Hi Attila,
AFAIK we only have 10 minute data - I see a jump at around 18:11 UTC.
a data-file with the last 10 days is available here
https://monitor.mikes.fi/qdata-logger/A10/102.txt
location ca N60° 10' 49.3145" and E24° 49' 35.4380"
have fun!
Anders
[image: image.png]
On Sun, Jan 16, 2022 at
We use this simple python script with RPi and a 7" RPi screen in many labs
just to have a simple clock display. AFAIK the timing and update rate is
good enough for human visual readout.
The RPis get time over NTP.
https://github.com/aewallin/digiclock
In this application RPis seem to last for many
FWIW we've played with various SMA-to-SFP converter boards in the lab for
10MHz or 100MHz distribution.
A bare-bones SFP board is e.g.
https://github.com/aewallin/SFP-Breakout-Board
That interfaces directly to the differential AC-coupled TX and RX pins of
an SFP.
If you want some buffering (and
FWIW, this paper argues that spin squeezing may only help in clocks with a
few hundred/thousand atoms, and clock lasers may need to improve a lot to
take full advantage:
https://arxiv.org/abs/1911.00882
On Fri, Dec 18, 2020 at 1:51 AM Bill Woodcock wrote:
>
>
to being a part of the second microstepper prototype I will try to
build within 1-3 months.
regards,
Anders
On Tue, Jan 14, 2020 at 8:58 AM Anders Wallin
wrote:
>
> prototype block-diagram, short list of chips in the implementation, and a
> discussion on resolution now on ohwr.org:
> http
IEEE-UFFC recently posted some videos from IFCS/EFTF 2019, and there's one
by muquans: https://www.youtube.com/watch?v=1eHhdNk50uE
(for me, sound is extremely low in these... need to turn up volume to
almost max)
>
___
time-nuts mailing list --
Hi Simon, you can play around with different averaging ideas with e.g.
allantools (or some other adev-library). The script for the attached image
is here: https://gist.github.com/aewallin/a10966ac50846e264ca3ee97f2e0d832
(the script also plots time-series, PSDs, and histograms, which might
is given with an (conservative?) uncertainty
of 1.5e-15 [1]
regards,
Anders
[1] https://www.bipm.org/utils/common/pdf/mep/88Sr+_445THz_2017.pdf
On Fri, Dec 6, 2019 at 5:39 PM Anders Wallin
wrote:
> Hi all, you may find our live-stream from the lab amusing:
> https://www.youtube.com/w
Thanks for posting these!
The user-manual provides some details on the internals:
http://www.miles.io/PhaseStation_53100A_user_manual.pdf
Figure 6, page 35, would indicate that there is no analog mixing stage,
just direct ADC.
Maybe it also shows the ADCs clocked at (max) 125 MHz, with some HPF
>> At one time, only cesium standards were considered truly primary because
> of
> >> the definition of the second. However, the quantum mechanical
> constants of
> >> other atoms such as Rb have been measured to much more accuracy than
> the 5071
> >> so that Rb standards can be considered
Some of the confusion might come from different measurement systems dealing
with different data, either phase (in seconds), or frequency (fractional).
Sub-sampling works for phase-data, just throw away the in-between samples
and look at phase samples that are tau-distance apart.
Decimation works
prototype block-diagram, short list of chips in the implementation, and a
discussion on resolution now on ohwr.org:
https://ohwr.org/project/microstepper/wikis/Block-diagram
The obvious way to increase resolution (make the smallest frequency step
smaller) is to lower the IF.
I guess the limit is
fwiw, looks like the spectradynamics patent expired today:
https://patents.google.com/patent/US6278330B1/en
afaik that design (more or less) is also described in
https://doi.org/10.1109/FREQ.1998.717932
a variation is also https://doi.org/10.1109/EFTF.2012.6502322 (which might
be sold by
>
> The servo-loop will
> > thus need to probe the left and right side of multiple peaks in sequence.
> > Our pulse-sequence now does 100 probe-pulses in about 7 seconds. If we
> > probe left/right side of three pars (twelve frequencies in total) the
> > line-center can be computed about once per
een but no attempt is being made
> to choose one peak to work with?
>
> Like the speed up version a bit to impatient.
> Thank you for sharing with time-nuts Anders
> Paul
> WB8TSL
>
> On Sat, Dec 7, 2019 at 7:39 AM Anders Wallin
> wrote:
>
> > Hi Jim, yes you
Hi Jim, yes you are right the background is a camera-image (about 30x
magnification, maybe 1um per pixel). We use a microscope-objective, a
narrow 422nm bandpass filter, then an image-intensifier, and a fairly
standard CCD camera that looks at the output of the intensifier. When
everything is
Hi all, you may find our live-stream from the lab amusing:
https://www.youtube.com/watch?v=z9VFbs4FogY
The central bright dot is fluorescence at 422nm from laser cooling a single
trapped 88Sr+ ion. The ion emits about 1e7 photons/s at most and we
currently detect about 500 of those in a 20ms
FWIW meinberg's chart ends up at 1.1 us with similar assumptions:
https://www.meinbergglobal.com/english/specs/gpsopt.htm
you could check that your model gives similar values for the lower quality
oscillators, and longer free-run periods also?
