following loss of and restoration of the reference? By me definition of pure freq lock, there will generally be some permanent (but varying) frequency error, so that phase

Re: [time-nuts] Slightly OT - Magellan Car navigation displays wrong time

2019-05-18 Thread Dana Whitlow
Glen, This sounds like it might be one of those latent problems arising from the GPS week rollover that we've been warned about. Dana On Sat, May 18, 2019 at 4:00 PM Glenn Little WB4UIV < glennmaill...@bellsouth.net> wrote: > Did anything happen in the last 24 hours that would affect the time

Re: [time-nuts] Rooftop antenna and splitter

2019-04-29 Thread Dana Whitlow
Denny, That is certainly a large difference. But I'm not clear on one point that could easily be very important: Were the two antennas for the separate antenna test indoors, or on the roof? If indoor, I kind of suspect that the difference might mostly be attributed to the change in antenna

Re: [time-nuts] PRS-10 with 1 PPS IN goes nuts - 40 million degrees!

2019-04-18 Thread Dana Whitlow
Taka, What happens to the timing of the PPS output and/or the phase of the 10 MHz output during these wonky times? This inquiring mind wants to know, as it is getting pretty close to ordering a PRS-10 for its own use. Dana On Thu, Apr 18, 2019 at 3:45 PM Taka Kamiya via time-nuts <

Re: [time-nuts] It is possible to "recharge" a hydrogen maser?

2019-07-05 Thread Dana Whitlow
t subsystems could be isolated with high-vacuum valves and switches, with the result that we kept the maser operating throughout the two procedures, with only a subtle glitch in timing accuracy visible in the records when I checked after the fact. The observatory continued to operate with no disturbance

Re: [time-nuts] Used Hydrogen Maser

2019-07-10 Thread Dana Whitlow
Perry, The only H-maser with which I've had direct experience (the MHM-2010) costs around $250,000 new. But there are some other brands, mostly foreign. The immediate operating cost is that of AC power. IIRC, the '2010 uses about 100W or maybe 125W, *all the time*. The H-maser is *not* the

Re: [time-nuts] Galileo service currently degraded

2019-07-13 Thread Dana Whitlow
I wonder if a case could be made for multi-GNSS reception in the case of a poorly- located GPS antenna at the reception site. That is, could the benefits of having a lot more sats in the sky outweigh poorer performance of some of the systems with respect to other systems? Dana On Sat, Jul 13,

Re: [time-nuts] GPDSO Distribution amp that does not radiate ?

2019-07-13 Thread Dana Whitlow
Sure sounds to me like the distribution amp does have some sort of shielding problem, in effect. Are the power connections (whether AC or DC) properly filtered? Are all the coax connectors' bodies well-bonded to the metallic enclosure? You might want to try sniffing with a small diameter (~1

Re: [time-nuts] Advantages of GNSS ???

2019-07-08 Thread Dana Whitlow
One what? I see that it is a Ublox unit, but see no reference to the interesting modern units like the 9 series. Also, I note that the only reference on the board to "ant" is on the lower right corner, while what I suppose to be the actual antenna connector appears to be an SMA near the upper

Re: [time-nuts] A Research Proposal

2019-07-08 Thread Dana Whitlow
I'm surprised that the VF of HV transmission lines is noticeably less than unity, given that the dielectric is just air. Or does the distributed resistance do all the damage? Dana On Mon, Jul 8, 2019 at 8:00 PM jimlux wrote: > On 7/8/19 3:11 PM, Hal Murray wrote: > > > >

Re: [time-nuts] TimeLab phase difference (slope sec/sec)

2019-07-03 Thread Dana Whitlow
Chris, Ok, one source is a PRS-10. Is it the DUT or the reference? And if it's the DUT, what is the reference source? Dana On Tue, Jul 2, 2019 at 8:00 PM Chris Burford wrote: > Hi Bob, > > I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab > phase difference plot. Is

Re: [time-nuts] 60 Hz frequency and phase measurement

2019-07-02 Thread Dana Whitlow
I've always noted that casual attempts to pick up 60 Hz with small antennas etc see more harmonics and other trash than actual line frequency. But if you're in an office environment, why not plug something in? It's quite easy to build a simple passive diode clipper/filter that will plug into a

Re: [time-nuts] verifying synchronization with PPS

2019-07-08 Thread Dana Whitlow
Steve, I'm curious: in the absence of a PPS or other electrical output from your "computer", what is the nature of the time "output "? If it's just visual via a display, why not view the light output of the seconds digit with a photocell. Most of the transitions should produce an

Re: [time-nuts] TCXO improvement

2019-08-02 Thread Dana Whitlow
Question: Do you stabilize the oscillator inside the dewar, or do you stabilize the temperature of the dewar's outside environment? This may boil down to a slightly different expression: Where do you *sense* the temperature for the stabilization loop? On the crystal itself, or on the outside

Re: [time-nuts] PRS-10 Missing SP values in Appendix A.

