Re: [time-nuts] Question about frequency counter testing

to the ps averaged resolution you want only if they are worse >> than your one-shot base resolution one WRT the other. >> >> On Fri, Apr 27, 2018 at 3:38 PM, Bob kb8tq wrote: >>> Hi >>> >>> Consider a case where the clocks and signals are all clean a

Re: [time-nuts] Question about frequency counter testing

Hi Consider a case where the clocks and signals are all clean and stable: Both are within 2.5 ppb of an integer relationship. ( let’s say one is 10 MHz and the other is 400 MHz ). The amount of information in your data stream collapses. Over a 1 second period, you get a bit better than 9 digit

Re: [time-nuts] Question about frequency counter testing

Hi The degree to which your samples converge to a specific value while being averaged is dependent on a bunch of things. The noise processes on the clock and the measured signal are pretty hard to avoid. It is *very* easy to over estimate how fast things converge. Bob > On Apr 26, 2018, at 5:

Re: [time-nuts] nuts about position

Hi If you shop for a while on eBay, you can find older L1 / L2 survey receivers for < $300 and an antenna that will work for them for < $100. Yes it will take a bit of heavy duty shopping and some level of “wait and see”. How well they work and how much of a pain is associated with this proce

Re: [time-nuts] Want a student to do some experiment on timetnuts - Re: nuts about position

Hi Having once been very much involved in research grants and all the math that goes in-between the “zero pay labor” and the amount billed to on high ….. it can be pretty amazing just how little you can get done for $20K using free labor. :) Do software projects count? An analysis library

Re: [time-nuts] Question about frequency counter testing

-stamping like a stable 5GHz counter? The resolution of > a 200ps (one shot) interpolator can be replaced by a 5GHz > time-stamping counter. > > On Thu, Apr 26, 2018 at 12:28 AM, Bob kb8tq wrote: >> Hi >> >> Unfortunately there is no “quick and dirty” way to come up

Re: [time-nuts] nuts about position

Hi On something like a phone, you are likely looking at a combination of what the phone does and a contribution from “the cloud”. Part of that cloud contribution depends a bit on the carrier and how well they are doing their part of things. In one area you might have surveyed towers and a full G

Re: [time-nuts] LEA-6T TCXO measurements

Hi What you are looking at appear to be sawtooth jumps. Simply put, the module is looking at the closest edge on the TCXO to do it’s timing. When the device drifts, it can “slip” to another cycle. If you watch the PPS out, there are also artifacts that result from this process operating in a n

Re: [time-nuts] nuts about position

Hi Keep in mind when you look at the “peak to peak” numbers for solid tides that you may have to observe things for 20,000 years to see the full peak to peak…… They also are variable depending on just how close you are to what sort of coastline. ( = they interact with sea tides when you get clo

Re: [time-nuts] Question about frequency counter testing

Hi Unfortunately there is no “quick and dirty” way to come up with an accurate “number of digits” for a math intensive counter. There are a *lot* of examples of various counter architectures that have specific weak points in what they do. One sort of signal works one way, another signal works

Re: [time-nuts] nuts about position

Hi One of the “interesting features” of the ongoing bridge rebuilding process around here is the destruction of most of the benchmark locations. They were built into the old bridges and went away when the new ones went up. Now there are cute little brass disks on the new bridges. There is no i

Re: [time-nuts] nuts about position

Hi That sort of accuracy is pretty normal for a survey device. He needs to find a local surveyor who likes to look at stars :). I assume the telescope is not mobile and it’s a one time sort of thing. If he likes to romp around the question becomes how quickly he needs the location information

Re: [time-nuts] Cheap jitter measurements

Hi Now that it is “free for all”, Stable-32 is another good program to run your data past. It will do nice plots and a *lot* of different statistics. Bob > On Apr 25, 2018, at 7:01 AM, Tom Van Baak wrote: > > Hi Gary, > >> A little coding later and there are nice plots. They were compared

Re: [time-nuts] Better quartz crystals with single isotope ?

e 10 grams, the comparison has to be 100 > times more accurate than that for 1000 grams. > > Hope I haven't strayed too far off topic, and wasted my time. > > Bill Hawkins > > > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behal

Re: [time-nuts] Better quartz crystals with single isotope ?

