Re: [time-nuts] decimation versus decimation

Hi Dana, On 2020-02-25 15:55, Dana Whitlow via time-nuts wrote: > I'm confused: > > I seem to see multiple (at least double) meanings for the term > 'decimation'. > > One meaning is simply: "take every nth sample and discard > the others without regard to possible aliasing". This is sub-sampling.

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

Bert, I missed it because I do not have one or worked with one, which is not to say it is bad or anything, I just took the examples I recall because it is familiar to me. There is more of these for sure. I hope it was good enough to illustrate the points with some real-life examples. Cheers,

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

Hi, For white phase modulation noise and flicker phase modulation noise, ADEV depends on filter bandwidth, but not for the others, according to theory. This is naturally an approximation, but it works out like that pretty much in real life too, so it works as an approximation... until you try to

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

Hi, As one decimate data, one needs to be very very careful with bandwidth. It would make biases in values which would over-state stability. Yes, we have seen it happen. Even big names has come clean and confessed doing it wrong when they decimated the data. Cheers, Magnus On 2020-02-21 17:12,

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

Hi Taka, On 2020-02-22 04:55, Taka Kamiya via time-nuts wrote: > It's not like drinking from a fire hydrant.  It's like drowning in hoover > dam, get sucked into an inlet, pulverized by turbine blade, and getting spit > out into a stream.  Hmm, not exactly what I had hoped for as your

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

Hi Taka, On 2020-02-21 23:26, Taka Kamiya via time-nuts wrote: > I'm sorry, I messed up.  I jumped on more advance topic than I intended.  I'm > sure there were answers in the replies but they must have gone way over my > head because some of original questions still remain.  I bulletized (is

Re: [time-nuts] Frequency standards for different tau in Allen Dev measurement

put of a counter with no external clock attached as a clock with worse perfromance than rubidiums. Cheers, Magnus > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > > > On Saturday, February 22, 2020, 3:03:37 AM EST, Magnus Daniels

[time-nuts] Re: Low declination satellites...

Hi Ulf, Interesting! Curiously enough it's my Leica antennas that has spheric radomes. I should try to get one of them up, but the current antenna up will have to suffice until then. Cheers, Magnus On 2021-07-08 09:49, Ulf Kylenfall via time-nuts wrote: > What we found at the Onsala Space

[time-nuts] Re: metronome

Hi, Yeah, well, you know, the UART and typically Z80 can be more or less snappy. The oscillator waveform is not synced to the trigger of the oscillator, so you got cycle-slip there too. Just a few weeks ago someone was upset to see how sloppy a classic recoding was, and we old guys ended up

[time-nuts] Re: E5500 blues

solutions from vendors besides Keysight that evaluate source noise.  Possibly, even though you are measuring source noise, you have a corner case where the E5500 is nevertheless essential for some complicated reason. --- Rick Karlquist N6RK On 2021-08-18 06:42, Magnus Danielson via time-nuts

[time-nuts] Re: E5500 blues

John, On 2021-08-19 05:19, John Miles wrote: So, with a 5 MHz source, a RF generator that is doing DCFM lock of PLL and then analyse spectrum of that, that fails to lock this PLL loop, and I fail to get a monitored beat note that makes sense. So, I was hoping someone had done this and could

[time-nuts] E5500 blues

Fellow time-nuts, Is there anyone out there that may ease my teething issues on getting my E5500 phase-noise setup to start working? So, I have an E5500 variant based on 70420A, 89410A, E4420B, 53132A and 8563E. It fails to lock the PLL up and I fail to get a beat note. Someone that have

[time-nuts] Re: GPSDO testing

Hi Rob! Welcome! On 2021-08-22 14:48, Bob kb8tq wrote: Hi Welcome !!! At some point it is worth converting this stuff into relative units. They can be expressed in scientific form or engineering form. It saves a bit of time when working at this frequency today and that frequency tomorrow. It

[time-nuts] Re: Affordable 160 GHz Sampler

Hi Mike! On 2021-09-01 19:42, Mike Monett wrote: Conventional samplers for home brewers usually go to 1 GHz. The SD-32 sampler for the Tektronix 11801C mainframe goes to 50 GHz. The HP 110GHz oscilloscope costs around $1.3 Million USD, with a 10-bit resolution. Very impressive.