2019-09-13 Thread Dana Whitlow
Thanks Forrest, I've added this to my documentation packed for my own PRS-10; I suspect that I'm only a year or two from (possibly) needing it myself. Dana On Fri, Sep 13, 2019 at 3:00 AM Forrest Christian (List Account) < li...@packetflux.com> wrote: > Mainly wanting to post this to the list

Re: [time-nuts] Cheap GPSDO with OCXO from aliexpress

2019-09-10 Thread Dana Whitlow
I'd say that for the low price, the critical component (OCXO) can't be a very good one. It's too bad that the seller offers no real specifications (and that he/she doesn't write very good English). I'll be "listening" with interest. Dana On Tue, Sep 10, 2019 at 7:32 AM Adam Kumiszcza wrote:

Re: [time-nuts] Beginner's Atomic Clock

2019-09-17 Thread Dana Whitlow
lue 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: > > &g

Re: [time-nuts] Sawtooth Error Correction, WAS: Capturing NMEA and TICC timestamp data in time-correlated way?

2019-09-15 Thread Dana Whitlow
Assuming that the T'bird works as you stated, you might still want to know where in that sawtooth the supposedly "fixed" error falls. Maybe this is unimportant if all you want is a stable reference frequency source, or very important if you actually want to know what time it is. However, the

[time-nuts] Is the lifetime of a Rb standard dependent on operating orientations/

2019-07-23 Thread Dana Whitlow
It seems to me that the basic operation of the Rb cell and/or the filter cell and lamp must all involve the presence of some liquid Rb at normal operating temperatures. Otherwise, temperature regulation would not be a viable means of controlling the Rb concentration on the vapor mix. If I'm

Re: [time-nuts] Even Seconds Pulse option (1PP2S), HP 58503B

2019-09-29 Thread Dana Whitlow
I can't speak for 1/2PPS, but at the Arecibo Observatory we distributed 1PPS with every 10th second's pulse stretched to about twice the duration of the others. I did find that to be kind of handy every now and then, when troubleshooting things. Dana On Sun, Sep 29, 2019 at 8:36 AM Gregory

Re: [time-nuts] time-nuts Digest, Vol 184, Issue 13

2019-11-15 Thread Dana Whitlow
It looks to me like one might be able to exploit a resonance of the A-frame. Instead of whacking it with a mallet, vibrate the tube in the appropriate direction at the appropriate frequency and run up the amplitude until (hopefully) the ribbon ends touch on each cycle as indicated by electrical

Re: [time-nuts] Antique pendulum clocks

2019-11-20 Thread Dana Whitlow
Somewhere, a few years ago, I saw a video in which a fairly large number of metronomes were mounted on a common base and exhibited some interesting injection locking behavior. Personally I keep thinking of phase locking a G'father clock to a Rb standard. The trick will be to do so in a manner

Re: [time-nuts] Difference in antennas

2019-11-21 Thread Dana Whitlow
Most modern GPS receivers are very quiet even barefoot. So, one could argue that one should not have much more LNA gain in the antenna than required to make up for feedline loss, which should be easily calculable. While excess gain in the antenna can improve overall system noise figure a small

Re: [time-nuts] USB over optical fiber

2019-12-06 Thread Dana Whitlow
Even without any funny business with boost converters (or whatever). those copper wires make a nice antenna for coupling noise from both ends (PC and USB accessory) into the environment inside the chamber. Unless, of course, the cable is well-shielded, which you did not mention. I suppose it's

Re: [time-nuts] Using commercial video amplifier for 10MHz clock distribution.

2019-10-18 Thread Dana Whitlow
Hello Taka, As long as you stick to CW sinewaves *and* the distribution amp specs are honest when they say "buffered out puts", the problem is fairly simple. If you're not seeing distortion under your operating load and signal amplitudes, it's OK and I'd not bother to change anything. By

[time-nuts] Do ordinary clouds adversely affect GPS reception?

2019-10-22 Thread Dana Whitlow
A friend of mine living in SE lower Michigan recently bought a Geppetto GPS clock, and swears that it tends to lose satellite lock on cloudy days but does OK on sunny days. He is admittedly using a very poorly-sited antenna, placed in a window because his house has aluminum siding. He reports

Re: [time-nuts] 10MHz dist amps

2019-10-23 Thread Dana Whitlow
If you're doing beam forming, the "one amp driving multiple loads" approach is probably going to do the best and most stable job of getting what you need. And all your loads should be identical, not some mix of different makes/models. But you will need to find an amplifier that can deliver the

Re: [time-nuts] Do ordinary clouds adversely affect GPS reception?

