[time-nuts] Re: The amazing $5 timestamper, part 2: discovering a bug in my signal generator

[Detlef Schuecker via time-nuts]

Hi,

yes, the STM32F4xx series has the spread spectrum feature, the STM32F3xx 
does not. 
See the RCC_SSCGR (reset and control clock spread spectrum clock 
generation register), Bit 31 in 
dm00031020-stm32f405-415-stm32f407-417-stm32f427-437-and-stm32f429-439-advanced-arm-based-32-bit-mcus-stmicroelectronics.pdf,
 
catchy names :)).

But the STM32 are real fine machines imho..

Cheers
Detlef 




Von:"Lux, Jim" 
An: time-nuts@lists.febo.com
Datum:  05.05.2021 22:21
Betreff:[time-nuts] Re: The amazing $5 timestamper, part 2: 
discovering a bug in my signal generator



On 5/5/21 12:57 PM, Poul-Henning Kamp wrote:
> 
> Pluess, Tobias writes:
>
>> In my very first GPSDO I built, I used a STM32F303. This one had a 
quite
>> bad PLL stability, the frequency was varying over time in a sawtooth 
like
>> manner for some reason.
> It's called "spread-spectrum" and is done deliberately to game the EMI
> criteria for various certifications.
>
> By sweeping the frequency through a range, the peak energy of any one
> frequency, as averaged over a second, drops correspondingly.
>
> In many cases you can actually disable it, but you may have to punk the
> manufacturer quite hard to find out what bit to set or clear.
>
https://www.st.com/resource/en/application_note/dm00281138-stm32-mcus-spreadspectrum-clock-generation-principles-properties-and-implementation-stmicroelectronics.pdf


Says the STM32F2, F4, F7, but not the F3. But it might be similar.

You could look at the register map of the F3 for MODPER, INCSTEP, 
SPREADSEL, SSCGEN ?

A casual grep didn't find it.

There's also a scheme in another ap note about going in and changing the 
PLL fractional divider every millisecond using software. (I guess that's 
if you fail your radiated emissions test, and you're desperate?)
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[time-nuts] Re: PN measurement thesis published

[Detlef Schuecker via time-nuts]

Hi,

German is a gorgeous language, I can assure ;))
Im diving into it for decades now and still find new things.

Mark Twain showed a somewhat different opinion, see his 'The awful german 
language'.

Cheers 
Detlef

https://www.google.com/url?sa=t=j==s=web==2ahUKEwiA99Tz0-vvAhV9_rsIHYdMBaAQFjAFegQIAxAD=https%3A%2F%2Fwww.viaggio-in-germania.de%2Fawful-german-language.pdf=AOvVaw1J0ExTcPC0pVyuRCvBzH7y


"Lux, Jim"  schrieb am 06.04.2021 22:48:29:

> Von: "Lux, Jim" 
> An: time-nuts@lists.febo.com
> Datum: 06.04.2021 22:49
> Betreff: [time-nuts] Re: PN measurement thesis published
> 
> On 4/5/21 1:41 PM, Attila Kinali wrote:
> > On Mon, 5 Apr 2021 19:04:01 +0200
> > Hendrik  wrote:
> >
> >> I just realized a friend published her thesis on phase-noise 
measurement
> >> on her blog (in german):
> >>
> >> http://www.stefanie-engelhard.de/sites/default/files/2019-03/
> Diplomarbeit_Stefanie_Engelhard_0.pdf
> > I recently stumbled over this thesis and liked it a lot.
> > It is a well written treatise of phase noise measurement and the
> > practical aspects of it. It's a shame it's in German, It would
> > be a good document to point people to, who want to learn the
> > basics of phase noise measurement electronics. So, if you
> > know German, read it, it's worth it.
> >
> I suspect google translate would help you past any complex stuff. My >40 

> year ago high school German works for reading most technical writing - 
> Although I will say at first I saw Rauschen des Oszillators and read it 
> as Rauchen des Ozillators and wondered "Oscillator Smoke?"  Oh 
> Noise. Of course - and now it's Phasenrauschens which makes a lot of 
> sense to a time-nut.
> 
> 
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[time-nuts] Re: Complex PLL

[Detlef Schuecker via time-nuts]

Hi,

yes, got it, I think, thanks. 