Hi Quartz ball yes. It’s a fused quartz (as opposed to crystalline quartz) ball ….. Fused quartz is a lot easier to work with. In order to be piezoelectric, it must be crystalline. The piezo properties are what lets you make a resonator out of it. Bob > On Apr 22, 2018, at 6:28 PM, Brooke Cla

Re: [time-nuts] Better quartz crystals with single isotope ?

Hi If you get into “temperature nuts” territory, the triple point of water varies with the isotope “mix” in the standard. The “correct” mix turns out to be “mid continent deep well water”. If you make a resonator that is very thick, you also need to make it very wide. If you don’t, the widt

Re: [time-nuts] Better quartz crystals with single isotope ?

Hi > On Apr 22, 2018, at 1:46 PM, jimlux wrote: > > On 4/22/18 9:19 AM, Poul-Henning Kamp wrote: >> Silicon comes in a number of isotopes but 95% of it is Silicon-28. >> When you make pure mono-crystaline silicon, you get 50-60% better >> thermal conductivity if you only use Silicon-28 atoms. >>

Re: [time-nuts] Better quartz crystals with single isotope ?

Hi > On Apr 22, 2018, at 12:19 PM, Poul-Henning Kamp wrote: > > Silicon comes in a number of isotopes but 95% of it is Silicon-28. > > When you make pure mono-crystaline silicon, you get 50-60% better > thermal conductivity if you only use Silicon-28 atoms. > > Yes, you read that right: 50-6

Re: [time-nuts] GPS coordinate differences between APRS.FI and Google Maps

Hi In general the N/S E/W part of the location should be pretty good between various reporting systems. Altitude … maybe not so much. These days, whatever GPS reports as “location” generally is considered to be correct. Anybody using a different set of numbers is expected to translate over to

Re: [time-nuts] 4046 replacement

Hi If this is a new build, why use a 4046 in the first place? There are many newer parts that will do all sorts of things. If this is a repair of something that has been running for years, is it > 5V supply to the chips? If so, you are pretty much stuck with 4000 series CMOS. There are no fata

Re: [time-nuts] General Recommendation?

Hi Like most things in life, what you want and what you can afford generally are in opposition to each other :) The TimePod *is* the beast to use. A lot of us would love to get one at a “good price”. They sell for $10K and up from Microsemi when bought new. Exact price varies with the options e

Re: [time-nuts] Some thoughts about Crystal Oscillators

Hi > On Apr 15, 2018, at 1:01 PM, Gerhard Hoffmann wrote: > > > > Am 17.03.2018 um 00:57 schrieb Ulrich Rohde via time-nuts: >> https://synergymwave.com/articles/2013/04/full_article.pdf >> This may be still of interest... happy weekend, 73 de Ulrich, N1UL >> >> > > Since the weather did

Re: [time-nuts] Holdover: Z3801A vs KS-24361

Hi There isn’t much you can really see on a GPSDO comparing it to a normal OCXO. The OCXO simply is not accurate enough. You need something like a Cs standard, a different GPSDO, or a good Rb for the reference. (Yes, if you have a hydrogen maser, you *can* use that ….). First thing to check is

Re: [time-nuts] TCVCXO Adjustment

n do. Unless you consider those numbers, you aren’t going to get a solution. in a commercial situation, you can afford a reference that is orders of magnitude more accurate than the device you are working with. That cost money and time. You also can use equipment that minimizes the measurem

Re: [time-nuts] TCVCXO Adjustment

Hi It’s reasonable to expect the slope of the EFC to vary 2:1 over it’s range. Could be more, could be less. How much depends a lot on what the original OEM wanted on surplus parts. In the case of “bought new” you would have to check the data sheet. If there’s no spec, it’s reasonable to assu