[time-nuts] Oscilloquartz OSA 5515

Fellow time-nuts, Do any of you by any chance happen to have any documentation or possibly even the schematic on the OSA 5515? I have one, at it fails to lock up. The 8655S OCXO heats up nicely from 5,000166 MHz, with a bit of an undershot and stabilizes at about 4,99140 MHz. That for

[time-nuts] Re: Oscilloquartz OSA 5515

Hi Bernd, Den 2021-08-10 kl. 03:23, skrev Bernd Neubig: Hi Magnus, Magnus Danielson wrote: I have one OSA 5515, at it fails to lock up. The 8655S OCXO heats up nicely from 5,000166 MHz, with a bit of an undershot and stabilizes at about 4,99140 MHz. That for sure looks like the tell-tale

[time-nuts] Re: HP Z3801A info needed - 1PPS interface

Hi, Yes, you need to modify it to operate with RS232 levels. If one goes to the now more acient annals one find the instructions. Some of the resources may be on the brink of dropping of the web. It would be good if the many scraps of material was supplied on a common place, such as a

[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP

Hi, It kind of depends. The Z3801A was really crafted to meet the needs of CDMA mobile stations. That had it's life-span. Other GPSDOs can sit for very long time and when they fail, much around them can have changed, or mostly things have been added. It used to be that GPSes could be

[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP

Hi, Well, designs from before SA off did get better performance, even if not optimum for the new condition. As they where installed, it did in itself not cue for a shift, but rather, as the equipment it was installed with was tossed, these receivers could be salvaged and used on their own. It

[time-nuts] Re: HP Z3801A - Dead GPS Receiver - Oncore VP

in the era when LPro’s were $30, the outfit that was selling the Lucent timing module with them in it would happily sell you the entire setup, shelter and all. Bob On Oct 15, 2021, at 6:00 AM, Magnus Danielson via time-nuts wrote: Hi, Well, designs from before SA off did get better performance, even

[time-nuts] Re: Death of a Capacitor

Hi, For spikes and RF, common ground is a chimera, a bed-time story for kids. The quicker you learn to understand that "ground wire" or "ground connection" is just another wire that has resistance, induction, various offsets and different noise, the "common" part is very much a "Your Mileage

[time-nuts] Re: Rubidium oscillator : pack it in styrofoam or attach it to a heath-sink?

Hi, It's a complex picture as depending on temperature of the components, and other aspects such as RF intensity, sensitivity to this or that changes, line with changes etc. It also depends on the actual buffert gas mix, which by the way changes over time due to leakage. There is really

[time-nuts] Re: Rubidium oscillator : pack it in styrofoam or attach it to a heath-sink?

seperate the boards and get them away from the heat while leaving the hot items as is? The leads can be lengthened, even the RF. Regards Paul WB8TSL On Tue, Oct 5, 2021 at 4:09 PM Magnus Danielson via time-nuts mailto:time-nuts@lists.febo.com>> wrote: Hi, It's a complex p

[time-nuts] Re: Rubidium oscillator : pack it in styrofoam or attach it to a heath-sink?

leaving the hot items as is? The leads can be lengthened, even the RF. Regards Paul WB8TSL On Tue, Oct 5, 2021 at 4:09 PM Magnus Danielson via time-nuts < time-nuts@lists.febo.com> wrote: Hi, It's a complex picture as depending on temperature of the components, and other aspects such

[time-nuts] Re: Death of a Capacitor

Hi, On 2021-09-27 16:28, Lux, Jim wrote: On 9/27/21 7:22 AM, John Ackermann N8UR wrote: Indeed, Dana.  Texas Instruments has a nice "designer workbench" for their switching regulators like the TPS53400 to help select the components.  Using that worked much better than trying to follow the

[time-nuts] Re: Seeking advice: Is this the right way to check very short term (below 1s) stability?