I calculate the complex quotient of the incoming complex signal and the 
local complex oscillator. I feed the imaginary part of the quotient to the 
PI controller, thus forcing it to zero. The local oscillator is updated by 
multiplying it with ( real(quotient)+j*PIOutput ). Forcing the imaginary 
part of the quotient to zero means that incoming signal and local 
oscillator are in phase.

See Matlab code and the image. 
No atan/cos/sin, just mere multiplication :)) 

Thanks

Cheers
Detlef Schücker
DD4WV

clear
n=1;
T1=0;
T2=0.01;
s0=exp(j*2*pi*200*(0:n-1)/n);
s1=zeros(1,n);
s2=zeros(1,n);
s3=zeros(1,n);
for(k=1:n)
 s1(k)=(s0(k)/T2);
 T1=T1+imag(s1(k))/4000;
 s2(k)=0.03*imag(s1(k))+T1;
 s3(k)=T2;
 T2=T2*(real(s1(k))+j*s2(k));
 
end;
plot(1:n,real(s3),'b.-',1:n,real(s0),'r.-') 
return





"Magnus Danielson"  schrieb am 17.03.2021 19:20:49:

> Von: "Magnus Danielson" 
> An: time-nuts@lists.febo.com
> Datum: 17.03.2021 19:59
> Betreff: [time-nuts] Re: Complex PLL
> 
> Hi,
> 
> On 2021-03-17 17:20, Detlef Schuecker via time-nuts wrote:
> > Hi time-nuts,
> >
> > a PLL takes the phase difference of the incoming signal and the 
> > synthesized signal and feeds that in a loop filter. The output of the 
loop 
> > filter is used to steer the local oscillator. 
> >
> > In my setup I have an incoming complex signal and my local oscillator 
is 
> > generating a complex signal as well. So calculation of the phase 
> > difference is just the quotient of the incoming signal and the local 
> > oscillator, it is a sampled system. I take the quotient, calculate the 

> > angle using the atan function and then I feed it in the loop filter, a 
PI 
> > controller. The output of the loop filter is converted to a complex 
phase 
> > increment for the local oscillator with the sin and cos function. 
> >
> > Now I have to get rid of the atan, cos and sin functions.
> >
> > I am looking for a loop filter which takes the quotient of the 
> > incoming/synthesized signal as a complex value. The output of this 
loop 
> > filter should be the phase increment for the local oscillator. It 
should 
> > not use the angle of the complex value explicitly, as this will 
involve 
> > the atan/cos/sin functions.
> >
> > Is someone aware of such a loop filter? I surfed through Gardners' 
> > 'Phaselock Techniques' but did not find a hint.
> 
> That book is full of hints. Costas loop is one. Actually, you could just
> do complex multiplication and only use the real output (and thus remove
> half the complex multiplication) and use that output of the
> multiplication as input to normal PI-regulator, that will lock up and
> achieve everything you want. You can then also remove the sine with a
> squarewave. There is some benefits and losses in doing that, which may
> or may not be relevant.
> 
> There is a richness of complex detectors to be found in GPS literature,
> such as that of "Understanding GPS principles and applications" of
> Kaplan and Hegarty. You can also look at "Phase-locked loop circuit
> design" by Wolaver for additional inspiration. You end up finding that
> Garners' book is actually very comprehensive if you only take time to
> dwell into it.
> 
> Let me know if you need more hints.
> 
> Cheers and 73,
> Magnus SA0MAD
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[time-nuts] Complex PLL

[Detlef Schuecker via time-nuts]

Hi time-nuts,

a PLL takes the phase difference of the incoming signal and the 
synthesized signal and feeds that in a loop filter. The output of the loop 
filter is used to steer the local oscillator. 

In my setup I have an incoming complex signal and my local oscillator is 
generating a complex signal as well. So calculation of the phase 
difference is just the quotient of the incoming signal and the local 
oscillator, it is a sampled system. I take the quotient, calculate the 
angle using the atan function and then I feed it in the loop filter, a PI 
controller. The output of the loop filter is converted to a complex phase 
increment for the local oscillator with the sin and cos function. 