Re: [time-nuts] TCVCXO Adjustment

Hi That’s one possible application. Jim’s VLBI in the back yard is another possible application. If this is aimed at “distributed VLBI” then the requirements are … errr … pretty tight. Bob > On Apr 14, 2018, at 4:43 PM, Chris Caudle wrote: > > On Sat, April 14, 2018 8:37 am,

Re: [time-nuts] TCVCXO Adjustment

d the data will be pretty sparse. It’s still a bit unclear what the target accuracy is (or even if the TCXO needs setting at all …). Bob > > On Sat, Apr 14, 2018 at 2:37 PM, Bob kb8tq wrote: > >> Hi >> >> The gotcha is that you do not have a calibrated adjustment.

Re: [time-nuts] TCVCXO Adjustment

Hi The gotcha is that you do not have a calibrated adjustment. Put another way, there isn’t a perfect correlation between DAC bits and ppm. Each adjustment you make is subject to a bit of error. When you are trying to get within a ppm, your measurements are quicker, so the larger error ( percent

Re: [time-nuts] TCVCXO Adjustment

Hi The uBlox based parts will provide pretty good timing into a directly connected PC. By that I mean, they are on a dedicated USB controller hooked directly to the CPU. In this context, the objective is microsecond level timing. We’re not after a TimeNut couple of nanoseconds. Even if it’s 10

Re: [time-nuts] TCVCXO Adjustment

Hi Yes you could. If you are listening to them by ear, something in the ~100 ms range is probably a good guess in terms of precision. There are also propagation issues that may come in with a broadcast system. If you are still after 0.1 ppm, that gets you out to a million seconds per adjustm

Re: [time-nuts] TCVCXO Adjustment

Hi With NTP (or any other timing system) you really need 3 or more sources to sort things out. If you only have one source, eventually everything will converge on it. That’s not to say that it will be correct, you simply will be 100% locked to it. GPS modules are a “sub $20” sort of thing the

Re: [time-nuts] TCVCXO Adjustment

Hi If you have a GPS on your local lan, just use it for the calibration. There’s no need for NTP to get involved. If you are running NTP over a normal home setup going to the internet, then you will be doing very well to get low ms with NTP. Going back to the original post, the request is for

Re: [time-nuts] TCVCXO Adjustment

Hi NTP will give you “millisecond" level accuracy / stability. If you want to set an oscillator to 0.1 ppm, you will need to run for over 10,000 seconds. It is not uncommon to have things out in the 10 ms range. That would put you at 100,000 seconds. In more common units, a couple of hours to

Re: [time-nuts] Holdover: Z3801A vs KS-24361

Hi > On Apr 12, 2018, at 1:30 AM, Hal Murray wrote: > > On that Status page, A Z3801A says: > Predict 2.5 us/initial 24 hrs That sounds about right for a 3801. The prediction is something better than a wild guess and not what one would call a solid number. > > A KS-24361 says: > Predic

Re: [time-nuts] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?

HI > On Apr 11, 2018, at 5:38 PM, Richard (Rick) Karlquist > wrote: > > The aging spec on the 10811 is 5 parts in 10^10 per day. > After 60 days, it could be off 30 ppb. So what we > have here is a non-ovenized AT cut that is better > than an ovenized SC cut. I'm sure. As a practical point -

Re: [time-nuts] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?

Hi Guess at the aging Cut the crystal so it’s fairly flat at 25 to 35C Do a basic / simple temperature compensation (TCXO) …. and count on the errors to average out. The success of all that will depend a lot on how close your wrist is to the environment they used for their guesswork. Did the

Re: [time-nuts] suggestions on getting 24 Mhz ?