On Fri, Nov 29, 2019 at 3:32 AM BJ wrote:
> Dear
; room temperature vacuum and the laser cools
> > > just the atoms. It appears to be the latter.
> > >
> > > So the enclosure has low emissivity so it
> > > doesn't transfer too much heat to the atoms
> > > by radiation?
a short writeup of our phase-meter/digital-DMTD tests with an Ettus B210 is
now on researchgate:
https://www.researchgate.net/publication/336825605_Software_Defined_Radio_Based_Phase_Meter_for_Frequency_Metrology
an ADEV of 2e-14 at 1s in 0.5 Hz bandwidth is fairly straightforward to
achieve, for
ptti2018:
https://www.researchgate.net/publication/322920519_Long_term_frequency_instability_of_a_portable_cold_87Rb_atomic_clock
ifcs2018:
https://www.researchgate.net/publication/325499937_A_portable_cold_87_Rb_atomic_clock_with_frequency_instability_at_one_day_in_the_10-15_range
this one is
FWIW some measurements:
http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_test_pn.png
and
http://www.anderswallin.net/wp-content/uploads/2016/09/fda_2016-09-12_PN.png
and
https://www.febo.com/pages/amplifier_phase_noise/
my ohwr-design uses better op-amps, giving slightly
>
>
> I am keen to measure close in phase noise 1Hz to 1 MHz offset on 100 MHz
> clocks.
>
We have some preliminary results on 100MHz using an Ettus B210 SDR.
The RF front-end is an AD9361, and if you search on ebay you will find B210
clones at about half the NI/Ettus price (haven't tried
> Anders,
> Thanks for sharing your results! I am a but surprised that you have so
> large
> variations, I wonder how much the antenna placement affects the results.
> Just for fun - can you tell us more about how your antenna is place now?
>
Current antenna placement was restricted by the 5m
Hi Michael, thanks for the reminder about your slides!
Your page 4 has the two setups. I think you are right in that the F9T
doesn't seem to take an external receiver clock (even if working with the
bare part, not the RCB-board).
(FWIW, AFAIK the not-so-low-cost septentrios use the left external
> If I am able to connect TimeLab with my FCA3103 in the future I also
> want to compare this TIC with the
> FA1 and TSA3011. Also important would be the fact whether the 'cheaper'
> versions could be used to measure phase
> noise as the TimePod 5330A or the PhaseStation 53100A devices and how
>
maybe the measurement principle is similar to the PicoPak?
http://www.stable32.com/PicoPak%20App%20Notes%20Links.htm
Do open it up! And send a high resolution picture to the ist ;)
A.
On Sat, Aug 31, 2019 at 1:11 AM Mark Sims wrote:
> (Hopefully this is not a duplicate post... hotmail has
FWIW for the 10MHz distribution amplifier I have been using LT1963 (40
uVrms in 10Hz to 100kHz) which is about 40x worse than the LT3042 spec of
0.8 uVrms in 10Hz to 100kHz.
With decent op-amps I think the distribution-amp performance is limited by
the op-amp noise and thermal noise in the
Hi Taka,
I made an 1:8 multiplexer with TE HF3 relays. They are specified up to 3
GHz, but the 'tree'-design has log2(8) = 3 levels - i.e. the signal always
passes through three relays.
in practice I got around 1 GHz -3dB bandwidth, which I think is OK for 1PPS
Hi Luiz,
We replaced H-source one Kvarz active HM during the summer of 2016. After
6-9 months of so of 'warm up' and settling down it is back up to maximum
TAI weight.
We got the new H-source bottle (size of a mini coke-can) and instructions
from the manufacturer.
>From what I recall the steps are
page 48 here has some notes on time-base error:
http://leapsecond.com/hpan/an200-3.pdf
for time-interval measurement the number of digits matter. if you keep
time-intervals 'small', say 123.45 ns (probably can't resolve much below
10ps anyway with a TICC) then a time-base with only about 5-6
FWIW since about a month back AllanTools has an example matplotlib-script
that generates graphs similar to Stable32
http://www.anderswallin.net/2019/05/this-is-not-stable32/
that is, if you are prepared to do a bit of python programming...
you need the example-scripts from github, not the older
FWIW UNAVCO now lists some actual hardware models with issues/no-issues and
links to further material:
https://kb.unavco.org/kb/article/preparing-gps-gnss-receivers-and-hardware-for-the-april-6-2019-gps-week-number-rollover-wnro-867.html
On Sun, Mar 31, 2019 at 10:00 PM Bob kb8tq wrote:
> Hi
>
We've tinkered with SFP-to-SMA adapter boards like this:
https://github.com/aewallin/SFP2SMA_2018.03
http://www.anderswallin.net/2018/04/500-mhz-sfp-board-v4/
although designed for 1 Gbit (1.25 GHz, or 800 ps 'bits') they work down to
10 MHz (and 5 MHz IIRC).
With a decent interface-board and a
If you search for "GNSS time transfer" you will find a lot of papers etc.