Now I have to get rid of the atan, cos and sin functions.

I am looking for a loop filter which takes the quotient of the 
incoming/synthesized signal as a complex value. The output of this loop 
filter should be the phase increment for the local oscillator. It should 
not use the angle of the complex value explicitly, as this will involve 
the atan/cos/sin functions.

Is someone aware of such a loop filter? I surfed through Gardners' 
'Phaselock Techniques' but did not find a hint.

Thank you
Detlef Schücker

DD4WV

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Re: [time-nuts] Mains Frequency

[Detlef Schuecker via time-nuts]

The Berlin grid was isolated from '48 until begin of the '80s. Berlins 
BEWAG was very proud of running a stable net on this island. They used a 
big bunch of energy storage devices: steam under pressure, batteries etc. 
to keep the frequency and phase stable. In begin/mid '80s they built a 
380kV power line from West-Germany (Buschhaus) to Berlin crossing the GDR. 
So Berlin was hooked to the west-european frequency. 

After the fall of the wall they disconnected this line and hooked up to 
then USSR driven east german grid. That was for commercial reason, 
reportedly they saved a Million Marks a day. So Berlin had the same grid 
frequency as Moscow, and many clocks on churches, towers, the city hall, 
public clocks on poles etc. ran on that frequency. The USSR grid had a 
much bigger limit on the phase, so the grid driven clocks sometimes lost 
or won 15min a day, as far as I remember. Sometime in the '90 they 
switched to the west-european grid for then reunified Germany. 

There were similar developments for other european satellite states of the 
USSR, i.e. Hungary. They had a long direct 750kV DC-connection, for a 
great distance you use DC. In '92 I visited the DC/AC converter in 
Budapest, installed in a rather big hall. It was cooled by de-ionized 
water, which was so aggressive to get ions that they could not use any 
metal for fittings but they had to use glass. In this big hall there was a 
fairytale castle made of glass pipes, tubes, coolers etc., very 
impressing.

In the old times :-|
Cheers
Detlef Schücker


"time-nuts"  schrieb am 12.02.2021 
20:41:25:

> Von: "Alex Pummer" 
> An: time-nuts@lists.febo.com
> Datum: 12.02.2021 22:39
> Betreff: Re: [time-nuts] Mains Frequency
> Gesendet von: "time-nuts" 
> 
> at the time I grew up in Eastern Europe -- "communist time" -- they kept 

> he clocks using the line frequency as reference -- by counting the 
> periods during the day and week and for longer time for equal time 
> interval the "provided" equal number of line frequency periods, as 
> longer the time interval was as more precise was the time.  That way the 

> clocks were relative accurate. They could do it since everything was 
> "central governed".
> 
> On 2/12/2021 9:24 AM, Lux, Jim wrote:
> > On 2/12/21 8:23 AM, Thomas D. Erb wrote:
> >> "I would think they try to hold it over 1 day, so that mains driven
> >>
> >> clocks don't run slow or fast.? That being said, I wonder how many
> >>
> >> clocks are still being built using a synchronous motor drive? Given 
that
> >>
> >> all the clocks on appliances in my kitchen have drifted apart, I'll 
bet
> >>
> >> they use their internal microcontroller crystal as a reference."
> >>
> >> Actually I think all of my kitchen appliances use line frequency for 
> >> time reference - it's so easy to count.
> >
> >
> > Maybe.. you've got to condition the AC from the secondary side of the 
> > transformer and use a pin to bring it in on, which requires at least 2 

> > or 3 passive components, and you already have a crystal for the 
> > microcontroller (thinking here of oven timers and the like, which have 

> > a numeric display).  These applications are super price sensitive, and 

> > those 2 or 3 components cost money, in components, in board space, and 

> > in assembly costs. Pennies to be sure, but...
> >
> > And the fact that my appliances drift on the order of a minute in a 
> > month, differently. So maybe some count cycles and some have a rock.
> >
> >
> >
> > ___
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> >
> >
> 
> 
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Re: [time-nuts] Daft idea with the National Grid

[Detlef Schuecker via time-nuts]

Hi,

zero cross detection is not the best way to track grid frequency. 
I built my grid frequency tracker with a uC sampling the grid at 160ks/s 
and 12Bit. It is clocked by a TCXO. I fit a sine wave for every cycle of 
the grid. 