Hi > On Apr 11, 2018, at 12:11 PM, Graham / KE9H wrote: > > Phase noise is (usually) more important than absolute frequency accuracy. It’s probably well worth looking into exactly what you are after in terms of phase noise, spurs, and stability *before* deciding on a solution. In some cases

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 11, 2018, at 4:58 AM, Hal Murray wrote: > > > g...@rellim.com said: >> It tests the time to do two back to back clock_gettime(). > > That's the time it takes to read the clock. That's not what I mean by > granularity but I think I see how you might use that word. The comment at

Re: [time-nuts] TCVCXO Adjustment

Hi On a TCXO a proper 12 bit DAC should do fine. The “don’t use for DC” DAC’s that are built in to a MCU …. who knows. At DC they probably aren’t 12 bits anyway. If the TCXO is rated to age < 1 ppm per year and has a 10 ppm EFC (yes you *could* wonder about that combo) the DAC would need to dr

Re: [time-nuts] TCVCXO Adjustment

Hi In a commercial setting calibration would be done against a local standard. It might be checked with a counter. It also might be checked against something more complex. A reasonable level of calibration would be 0.1 ppm. Anything much more accurate than that would be quickly swamped by the t

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 5:05 PM, Dan Kemppainen wrote: > > Hi Bob, > > The performance counter does not use the system time calls, NTP, etc. It's an > independent counter clocked from raw CPU clock. So you have a ~300pS > Timestamping counter in the processor. Why not use that hardware to do

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 2:59 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> Yes, but looping back to the start of this thread, the intent is to actually >> measure the jitter directly. That’s where the whole need for a stamped >> pulse comes from. To paraphrase the earlier comments, the i

Re: [time-nuts] Dual GPSDO - any advantage?

Hi Looks like 100 is all he had (or all he put up on this auction). It will be interesting to see what (if anything) we all get ….. Bob > On Apr 10, 2018, at 12:44 PM, W7SLS - Scott Scheirman > wrote: > > I ordered 2. We shall see > Scott > No connection with seller(s) > > Sent from my iPh

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 12:23 PM, David J Taylor via time-nuts > wrote: > > Hi, > > Yes, but isn't generating pulses OUT of a PC with low latency/jitter one > of the difficult issues? > > If we (somebody smarter than me...) flip this around and modify a copy > NTP to grab the QueryPerforman

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 11:56 AM, Dan Kemppainen wrote: > > Hi, > > Yes, but isn't generating pulses OUT of a PC with low latency/jitter one of > the difficult issues? > > If we (somebody smarter than me...) flip this around and modify a copy NTP to > grab the QueryPerformanceCounter valu

Re: [time-nuts] Dual GPSDO - any advantage?

ever turn up, > looks and smells very much like the standard eBay scam to me. > > > > > > On 10 April 2018 at 14:52, Bob kb8tq wrote: > >> Hi >> >> Simple answer is that the “simple” approaches don’t do much to improve >> things. >> Errors

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 9:59 AM, Dan Kemppainen wrote: > > Hi, > > Don't know how good they are, but there are two functions in the kernel32 lib > in windows that are related to a cpu performance counter, > QueryPerformanceCounter and QueryPerformanceFrequency. (Maybe Linux has > similar?)

Re: [time-nuts] Dual GPSDO - any advantage?

Hi Simple answer is that the “simple” approaches don’t do much to improve things. Errors are indeed un-correlated, even off of the same antenna. You *could* average the result off of the two. That might improve things by sqrt(2). My experience is that the bumps and lumps (when they do occur) ar

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 10, 2018, at 6:58 AM, Hal Murray wrote: > > > kb...@n1k.org said: >> The kernel clock comes from the CPU clock. That CPU clock is phase locked to >> a crystal. If you have a CPU that is driven by a VCXO that is a *very* >> unusual CPU board. The crystal runs at an arbitrary frequen

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 4:53 PM, Hal Murray wrote: > > > kb...@n1k.org said: >> Somewhere in the NTP algorithm, there is a “zero error” estimate. GPS >> modules have the same thing buried in them. A GPS module (like NTP as >> described above) can only *express* a PPS modulo some clock rate. GPS

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

nds like *IDN? > and *TST? > > On Mon, Apr 9, 2018, 12:24 PM Bill wrote: > >> I have two of these with 488 interfaces. >> Would appreciate any 488 info you get. >> br...@otelco.net >> >> -Original Message- >> From: Bob kb8tq >> Se