Erik, Den 2021-11-28 kl. 19:19, skrev Erik Kaashoek: As the collection of frequency sources and counters in my home lab is growing I'd like to understand the performance of the frequency sources. Two different GPSDO do help to check long term stability. But the Rubidium frequency standard I

[time-nuts] Re: 5065A - A15 (PSU)

Paul, Mine isn't loud, but I can hear it and it annoys me. As I do not have much other things causing noise, one becomes aware of that constant tone. Then again, the frequency is high enough that it is relatively easy to locate it in the room. Thing is, the ear is about most sensitive to

[time-nuts] Re: OCXO Oven design (was: E1938A phase noise improvement)

Hi, On 2021-12-26 23:38, Attila Kinali wrote: On Sun, 26 Dec 2021 15:54:06 -0500 Bob kb8tq wrote: The market is what dictates how fancy an OCXO gets made. Bottom line is that there really isn’t that big a market (and willingness to pay for super duper TC). If indeed you could do all the

[time-nuts] Re: Frequency Standard - Where Can I Get One.

Hi, So, on that note. I am surprised that I have not seen popular telecom rubidiums being reverse-engineered. For instance, the LPRO-101 should have been reverse-engineered a long time. Some of the circuitry is known from patents, but those do not build up a complete schematic. I've

[time-nuts] Re: Can ADEV of a frequency source be correctly determined using a continuous time-stamping frequency counter?

Hi, I strongly recommend the HP AN200 series of application notes. Having those alongside Enricos slides is a good start for those new in the field. There is one variant of averaging which is used in the HP5328A/B counters that is described there that is not covered in Enrico Rubiolas

[time-nuts] Re: Can ADEV of a frequency source be correctly determined using a continuous time-stamping frequency counter?

ot; that they called "continuous count".  However, it was limited to something like 3 MHz.  So a 100 MHz counter would only continuously count signals below 3 MHz. So you need to verify for what bandwidth your specific counter model is truly doing continuous count. Rick N6RK On 11/9/2021

[time-nuts] NIST Technical Note 2187 - A Resilient Architecture for the Realization and Distribution of Coordinated Universal Time to Critical Infrastructure Systems in the United States

Fellow time-nuts, NIST just published the technical note 2187 that probably some of you might find interesting. It's for free download here: https://nvlpubs.nist.gov/nistpubs/TechnicalNotes/NIST.TN.2187.pdf I think you will find quite a bit of interesting material in there. Just recall, the

[time-nuts] Re: Project Great

Hi Jim, Den 2021-11-28 kl. 01:26, skrev Lux, Jim: Not only is the CSAC low power (~ 100 mW) it's physically small, which is attractive for some applications (inside a cubesat, for instance).  It used to be price competitive with a Rb, too ($1000-1500, as I recall) but now they're about $5k. 

[time-nuts] Re: Project Great

Hi, Den 2021-11-29 kl. 10:57, skrev Hal Murray: j...@luxfamily.com said: And a lot ofsources may have a low flat spot in the curve, but it eventually trends up. Except for primary standards like Cs beam. What's magic about "primary standard" or "Cs beam" that keeps the ADEV from trending up?

[time-nuts] Re: Project Great

Hi, There is an overemphasis on the atom being used, and especially on cesium as that is what is used for SI definition. However, actual implementation means actual physical devices, and the physical devices have a physics package, for which details will be important to the actual

[time-nuts] Re: GPS D (i.e. gpsd) roll over bug..Oct 24th

Hi, On 2021-10-22 17:58, Kevin Rowett wrote: For those using GPSD (https://gpsd.gitlab.io/gpsd/index.html ) to read GPS receivers, and get the GPS time, there is a bug that could cause problems on Oct 24th.

[time-nuts] Re: GPS D (i.e. gpsd) roll over bug..Oct 24th

Björn, The C/A code format have seen much greater changes before that. It's extention from 24 to 32 birds was not small, neither was the addition of the GPS-UTC corrections. Cheers, Magnus On 2021-10-22 21:29, Björn wrote: ”It's actually a systemflaw that never was fixed in L1 C/A code. It

[time-nuts] Re: GPS D (i.e. gpsd) roll over bug..Oct 24th

Chris, On 2021-10-22 22:18, Chris Caudle wrote: On Fri, October 22, 2021 12:22 pm, Magnus Danielson via time-nuts wrote: I find it amusing, as this was discussed on ntp-questions email-list in mid August 2013, and clearly explained with due references. According to the problem report

[time-nuts] Re: Can ADEV of a frequency source be correctly determined using a continuous time-stamping frequency counter?

Hi Erik, On 2021-11-09 18:26, Erik Kaashoek wrote: As far as I understood the ADEV at a Tau of 1 second is a statement about the amount of variation to be expected over a one second interval. Rather, the variation of readings of a frequency estimation done over a span over 1 second. It would

[time-nuts] Re: HP 5065A, no 2nd harmonic.

