Re: [time-nuts] leapseconds, converting between GPS time (week, second) and UTC

Hi Welcome to yet another chapter in the very long book “why leap seconds are bad”. There are a lot of posts going into may of the ways they messes up code and updates. Keeping a library up to date with a leap second that might be a few months out …. yikes ….. Recompiling all your code (if

Re: [time-nuts] Ublox F9P multi-band GPS receiver

. One would *assume* the F9P does the same thing. It never seems to show up in quite the same big bold print…. Bob > On Jan 21, 2019, at 8:44 AM, Bob kb8tq wrote: > > Hi > > >> On Jan 21, 2019, at 1:41 AM, Mark Sims > <mailto:hol...@hotmail.com>> wrote: >>

Re: [time-nuts] Ublox F9P multi-band GPS receiver

3.89 more than a >> ZED-F9P. I would have gladly paid $14 more for a version of the >> SparkFun board using the T(iming) version instead :(. >> >> On Mon, Jan 21, 2019 at 12:10 AM Bob kb8tq wrote: >>> >>> Hi >>> >>> From a *v

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi To be more precise, what you want is a L1/L2/L5 triple band antenna. Bob > On Jan 21, 2019, at 11:32 AM, Bob kb8tq wrote: > > Hi > > Based on the F9P data sheet, you will need an L1 / L2 antenna that is wide > enough > to get the Galileo E5B as well as the Glonas

Re: [time-nuts] Ublox F9P multi-band GPS receiver

2C.. > > Ole > >> 21. jan. 2019 kl. 17:32 skrev Bob kb8tq : >> >> Hi >> >> Based on the F9P data sheet, you will need an L1 / L2 antenna that is wide >> enough >> to get the Galileo E5B as well as the Glonass L1OF and L2OF bands. The >&g

Re: [time-nuts] Ublox F9P multi-band GPS receiver

nnections on the bottom > of the new chip), but it seems like the actual electrical interface is > probably the same in the important ways, so it might be possible to make an > adapter board, maybe... > > -j > > On 1/21/19 8:32 AM, Bob kb8tq wrote: >> Hi >>

Re: [time-nuts] Ublox F9P multi-band GPS receiver

> > On 21/01/2019 12:33 PM, Bob kb8tq wrote: >> Hi >> >> To be more precise, what you want is a L1/L2/L5 triple band antenna. >> >> Bob >> >>> On Jan 21, 2019, at 11:32 AM, Bob kb8tq wrote: >>> >>> Hi >>> >>>

Re: [time-nuts] Ublox F9P multi-band GPS receiver

f 3.3V. Depending on which part of the page you read it will cover (or might cover) everything on all of the bands. Bob > On Jan 21, 2019, at 2:44 PM, MLewis wrote: > > Like these? > http://www.tallysman.com/index.php/gnss/products/antennas-triple-band/ > > On 21/01/2019 12:33 PM

Re: [time-nuts] Ublox F9P multi-band GPS receiver

; The one thing which is missing is a external frequency input. You can get a > frequency output in its place, but it does not fully replace the input. > That's where the module vs. chip comes in. > > Very tempted to try one out. > > Cheers, > Magnus > > On 2019-01-22 01:

Re: [time-nuts] Help with Novatel OEM6 external oscillator

Hi Simple answer is: 1) (assuming you just want GPS) to try each of the settings and see what gives you the best signal to noise. I’d bet they have very little impact if you have a good oscillator. 2) If you are building a GPSDO, the only useful setting is USER. There it’s a matter of

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi From a *very* quick read of the doc’s: 1) The device *does* have a position hold capability 2) There is some level of data on the time pulse. It it only 1 ns resolution? 3) It does appear to support Galileo and Glonas in addition to GPS. 4) It is clearly multi-band for GPS. It is

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi The only gotcha I see on that part is the gain spec. If the module really does need 30 to 40 db of gain ahead of it, that antenna does not quite make it. That’s with zero cable loss. Tack on a typical chunk of cable with 6 db of loss and you are even further outside of the uBlox

Re: [time-nuts] Ublox Neo M8T no output on TP2 question please?