Fitting a sinewave is a linear problem, you do not need any approximations 
and it is doable with a small uC. The samples of a sinewave are the 
solution to the difference equation sig(n+1)=2*cos(w)*sig(n)-sig(n-1), 
which is a linear equation for the unknown cos(w). That is straight and 
simple linear algebra. I get a precision in the range of 4E-4 Hz.

>>
Years ago I recall reading accounts of efforts in the U.S. and perhaps 
Canada to track down the cause(s) of small but noticeable changes in the 
frequency of certain regional power grids that seemed to occur at more or 
less the same time each day. 

In the european grid you have stable frequency changes in a 15min 
timeframe, frequency being high in the morning and at night and low in the 
afternoon. The 15 min timeframe is due to the 15min trade periode of the 
European Energy Exchange trading platform located in Leipzig. The energy 
brokers show a deterministic under/over-estimation of the european power 
consumption which results in power shortage/surplus and thus frequency 
rise or fall. 

If I were a stock exchange geek I'd turn this information into money, much 
money :))

Cheers
Detlef 


"time-nuts"  schrieb am 08.02.2021 
23:59:07:

> Von: joekok...@epios.eu
> An: time-nuts@lists.febo.com
> Datum: 09.02.2021 00:05
> Betreff: Re: [time-nuts] Daft idea with the National Grid
> Gesendet von: "time-nuts" 
> 
> Dear all,
> 
> it is quite an interesting premise. I think one of the challenges is to 
> even measure these small deviations in frequency. The time correlation 
> can be achieved with GNSS but the actual determination of the 
> zero-crossing might be the problem. I think the ZCD must be better than 
> 100ns for this in each cycle. Local noise and environment conditions 
> render it quite difficult. When constructing a filter for the 50Hz, the 
> components must be very well designed to cope with the different 
> temperature, local noise and voltage amplitudes at two different places.
> 
> Regarding disruptions in the grid: there are various regulation 
> mechanisms. Generally the first 10-20 seconds physical effects stabilize 

> the grid. Afterwards the automatic control takes over.
> 
> - saved rotational energy: an initial frequency drop due to a unexpected 

> change in load or production is smoothed out by the inertia of all the 
> generators, motors, pumps, etc. For a 10% mismatch in power without 
> additional measures, the initial frequency drop would be about 1Hz per 
> 30 seconds.
> 
> - self-regulation: a 1% drop in frequency leads to a ~2% reduction of 
> load due to frequency dependent loads;
> 
> - primary, automatic load-frequency control takes about 30 seconds to 
> activate
> 
> After this rather short timescales, as Poul-Henning mentioned the human 
> factor (trading) has the biggest impacts on grid stability. It is 
> clearly visible with a periodicity of 15 minutes and more pronounced in 
> the evenings.
> 
> A small note on the recent frequency drop in the European grid:
> https://www.entsoe.eu/news/2021/01/26/system-separation-in-the-
> continental-europe-synchronous-area-on-8-january-2021-2nd-update/
> 
> Best
> Joe
> 
> On 2/8/21 8:46 PM, Mark Spencer wrote:
> > Years ago I recall reading accounts of efforts in the U.S. and 
> perhaps Canada to track down the cause(s) of small but noticeable 
> changes in the frequency of certain regional power grids that seemed
> to occur at more or less the same time each day.
> > 
> > 
> > Mark Spencer
> > m...@alignedsolutions.com
> > 604 762 4099
> > 
> >> On Feb 8, 2021, at 6:48 AM, Lux, Jim  wrote:
> >>
> >>> On 2/8/21 12:02 AM, Poul-Henning Kamp wrote:
> >>> 
> >>> Lux, Jim writes:
> >>>
>  If you happen to own something like a steel mill running electric
>  furnaces or an aluminum refinery, so you can manipulate the load...
> >>> More scary:  Several independent studies have shown that even 
relatively
> >>> moderate bot-nets in the hands of somebody who knows the math of 
grid
> >>> stability would mean no grid stability.
> >> This is a generalized concern with distributed generation (i.e. 
> rooftop solar panels on houses), because a bug in the controllers 
> for the line connected inverter could really screw things up. I 
> suppose there's also concerns about  malicious activity, but fiascos
> like the NEST thermostats stopping  in winter of 2015/2016 are more 
likely.
> >>
> >>
> >> ___
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[time-nuts] near-Blackout Europe