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 2:19 PM, Achim Gratz wrote: > > Bob kb8tq writes: >>> Similarly, the box should be able to give me a pulse at a known time. >> >> how do you set up NTP to do that? > > Not at all, that must be done in the kernel if you want any accu

Re: [time-nuts] Weird Stuff WareHouse shutting down

Hi > On Apr 9, 2018, at 9:30 AM, jimlux wrote: > > On 4/8/18 8:20 PM, Glenn Little WB4UIV wrote: >> The USB stuff has no front end and stability and calibration is highly >> questionable.. > I'm thinking here of the $1K sort of device - traceable cal, quite stable, > etc. > > Not the $20 RTL-

Re: [time-nuts] Cheap jitter measurements

Hi > On Apr 9, 2018, at 2:53 AM, Trevor N. wrote: > > Bob kb8tq wrote: >> Hi >> >> Without the ability to put out a “known good” time pulse there is no quick >> way to >> check NTP. GPS modules suffer a similar issue. They put out a pulse and a >&

Re: [time-nuts] ADEV dead time w/ HP 53131A & TimeLab

Hi The basic fact is that oscillators drift on *all* time scales. How much they drift depends on the type of oscillator. A free running VCO based on a PCB resonator will drift differently than a bare crystal oscillator. An OCXO will have different drift characteristics than a bare oscillator.

Re: [time-nuts] Cheap jitter measurements

Hi Without the ability to put out a “known good” time pulse there is no quick way to check NTP. GPS modules suffer a similar issue. They put out a pulse and a “correction” (sawtooth error) to tell you what they just told you. Doing the same sort of thing with NTP may be possible. Indeed the

Re: [time-nuts] Help improving impedance measurement by having a better clock

Hi I believe we are talking about material impedances here rather than electrical impedance. One of the weird things about this is that frequency (as in frequency accuracy) *can* be a contributor to the resultant error. Thus my original question about just what the concern actually is….. Bob

Re: [time-nuts] Cheap jitter measurements

Hi Ok, I’ll bite …. > On Apr 8, 2018, at 3:36 PM, Tom Van Baak wrote: > What do you mean by "jitter" and what do you really want to do? >>> I mean jitter as NTP defines jitter. Whatever that is. >> >> I think you need to figure out what you want to do so you don't fool >> yourself. >>

Re: [time-nuts] Tbolt temperature sensitivity.

Hi Back a while, I ran a fleet of TBolt’s and other GPSDO’s for quite a while. They all ran into HP counters to monitor the PPS outputs. I never saw any of them hit or slip at the 100 ns level. Indeed different GPSDO firmware does the time / frequency tradeoff differently. I’ve also run them ag

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

Hi Actually the manual is moot on any sort of remote control. The RS-232 section refers you to an insert in the back of the manual. I’d guess that the 488 stuff was done the same way. Nasty question: Are you sure you have the 488 option installed? It would not be the first piece of gear pro

Re: [time-nuts] Help improving impedance measurement by having a better clock

Hi I’m not at all sure that the clocks will really get into the measurements. The PLL does have jitter, but it has zero frequency error. One way to get around the whole issue is to use an outboard device with its own clock. 400 KHz is a bit high for the integrated audio ADC / DAC parts. Drop

Re: [time-nuts] TS2100 OCXO Conversion: Command exploration

Hi Piezo was in Carlisle rather than Carlyle PA. It was absorbed into the Corning / Oak empire almost 20 years ago. Corning / Oak amalgamated with Vectron a bit over ten years ago. Piezo was the original OCXO supplier on the TBolt boards. If it is a TBolt part, just like the later OCXO’s it w

Re: [time-nuts] Weird Stuff Warehouse shutting down

Hi Over the years, this has been the fate of a *lot* of surplus / goodie outfits. They have a “deal” on some property and that runs out. Sometimes it’s a sale with the neighborhood improving. Other times it’s the roof needing repairs and nobody sees the need to do them until it is way to late