Hi This has swung over to the “is it legit” / supported question. What’s below is *only* in reference to that part: There are various levels of “legit” when it comes to these modules. Some are 100% uBlox produced units with flash code. Some are equally 100% uBlox, but have the firmware in

Re: [time-nuts] Modern signal generators

that “good enough” may be way far away from “pretty good” and yet even more distant from “as good as it gets”. The question on any system is always “how good do you need / what are you doing?” …. Bob > On Dec 12, 2018, at 8:49 AM, jimlux wrote: > > On 12/11/18 3:26 PM, Bob kb

Re: [time-nuts] Modern signal generators

Hi I don’t know if it’s expected / surprising / alarming, but a lot of pretty well respected amateur transceivers have the SiLabs parts buried in the heart of their “synthesizer” section. Cost (obviously) is an issue in any design. That said, they seem to be “good enough” that the designers

Re: [time-nuts] SiT5155 GNSS/GPS VCTCXO modules

Hi It would be nice to see an ADEV plot if indeed GPSDO use is a target market. Bob > On Dec 18, 2018, at 2:02 PM, Russ Ramirez wrote: > > A new part at Digikey that looks promising for disciplined oscillator > designs. > > https://www.sitime.com/datasheet/SiT5155 > > Russ > K0WFS >

Re: [time-nuts] question about multi-way measurement

Hi One simple answer is that it’s not always 1:1 comparisons. The “three corner hat” approach is indeed used to compare three devices at one time. There are some issues with doing that. There are *lots* of papers on where the limits come from and what you need to do ( = pick fairly similar

Re: [time-nuts] Modern signal generators

Hi There are I2C versions that can be set to “any frequency”. That’s what people are using for synthesizers in radios. Again - one can debate just how good an idea this all is. Bob > On Dec 11, 2018, at 1:23 PM, Richard (Rick) Karlquist > wrote: > > > > On 12/11/2018 9:13 AM, djl

Re: [time-nuts] Modern signal generators

Hi As I said, just how rational using these parts in a radio …. not at all clear to me. Back when I went to school, stuff that was this noisy was not in the “greatest” category. That was a *very* long time ago. Oddly enough best performance synthesizers have gotten better. (as the posted

Re: [time-nuts] HP Cesium Standards in the International Atomic Time Scale, the legend of Felix Lazarus, and the "top cover

Hi There *are* people who get really surprised when a part they last bought in 1968 comes back with a “no bid” to their inquiry for spares ….. Bob > On Dec 23, 2018, at 7:48 PM, jimlux wrote: > > On 12/23/18 4:20 PM, Richard (Rick) Karlquist wrote: > >> With 20:20 hindsight, I can

Re: [time-nuts] HP Cesium Standards in the International Atomic Time Scale, the legend of Felix Lazarus, and the "top cover

Hi The gotcha is - if you have a very unique part in a device and it goes away, how many years of stock do you buy on the “last chance” order? In the case of the 5071, I’d bet a pretty good brand of six pack that nobody on the planet would have guessed 20 years ago that it still would be in

Re: [time-nuts] HP Cesium Standards in the International Atomic Time Scale, the legend of Felix Lazarus, and the "top cover

Hi Indeed back at Motorola, a lot of that stuff got transferred into the engineering stock room after a while. Just how that worked out budget wise …. one wonders …. Bob > On Dec 24, 2018, at 11:53 AM, jimlux wrote: > > On 12/24/18 5:36 AM, Bob kb8tq wrote: >> Hi >> T

Re: [time-nuts] simple phase finder

Hi > On Dec 5, 2018, at 8:45 AM, jimlux wrote: > > On 12/5/18 5:39 AM, Poul-Henning Kamp wrote: >> >> In message <4a8ff8d6-70b2-782e-cb79-21c7e9a49...@earthlink.net>, jimlux >> writes: >>> If I were decoding WWVB to start, I'd break my samples up into 0.1 >>> second or 0.5 second