Hi Jared, One of my 5065's have exactly this fault. One approach is to rebuild with a new power inverter. Another is to rebuild the amplifier board so it does not need -20 V and can operate only on +20 V. There should be DC-DC inverters, but I failed to grab a suitable pre-built board for

[time-nuts] Re: NIST NTP servers way off for anyone else?

Hi, On 2021-12-14 02:26, Adam Space wrote: I'm not sure if anyone else uses the NIST's NTP servers, but I've noticed that the offsets I'm getting from Gaithersburg servers seem to be really far off, like 40-50 ms off. This is pretty odd since they usually have a 2 - 3 ms accuracy at worst. It

[time-nuts] Re: NIST NTP servers way off for anyone else?

. Is this the norm for consumer grade connection? It seems to be for me. On Wed, Dec 15, 2021 at 10:53 AM Magnus Danielson via time-nuts < time-nuts@lists.febo.com> wrote: Hi, Expect network routes to be more dispersed these days, as it is needed. While the wedge plot is a classic for NTP,

[time-nuts] Re: NIST NTP servers way off for anyone else?

Hi, Expect network routes to be more dispersed these days, as it is needed. While the wedge plot is a classic for NTP, it may be interesting to plot forward and backward path histograms independently. Cheers, Magnus On 2021-12-15 16:25, Adam Space wrote: Yeah I think it is localized.

[time-nuts] Re: NIST NTP servers way off for anyone else?

Hi, On 2021-12-14 17:26, Steven Sommars wrote: The Gaithersburg servers are accurate. This plot shows Gaithersburg time-e-g.nist.gov for the current month. [image: image.png] My monitoring client is located near Chicago and is Stratum-1 GPS sync'd. Typical round-trip time to Gaithersburg is

[time-nuts] Re: Project Great

Hi Michael, Thanks for that plot. I think it sumarizes fairly well what typical devices of today achieves. There is rubidiums and quarts that go into the 1E-14s, but most do not. The old plot uses a "span" for the different technologies and that helps to avoid the "but this device/product"

[time-nuts] Re: Rb standards (was: Project Great)

Hi Attila, Den 2021-12-02 kl. 00:10, skrev Attila Kinali: On Mon, 29 Nov 2021 13:23:33 + "Poul-Henning Kamp" wrote: The resonance we measure is not the real one, but one affected by the doppler-shift of the atoms speed, ie: velocity without sign, in the direction of interrogation.

[time-nuts] Re: Z3801A Temperature

Hi, Well, "ambient temperature" as per telecom terminology means the temperature of the surrounding air in the aisle of the rack. The Bellcore/Telcordia GR-63 and ETSI EN 300 019 (series) would stand for the formal definition. This is also in line with the AT Reliability manual. It is expected

[time-nuts] Re: PICDIV stability (was: Crystal oscillator for a begginer)

Hi Hal, On 2022-01-07 21:40, Hal Murray wrote: The two biggest outside influences on the PICDIV are supply voltage and temperature. Another interesting influence is the number of outputs that are switching and the load on them. In particular, if you have several outputs running at different

[time-nuts] Re: PICDIV stability (was: Crystal oscillator for a begginer)

Hi, The traditional way is to lock an oscillator and look at the phase detector output. You get a high-pass filter from the locking, but for many purposes that's just fine. In some cases it is called "the golden PLL method". Cheers, Magnus On 2022-01-09 18:04, Marek Doršic wrote: Is

[time-nuts] Re: HP105B

Hi, On 2022-01-17 08:42, Poul-Henning Kamp wrote: Magnus Danielson via time-nuts writes: No, not for HP. Somewhere on one of the HP memory webpages there is a presentation where somebody claims the longest lived HP product is a particular microwave gadget, I seem to recall it being

[time-nuts] Re: Clock specs for audio (was: High precision OCXO supplier for end costomers)

Hi, On 2022-01-10 15:41, Attila Kinali wrote: On Mon, 10 Jan 2022 12:35:17 +0100 Attila Kinali wrote: That said, are yo sure you need such stringend phase noise requirements? It's audio. Nobody is going to hear whether the noise is -60dBc or -80dBc @ 1Hz, much less -120dBc. To give here a