For example these might get you started:
https://www.bipm.org/ws/CCTF/TAI_TRAINING/Allowed/Fundamentals/Training-2012-GNSS-Defraigne.pdf
https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7909843
I tried to collect some
I've tried to collect links to frequency/pulse distributor designs over
here:
https://www.ohwr.org/project/pda-8ch-fda-8ch/wikis/Similar-Projects
if something good is missing let me know!
AW
>
> > But how do I do this
> on 10MHz side? I'd like to have minimal distortion
> (sine wave) and
AD replied to my message on the AD forums: (upon inspection they will
revise the datasheet to say the resolution is 47 bits now... ha!)
https://ez.analog.com/dds/f/q-a/107510/ad9912-ftw-lsb-always-zero
the datasheet has a copyright "2007-2010" so maybe the chip has been out
for 11-12 years already
he results!
Anders
On Mon, Feb 18, 2019 at 7:01 PM Magnus Danielson wrote:
> Hi Anders,
>
> On 2019-02-18 14:47, Anders Wallin wrote:
> > Hi all,
> > We've tried to measure the 1e9/2**48 = 3.55uHz frequency resolution of an
> > AD9912 DDS (clocked at 1GHz SYSCLK), bu
Hi all,
We've tried to measure the 1e9/2**48 = 3.55uHz frequency resolution of an
AD9912 DDS (clocked at 1GHz SYSCLK), but found that the output corresponds
to an FTW with the LSB set to zero.
Results around 10MHz output, where we expect a step of 3.55 uHz for each
step of the FTW, but instead see
I played around with this today, recording 5 minute runs: freerunning, P/10
gain, P gain, 10x P gain (where P is some unknown value...)
I then added either a 1M/100n or 500k/100n integrator which really only
shows in the TDEV-plot, not in the PN-plot.
https://photos.app.goo.gl/V9xL5MkVsL6RLRXJ7
Hi all, is there are rule-of-thumb or simple paper/presentation of how to
choose PLL-gains?
I have a phase-detector that gives out a slope of roughly 1 V/rad, followed
by an op-amp circuit with proportional, integral, and double-integral gains
summed into one voltage [0, 3.3V] on the tune-pine of
from 1995-05-28 to 2019-01-11 is exactly 1024 weeks, do your receiver has a
GPS-week rollover problem...
On Sat, Jan 12, 2019 at 12:16 AM Toby Riddell
wrote:
> Hi all,
>
> I got my Soekris net4501 hooked up to an oncore module and antenna and
> ntpns has been talking nicely to the oncore. After
where the MDEV-coefficients come from - maybe the Dawkins et al.
paper? (worth adding to wikipedia also?)
Also for flicker-PM there seems to be (slightly) different versions of the
ADEV pre-factor in different references.
Anders
On Sat, Oct 27, 2018 at 10:08 AM Anders Wallin
wrote
> Is this some elemental effect of integration (sqrt(n) or some such), or am
> I seeing the effects of bandwidth and/or bias-functions or other esoterica?
>
FWIW the python "colorednoise" (aka. Kasdin-Walter) repo has a figure:
https://github.com/aewallin/colorednoise
and code that generates the
FWIW the round-trip delay on our 900km White Rabbit link looks like so
(lower graphs. upper are a local Cs-clock vs. the fiber-time):
http://monitor.mikes.fi/mikes_kaja/
No fault-lines, earthquakes, or volcanoes in Finland I'm afraid. That's a
standard 2-fiber (separate TX and RX fibers) DWDM
Is PPP-AR "ambiguity resolution" the same (or similar) as iPPP from CNES
(code or service not publicly available AFAIK)?
iPPP time/frequency transfer is a useful improvement over PPP, see e.g.
http://cnfgg.eu/pdf/G2_2015/Gerard%20PETIT.pdf
On Sat, Jul 14, 2018 at 3:58 AM Mark Sims wrote:
> I
FWIW I have done some comparisons between the nrcan gpspp-code (behind the
csrs service), ESA gLab, and rtklib. There are mostly undocumented scripts
over here:
https://github.com/aewallin/ppp-tools
My tests were with dual-frequency RINEXes - haven't tried single-frequency
at all.
better and
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