Re: [time-nuts] new WWVB BPSK dev board

Hi The I2C clock rate is going to matter a bit in terms of what you can achieve. Since the device is targeted at low power, the max practical baud rate may not be very high. I2C can have a lot of wait in it ... There are a lot of registers dumped after each “reception attempt”. There also is

Re: [time-nuts] simple phase finder

that claim sub-500KHz coverage. Many of them have been so deaf down there as to be completely useless. The signals are fairly strong, but indeed the radios have been very deaf …. It’s not just about the antenna. Bob > On Dec 5, 2018, at 9:51 AM, jimlux wrote: > > On 12/5/18 6:32 AM, Bob kb

Re: [time-nuts] new WWVB BPSK dev board

Hi We’ve been chatting about how drop dead simple it is to spend a couple minutes and come up with a SDR for the new modulation for …. ummm ….. errr …. how many years now? :) So far not a lot has turned up. Bob > On Dec 4, 2018, at 3:14 PM, Poul-Henning Kamp wrote: > > > In message

Re: [time-nuts] new WWVB BPSK dev board

Hi So, backing off a bit: Assuming you are going to compare two data points a bit over 24 hours apart (100,000 seconds): Accuracy of reading pairResult pp Result sci 100 ms 1 ppm 1x10^-6 10 ms

Re: [time-nuts] new WWVB BPSK dev board

Hi Again to re-go over what has been said in the past: Unless they start filling the “extra” bits on the WWVB signal with something (are they doing this ) the whole modulation pattern is predictable. Once you know what time it is “now” what happens from then on can all be calculated. I

Re: [time-nuts] new WWVB BPSK dev board

Hi The “good sound card” in this case is indeed not quite as easy to find as one might think. Most people playing with audio rarely are concerned once you get past 20KHz or so. Finding a card that stays quiet past 40 KHz can be tough. Even on a 192 KHz card, one can find anti-alias filters

Re: [time-nuts] Trueposition Antenna Location

measure with what I already have. I don't have a TIC. > > Regards, > > Mark > > > On Mon, Dec 3, 2018 at 5:10 PM Bob kb8tq wrote: > >> Hi >> >> Let’s back up a bit: >> >> The input to an ADEV calculation is a record of phase (time betwe

Re: [time-nuts] new WWVB BPSK dev board

Hi The interference “front” turns out to be over the US rather than over the UK. Power, distance, and propagation all get into the “why”. The answer is that you get crazy fades and phase shifts as a result. Bob > On Dec 3, 2018, at 9:20 PM, Paul Bicknell wrote: > > Hi All > > There is a

Re: [time-nuts] Trueposition Antenna Location

should result in the same FFT window time and check > that. > > I'm scratching my head here. > > Regards, > > Mark > > > On Mon, Dec 3, 2018 at 6:28 AM Bob kb8tq wrote: > >> Hi >> >> ADEV is pretty well documented and the results should *not

Re: [time-nuts] Trueposition Antenna Location

it a few times in the next few days and will also try to move > the antennas to a location with lower multipath. > > Thanks for the suggestions, > > Mark > > > On Sun, Dec 2, 2018 at 2:16 PM Bob kb8tq wrote: > >> Hi >> >> Looking at the data, I’m g

Re: [time-nuts] Ashtech Z12T

to get with our high performance cesium about 5. 10-13 . Offset is > for us without any utility. > You spoke about Novatel boards ; can you please explain more. > > JFP > > > > > -------- > On Wed, 11/28/18, Bob kb8tq wrot

Re: [time-nuts] Trueposition Antenna Location

Hi Looking at the data, I’m guessing the slower sample rate was done last. If so, you may not be letting the GPSDO’s “warm up” long enough. Most designs take days (if not weeks) to get to their ultimate stability. Bob > On Dec 2, 2018, at 11:16 AM, Mark Goldberg wrote: > > I broke down and