[Detlef Schuecker via time-nuts]

Dear time-nuts,

on Jan.8, 13:04:54 UTC, the european grid frequency dropped from 50.0269Hz 
to a minimum of 49.7343Hz 13.4sec later, see fig 1, plot starting at 
13:00, x-axis in sec. .

As a result southeast Europe was split from the rest, the frontier 
crossing the Balkan countries, see 

https://www.entsoe.eu/news/2021/01/15/system-separation-in-the-continental-europe-synchronous-area-on-8-january-2021-update/

At 13:42:35 the western frequency was back at the 50Hz level, some time 
later they managed to resync the east und reconnected. Reasons are still 
under examination. A high western demand faced a southeastern production, 
so after the split the western frequency went down, the eastern frequency 
went up.

At 79/50 sec. after the event the primary control kicked in at 49.9035Hz 
and brought it up again to 49.9308 but eventually failed, see fig2.

In the 13. hour that day they failed to deliver 112 sinewaves. Now ENTSO-E 
has to decide: readjust the wall clocks in Berlin or Athens? ( think they 
decide for the west :)) ) 

Reportedly at a frequency below 49.8Hz big loads, like pumps for 
reservoirs or industrial customers are switched off automatically.

In 2011 the German Government launched a scenario for a blackout, detailed 
as a script:
https://www.tab-beim-bundestag.de/en/publications/books/petermann-etal-2011-141.html

The authors exspect that the drivers trapped in a parking garage will 
violently break the disfunctional barriers after 3h.

Big things to come, the next desaster ? Hopefully not, fingers crossed.

Cheers
Detlef




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Re: [time-nuts] WWVB SDR discussion

[Detlef Schuecker via time-nuts]

Hi,

you do not necessarily need a variable ( physical ) oscillator. You mix 
the signal down in the digital domain. A 'digital local oscilator' is a 
mere complex value, which is rotated and the power is adjusted:

#define CMUL(_a,_b,_c)  \
{ _c.re = _a.re*_b.re-_a.im*_b.im; \
  _c.im = _a.re*_b.im+_a.im*_b.re; }
#define CROT(_a,_w) 
{ fcomplex_t hh; \
  CMUL(_a,_w,hh); \
  _a.re=hh.re*hh.re+hh.im*hh.im; \
  if(_a.re<1.0f){ \
 hh.re *= (1.0f+1e-6); \
 hh.im *= (1.0f+1e-6); \
  } else { \
 hh.re *= (1.0f-1e-6);  \
 hh.im *= (1.0f-1e-6);  \
  } \
  _a.re=hh.re; \
  _a.im=hh.im; \
}


The sample rate is not an integer multiple of the signal frequency, that 
is not necessary. 


> part, unfortunately.  My tuned loop seems still too broadband, even
> after a couple more poles of op-amp filter.  I have a bunch of 60-kHz
> tuning-fork crystals and wanted to try a crystal filter like the "pros"

Good point. 
Firstly I tried a tuned resonant LC circuit with a BF245 preamplifier to 
keep a high Q.
Secondly an accurate ADC is an option. With 24Bit you get more than 100dB 
dynamic range, so you dont care about a 60dB stronger nearby interferer.

I want to phase track at least 2 time broadcasters eg Anthorn and DCF77 
and try to do a hyperbolic navigation with the phase difference. The LC is 
tuned by MOSFET switched capacitors. A STM32 should suffice for the thing. 
See, how far ( or near, in terms of navigation ) I can get :).

