[time-nuts] Re: Where do people get the time?

[Peter Vince]

On Sun, 2 Jan 2022 at 17:57, Hal Murray  wrote:
>
>
> How far off does the audio have to be before it doesn't look/sound
right?  How
> accurately does the typical movie process get things aligned?


I used to work in broadcast television, and find that most people would
notice a couple of "frames" (80ms here in the UK) - we, trained and looking
for it, would notice one frame (40ms).  But it is more disturbing if the
sound is early, as that is so unnatural.  At that sort of level though, it
is quite hard to tell if it is early or late, especially as the actors
won't just stand there saying the same thing time and again :-)

Because the sound and video don't use the same frame rates, MPEG codecs
have a hard time getting it right.  We developed a test signal which
measured the time between a blip on the sound and a flash on the vision,
and used it regularly when lining up links.

Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Re: Leap indicator set to 1 !

[Peter Vince]

Sorry Andy, the latest IERS Bulletin C  (
https://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat)  specifically says
that there WON'T be a leap second this new-year.

Regards,

 Peter Vince


On Sat, 27 Nov 2021 at 20:19, Andy Talbot  wrote:
>
> A leap second is due 31 December.   I'm sure I've seen reference to a
"leap
> second pending" flag in some reference to time keeping somewhere.
>
> Andy
> www.g4jnt.com
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Re: [time-nuts] ISS NTP operation problems.

[Peter Vince]

Using NTP, with long and asymmetric path delays, seems like a recipe for
disaster.  Can they not simply use a GPS receiver?
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Radio Controlled Clocks

[Peter Vince]

Hello Andy,

 I have an old Maplin digital LCD clock for MSF, and that is always
about a second slow, but the Coopers analogue clocks are MUCH closer, as is
the Junghens DCF digital LCD clock.  But the Junghens DCF clock always
misses one or other of the DST changes!

 Peter


On Sun, 27 Dec 2020 at 12:11, Andy Talbot  wrote:
>
> With this talk of Radio Controlled clocks...
> I have three domestic RC clocks here, receiving the UK 60kHz signal, MSF.
>   However, I notice that when compared against a GPS clock, timed from the
> 1 PPS signal & NMEA output, they all are a few hundred milliseconds fast,
> ie the display changes just before the GPS derived time.
...
...
> I only ever have digital display clocks, so wouldn't know if the same
> happens with round ones with hands.Anyone else using domestic MSF or
> DCF77 clocks who have observed this?
>
> Andy
> www.g4jnt.com
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Rebroadcasting time signals [WAS: La Crosse Clocks - ]

[Peter Vince]

Do your receiver clocks need continuous access to the signal?  The several
radio-clocks I have here in England only enable their receiver for a few
minutes at about 01:00 to reset themselves, and then put the receiver to
sleep again.  If yours are similar, your rebroadcast system could be
similarly timed and significantly reduce power usage.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Rapco 1804M manual and Control Mode Access ?

[Peter Vince]

Where I worked we had a few of a later model Rapco 1804 (1804 L26 D2) which
had an LPRO Rubidium inside, and gave out 10MHz.  That had an eight-channel
Trimble receiver, but I'm afraid I can't remember the model number.

I wasn't very impressed by the disciplining algorithm which, once it had
settled down, just seemed to average the readings for 8000 seconds, and
then apply a step-change to the ruby's EFC.  This often resulted in
frequency jumps of several parts in 10^11 :-(

As stated in the manual that was linked, it was possible to disable the
automatic disciplining by issuing the RL command to "lock" the EFC.  It was
then possible to steer the EFC externally - the RV command reading the
current value, and the @V command changing it.  Said EFC was driven by a
16-bit DAC, which gave an average frequency-step size of about 6.7 E^-14.

Regards,

 Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 81, not quite a random number

[Peter Vince]

And of course 06:06:06 on the 6th June 2006, for those using 2-digit
years.  I snapped that on our old time system at work, with the time
displayed by the top unit, and the date on the bottom unit.

Ah - simple pleasures :-)

 Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Stanford University online GPS course

[Peter Vince]

I've just been told about an online undergraduate course on the GPS system
done by Stanford University.  I don't remember reading about it on here,
and a quick check of the archives drew a blank.  The course is completely
free, and on YouTube at:


https://www.youtube.com/watch?v=o1Fyn_h6LKU&list=PLGvhNIiu1ubyEOJga50LJMzVXtbUq6CPo&index=1

Turns out it was made in 2014, and the website mentioned is no longer
available.  However, the course does look very interesting.  It is split
into six sections, and the intention seems to have been for students to do
these one a week.  Each section is split into ten videos of about ten to
twenty minutes each, so it comes in bite-sized chunks.  I've just watched
the first section, and it was very gentle and understandable - largely
because it was covering material I already knew.  There is the promise of
some heavy mathematics later on, so we'll have to see.