Re: [time-nuts] Project GREAT - Galloping Galileo version

lux wrote: > > On 12/9/18 7:08 AM, Bob kb8tq wrote: >> Hi >> On a normal OCXO or TCXO design you would put the product in a >> package with a hermetic outer wall to keep out crud and moisture. >> Per the papers cited you would put a small vent hole in a “space grade” >

Re: [time-nuts] Project GREAT - Galloping Galileo version

on picking up a thermal vac chamber …. How different is the performance with air in the package? It turns out to be very much a “that depends” sort of thing. Usually not as big a deal on a TCXO as on an OCXO. Bob > On Dec 8, 2018, at 9:29 PM, jimlux wrote: > > On 12/8/18 4:52 PM,

Re: [time-nuts] Project GREAT - Galloping Galileo version

Hi You might be surprised by how well the CSAC does in orbit. There have been a lot of cases over the years where a device has done much better once it is away from “poking fingers” like pressure and other semi-random stuff …. Bob > On Dec 8, 2018, at 1:49 PM, jimlux wrote: > > On 12/8/18

Re: [time-nuts] Comparing the performance of 17 different GPSDOs

Hi At least the HP boxes run through a series of filter settings and do a pretty good job of handling the “lack” of SA. The one thing that is very apparent in the TDEV data on the 3801 is the lack of sawtooth correction. I suppose you could call that a SA optimization that no longer is on the

Re: [time-nuts] new WWVB BPSK dev board

Hi Given the large “fade” of WWVB over a 24 hour period (it’s not always ground wave ….) most decent receivers in the past have run a front end with AGC on it. Indeed 24 bit ADC’s ( > 16 bit ENOB) are out there for not a massive amount of money. It is a bit unclear just how much fade you

Re: [time-nuts] WWV Doppler Shift

Hi Having looked at WWV with a Carrier -> BFO -> audio card approach (and a radio locked to an Rb standard …) you have dig a bit to find a situation that is beyond a tenth of a ppm. If you average over minutes or tens of minutes (which is exactly what you do with WWVB) the only time you get

Re: [time-nuts] WWV Doppler Shift

Hi > On Nov 21, 2018, at 12:12 PM, Tom Van Baak wrote: > > Donald E. Pauly, WB0KVV wrote: >> Ft Collins is at 5,003 ft and clocks there run fast by 1.663·10^-13. >> (g/c^2)/meter) compared to sea level. How did you correct for >> altitude on yours? I presume that frequency is defined at sea

Re: [time-nuts] TimeSource 2500

Hi Do you have good reason to believe that it’s not DOA? It’s been a *long* time since these were common on the surplus market. I would not be real surprised to find that what’s floating around has been through several owners at this point. Bob > On Nov 21, 2018, at 6:05 PM, Dmitry Khorkin

Re: [time-nuts] New very small OCMO

Hi Ovenized MEMS oscillators have been around for quite a while. They go back at at least a decade and likely quite a bit further. Bob > On Nov 16, 2018, at 12:03 PM, Chris Caudle wrote: > > I did not see any mention of this on the list. Could be interesting in > some contexts: >

Re: [time-nuts] Short term 10MHz source

Hi Next we would need LH support for three TICC’s to do three corner hat …. :) Maybe a module for each TICC ….. Bob > On Jan 8, 2019, at 2:37 PM, Magnus Danielson wrote: > > Hmm... and idea. > > For some GPSDOs you get a PPS and is "raw" from GPS module and not > resynthesized from the

Re: [time-nuts] Short term 10MHz source

Hi A very software defined radio centric way to look at the same thing: If you have a SDR with a noise free front end and a perfect ADC, the radio may be deaf. Small signals come in and no bits are toggled. That’s what you get on the “phase locked” channel in the TIC. (yes this assumes the

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

Hi Pretty much every DVM out there spits out more digits than make sense accuracy wise. It certainly makes sense to note in the doc’s what the accuracy / resolution of the device is. Keeping the extra digit does not cost anything in this case. It *might* come in useful if somebody spent the

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

Hi For a quick dive into the basics of what has to happen in order to get more bits from an ADC when decimating: http://www.ti.com.cn/cn/lit/an/snoa232/snoa232.pdf Is a free on the internet source. There are somewhat better (and more