Cheers
Detlef
DD4WV
 





 

Detlef Schücker


"time-nuts"  schrieb am 10.08.2020 
23:18:29:

> Von: "Mark Haun" 
> An: time-nuts@lists.febo.com
> Datum: 11.08.2020 00:29
> Betreff: Re: [time-nuts] WWVB SDR discussion
> Gesendet von: "time-nuts" 
> 
> No more so than for a GPSDO using a microcontroller.  In this case, the
> MCU would steer an external oscillator using an appropriately long time
> constant, based on a phase tracking loop.  In my tentative block
> diagram, the oscillator is a cheap 26 MHz OCXO which supplies the MCU
> clock and (as a byproduct) the internal ADC sample rate.  The basic plan
> for an STM32L4 was something like
> 
> 26 MHz clock input from OCXO
> 78 MHz MCU clock (x3 via internal PLL)
> 3.12 MHz ADC sample rate (78 MHz / 25)
> 13x downsample to 240 kHz using DFSDM block (hardware CIC)
> sign flip and deinterleave into I and Q channels (I, Q, -I, -Q, ...)
> downsample again, to ~ 10 Hz or so; do SDR stuff at this rate
> carrier tracking loop runs back outside the MCU to the OCXO control
> input, via PWM DAC
> 
> With care, the internal ADC gives you about 11 good bits at the high
> sampling rate.  Assuming white noise (questionable I suppose), this
> yields something like 18 noise-free bits at the low rate where the phase
> tracking and decoding happens.
> 
> Prerequisite is an analog input centered around 60 kHz with less than
> 3.6Vp-p amplitude.  There are no particular bandwidth requirements
> (Nyquist is 1.5 MHz!) as long as it is narrow enough to avoid clipping
> from strong interfering signals.  I am having a hard time with this
> part, unfortunately.  My tuned loop seems still too broadband, even
> after a couple more poles of op-amp filter.  I have a bunch of 60-kHz
> tuning-fork crystals and wanted to try a crystal filter like the "pros"
> do in cheap consumer clocks, but I can't figure out a circuit to do this
> (weak on analog).  So if anyone wants to tackle that and send me a
> working design, I'm happy to do the easy stuff, i.e. the DSP/SDR parts 
;)
> 
> Mark
> 
> On 10-Aug-20 11:45 AM, paul swed wrote:
> > Hello to the group.
> > Have been looking forward to seeing how the STM32 SDR project might be
> > going.
> > SDR is a weak spot for me. So been reading. And believe the answer is 
that
> > a SDR solution may work for AM code and even BPSK code to an extent. 
But
> > doesn't the sampling destroy the quality of the incoming signal for
> > establishing a locked reference?
> > Regards
> > Paul
> > WB8TSL
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Re: [time-nuts] WWVB PM Time Questions

[Detlef Schuecker via time-nuts]

Hi,

> principles.  The STM32L4 series which I often use has a pretty decent
> ADC: fast (5 MSPS), with about 11 good bits in differential mode, and
> "proper" hardware downsampling (called the DFSDM in the manual).  If the

Yes, the STM32 series also have built-in OPAmps, so one could hook up a 
loop or a ferrite directly to the uC without too much external components. 
Sampling at 160ks/s should suffice to get the phase and DCF77 is in reach 
as well. At this rate you have ~500-1000 processor ticks per sample which 
should be enough to do real time demodulation.

Very nice project.

Cheers
Detlef Schücker


"time-nuts"  schrieb am 22.07.2020 
18:44:08:

> Von: "Mark Haun" 
> An: time-nuts@lists.febo.com
> Datum: 22.07.2020 19:29
> Betreff: Re: [time-nuts] WWVB PM Time Questions
> Gesendet von: "time-nuts" 
> 
> Hi Ray,
> 
> A similar project has been on my to-do list for a couple of years now
> (so don't hold your breath!).  It should be possible to do this using
> the built-in ADC for a really nice, minimalist demonstration of SDR
> principles.  The STM32L4 series which I often use has a pretty decent
> ADC: fast (5 MSPS), with about 11 good bits in differential mode, and
> "proper" hardware downsampling (called the DFSDM in the manual).  If the
> noise is white it should be easy to get > 16 good bits into the
> demodulator.  My plan was to clock the MCU from a cheap OCXO and make it
> part of the carrier tracking loop, for a simple WWVB disciplined 
oscillator.
> 
> I also have some questions about the NIST document, but in general, I
> think you need to assume that your receiver is already locked, in which
> case you know when to expect the transitions.  Getting to this point
> (acquisition) is another story, but there are all sorts of
> correlation-based tricks that you can use, similar to GPS code
> acquisition.  As others have noted, carrier phase lock can be aided by
> squaring.
> 
> My problem is that the SDR stuff is all pretty straightforward for me,
> but the analog electronics leading up to the ADC are black magic.  I
> have a preamp circuit modeled on John Magliacane's design
> (http://www.arrl.org/files/file/QEX_Next_Issue/2015/Nov-Dec_2015/
> Magliacane.pdf),
> fed from a ~ 60-turn tuned loop made from old ribbon cable, but I am
> having problems getting anything "reasonable" looking on the scope.  I
> don't know if the problem is my suburban location or if you really can't
> see the signal until you get the bandwidth << 1 kHz. (I am using
> RC-tuned op-amp stages so the -3 dB response is necessarily a few kHz.) 
> Eventually I would like a small loopstick design with a crystal filter
> like the off-the-shelf clocks use, but I haven't a clue how to get
> there.  Maybe this project would benefit from a collaboration :)
> 
> Regards,
> Mark
> 
> On 21-Jul-20 4:37 PM, rcb...@atcelectronics.com wrote:
> > I want to decode the WWVB time information using the BPSK information
> > that is broadcast. I will use a STM32 to do the actual decoding of the
> > bit stream. This is just an exercise in "can I do it?" as I know I can
> > buy clocks for $30 that use the BPSK method. At one time you could buy
> > an IC that output the data stream but I believe there is nothing
> > currently available to do that.
> >
> > I read the document "Enhanced WWVB Broadcast Format" by John Lowe from
> > NIST. One thing that is confusing to me is this paragraph: "Although 
the
> > phase representing the information in each symbol is shown to be
> > available before the amplitude in it transitions from VH to VL, it is
> > recommended that receivers extract it only from the high amplitude
> > portion of the symbol. This is not only because of the higher power
> > there, allowing for more robust phase demodulation, but also because 
the
> > low amplitude portion may be used in the future for additional (higher
> > rate) phase modulation."
> >
> > How would you detect the phase had changed if you don't detect it when
> > it changes at 100 msec after the carrier level drops? After the signal
> > reverses phase wouldn't any reference you are using then be in lock 
with
> > the current phase of the signal after it has changed?
> >
> > Or would you use a locally generated 60 kHz ultra stable signal as the
> > phase reference? If so, how would you keep your local source locked to
> > the 0 degree phase signal of WWVB and have it ignore the 180 degree
> > phase shift?
> >
> > I have done a lot of searching and reading from various sources. But I
> > haven't really found a good explanation of the hardware that would be
> > used to detect the phase changes. Is there a block diagram somewhere
> > that would illustrate the steps needed to detect the change during the
> > high power portion of the WWVB signal?
> >
> > I am going to put together a 60 kHz amplifier using a couple of
> > FET/transistors and a couple of high speed opamps. Then I can observe
> > the signal on my scope. Using the output of the amp I can then try to
> > 

Re: [time-nuts] low power divide by 5

[Detlef Schuecker via time-nuts]

Hi,

yes, it is self-clearing. It cycles 0 4 6 7 1 (leftmost FF MSB), 2 clears 
to 7, 3->1, 5->2. On one output you get 3/5 duty cycle, on the other two 
you get 2/5. 

Detlef Schücker




Von:"Robert LaJeunesse" 
An: time-nuts@lists.febo.com
Datum:  01.07.2020 09:30
Betreff:Re: [time-nuts] low power divide by 5
Gesendet von:   "time-nuts" 



Take a look at the "modified" shift-register like counter in the attached 
jpg file. When simulated online it behaved as expected for a divide by 5. 
I believe it also is self-clearing from illegal states, but the other 
simulator I tested that in wasn't good for documenting the design.