Re: [time-nuts] Environmental sensor recommendations

Hi Just to be very clear about this issue: Your room temperature “moves” at a rate dimensioned in degrees / hour (like 2 degrees / hour) and the period should be out in the half hour to couple of hours range. Put another way, it’s a 1,800 to > 5,000 second sort of thing. Operating with typical

Re: [time-nuts] Environmental sensor recommendations

Hi Since the DAC is integrated into the *guts* (FPGA) on the board, there really isn’t a way to pull it out. There *might* be a way to feed it a better reference (which likely is the bigger issue). Since there are no schematics for a TBolt there’s not much of a way to do this or that. If you *

Re: [time-nuts] Cheap jitter measurements

Hi Whatever you want to call it (jitter / wander / noise / crud ), an Rb in a stable temperature environment ( a few degrees C per hour) will have “stuff” with the dimensions of nanoseconds when compared to a good GPS. A “normal” NTP setup with a crystal on the motherboard as it’s main flywhee

Re: [time-nuts] Environmental sensor recommendations.

Hi Thermocouples are *really* low output voltage devices at “normal” temperatures. That gets you in to fairly fancy measurement setups ( no “just strap it to an ADC input” stuff). They also require cold junction compensation. They measure offset temperature to that junction. You do a lot of wo

Re: [time-nuts] Environmental sensor recommendations

wrote: > > If you use an "interchangeable" NTC like > https://br.mouser.com/ProductDetail/US-Sensor/PS103J2 you can skip the > calibration part. > > Edésio > > On Thu, Apr 05, 2018 at 09:20:56AM -0400, Bob kb8tq wrote: >> Hi >> >> By f

Re: [time-nuts] Environmental sensor recommendations

Hi By far the highest resolution sensor you will come across is a thermistor. It also has a pretty narrow range in terms of maintaining high resolution. That’s fine for something with a target temperature ( OCXO oven) and not so fine for monitoring outdoor temperature year round. If you want

Re: [time-nuts] new longwave time service planned in India

Hi It’s also *way* cheaper than putting up your own satellite based timing and navigation gear. I suspect that the whole “what if this or that set of sat’s have issues?” thing is beginning to sink in …. Bob > On Apr 4, 2018, at 2:47 AM, Poul-Henning Kamp wrote: > > > In message

Re: [time-nuts] quartz / liquid nitrogen

Hi If the objective is great phase noise far removed from carrier, there’s a gotcha. Let’s say you have a 10 dbm source at room and it’s broadband is at KTB of -174 + 1db. That gives you -183 dbc. You cool your oscillator to whatever and KTB goes down to -194. You do a bang up job at that temp

Re: [time-nuts] Cheap jitter measurements

Hi I would add the HP 5335 to the list of counters to look for. The surplus market can be really weird. A 5334 *should* be less than a 5335, but on any given day, that may not be true. The 5370 and 5345 are also worth looking for. Target price (at least for me) wold be < $150 for a quick buy a

Re: [time-nuts] quartz / liquid nitrogen

Hi > On Apr 2, 2018, at 11:18 PM, jimlux wrote: > > On 4/2/18 1:39 PM, Hal Murray wrote: >>> If not Nitrogen, how about dry ice (-109F -78C)? >> Dry ice is relatively easy to get. It wouldn't be hard to try a quick >> experiment. > > > CTE mismatch in packages will be a significant problem -

Re: [time-nuts] quartz / liquid nitrogen

Hi > On Apr 2, 2018, at 5:38 PM, Attila Kinali wrote: > > On Mon, 2 Apr 2018 12:46:26 -0700 > "Tom Van Baak" wrote: > >> Has anyone tried running a quartz oscillator at liquid nitrogen >> temperatures: -196 C (-321F, 77K)? It's probably impractical commercially, >> but maybe something of v

Re: [time-nuts] quartz / liquid nitrogen

Hi If you dig back in the FCS archives, you will find papers on “cold” OCXO’s. You also will find papers on cryo cooled quartz. The bottom line appears to be that if you are going to all the trouble of cooling things, sapphire (or other exotic materials) are a better bet. Quick simple answe