[time-nuts] Re: Types of noise (was: Phase Station 53100A Questions)

Dear Joe, On 2022-02-13 23:31, Joseph Gwinn wrote: On Sun, 13 Feb 2022 03:30:30 -0500, time-nuts-requ...@lists.febo.com wrote: time-nuts Digest, Vol 214, Issue 15 Attila, Date: Sat, 12 Feb 2022 20:38:48 +0100 From: Attila Kinali Subject: [time-nuts] Types of noise (was: Phase Station 53100A

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

Hi Erik, I only saw that thread later, and I will have to return to that as I have a little more energy. I'm trying to get you up to speed with the many variants there is, and there is plenty experience here to feed from. What may be true for one device will not make any sense for another.

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, cause identified

Erik, So, your pick of VC-TCXO is one that obviously seems to use the fractional synthesis to both set the output frequency as well as compensate for temperature. The modulations you have will be intrinsic to the pick. As you lock your VC-TCXO to a GPS, the average frequency will be locked

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, solved

Erik, What you describe is a classic problem. Especially oven controlled oscillators will have GND and VCC issues. I recommend you to look att both frequency and phase deviation plots. Systematics like these is mangled up in a ADEV plot. Regardless of what isuse you really had, I hope you

[time-nuts] Re: Types of noise (was: Phase Station 53100A Questions)

Hi, On 2022-02-20 00:08, Joseph Gwinn wrote: Message: 14 Date: Sat, 19 Feb 2022 01:12:05 +0100 From: Magnus Danielson Subject: [time-nuts] Re: Types of noise (was: Phase Station 53100A Questions) To: time-nuts@lists.febo.com Message-ID: Content-Type: text/plain; charset=UTF-8;

[time-nuts] Re: Testing GPSDOs

Hi Hal, On 2022-02-20 09:41, Hal Murray wrote: kb...@n1k.org said: Can you build this or that from scratch? Sure you can. Being sure that it does indeed work correctly .. not so easy. Let's change the discussion a bit. Assuming I have a GPSDO, home built or eBay, how can I test it with a

[time-nuts] Re: Validating GPSDO control loop with simulation and measurement. Is this amount of difference between measurement and simulation to be expected?

Hi Erik, A few comments and suggestions on the way. Please note that for a PLL, a PID is equivalent to a PI regulator. Turns out that the P and D factors of the PID sums to form the P of the PI regulator, while the I transfer right over. I have seen no benefit in real implementation of

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

Hi Erik, I think you have yourself a digital TCXO controller. Those use a tempsensor, use the reading to calculate the compensation and the use a normal varactor control to steer the frequency. Older TCXOs use a resistor/thermistor network to do the same work. You can probably read up on the

[time-nuts] Re: Types of noise (was: Phase Station 53100A Questions)

Hi Joe, On 2022-02-21 20:52, Joseph Gwinn wrote: time-nuts Digest, Vol 214, Issue 22 On Sun, 20 Feb 2022 03:30:27 -0500, time-nuts-requ...@lists.febo.com wrote: Message: 5 Date: Sun, 20 Feb 2022 01:13:50 +0100 From: Magnus Danielson Subject: [time-nuts] Re: Types of noise (was: Phase Station

[time-nuts] Re: Validating GPSDO control loop with simulation and measurement. Is this amount of difference between measurement and simulation to be expected?

Hi Erik, On 2022-02-26 17:36, Erik Kaashoek wrote: Magnus, Bob, Thanks for the replies. @Magnus, I need to study your input a bit longer. What I currently fail to understand is : Should there be a low pass filter with a 1/100 s corner frequency in series with the Vtune when the ADEV of the

[time-nuts] Re: Catching range of GPSDO

Erik, On 2022-03-03 21:36, Erik Kaashoek wrote: The GPSDO I'm building started with frequency locking but now I'm adding phase locking so the time stamping counter can be on GPS time. A first version works with a PI controller setting the vc-tcxo Vtune DAC based on the phase difference of the

[time-nuts] Re: Timestamping counter techniques : dead zone quantification

Erik, You should be aware that cross-talk of transitions is a factor here. It "pulls" the transition to the time-base clock. It can be worth evaluating this by delaying the time-base clock in controlled manor and measure non-linearity of the time-stamps. A similar test is done between two