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

Hi In the case of most typical downconversion setups, the samples are tossed out by the filter. If you put 1,000 samples into a CIC decimator and it is a 1000:1 device, only one sample comes out. I signal processing it is called a decimator none the less. Bob > On Jan 10, 2019, at 1:24 PM,

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

Hi Separate reply because it is a very different case: If you are doing ADEV for longer tau, you *do* indeed use case A. You simply throw away 9 out of 10 samples when going from 1 second tau to 10 seconds. There are a number of papers out there on just why this is the correct thing to do in

Re: [time-nuts] Short term 10MHz source

Hi It’s a cool little time interval counter: https://www.tapr.org/kits_ticc.html It’s one of a number of very useful TimeNut gadgets we can thank John Ackermann, our list administrator, and others for designing. Bob > On Jan 5, 2019, at 7:35 AM, Paul

Re: [time-nuts] Portable Time Standard

Hi The most common approach to “monitor” a quartz movement is to listen to it at 32,768 KHz with a tuned microphone. If it is an analog movement, then one can detect the sound of the motor driving the mechanical side. Do you need a device with a visual readout or are you after something that

Re: [time-nuts] Short term 10MHz source

Hi The “kit” comes fully assembled / tested and ready to go. Indeed see your local 3D printer for a case. Bob > On Jan 8, 2019, at 10:31 AM, W7SLS wrote: > >>> "Kits: TICC Timestamping/Time Interval Counter” >>> https://www.tapr.org/kits_ticc.html > > Is

Re: [time-nuts] Short term 10MHz source

Hi Use the Rb as your reference and log the time offset of its PPS. Manually steer vs a 10 hour GPS PPS data set once a week. You probably will stretch it out to a couple weeks after things settle in. More or less: PPS starts at some offset. Call that zero. As the days go along: PPS goes

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

Hi Most of the traditional rules about phase noise apply out to 10 or 20% of the “carrier” frequency. If the carrier is 1Hz, then you are talking about the traditional definitions holding out to 0.1 or 0.2 Hz relative to carrier. That’s *deep* in the 1/F noise part of the divider’s “noise

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

Hi Coming back to the basics of the design: If you are playing with a normal radio, a BFO that drifts under a few Hertz is going to be pretty much un-noticable. Drift is a bit of an elastic term in this case since it can cover a bunch of different parameters on an oscillator (temperature as

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

encies from > the 1PPS from GPS receivers. I don't know much the architecture of GPS > receivers, but it seems > to me it would sure be nice if there were some convenient way to extract a > clean signal at the > chipping rate, for use in generating standard reference frequencies. > &

Re: [time-nuts] Project GREAT - Galloping Galileo version

Hi What, no 0.046 +/- -.002” vent hole? That used to be a requirement on this sort of thing. Bob > On Dec 8, 2018, at 6:35 PM, jimlux wrote: > > On 12/8/18 11:30 AM, Bob kb8tq wrote: >> Hi >> You might be surprised by how well the CSAC does in orbit. There have be

Re: [time-nuts] Trueposition Antenna Location

Hi There are lots more issues to GPSDO stability than just antenna placement. Indeed you are correct that a location that keeps you out of holdover is a must. Ideally you want to be able to lock on to 4 sats at all times. That generally equates to being able to “see” something in the > 6 range

Re: [time-nuts] SiT5155 GNSS/GPS VCTCXO modules

to tame …. The result would be a bit “faster” loop that lets a bit more of the GPS noise through. Bob > On Dec 19, 2018, at 2:16 PM, Achim Gratz wrote: > > Bob kb8tq writes: >> It would be nice to see an ADEV plot if indeed GPSDO use is a target market. > > The common da

Re: [time-nuts] Minicircuits SYPD-1

Hi There have been several threads on the SYPD-1 and it’s cousin in a different package the RPD-1. Both are designed targeted as phase detectors rather than mixers. While you can never say “always” the best performance generally is to drive both RF ports hard from matched sources. Terminate