So if you are running out of things to do in self-isolation on a rainy
afternoon, you might care to give this a look - it may well help with our
understanding!

Regards,

  Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Symmetricom analog network clocks.

[Peter Vince]

I have several Leitch clocks.  These are (were?) widely used in
broadcasting studios, and locked to SMPTE/EBU timecode (or mains frequency,
or their internal crystal).  Often available on our favourite auction site
- see, for example:  https://www.ebay.com/itm/123679630402
The second hand can be set to sweep or "step", but the latter is a fast
sweep between seconds, and then a pause, so is virtually silent (critical
for a broadcast studio!)  They come in various sizes: 8 inch, 12 inch, and
18 inch.  They were extremely reliable at work, and I've been delighted
with the couple I now have at home.

Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Yukon to make Daylight Saving Time permanent after final time change Sunday

[Peter Vince]

I've just seen a news item on the Ganadian Global News website announcing
that the Yukon will remain on Daylight Saving Time indefinitely after the
forthcoming change to DST.  See:


https://globalnews.ca/news/6633447/yukon-permanent-daylight-saving-time/

Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] uBlox F9T

[Peter Vince]

Further to Bob's message, these PDFs can be downloaded from Ublox's website
at:


https://www.u-blox.com/en/product/zed-f9t-module#tab-documentation-resources

and similarly for the F9P:


https://www.u-blox.com/en/product/zed-f9p-module#tab-documentation-resources

Regards,  Peter


On Fri, 28 Feb 2020 at 13:47, Bob kb8tq  wrote:
>
> Hi
>
> For any out playing with the F9T, there is a new version of the manuals
out. They also have
> an update to the “ROM boot loader" code. I have yet to work out if you
can do a field upgrade
> on that part of it. My guess is “not so much”.
>
> Still no stock at any of the “usual” US distributors. The F9P and F9P kit
are in stock at Digikey
> for the same sort of prices ($199 / $250) as earlier in the year.
>
> Bob
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Yesterday was the first palindromic date for 909 years

[Peter Vince]

Bit late, sorry, but I've just heard that yesterday's date was the first
palindromic date for 909 years, and there won't be another for 101 years.

Even more significantly, it's palindromic in all three common 'long' date
formats: UK (dd-mm-), US (mm-dd-year) and ISO (-mm-dd); I  believe
that will never happen again.

Also it's the 33rd day of the  year and there are 333 days remaining in the
year!

See this report:

http://www.thenewportbuzz.com/for-first-time-in-909-years-today-is-a-palindrome-02-02-2020-the-same-forwards-and-backwards-and-it-wont-happen-for-another-101-years/
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] IERS leap second bulletins?

[Peter Vince]

Further to Tom's message, I have also bookmarked this web page:

https://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat

Regards,

  Peter


On Tue, 31 Dec 2019 at 13:36, Dana Whitlow  wrote:

> How does one access the IERS bulletin C (or whatever is
> applicable these days) for leap second info?
>
> Now when I try to do so, I get the following:
>
> The requested URL was rejected. Please consult with your administrator.
> Your support ID is: 11450193631126308915
>
> Well, I am the administrator of my own computer,
> and I've certainly not done anything to block such access.
>
> Thanks,
>
> Dana
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 90ms delay of time signal on phase-modulated carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)

[Peter Vince]

Hi Steve,

On Thu, 21 Nov 2019 at 01:00, Steve Allen  wrote:
>
> The current version ITU-R TF.460-6 says that time signals should
> not deviate by more than 1 ms from UTC.
>
> How can these broadcasts justify such a large offset?

The signal is only used (as far as I am aware, a few Time Nuts apart) for
controlling domestic electricity time switches for people on the
"Economy-7" tariff, which gives them cheaper electricity overnight for
storage heaters for seven hours.  As such, I suspect even a fraction of a
second is overkill.

 Regards,

  Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] 90ms delay of time signal on phase-modulated carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)

[Peter Vince]

As I mentioned in a previous message about observed anomalies with the DST
change on DCF77, Pieter-Tjerk in the Netherlands noted that the time
encoded on the phase-modulated carrier of the BBC's 198KHz signal in the UK
was about 900 milliseconds early.  Having queried that with a contact in
the BBC, a problem was found and corrected, but Pieter-Tjerk reports the
signal is now about 90 milliseconds late.  A further query with my contact
reveals that this is to be expected.  The signal to be phase-modulated is
assembled at our Crystal Palace transmitter is south-east London, and then
sent (over fibres) to Droitwich in the midlands, and Westerglen and
Burghead in Scotland.  Coding and decoding delays on that transmission path
result in the observed delay.  No compensation is attempted, as the result
is perfectly adequate for the intended use - controlling off-peak
electricity time switches.  I hope this info is of interest to our European
members.

Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] DST change on DCF77

[Peter Vince]

At the end of October, after the DST change, a colleague had noticed an
error on his DCF77 decoder program, and wondered if there had been a
transmission error - it is always hard to believe your own code is at fault
:-)  Pieter-Tjerk de Boer kindly replied with an extract of his log-file
showing the DCF77 transmission was fine, but noted that the time carried by
the phase-modulated carrier of the BBC's 198KHz Long Wave radio signal was
early by about 0.9 of a second!

I mentioned this to a contact at the BBC who looked into the problem.
Apparently some equipment had been temporarily replaced earlier in the year
as it would have failed at the GPS week-number roll-over event.
Unfortunately said new equipment hadn't been perfectly configured, with the
observed result.  A completely new system is to be installed next year, but
in the meantime the configuration problem has been corrected, so the BBC
signal should be "perfect" again!

Thanks again to Pieter-Tjerk for bringing this to our attention - goes to
show that "amateurs" can still provide a useful service :-)

Regards,

 Peter


On Wed, 30 Oct 2019 at 22:15, Pieter-Tjerk de Boer 
wrote:
>
> Hello Peter,
>
> While monitoring DCF77, MSF, and other longwave time signals during the
> DST change this weekend, I did not observe any irregularities.
> I don't have a recording of the raw signals, but here is the decoded data,
> including reception timestamps in the last column:
>
> BBC: 00:581572137879.092676
> DCF77_PM: 2019-10-27 02:581572137880.001366
> DCF77_AM: 2019-10-27 02:581572137880.001398
> TDF:  2019-10-27 02:58 +0200  1572137880.001817
> MSF:  2019-10-27 01:58 +0100  1572137880.002950
> RBU:  2019-10-27 03:58 +0300  1572137880.006877
>
> BBC: 00:591572137939.092602
> DCF77_PM: 2019-10-27 02:591572137940.001373
> DCF77_AM: 2019-10-27 02:591572137940.001407
> TDF:  2019-10-27 02:59 +0200  1572137940.001608
> MSF:  2019-10-27 01:59 +0100  1572137940.002951
> RBU:  2019-10-27 03:59 +0300  1572137940.006869
>
> BBC: 01:001572137999.092559
> DCF77_PM: 2019-10-27 02:001572138000.001382
> DCF77_AM: 2019-10-27 02:001572138000.001419
> TDF:  2019-10-27 02:00 +0100  1572138000.001550
> MSF:  2019-10-27 01:00 +  1572138000.002903
> RBU:  2019-10-27 04:00 +0300  1572138000.006862
>
> BBC: 01:011572138059.092783
> DCF77_PM: 2019-10-27 02:011572138060.001379
> DCF77_AM: 2019-10-27 02:011572138060.001415
> TDF:  2019-10-27 02:01 +0100  1572138060.001530
> MSF:  2019-10-27 01:01 +  1572138060.002906
> RBU:  2019-10-27 04:01 +0300  1572138060.006861
>
>
> BBC is the phase modulation on their 198 kHz AM transmitter, encoding UTC.
> DCF77_PM and _AM are the phase and amplitude modulation of DCF77 on 77.5
kHz.
> TDF is the French 162 kHz signal.
> MSF is 60 kHz from the UK.
> RBU is 66⅔ kHz from Russia, where no DST change was made this weekend.
>
> The last column is the reception time as a Unix timestamp, w.r.t. a
LORAN-synchronized clock.
> Clearly, the BBC signal is about 0.9 s early; the others are slightly late
> due to propagation time from their transmitters to my receiver location
> (Enschede. The Netherlands).
>
> Regards,
>   PieterTjerk, PA3FWM
>
>
> On Mon, Oct 28, 2019 at 06:26:05PM +, Peter Vince wrote:
> > Was anyone here monitoring DCF77 during the summer-time change this
> > weekend?  An acquaintance has recently modified his code that receives
MSF,
> > and noticed an anomaly - his log shows the minute 02:59 CEST was
missing.
> > It seems tremendously unlikely that there was any kind of fault with
DCF,
> > but sadly he doesn't have a recording of the actual RF signal, just his
> > decoder output.  So I was just wondering if anyone else noticed anything
> > untoward, or maybe even, does anyone have a recording of the signal
itself?
> >
> >  Thank you,
> >
> >   Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] DST change on DCF77

[Peter Vince]

That's fantastic - thank you so much!