[time-nuts] Re: Timestamping counter techniques : phase computation question

Hi Erik, On 2022-01-30 12:46, Erik Kaashoek wrote: In a timestamping counter I'm trying to calculate phase and frequency using statistical techniques. The counter has two counters, one for the input events and one for an internal clock. The capturing of these counters happens synchronized

[time-nuts] Re: Timestamping counter techniques : phase computation question

Erik, On 2022-01-31 20:32, Erik Kaashoek wrote: Thanks all for the good input. @Magnus, I need some time to understand the math as it has been over 30 years since when I used to do this kind of math. There is no intention to store the collected captures, only to present a measurement at the

[time-nuts] Re: Timestamping counter techniques : phase computation question

Erik, On 2022-01-31 22:17, Erik Kaashoek wrote: @Magnus The time interval of the capturing of the counters is not always exactly the same. There could be even substantial variation if the capture interval is close to the event interval. Is this a problem for the calculation method you propose?

[time-nuts] Re: Timestamping counter techniques : dead zone quantification

long term) there is clearly some work to do. Erik. On 3-2-2022 17:14, Magnus Danielson via time-nuts wrote: Erik, You should be aware that cross-talk of transitions is a factor here. It "pulls" the transition to the time-base clock. It can be worth evaluating this by delaying the time-base clock

[time-nuts] Re: Is this bad OCXO behavior?

Hi, As you run the OCXO without the lock to the maser, what does it do then? Can you probe the input before the loop? The EFC Voltage is a consequence of the loop action, so sorting out what is a oscillator thing and what is sourced by other things becomes much easier by opening up the loop

[time-nuts] Re: HP105B

Hi, No, not for HP. The HP200A through D products where separate products for 8 years, then the 200A and 200B was merged to the 200AB and the 200C and 200D merged into 200CD that was running for 37 years, totaling in 45 years of continuous production. Not bad for a tube-based oscillator. The

[time-nuts] Re: GPSDO Control loop autotuning

Tobias, On 2022-04-09 18:13, Pluess, Tobias via time-nuts wrote: Hi all, My reply to this topic is a bit late because I have been busy with other topics in the meantime. To Erik Kaashoek, You mentioned my prefilter. You are absolutely right, I looked again at my prefilter code and decided it

[time-nuts] Re: GPSDO Control loop autotuning

Hi Matthias, On 2022-04-21 23:20, Matthias Welwarsky wrote: On Dienstag, 12. April 2022 00:52:42 CEST Magnus Danielson via time-nuts wrote: A trivial state-space Kalman would have phase and frequency. Assuming you can estimate the phase and frequency noise of both the incoming signal

[time-nuts] Re: Underlying math of cross-correlation PN Test Sets

Hi, On 2022-04-25 01:57, Joseph Gwinn wrote: I'm digging into the basic math of how cross-correlation phase noise test sets (like the 53100A) work, so I'm looking for good articles on the complex-exponentials math. One item of interest is the effects of imperfections in the power dividers that

[time-nuts] Re: Simple simulation model for an OCXO?

Hi Matthias, On 2022-05-14 08:58, Matthias Welwarsky wrote: On Dienstag, 3. Mai 2022 22:08:49 CEST Magnus Danielson via time-nuts wrote: Dear Matthias, Notice that 1/f is power-spectrum density, straight filter will give you 1/f^2 in power-spectrum, just as an integration slope. One approach

[time-nuts] Re: Simple simulation model for an OCXO?

Hi Carsten, On 2022-05-14 11:38, Carsten Andrich wrote: Hi Magnus, On 14.05.22 08:59, Magnus Danielson via time-nuts wrote: Do note that the model of no correlation is not correct model of reality. There is several effects which make "white noise" slightly correlated, even if thi

[time-nuts] Re: Simple simulation model for an OCXO?