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi No need to hurry on the L5 GPS data writer if the F9 is the issue. It does not (at this point) do GPS L5. It will do L1 / L2C but the L5 box is grayed out. It should do E5 if you have the right antenna. Since there is an L5 box there in uCenter, one would guess it might come along eventually

Re: [time-nuts] Ublox F9P multi-band GPS receiver

ironic > that the most knowledgeable guy on Ublox support forum is not even affiliated > with the company. > > Their products are amazing for what they cost but I'll switch at a drop of a > hat when something worthy comes along. > > Leo > >> From: Bob kb8

Re: [time-nuts] Frequency standard

Hi What are the alternatives: 1) If you are doing it by ear and listening to WWVB beats and fading, something around 0.1 ppm (one hertz at 10 MHz) is doing pretty well. I suppose if you lived in Ft. Colins you could do better. 2) A typical OCXO in a counter will drift and age. Depending a

Re: [time-nuts] Ublox F9P multi-band GPS receiver

millions of dollars to re-shoot those masks. Bob > On Jan 25, 2019, at 9:58 PM, MLewis wrote: > > On 25/01/2019 7:56 PM, Bob kb8tq wrote: >> ... >> >> Doing a buy on the F9T might be easier if the part actually existed ….. >> Right now it is still in the &g

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi On a “chip" based setup like this, it’s a matter of pulling the TCXO and putting in some wires. Whatever frequency the TCXO used to supply, that’s what your magic external device needs to provide. The designers do not seem to allow you to provide a variety of input frequencies. Given how

Re: [time-nuts] Ublox F9P multi-band GPS receiver

Hi It’s only a two band device for each system as far as I can see. Even if you *could* do both GPS L2 and GPS L5, you would have to pick one or the other. Like a lot of this that’s about as clear as mud …. Right now the number of sat’s doing this and that makes the choice of L2 pretty easy to

Re: [time-nuts] Frequency standard

Hi So what’s the downside to all this: Keeping an OCXO (and counter) turned on 24 hours a day, 365 days a year burns power. If you also live in air conditioning land, you pay even more to get rid of the heat from the power. Sit down and do the math. You likely will find this is not as cheap

Re: [time-nuts] Rooftop antenna and splitter

Hi With things like the uBlox F9 now out on the market cheap …. I would go with an antenna that will do L1 / L2 / L5 and work with everything that it up there. You still are in the “under $100” range (delivered) for new product from China. It’s a good bet that the guts of all of them are made

Re: [time-nuts] PPS clock module

Hi I don’t think anybody runs a clock off of a PPS :) That would be nutty …. The closest I have seen is to womp up a “pulse 60 times” gizmo. Drive that off of the PPS. Feed the output into something designed for use in a bedside clock. I’d guess an 8 pin PIC and a few (dozen) lines of code

Re: [time-nuts] Rooftop antenna and splitter

tually seen commercial antennas where resistors > were added (before LNA) to improve antenna return loss! > > On 27.01.19 14:28, Bob kb8tq wrote: >> Hi >> >> With things like the uBlox F9 now out on the market cheap …. I would go with >> an antenna that will do L1

Re: [time-nuts] Connector help?

Hi Yes I know, this is beating a dead horse ….. Since the HP splitter will knock out everything that is not right on top of GPS, are you sure you want to go that route? Yes it does depend a bit on the antenna. If it’s one of the telecom / narrowband gizmos then the splitter will not have much

Re: [time-nuts] 4.19 MHz xtal

Hi Simple answer is that it likely is an AT cut crystal. You can get a 1 ppm-ish sort of stability over 0 to 50 C out of an AT. The 32 KHz crystal you sort of expect to see likely has a couple hundred ppm-ish stability over the same temperature range. 32 KHz crystal have been the norm in

Re: [time-nuts] Rollover: Thunderbolt

gt; > On Sun, Mar 31, 2019 at 10:00 PM Bob kb8tq wrote: > >> Hi >> >> Pretty much all of the GPSDO’s on eBay are long past their “end of >> support” date. In a lot of cases, even >> when “in support” free updates were not available, even to OEM customers. >>