  Regards,

   Peter


On Wed, 30 Oct 2019 at 22:15, Pieter-Tjerk de Boer 
wrote:

> Hello Peter,
>
> While monitoring DCF77, MSF, and other longwave time signals during the
> DST change this weekend, I did not observe any irregularities.
> I don't have a recording of the raw signals, but here is the decoded data,
> including reception timestamps in the last column:
>
> BBC: 00:581572137879.092676
> DCF77_PM: 2019-10-27 02:581572137880.001366
> DCF77_AM: 2019-10-27 02:581572137880.001398
> TDF:  2019-10-27 02:58 +0200  1572137880.001817
> MSF:  2019-10-27 01:58 +0100  1572137880.002950
> RBU:  2019-10-27 03:58 +0300  1572137880.006877
>
> BBC: 00:591572137939.092602
> DCF77_PM: 2019-10-27 02:591572137940.001373
> DCF77_AM: 2019-10-27 02:591572137940.001407
> TDF:  2019-10-27 02:59 +0200  1572137940.001608
> MSF:  2019-10-27 01:59 +0100  1572137940.002951
> RBU:  2019-10-27 03:59 +0300  1572137940.006869
>
> BBC: 01:001572137999.092559
> DCF77_PM: 2019-10-27 02:001572138000.001382
> DCF77_AM: 2019-10-27 02:001572138000.001419
> TDF:  2019-10-27 02:00 +0100  1572138000.001550
> MSF:  2019-10-27 01:00 +  1572138000.002903
> RBU:  2019-10-27 04:00 +0300  1572138000.006862
>
> BBC: 01:011572138059.092783
> DCF77_PM: 2019-10-27 02:011572138060.001379
> DCF77_AM: 2019-10-27 02:011572138060.001415
> TDF:  2019-10-27 02:01 +0100  1572138060.001530
> MSF:  2019-10-27 01:01 +  1572138060.002906
> RBU:  2019-10-27 04:01 +0300  1572138060.006861
>
>
> BBC is the phase modulation on their 198 kHz AM transmitter, encoding UTC.
> DCF77_PM and _AM are the phase and amplitude modulation of DCF77 on 77.5
> kHz.
> TDF is the French 162 kHz signal.
> MSF is 60 kHz from the UK.
> RBU is 66⅔ kHz from Russia, where no DST change was made this weekend.
>
> The last column is the reception time as a Unix timestamp, w.r.t. a
> LORAN-synchronized clock.
> Clearly, the BBC signal is about 0.9 s early; the others are slightly late
> due to propagation time from their transmitters to my receiver location
> (Enschede. The Netherlands).
>
> Regards,
>   PieterTjerk, PA3FWM
>
>
> On Mon, Oct 28, 2019 at 06:26:05PM +, Peter Vince wrote:
> > Was anyone here monitoring DCF77 during the summer-time change this
> > weekend?  An acquaintance has recently modified his code that receives
> MSF,
> > and noticed an anomaly - his log shows the minute 02:59 CEST was missing.
> > It seems tremendously unlikely that there was any kind of fault with DCF,
> > but sadly he doesn't have a recording of the actual RF signal, just his
> > decoder output.  So I was just wondering if anyone else noticed anything
> > untoward, or maybe even, does anyone have a recording of the signal
> itself?
> >
> >  Thank you,
> >
> >   Peter
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] DST change on DCF77

[Peter Vince]

Was anyone here monitoring DCF77 during the summer-time change this
weekend?  An acquaintance has recently modified his code that receives MSF,
and noticed an anomaly - his log shows the minute 02:59 CEST was missing.
It seems tremendously unlikely that there was any kind of fault with DCF,
but sadly he doesn't have a recording of the actual RF signal, just his
decoder output.  So I was just wondering if anyone else noticed anything
untoward, or maybe even, does anyone have a recording of the signal itself?

 Thank you,

  Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] uBlox F9T testing - best settings?

[Peter Vince]

Hello Michael,

 Thank you for your Powerpoint presentation slides - if the paper you
mentioned added some descriptive words, I would love to see that.

Might I ask why you didn't use the F9P in dual-frequency mode, as I
understood that gives a much better result, being able to (almost?)
eliminate ionospheric effects?

 Regards,

  Peter


On Sun, 22 Sep 2019 at 01:00, Michael Wouters 
wrote:
>
> We did some work on single-frequency time-transfer with the F9P earlier
> this year which we presented at IFCS-EFTF in April.
> http://www.openttp.org/downloads/Multi-GNSS_IFCS-EFTF_2019.pdf
> There's a paper too, which I should upload.
> In short, the F9P is very suitable for code-based time-transfer, and we
> will be using it , or the F9T, in the next iteration of our time-transfer
> system.
> ...
> Regards
> Michael
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 198 Khz reference in the UK

[Peter Vince]

Hello Paul,

 Were you aware that there is a 25Hz phase modulation (of ±22.5°)
carrying low frequency data?  Could that be messing up your locking?