Hi Matthias, On 2022-05-14 12:30, Matthias Welwarsky wrote: On Samstag, 14. Mai 2022 18:43:13 CEST Carsten Andrich wrote: However, even for the 2^16 samples used by the CCRMA snippet, the filter slope rolls off too quickly. I've attached its frequency response. It exhibits a little wobbly 1/f

[time-nuts] Re: Optimizing GPSDO for phase stability

r. However, for test purposes it can be set lower to make jitter peaking and thus resonance frequency easier to observe. Cheers, Magnus Erik. On 27-5-2022 21:30, Magnus Danielson via time-nuts wrote: Dear Erik, On 2022-05-27 18:02, Erik Kaashoek via time-nuts wrote: The GPSDO/Timer/Count

[time-nuts] Re: Build a 3 hat timestanp counter

Hi Hans-Georg, On 2022-05-28 17:04, Hans-Georg Lehnard via time-nuts wrote: Hello Magnus, I understood that simply sampling 3 channels fast and averaging does not solve all the problems ;-). Sure, I just want to illustrate how various approaches could allow you to get the most out of the

[time-nuts] Re: Realtime comparing PPS of 3 GPS

Erik, The NEO-7M may have sawtooth correction output, have you checked that and made compensations? Since the oscillator is not steered and free-floating, the cycle-assignment of the PPS may be less than optimal so just measuring that without the compensation can cause a wider range of PPS

[time-nuts] Re: Build a 3 hat timestanp counter

as coarse time. So I only have to read the fine timer and the calibration register from the TDC. The TDC cannot measure from 0, so a reference cycle is added. (t = x +100ns). For the averaging I had thought of a linear regression. Hans-Georg Am 2022-05-25 01:18, schrieb Magnus Danielson via time-

[time-nuts] Re: Time-nuts at WSTS conference

Tom, We set new standards all the time! (Misspelling was unintentional) Cheers, Magnus On 2022-05-12 16:29, Tom Holmes wrote: "scotsh whiskey" Was this intentional to indicate that more than a little bit of imbibing was involved in arriving at the new standards? Tom Holmes, N8ZM

[time-nuts] Re: Can the ADEV of a GPSDO output ever be lower than the minimum of the ADEV of the internal oscilator and the ADEV of the GPS PPS?

Hi, On 2022-05-09 15:05, Attila Kinali wrote: On Fri, 29 Apr 2022 16:53:58 +0200 André Balsa wrote: Mathematically, no, a GPSDO cannot have a lower uncertainty (ADEV) than the minimum observable uncertainty (ADEV) of the combined oscillator (disciplined clock) and PPS (disciplining clock)

[time-nuts] Re: Simple simulation model for an OCXO?

Hi Carsten, On 2022-05-13 09:25, Carsten Andrich wrote: On 11.05.22 08:15, Carsten Andrich wrote: Also, any reason to do this via forward and inverse FFT? AFAIK the Fourier transform of white noise is white noise, [...] I had the same question when I first saw this. Unfortunately I don't

[time-nuts] Re: Build a 3 hat timestanp counter

Hi, The first limit you run into is the 1/tau slope of the measurement setup. This is often claimed to be white phase modulation noise, but it is also the effect of the single-shot resolution of the counter, and the actual slope level depends on the interaction of these two. So, you might

[time-nuts] Re: Optimizing GPSDO for phase stability

Dear Erik, On 2022-05-27 18:02, Erik Kaashoek via time-nuts wrote: The GPSDO/Timer/Counter I'm building also is intended to have a stabilized PPS output (so with GPS jitter removed). The output PPS is created by multiplying/dividing the 10MHz of a disciplined TCXO up and down to 1 Hz using a

[time-nuts] Time-nuts at WSTS conference

Fellow time-nuts, This week I spend my time at the WSTS conference in Denver. While here in my commercial capacity, there is a lot of professionals lurking the list that shows up to shake the hand and say hi. Turns out that many lurk out here and read and learn lot of useful stuff. While

[time-nuts] Re: Repeatability of stability measurements

Hi Hans-Georg, Does the E1740A also has the STP2945 as timing reference? First of all, you have nice illustrations of the white phase modulation noise slopes, of tau^1.5 as expected in the MDEV. Trouble is, it's not pure WPM noise, but a mixture of the noise and the quantization effect. So,

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

Hi, A well established method is to use a separate offset RF generator that you can steer frequency to form suitable offset and amplitude to form known level. You can now inject this ontop of a signal to measure. Consider that you steer your offset frequency to be +1 kHz of the carrier you

[time-nuts] Re: Isolation amp transistors

Hi, On 2022-07-07 07:22, Bob kb8tq via time-nuts wrote: Hi On Jul 6, 2022, at 1:53 PM, Richard Karlquist via time-nuts wrote: The 2N5179 has high base spreading resistance (decreases isolation). As does sticking a resistor (even a small one) in series with the base …. Yes, inductance is