Re: [time-nuts] Yet another GPSDO project.

ation delay of the logic producing this delay is not accurately known, > the delay is not 300ns but 300ns + some offset, isn't it? > > > Tobias > HB9FSX > > > From: time-nuts [time-nuts-boun...@lists.febo.com] on behalf of Bob kb8

[time-nuts] F9T Info

Hi Looks like uBlox has released the basic info on the protocols and interfacing of the F9T. https://www.u-blox.com/en/product/zed-f9t-module#tab-documentation-resources There are still a few documents referenced in what they did release that have not yet popped up on the web site. Still

Re: [time-nuts] F9T Info

Hi There are two programs that I am sure can communicate correctly with the F9T. 1) The ever popular Lady Heather (in the current beta). Thanks Mark !!. 2) The uBlox supplied uCenter program from version 19 on. I *suspect* that other programs can / will soon communicate as

Re: [time-nuts] Lars GPSDO

e. I see Digi-Key has a service where you buy the > chip and they will deliver it soldered to a breakout board for a few $ > extra. I may give that a try > > On Fri, Apr 5, 2019 at 5:21 PM Bob kb8tq wrote: > >> Hi >> >> If you do decide to play with the AD5680, be

Re: [time-nuts] Lars GPSDO

Hi If you do decide to play with the AD5680, be careful of the “tone” on the output at about 180 Hz. You might also want to check the noise inside 100 Hz since the spec sheet is of no help there. If the 180 Hz is the third harmonic of something much larger at 60 Hz …. yikes ….. Since there

Re: [time-nuts] Lars GPSDO

Hi One thing that may well help in terms of internal bias resistors on an OCXO is that they often are inside the ovenized section of the device. There’s no guarantee of course. If you have an effective thermal gain “in the hundreds”, a common 50 ppm/C resistor set would get down to a

Re: [time-nuts] Lars GPSDO

Hi One thing to watch out for on any OCXO, but more on ones with crazy large tuning ranges: As the OCXO changes temperature, it’s current draw changes. It’s amazing just how much voltage drop you get in some seemingly well laid out boards when this occurs. The gotcha is that a “bias it up” with

Re: [time-nuts] GPS week rollover

Hi Obviously the real answer is going to be “that depends”. Back when I worked for a living, we had an HP generator that would “play back” a recorded ~ 30 minute set of GPS “full sky” observations. It was strictly a playback with no real way to tweak this or that. We also had a single

Re: [time-nuts] GPS week rollover

Hi If you want it to behave like a signal generator ( variable output level) that also is another rabbit hole to run down. Since the signals are well below the noise after full spreading (and not all that strong before spreading) it takes some care to get that right. On a production basis,

Re: [time-nuts] GPS-SDR-SIM

Hi The GPS ephemeris stuff is in there as are the almanacs. They are in a weird location. Last time I grabbed them it took more looking than it should have. The gotcha is that all of them are for the past. If you are trying to test for future events, they aren’t going to be of much use. Also

Re: [time-nuts] Absolute time accuracy pre-Cesium?

Hi TIme is “just a number”, it has no inherent granularity. If you need to measure at the 10^-?? level, the units will not be the problem. Coming up with a device that provides 10^-15 or 10^-18 sort of stability (let alone accuracy …. yikes ….) would take a pretty big limit on your charge

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

Hi I randomly came across: Publications of the United States Naval Observatory January 1, 1900 U.S. Government Printing Office Which turns out to be a Google E-Book. It goes into some detail about just how the transit data contained in it was obtained. For the (free) price it’s worth taking a

Re: [time-nuts] Yet another GPSDO project.