Re: [time-nuts] GPS ANTENNA

t;> Dave >> >> -Original Message- >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob >> kb8tq >> Sent: 01 April 2018 14:43 >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] GPS ANTENNA

Re: [time-nuts] GPS ANTENNA

> Subject: Re: [time-nuts] GPS ANTENNA > > An unusual attenuator with a DC pass. > > On Sun, Apr 1, 2018 at 10:21 PM, David C. Partridge > wrote: >> Or use a choke ring survey antenna and an attenuator :) >> >> Dave >> >> -Original Message- >

Re: [time-nuts] New GNSS chipsets

Hi > On Apr 1, 2018, at 9:47 PM, Hal Murray wrote: > > > mag...@rubidium.dyndns.org said: >> I have advocated for receivers able to handle multiple frequencies and >> multiple GNSS for some time, sneaking it into documents, so there should be >> some preparations for this now. > > How well d

Re: [time-nuts] New GNSS chipsets

t been widely available at rational prices. Hopefully the > new "9" series will be, also. As for the ST Micro, I haven't a clue, but > considering how their microcontrollers are so widely available from China, > who knows what will happen. > > Joe Gray > W5JG >

Re: [time-nuts] GPS ANTENNA

t; -Original Message- >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq >> Sent: 01 April 2018 14:43 >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] GPS ANTENNA >> >> Hi >> >> Indeed

Re: [time-nuts] New GNSS chipsets

Hi I’d bet a warm glass of beer ( pick up only, no free delivery ) that you will not see them in user level modules ( = something you can fire up) at a rational price ( < $500) for quite a while ( = years …). The target market is integration in self driving / autonomous vehicles. If you ar

Re: [time-nuts] GPS ANTENNA

Hi Indeed, it is *very* easy to put to much gain in front of a timing GNSS receiver. These beasts are trying to dig out a signal that you can’t even see with a spectrum analyzer. It’s way to far below the noise floor to detect that way. They optimize things pretty tightly to get that done (and

Re: [time-nuts] TV Signals as a frequency reference

Hi To a great extent it depends on who was running the tech side of things. If the guy in charge dug into it, they may have had a pretty fancy timing setup. If it was a “don’t bother / don’t dig / not very broken” sort of thing, the setup may have been pretty crazy. Bob > On Mar 31, 2018,

Re: [time-nuts] TV Signals as a frequency reference

Hi My comments really were a bit brief…. indeed there *are* clocks in the modern signals. Those clocks come over as part of the signal you get. The must be a way to build something that would get at those clocks. You still have the same basic issue as with the “old” signals. Does it go through

Re: [time-nuts] TV Signals as a frequency reference

Hi > On Mar 30, 2018, at 6:13 PM, Hal Murray wrote: > > > fgr...@otiengineering.com said: >> Now that analog TV has gone away, so >> have these signals. > > What do the local TV stations use for a frequency reference? Anything from a crystal oscillator to a Cs standard. It’s very much a “

Re: [time-nuts] WWV/CHU

Hi > On Mar 30, 2018, at 12:42 AM, Hal Murray wrote: > > > jim...@earthlink.net said: >> Hal, you should know better than to have a question like "get time" on this >> list without specify the precision and accuracy . > > I was thinking of measuring the results, and maybe comparing vario

Re: [time-nuts] WWV/CHU

Hi There are a *lot* of HF receiver gizmos out there these days. Is $5 to much to spend? Does the budget make it up to $300? Do you want to pick up *every* time transmission at once? (as constrained by propagation). For something like 5 MHz / 10 MHz WWVB plus CHU, there are $20 demo boards th

Re: [time-nuts] WWV/CHU

Hi If you are running 10 MHz as your lab standard, you *will* have 10 MHz floating around. Add to that various 10 MHz OCXO’s here or there on the bench and you have even more odd stuff right at 10 MHz. Yes, if you run triple shield coax for your standard lines and your antenna is 1000’ from yo

Re: [time-nuts] Teardown of Chinese made eBay GPS antenna.