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

the “carrier” and injected signals. The slope at zero on the beat note is likely to be *much* more accurate ( even if gain measurement at audio gets thrown in …) Bob On Jul 7, 2022, at 5:19 PM, Magnus Danielson via time-nuts wrote: Hi, A well established method is to use a separate offset RF

[time-nuts] Re: Repeatability of stability measurements

Hi Hans-Georg, Maybe it is better to refer to this as the inverse of 20,48 GHz, since that is the virtual clock rate of the interpolated coarse-clock. Considering that it is 2048 * 10 MHz, it is not hard to imagine that a coarse clock of say 80 MHz is then interpolated by 256 to achieve that,

[time-nuts] Re: Should a double oven XO be thermally isolated or just draft protected?

Hi Eric, On 2022-07-01 16:40, Erik Kaashoek via time-nuts wrote: I'm trying to build a stable reference for a phase noise meter project and have acquired a double oven XO that boosts high short term stability (below 1e-12/s). But the spec also states that, even with the double oven, there is

[time-nuts] Re: Should a double oven XO be thermally isolated or just draft protected?

Hi David, We did a fairly simple measurement setup at work. We had the oscillator sitting on a small test-board and measured the frequency from start. Then a few seconds in we shifted the direction of a fan at some distance onto the oscillator. We then did this with a variation of simple

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

Hi Mike, On 7/8/22 15:34, Mike Monett via time-nuts wrote: You wrote: Mike, He was using an analog mixer, but your comment about XOR mixer does not apply to analog mixers. Your oversimplification that analog mixer and XOR gates being the same thing does not apply here, and thus the

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

Hi Erik, On 7/8/22 17:12, Erik Kaashoek via time-nuts wrote: Not something I want to implement on short notice but maybe for the future. The biggest limitation in this DIY PNA is the phase noise of the reference OCXO and the noise of the opamp amplifying the output of the mixer. So I was

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

Erik, On 7/9/22 22:06, Erik Kaashoek via time-nuts wrote: Getting the simple PNA to lock was a bit difficult due to the overly simplistic translation of the mixer output to the Vtune of the OCXO To get some more flexibility I added a summing opamp that summed the mixer output with the output of

[time-nuts] Re: What about the frequency discrimination method? (offshoot from DIY PN analyzer)

Ed, On 7/9/22 22:26, ed breya via time-nuts wrote: I've been following the thread about Erik's DIY PN analyzer, and wondering if it might be easy enough to use a frequency discrimination method. I'm opening this in a different thread to avoid muddying the water on the original (and long) one.

[time-nuts] Re: DIY Low offset Phase Noise Analyzer (Erik Kaashoek)

Hi Erik, On 7/10/22 17:52, Erik Kaashoek via time-nuts wrote: I've updated the schematic to include the latest additions and added some new measurements Schematic: http://athome.kaashoek.com/time-nuts/PNA/Simple_PNA.pdf The resistor values (many 18k) are a bit weird but I happen to have a

[time-nuts] Re: What about the frequency discrimination method? (offshoot from DIY PN analyzer)

Hi Ed, On 7/10/22 20:26, ed breya via time-nuts wrote: Hi Magnus, I know what you mean about not needing a quadrature splitter - if you have a very wide phase or delay tuning range - but I'm picturing getting most of the way to quadrature with a fixed structure for a given frequency, and

[time-nuts] Re: First PN measurement results at 1 Hz to 20 kHz from carrier

step from 0,-20,-40, -60 to -80dB Any feedback? Erik. On 26-6-2022 20:52, Magnus Danielson via time-nuts wrote: Hi Erik! Great progress! Sure interesting to look at them phase-noise plots, right? It's a really good tool in addition to the stability of ADEV and friends. As I recall it,

[time-nuts] Re: First PN measurement results at 1 Hz to 20 kHz from carrier

a side-band at 27 dB bellow the carrier, makes a -30 dBc phase modulation. [1] https://pure.mpg.de/pubman/faces/ViewItemOverviewPage.jsp?itemId=item_152164 Cheers, Magnus Any feedback? Erik. On 26-6-2022 20:52, Magnus Danielson via time-nuts wrote: Hi Erik! Great progress! Sure interesting

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