 The National Physical Laboratory here in England monitors the signal,
and publishes a bulletin every month with their measurements.  This is
available by email subscription from
https://www.npl.co.uk/products-services/time-frequency/gps-bulletins   and
supposedly the current version can be downloaded, but I'm afraid I've not
been able to find a link on their site :-(

 Regards,

  Peter


On Mon, 9 Sep 2019 at 02:23, Paul Bicknell  wrote:

>
> Hi
> regarding the 198 Khz reference in the UK can any one in the
> UK tell me what the current accuracies are as
> I am using 2 Quartzlock and not achieving 4 parts in 10 /8
>
> Regards Paul
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Low frequency noise measurement (was BG7TBL FA1 frequency analyzer )

[Peter Vince]

On Thu, 5 Sep 2019 at 19:00, Bob kb8tq  wrote:

> ...If you indeed want to do a quick and simple measurement that goes into
> 1 Hz ( or possibly less)
> the answer is to use a mixer based setup. A single mixer setup ( half of a
> DMTD) will do a much
> better job than a counter based approach. Cost wise it is not very
> expensive at all …
>
> Bob
>

I wonder if one of you clever people could design a circuit, and get kits
produced by TAPR ?

 Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Galileo service currently degraded

[Peter Vince]

Hi Mark,

 What prompts Heather to mark visible satellites as yellow, and not use
them?  Maybe that the calculated results are too far away from your known
position?

 Regards,

  Peter


On Sat, 13 Jul 2019 at 18:20, Mark Sims  wrote:

> ...   Sats that are visible but not being used for navigation are flagged
> in YELLOW.  Sats that are actively being used are shown in GREEN and are
> used to draw the satellite count plot line (CYAN line at the bottom of the
> plot area).
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 60Khz received on Wide-band WebSDR

[Peter Vince]

Hello Donald,

 That website is in the Netherlands (aka Holland), and so no, what it
hears on 60Khz is the English MSF transmission from Anthorn in Cumbria, in
the north-west of England.  See the National Physical Laboratory's website
page at:  https://www.npl.co.uk/msf-signal

Regards,

  Peter Vince


On Sat, 6 Jul 2019 at 17:06, D. Resor  wrote:

> From another list I was directed to this link for those who do not have a
> shortwave radio.
>
> http://websdr.ewi.utwente.nl:8901/
>
> I entered the frequency of 60Khz and am curious to know if this the WWVB
> transmission I am hearing or something else?
>
>
> Donald Resor
> N6KAW
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Aerial coax downlead placement

[Peter Vince]

On Fri, 5 Jul 2019 at 18:01, WigglePig  wrote:

> If there are currents in the braid to upset then your antenna system is
> not working as you might believe.
>

I was working on the simplistic assumption that for a current to flow,
there must be a complete circuit, so the current flows down the centre
conductor, and must come back up the braid.  But I gather that unlike DC,
RF is "black magic", and only flows on the inside of the braid - if all the
impedances match.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Aerial coax downlead placement

[Peter Vince]

Thank you all for your replies.  A case of a little knowledge being a bad
thing in my case.  But at least I was aware of a potential problem to be
considered! :-)

Thanks again,

 Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Aerial coax downlead placement

[Peter Vince]

Hello all,

 A new contact, whose background is in computer programming rather than
RF, is getting into accurate GPS positioning, and has been tapping me for
any knowledge I might have.  I persuaded him to get the new Ublox F9P
receiver and also a "proper" dual-band antenna - albeit from China, so
affordable!  This seems to be going quite well, and he sent a photo today.
He has mounted said aerial on what looks like a six-foot pole which is
good, but currently the coax down-lead is just hanging - flopping about in
the breeze.  Now that is bad for so many reasons :-)  However, I am not
sure of the best advice to give him.  I'm sure I heard that you should
never drop the coax down the middle of your support-pole, as the conducting
pole will mess up the characteristics of the cable by affecting the
currents in the outer braid.  And so similarly, you presumably don't really
want to tie-wrap it tightly to the outside of the pole for pretty much the
same reason.  So my gut instinct would be to put some (half-inch??)
insulating spacers between the coax and the pole where the tie-wraps go.
Now when I worked in a TV shop in my youth, they didn't bother with any of
that - a) they probably didn't know about any such effects, b) they
certainly couldn't have been bothered, and c) TV signals are strong, so it
wouldn't have made a significant difference.  GPS signals, however, are NOT
strong, and need to be treated with much more respect - especially if you
are after some seriously good positional accuracy.  Is my idea right, or am
I barking up completely the wrong tree?

 Thanks in advance,

  Peter  (London, England)
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] UBlox as a reference clock source - accuracy ??