Hi How much impact your distribution setup has on the OCXO phase noise depends a *lot* on how quiet the OCXO is. If it is in the -170 dbc/ Hz range, then pretty much anything can mess up the phase noise …. Bob > On Mar 27, 2019, at 5:05 PM, Tobias Pluess wrote: > > Hi Leo, > > sorry for

Re: [time-nuts] multimeter

Hi Also depends a bit on why you are shopping. If the answer is “lost the second one this year” then the debate over holding calibration likely isn’t of much relevance. If the answer is that the nixie tubes in the prior unit finally got to dim to read …. not quite the same issue. Bob > On

Re: [time-nuts] F9T ADEV

Hi The F9T seems to really like the 4072.1 “uBlox” message. Since you can only get that from an F9T …. that’s that. Of course if you are not looking for the differential timing mode, that may not be a big deal. Probably of more interest than the base / rover timing is the dual frequency

Re: [time-nuts] Oscillator Aging Trends

Hi Very nice plots and some useful information. At some point the question becomes what the 8607 is doing. Both are seeing changes in temperature (and pressure). Eventually that will get into the picture. From the plots so far …. not so much yet. Will we be getting weekly updates for the

Re: [time-nuts] Good clean-up oscillators

circuit fed by a temperature compensation network of some sort. That and the lack of thermal buffering are what degrade the close in performance when you *do* use a fancy crystal. Bob > On Feb 18, 2019, at 10:24 AM, Attila Kinali wrote: > > On Wed, 23 Jan 2019 17:31:04 -0500 > Bob

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

in the mid 1990’s ….memory is only just so good ... Bob > On Feb 25, 2019, at 9:56 AM, jimlux wrote: > > On 2/25/19 5:48 AM, Bob kb8tq wrote: >> Hi >> Indeed there is both a minimum and a maximum working voltage for a properly >> derated electrolytic >> capacitor

Re: [time-nuts] F9P

ty. > > Didier KO4BB > > On Tue, Feb 26, 2019, 9:01 PM Bob kb8tq wrote: > >> Hi >> >> If you go over to the ever accurate Digikey site, you will find that the >> F9P module is now obsolete. That *may* be a new record >> for “introduced but not in stoc

Re: [time-nuts] F9P

Hi I would *hope* that Sparkfun buys enough combined product from uBlox to be able to go direct. That may not be the case though. uBlox would only sell to Vectron in full reels of 2,000 ~ 4,000 pieces. (yes, that’s a over $100K of inventory on that reel there …). For about the same money,

Re: [time-nuts] injection locking crystal oscillator

Hi How close to frequency is the 10 MHz oscillator? Is the crystal a fundamental? The degree you can injection lock an oscillator is (as Danna notes) a bit difficult to predict. Your chances improve if the oscillator is low(er) Q. They also improve if it is tuned very close to frequency.

Re: [time-nuts] ZED F9T first look

Hi Not to surprisingly: the same set of tests on the F9P give pretty much identical results. He ran a bunch of navigation tests. Not at all surprising. It wouldbe nice if *somebody* could get that board and compare it to a Cs …. maybe also check it out against a popular piece of software as

Re: [time-nuts] injection locking crystal oscillator

Hi Where it gets nasty is when you realize that Q is just an approximation for the phase slope of the oscillator at the operating point……. The Q of a crystal does not change as a function of frequency. The rate of impedance change vs frequency most definitely does. As you approach parallel

Re: [time-nuts] ZED F9T first look

Hi Since apparently there are others following along on the F9P: The uBlox C099-F9P kit comes with a trial subscription to the uBlox / Smartnet RTK correction service. They are abundantly unclear on how long the trial is for. Turns out it is a 30 day free trial. The offer (at least on the

[time-nuts] F9P

Hi If you go over to the ever accurate Digikey site, you will find that the F9P module is now obsolete. That *may* be a new record for “introduced but not in stock yet” to “gone and never will come back”. One *might* also note that they now have the uBlox version of the evaluation board for

Re: [time-nuts] Motorola MC68HC11 Crystal

Hi First off, the programmer will work with any of the crystals you are talking about. You should be fine at 0.1% which would be +/- 7.4 KHz relative to 7.3728 MHz. Indeed you should find that serial com will work fine at offsets even greater than this. In terms of birdies - does the radio

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