Bob L.

> Sent: Tuesday, June 30, 2020 at 6:47 PM
> From: "dschuecker" 
> To: time-nuts@lists.febo.com
> Subject: Re: [time-nuts] low power divide by 5
>
> Hi,
> 
> a divide by five should possible with a synchronous state-machine made 
> of 3 ( sufficiently fast-) JK-FlipFlops.
> 
> All 3 FFs are clocked with the input freq. , the outputs of the FFs are 
> fed back to the the JK-inputs,  the divided freq. is output of one of 
> the FFs.
> 
> Additional constraints: no external ANDs or ORs or NOTs, the 
> state-machine does not get stuck in the 3 unused states.
> 
> This turned out to be a very interesting problem and I do not yet come 
> up with a solution. Maybe there is none. Analytical solutions all 
> failed, I will try a brute force enumeration attack tomorrow.
> 
> lots of fun !
> 
> Cheers
> 
> Detlef
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[time-nuts] low power divide by 5

[Detlef Schuecker via time-nuts]

Hi,

there are three JK-FF, with Q1 as MSB, Q3 as LSB. J1,K1 ist input to Q1, 
etc. .
There are 8^6 possibilties (6 inputs to the Qx or QxNOT or to HIGH or to 
LOW) of which
2069 generate a cycle length of 5.

The following wiring will generate the cycle 1 3 5 2 4 :

J1=Q2
K1=Q1
J2=Q3
K2=Q2
J3=Q2NOT
K3=Q1

Q3 is output with a 3/5 duty cycle.
The unused state 0 will migrate to 1,6->0,7->0.
So the machine does not get stuck.

Cheers
Detlef 


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Re: [time-nuts] Mains frequency data for Europe

[Detlef Schuecker via time-nuts]

Hi,

I uploaded european frequency data starting 2019 to ftp site 
'dschuecker.dyndns.org' name/pw 'mainsf'.

feel free to download

Cheers Detlef




Von:"Azelio Boriani" 
An: "Discussion of precise time and frequency measurement" 

Datum:  25.03.2020 02:30
Betreff:Re: [time-nuts] Mains frequency data for Europe
Gesendet von:   "time-nuts" 



The entsoe.eu site is full of 404... the only site I can find with
frequency data is this (for the Belgian grid):


What happened to the grid frequency in Europe in Jan 2019 and Apr 2019:
<
https://www.next-kraftwerke.com/energy-blog/who-is-disrupting-the-utility-frequency
>


On Wed, Mar 25, 2020 at 12:52 AM Pieter-Tjerk de Boer
 wrote:
>
> Hello Attila,
>
> In principle I have that data (I've been logging the grid's phase since 
2008),
> but I'll need to do a bit of work to extract it to a usable format.
> Please contact me off-list.
>
> Regards,
>   Pieter-Tjerk
>
>
> On Tue, Mar 24, 2020 at 04:30:25PM +0100, Attila Kinali wrote:
> > Hi,
> >
> > Does someone here have recordings of the mains frequency of the west
> > European Grid from the last weeks and from the same time last year?
> > There is something I've been told which I would like to fact-check.
> > I wasn't able to find anything online.
> >
> > Thanks in advance
> >
> >   Attila Kinali
> > --
> > Science is made up of so many things that appear obvious
> > after they are explained. -- Pardot Kynes
> >
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Re: [time-nuts] Aerial coax downlead placement

[Detlef Schuecker via time-nuts]

Hi,

> Plus as the pole moves in the wind (they all do) the cable can move
> about inside, and if repeatedly impacting the inside of the pole over
> time, that will damage the cable.

You fix the cable inside the pole by applying three cable ties as a
triangle in regular intervalls. The loose ends of the cable ties will
center the cable inside the pole. That is how we do it in sailing. You do
not want a cable flapping against the inside of the mast, which is the
pole.
That does not solve the prolem of the cable weight, you need a pull relief
anyway.

Cheers
Detlef
DD4WV
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