[Peter Vince]

On Thu, 20 Jun 2019 at 14:08, David Slipper  wrote:
>
> That is probably good enough for my needs and certainly better than the
cheap XOs in the instruments.
>
> BTW I just came across a document "GPS-based Timing Considerations with
u-blox 6 GPS receivers - Application Note" that makes interesting reading.
>
> Many thanks
> Dave


Download link:


https://www.u-blox.com/sites/default/files/products/documents/Timing_AppNote_%28GPS.G6-X-11007%29.pdf
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] NASA press-release about launch of mercury-ion atomic clock

[Peter Vince]

NASA have just issued a press-release about a forthcoming SpaceX Falcon
launch scheduled for Saturday the 22nd of June.  Two satellites should be
of particular interest to this group: a mercury-ion atomic clock, and some
cube-sats intended to help characterise the atmosphere in order to improve
the accuracy of GPS reception.  NASA press releases can be seen here:
https://www.nasa.gov/news/releases/latest/index.html

The latest, in part, reads:

May 15, 2019
MEDIA ADVISORY M19-037
Media Invited to SpaceX Falcon Heavy Launch of Four NASA Missions
Media accredation is open for SpaceX’s third Falcon Heavy launch.

...

The Enhanced Tandem Beacon Experiment (E-TBEx) explores “bubbles” in the
electrically-charged layers of Earth's upper atmosphere, which can disrupt
key communications and GPS signals that we rely on down on the ground. Such
bubbles currently appear and evolve unpredictably, making them difficult to
characterize from the ground. Increasing our understanding of them will
help us prevent the disruption of the many radio signals that pass through
Earth's upper atmosphere. The two NASA CubeSats on this mission will work
in concert with the six satellites of NOAA's COSMIC-2 mission. Varying
orbital positions among the eight spacecraft will give scientists chances
to study these bubbles from multiple angles at once.

See:  https://www.nesdis.noaa.gov/content/cosmic-2-mission


A new kind of atomic clock aims to let spacecraft conduct precise
navigation on their own, instead of waiting for trajectory information from
Earth. This versatile technology also has science and exploration
applications. The Deep Space Atomic Clock can be used to study planetary
gravity fields and atmospheres, or could even enable a GPS-like capability
on the surface of the Moon. The technology demonstration mission, developed
by NASA’s Jet Propulsion Laboratory in Pasadena, California, is the primary
payload on General Atomics’ Orbital Test Bed spacecraft.

See: https://www.nasa.gov/mission_pages/tdm/clock/index.html


...

To learn more about the STP-2 mission, visit:

https://www.spacex.com/stp-2
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Garmin GPS12XL V3.51

[Peter Vince]

I dug out my old Garmin GPS-III's (mid 1990's vintage !).  The internal
backup batteries had completely died after many years of non-use, so it
took a while for them to find the satellites, but when they did, they, of
course, came up with an August 1999 date.  A quick "Google" found that
someone is hosting a zipped Windows executable (apparently originally from
Garmin) that you run when the satnav is connected to your PC via a serial
cable, and it corrects whatever internally so that the date is reported
correctly.  Works like an absolute charm!  The program doesn't say it is
specifically for the GPS-III, so it might be using a standard
(undocumented, of course!) message that will work on a whole bunch of
receivers.  Might be worth giving it a try?  See:

 https://sites.google.com/site/gnbaddeley/GpsEow_V1.20_PC_Software.zip

Regards,

 Peter


On Mon, 8 Apr 2019 at 14:01, David J Taylor via time-nuts <
time-nuts@lists.febo.com> wrote:

> I checked today the GPS12XL I have, and that came up with a date in
> August 99, before dying a few minutes later. Firmware 4.57.
> []
> John
> 
>
> John,
>
> I think my 12XL firmware 4.60 is OK.  Perhaps you can update the firmware?
>
> Cheers,
> David
> --
> SatSignal Software - Quality software for you
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

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

[Peter Vince]

Thank you all!

 Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

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

[Peter Vince]

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

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

[Peter Vince]

Thank you for your reply Magnus.  Could you please clarify then exactly
what "decimate" means in this context.  Is it "truncation", i.e.
eliminating or ignoring the last few digits, be they decimal or binary?
And/or is there some rounding involved?

 Peter


On Thu, 10 Jan 2019 at 13:01, Magnus Danielson  wrote:

> Peter,
>
> While the word derives back to the Roman times, today it is a technical
> term for data-reduction being used in professional literature, so it's
> meaning has already been established.
>
> For instance, in modern phase-noise measurement setups the sample-rate
> is around 100 MS/s, and that sample-rate of multiple ADCs with
> relatively high amounts of bits is way to high to hand over to software,
> so it is decimated down in steps in FPGA before handing over to
> software. Decimation is the term used in that context.
>
> Cheers,
> Magnus
>
> On 2019-01-10 13:01, Peter Vince wrote:
> > In his comment below, Mark has used the word "decimate".  There is much
> > debate about what this word means (presently, and/or in the past), but
> > common explanations refer back to Roman times when they apparently killed
> > one person in ten as a punishment, and similarly "tithes" - or taxes,
> where
> > one in ten was taken.  Now OK, you can argue this until the cows come
> home,
> > but the result is that the meaning isn't crystal clear, and particularly
> on
> > a technical forum where precision is paramount, and the entire reason we
> > are here, I believe accuracy and clarity of expression is also important.
> > In this instance, I believe "truncate" would be a better word.
> >
> >   :-)
> >
> >   Regards,
> >
> >Peter Vince
> >
> > On Wed, 9 Jan 2019 at 23:56, Mark Sims  wrote:
> >> ...
> >> And as far as decimating the TICC output values in firmware... please
> > don't.   Let the user decimate the values if they want to.
>
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

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

[Peter Vince]

In his comment below, Mark has used the word "decimate".  There is much
debate about what this word means (presently, and/or in the past), but
common explanations refer back to Roman times when they apparently killed
one person in ten as a punishment, and similarly "tithes" - or taxes, where
one in ten was taken.  Now OK, you can argue this until the cows come home,
but the result is that the meaning isn't crystal clear, and particularly on
a technical forum where precision is paramount, and the entire reason we
are here, I believe accuracy and clarity of expression is also important.
In this instance, I believe "truncate" would be a better word.

  :-)

 Regards,

  Peter Vince

On Wed, 9 Jan 2019 at 23:56, Mark Sims  wrote:
> ...
> And as far as decimating the TICC output values in firmware... please
don't.   Let the user decimate the values if they want to.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] A question from a newbie

[Peter Vince]

Hi Tom,

Like Daniel, I would also love to see your QBASIC programs please.

Thank you,

  Peter


On Fri, 2 Nov 2018 at 19:14, Daniel H. Pressler 
wrote:

> Tom,
>
>Thanks so much.  I downloaded both the suggest software packages and
> they
> look excellent.  It appears to me that my Arduino with phase comparator
> should be a data collection only environment since these programs seem to
> have all the whistles and bells I'm looking for.  I would appreciate
> anything you might have in QBASIC as well.  That will save me from the
> challenge of refreshing my C code skills.
>
>Again, thanks so much.  This was exactly what I was looking for.
>
> Respectfully,
>
>
> Daniel H. Pressler, KF2HP
>
>
>
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Tom
> Van Baak
> Sent: Thursday, November 1, 2018 9:54 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] A question from a newbie
>
> Daniel,
>
> There's simple C code at http://leapsecond.com/tools/adev_lib.c that does
> ADEV / MDEV / TDEV / HDEV.
> A sample ADEV program using that code is:
> http://leapsecond.com/tools/adev1.htm
>
> There are Python versions on the web if you're into Python and its
> ecosystem.
> If you want a QBASIC version let me know.
>
> The only thing you need to watch out for is that there are two forms of the
> ADEV formula. The "x" version takes phase difference as input. The "y"
> version takes fractional frequency difference as input. You can convert one
> to the other with differentiation or integration.
>
> Since your old GPIB and basic days there are some very nice tools that take
> all the pain out of ADEV now.
> One is Stable32, highly recommended. [1]
> The other is TimeLab, also highly recommended, especially if this is your
> first time doing clock statistics interactively. [2]
> Both have extremely well-written and informative documentation, worth
> reading even if you don't use the programs.
>
> /tvb
>
> [1] http://www.stable32.com/
> [2] http://www.ke5fx.com/timelab/readme.htm
>
>
> - Original Message -
> From: "Daniel H. Pressler" 
> To: 
> Sent: Thursday, November 01, 2018 3:05 PM
> Subject: [time-nuts] A question from a newbie
>
>
> >I was directed to this group when I asked this question of another group.
> > However, after reading some of the emails I am a real novice when it
> comes
> > to this stuff.  I worked with cesium and rubidium oscillators as Primary
> > Reference clocks in the telecommunication industry.  When I was there I
> > wrote a basic program to retrieve phase offset between two signals over
> GPIB
> > from a counter.  The program then calculated frequency accuracy and did
> some
> > Allan Variance calculations.  I am trying to replicate that with an
> Arduino
> > and a simple phase comparator.  I have forgotten the math and I am not
> smart
> > enough to glean it out of the data presented on the internet.  Can
> someone
> > point me to some example programs that will allow me to measure phase
> offset
> > over time and calculate frequency accuracy and do some basic Allan
> Variance
> > calculation.
> >
> >
> >
> > Thanks,
> >
> >
> >
> > Daniel H. Pressler, KF2HP
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Timed photography (was: Re: A silly question ...)

[Peter Vince]

Tom - I love the idea of taking (a series of) accurately timed
photograph(s), but have no idea how to go about it - can you please explain
how you did it for your mains-driven clock?