Hi So, after only two months in transit my examples of the “Chinese GPS Antenna” are here to poke at. They are from www.stotoncn.com and are labeled as being their part number GN-GGB0710. They clearly show 3.3V to 18V as the operating voltage on the box they came in a

Re: [time-nuts] Setting correct date on Trimble Thunderbolt receiver

Hi > On Mar 28, 2018, at 12:10 AM, Mark Sims wrote: > > Lady Heather's automatic rollover fixer works by looking at the year in any > time message that it sees. If it sees 10 consecutive year values less than > 2016, it assumes the receiver has rollover issues and then adds 1024 weeks > w

Re: [time-nuts] What does determine the short term stability of an Rb vapor cell standard?

Hi > On Mar 26, 2018, at 2:18 AM, Attila Kinali wrote: > > On Sun, 25 Mar 2018 15:28:10 -0400 > Bob kb8tq wrote: > >> Well, magnetic shielding, temperature coupling between cells, photo detector >> noise floor, phase noise of the various signals, basic stability of

Re: [time-nuts] What does determine the short term stability of an Rb vapor cell standard?

Hi > On Mar 25, 2018, at 9:18 AM, Attila Kinali wrote: > > Moikka moi, > > In the past, it has been again and again claimed that the HP 5065 has > such an outstanding short term stability because of its large vapor cell. > But the more I read, the less I believe this. E.g. if you look at the

Re: [time-nuts] WWVB Antenna revisited/Spectracom 8182

Hi There is a *lot* of analysis on the WWVB change in the archives. The bottom line seems to be that the change did not impact wall clocks and watches. The number of companies running WWVB phase synchronous gear *appears* to have been near zero at the time of the change. There certainly was no

Re: [time-nuts] WWVB Antenna revisited/Spectracom 8182

Hi You should DC block the output of the 8182 if you are going to run it straight to an antenna. The bigger issue is that WWVB changed their transmit format a couple years ago. The signal they now send is not compatible with a lot of gear out there. It turns out that the 8182 is included on th

Re: [time-nuts] Use the LT3042 for retrofit?

Hi The gotcha is not on the manufacturing end. When you show up with a dual ground pin part, the OEM asks: Where do I tell the PCB layout guys to put the other ground? The answer always comes back to “there’s only one ground plane, they will both connect to the same plane.”. If you get past th

Re: [time-nuts] Use the LT3042 for retrofit?

Hi You can either do the math … yuck …. or just try it. It turns out that with a “normal” sort of EFC sensitivity (< 1 ppm / V) on a “normal” frequency OCXO ( <30 MHz) , the voltage can have a bit of noise on it and the phase noise of the device will not suffer. Simply put - you can run it wi

Re: [time-nuts] Looking for information on True Position GPSDO.

Hi If you *do* go swapping around OCXO’s (or whatever) on a GPSDO board, it’s very nice to be able to change the internal “magic numbers” to get the control loop running properly again. The TBolt kind of spoiled us all in that regard. Most GPSDO’s are not very user friendly in this regard ( = y

Re: [time-nuts] ULN regulator with more current capability than LT3042?

Hi Getting the heat off of the regulator package may have other benefits ( like improved stability). A lot depends on just where the heat goes in each case ….. Bob > On Mar 18, 2018, at 4:41 PM, Gerhard Hoffmann wrote: > > > > Am 18.03.2018 um 21:13 schrieb John Ackermann N8UR: >> Reviving

Re: [time-nuts] Furuno GT-87

Hi I wonder if they will ever get around to dropping the “Galileo with firmware update” statements from *all* there spec sheets for the GT-87 and Opus-7 devices…… There has always been the basic issue of *how* an end user would be able to get such an update. Furuno does not seem to have a chan

Re: [time-nuts] EFTF 2018

Hi Highly recommended. I probably would not go on a yearly basis though …. Bob > On Mar 16, 2018, at 1:14 PM, Dana Whitlow wrote: > > Speaking of forums etc, does anybody in Time-Nuts attend anyof the > NIST Time and Frequency Seminars? I'm wondering if I'd get > much from it. > > I've thoug

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