celsius. As expected/visible in graphs,
this stabilizes the clocks of the time-servers a bit.
regards,
Folkert.
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> There was a discussion along these lines about using a RasberryPi or Arduino
> for this purpose a while ago on this forum --- try searhing for "WWVB
> Chronverter".
I tried this: https://github.com/hzeller/txtempus/
Works pretty good at a short distance (< 10cm).
a 4.7k ohm and
8.2k ohm resistor giving slightly less than 3.2v - will that work? or
will that attenuate the signal too much? The 50 ohm bnc cable between
the amplifier and the rpi is 3m long. Anything else I should be aware
of?
Regards,
Folkert van Heus
> > I wrote something this evening that just busy-loops waiting for a raising
> > edge and then writes down the current time to feed that to ntp.
>
> You are trading interrupt latency for user-kernel crossing delays and
> scheduler quirks.
Are you sure about the user-kernel crossings? Because
> > In FreeBSD you get all that for free:
> >
> >
> > https://papers.freebsd.org/2002/phk-timecounters.files/timecounter.pdf
> >
>
> "It is painfully obvious that the interrupt latency is the dominant
> noise factor in PPS timestamping in the second case."
I wrote something this evening
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Folkert van Heusden
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Hi,
I thought I understood just enough from electronics to be able to these
kind of experiments but apparently not (3 damaged rpi's and gps
modules).
I thought that if signal levels are in range of the device that will
read them and all grounds are connected, that you could safely for
example
ue. So "how good"
> > turns
> > > into measuring network (a)symmetries.
> > >
> > >
> > > --
> > > These are my opinions. I hate spam.
> > >
> > >
> > > _______
&g
Hi,
A few days ago I bought a Rigol DG1022Z function generator.
Works really well from what I can see. Especially compared to my
previous solution (a sound-card in my laptop with a few resistors and a
capacitor to adjust the signal level) :-)
Now I noticed that on the back there are a few bnc
Maybe a tiny bit on-topic but a nice watch nevertheless:
https://www.youtube.com/watch?v=DT5CafrZyDw
Syncing a pendulum to an audio synthesizer.
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Hi,
I'll reply to the reactions I received combined in one mail. I also
received an e-mail off-list, not adding that here (maybe there was a
specific reason for sending it off-list).
> Bob kb8tq:
MIDI gear spans many decades at this point. Some of it will have interesting
digital sub systems.
to output timestamps with milliseconds resolution).
The WiFi output is sampled using a raspberry pi 4 with tcpdump (with
name resolving disasbled).
Regards,
Folkert van Heusden
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> > I have one general question. I don't believe that an internal crystal in the
> > microcontroller will have the accuracy or precision required to have better
> > than a few milliseconds of accuracy (whereas NTP likes to live in the
> > microsecond realm), though I very well could be wrong on
past 30 days:
https://revspace.nl/grafiekjes/d/1/home?orgId=1=1h=24=now-30d=now
past 2 years:
https://revspace.nl/grafiekjes/d/1/home?orgId=1=1m=24=now-2y=now
Folkert van Heusden
--
> Thanks, Adam and Hal. I will have a play. I need to decide which of my
> flock to use, as some already sit in a fairly stable environment, and others
> are doing real work which may be affected by running the CPU at 100%.
>
> OK, there's a non-critical one rather nearer to a CH radiator than
Hi,
For fun I hooked up a TCXO to an Arduino. That Arduino then interfaces
the TCXO to the I2C in the VGA connector and then with some magic code,
it syncs the PPS signal to NTP.
https://vanheusden.com/misc/blog/2019-11-07.php
Curious what you think.
Regards,
Folkert van Heusden
> > Folkert van Heusden has a driver for NTP which includes PPS output:
> > https://vanheusden.com/time/rpi_gpio_ntp/
> > Perhaps this might help?
>
> Indeed I did! :-)
>
> But please note that the jitter is high, iirc around 18ms.
> Personally I would use htt
> Folkert van Heusden has a driver for NTP which includes PPS output:
> https://vanheusden.com/time/rpi_gpio_ntp/
> Perhaps this might help?
Indeed I did! :-)
But please note that the jitter is high, iirc around 18ms.
Personally I would use https://github.com/mlichvar/pps-gpio
https://hackaday.com/2019/06/26/accurate-time-on-your-pi-the-extreme-way/
(not mine!)
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> > Thanks for the raw data. Attached is Folkert-02.png which is the ADEV from
> > column 1 (your function generator vs. Arduino) and column 2 (your Adafruit
> > 1PPS vs. Arduino). In this case it's quite clear that the Arduino crystal
> > is much better than your func
from an expert but this graph looks a bit too good to be true.
Can anyone spot the mistake I make in the process?
regards
Folkert van Heusden
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