   Peter (London)


On Mon, 1 Oct 2018 at 09:39, Tom Van Baak  wrote:
...
> For hourly photos consider using a webcam or smart phone & time-lapse
photo app.
>
> Here's an example of measuring time drift in mains with a photo every 15
minutes. Watch how the red seconds hand drifts by up to 4 seconds during
the day: http://leapsecond.com/pages/tec/mains-clock-ani.gif
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] XKCD on time :)

[Peter Vince]

Also the ancient Egyptians through to the Romans;  See:

https://en.wikipedia.org/wiki/12-hour_clock#History_and_use



On Fri, 28 Sep 2018 at 14:17, Eric Scace  wrote:
>
> Which, if I recall correctly, was the system used in Japan immediately
before the adoption of Western time methods. Each day’s interval between
sunrise-sunset was divided into a six units… so, in comparison with an
absolute scale, the absolute duration of each unit of time varied from day
to day and location to location.
>
> More details here .


> > On 2018 Sep 28, at 04:58 , Hal Murray  wrote:
> >
> >  https://xkcd.com/2050/
> >
> > A new meaning for rubber seconds.
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Frequency over fiber (was WWV and legal issues)

[Peter Vince]

Hi Magnus,

 Could you please give us some idea of the magnitude of these effects?
Even if just whether we are talking about nano, pico, or femtoseconds?

 Thank you,

  Peter


On 2 September 2018 at 12:17, Magnus Danielson 
wrote:

> Hi Gerhard,
>
> I see that this became a separate thread.
> ...
> ...
>
> Acoustical sensitivity, low frequency changes.
>
> For optical clocks and frequency transfer, just the vibration from
> traffic and other activity causes disturbances which disturbes the group
> delay. What is done for these links is to actively compensate then using
> a return path and closing the loop with a controller, very much like a
> PLL. The length of the loop limits the bandwidth and hence how high up
> the compensation can be done, so for longer stretches, this needs to be
> repeated. They have now built links from PTB to SYRTE and NPL.
>
> Temperature shifts are slower, but also compensated though the active loop.
>
> Close proximity to strong power-currents have also been shown to cause
> modulations, so separate from power-cables if you can.
>
> Remember that the end nodes have very stable clocks, so their effects
> can be taken out of the equation. For other setups, such as telco
> operation, that's a completely different ballgame.
>
> Cheers,
> Magnus
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] WWVB Signal Generator

[Peter Vince]

Hi Mark,

 If you were able to include optional modulation for the UK's MSF
signal as well as WWVB, then I'd be very interested - especially if you
could persuade John and TAPR to produce a kit :-)   Europe's DCF would also
be a good selling point, but getting its 77.5KHz would be more difficult.

 Peter


On 25 August 2018 at 19:28, Mark Sims  wrote:

> If I was going to do it I would take a cheap Ublox 7M board (around $10
> with antenna),  program one of the time pulse outputs for 60 kHz (it
> divides evenly into 48 Mhz so no jitter),  feed  the Ublox serial data /
> 1PPS to an AVR chip (or $2 Arduino Nano  clone), and use that to modulate
> the 60 KHz output.   Total cost less than $20 and should get to to the
> microsecond level range.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/
> listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] History Channel "In Search of" Time Travel

[Peter Vince]

Ditto.  No sign of it in the foreseeable future on the UK version of the
History Channel.

 Peter


On Sat, 18 Aug 2018 at 20:50, Robert LaJeunesse  wrote:
>
> I would appreciate it, thanks.
>
> Bob LaJeunesse
>
> > Sent: Saturday, August 18, 2018 at 3:22 PM
> > From: "Dan Rae" 
> > To: time-nuts@lists.febo.com
> > Subject: Re: [time-nuts] History Channel "In Search of" Time Travel
> >
> > If anyone wants to see this I could upload a .mkv copy to Wetransfer for
> > download.
> > Dan
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 1PPS for the beginner

[Peter Vince]

I was astonished to see the pulse-width in the document defined from the
base of the (sharp-cornered!) edges, and not the mid-point - totally
impractical!  Near the top of the previous page it says: "If required for
testing purposes, the pulse width at the 50% level may be determined by
extrapolation."  Now OK, the very wide tolerance on the pulse-width makes
this all rather academic, but surely that spec wasn't written by an
engineer? :-)

 Peter

On 15 August 2018 at 05:03, Björn  wrote:

> Hi Bernd,
>
> One reference to 20us 1PPS pulse length is the ICD-GPS-060, see figure
> 3-2, page 3-3 (pdf page 19)
>
> https://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
>
> Group - Are there other standard documents defining duty-cycle, voltage
> levels, rise times etc?
>
> MfG
>
>  Björn
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.