2019-10-23 Thread Dana Whitlow
Andy, Isn't DirecTV downlinking around 12 GHz? Yet GPS L1 is at only ~1575 MHz. That's a huge difference with regard to scattering losses, and probably a fair amount of difference for water absorption losses as well. I've recommended that my old friend try putting his GPS antenna up in the

Re: [time-nuts] Do ordinary clouds adversely affect GPS reception?

2019-10-23 Thread Dana Whitlow
gt; https://ieeexplore.ieee.org/document/1337081 > ). > > Tim N3QE > > On Tue, Oct 22, 2019 at 2:01 AM Dana Whitlow > wrote: > > > A friend of mine living in SE lower Michigan recently bought > > a Geppetto GPS clock, and swears that it tends to lose > > satelli

Re: [time-nuts] Rubidium cell or lamp rejuvenation. WAS-HP 5065A owners, a question!

2019-10-26 Thread Dana Whitlow
Corby, I have a question to add regarding the HP units: is the tip temperature hot enough to melt Rb in addition to providing vapor? If so, doesn't the orientation of the physics package in earth's gravity have to be about correct in order to keep the excess Rb in the tip? Thanks, Dana On

Re: [time-nuts] Are minutes more important in astronomy than seconds and hours ?

2019-11-23 Thread Dana Whitlow
My idea is that for the time this was built and used, there was little or no need for really accurate time keeping in most astronomy work. The high accuracy/precision needs really didn't arise until the beginning of what I'll call "modern astronomy", which I'll loosely define as the discovery of

Re: [time-nuts] Are minutes more important in astronomy than seconds and hours ?

2019-11-23 Thread Dana Whitlow
Celestial navigation users might object to the notion that seconds are not important. That is, if you can find anybody still exercising that art. In that arena, folks are taught to read seconds first, then minutes, then hours. Depending on the latitude, one second can lead to something like 1/4

Re: [time-nuts] Distributing GPS L1 signal to many GPS devices

2019-09-24 Thread Dana Whitlow
You could minimize problems with accumulated differential delays by *not* daisy chaining- rather arrange the splitters in a hierarchical fashion so that all your outputs have an equal number of splitters in the path. I think your problem is that you started with more than one GPSDO. You need to

Re: [time-nuts] HP105B HP 105B 1 amp fuse blowing

2019-10-11 Thread Dana Whitlow
I once read that Supercapacitors come up short in handling really short spikes, and that this is not due to physical inductance arising from the structure. Rather, the issue was of a subtle (to me) electrochemical nature. Can anyone either confirm or refute this? Inquiring minds want to know.

Re: [time-nuts] What is the BEST crystal?

2020-03-01 Thread Dana Whitlow
Bruce, is there any text about the ring resonator which discusses the features in the interferogram? Also I'd be interested in the configuration of the electrodes. My present interpretation is that the vibratory resonance stems from contra-rotating modes each propagating around the ring, and

Re: [time-nuts] Synchronisation of crystal oscillators

2020-03-01 Thread Dana Whitlow
Yes, oscillators that are harmonically related can indeed injection lock. I've done it in a project about 40 years ago. In your case, you need to avoid RF cross-coupling between the oscillators. This includes both electromagnetic coupling, "direct coupling" via use of a common power supply, and

Re: [time-nuts] Are there SC-crystals out there in the wild that are not Overtone?

2020-02-27 Thread Dana Whitlow
If you start off viewing the crystal in series (S21) I believe that you'll be able to see some response far enough away from the resonance to make it easier to find. Dana On Thu, Feb 27, 2020 at 9:39 AM Magnus Danielson wrote: > Hi, > > Even if my VNA steps in 1 Hz if I ask it kindly, it can

Re: [time-nuts] Time-Nutters-- Adding Rubidium to a Thunderbolt...?

2020-03-03 Thread Dana Whitlow
Matthias, You said that the LPRO has a pulling range of 4 PPM. Really? I would think that 4PPB would be much more likely for a Rb. Dana On Mon, Mar 2, 2020 at 3:21 PM Matthias Welwarsky wrote: > On Montag, 2. März 2020 18:32:44 CET Skip Withrow wrote: > [...] > > The Thunderbolt DAC steps

Re: [time-nuts] Time-Nutters-- Adding Rubidium to a Thunderbolt...?

2020-03-01 Thread Dana Whitlow
Probably the easiest solution would be to feed 1 PPS from the T'bolt into a full-featured PRS-10 Rb, then fiddle with the loop parameters in the PRS-10 to best suit your needs. Unfortunately, I'm told that most of the surplus PRS-10s have been stripped of this capability. But a new PRS-10 *does*

Re: [time-nuts] Digital Pots, wiper noise and fine tweaking oscillators

2020-01-27 Thread Dana Whitlow
Perrier, I see that several others have beat me to the punch on the digipot issues. So I think I'll sit this one out and just try to learn. Dana On Mon, Jan 27, 2020 at 7:50 AM Dana Whitlow wrote: > Perrier, > > In answer to your 2nd question, I am unaware of any oscillator t

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