Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Bill Byrom]

Here is a project which mixed the Time Kube IF output back to 10 MHz for
use as a frequency (not time) 
standard:http://schematicsforfree.com/archive/file/Oscillators%20and%20Generators/Misc/10Mhz%20Frequency%20Standard%20Using%20Wwv.pdf
I believe that the Time Kube uses a 3-transistor mixer / 455 kHz IF
amplifier signal chain, followed by an IC audio amplifier. I would think
that the signal delay inside the receiver from antenna to audio output
would be a couple of hundred microseconds, much less than one cycle of
the demodulated audio “tick”.--
Bill Byrom N5BB



On Fri, Dec 8, 2017, at 07:13 AM, jimlux wrote:
> On 12/7/17 1:29 PM, Bill Hawkins wrote:
> >
>
> > So yes, this could be interesting for a hobbyist, but it won't add
> > anything to Science.
> > A MASER is overkill. Heck, so are Rubidium and Caesium.
> > A naked crystal will be rock solid compared to received WWV.
> >
> > OTOH, NTP has marvelous mathematical tricks to reduce Internet
> > propagation delay.
> > A scheme to reduce varying atmospheric delay would be useful,
> > if there> > weren't much better ways to get a standard frequency.
> >
>
> What you are talking about is "better ionosphere modeling", which is
> something that a lot of people have spent a lot of time and effort on,> 
> without a lot of success.  That said, there are some real time
> ionograms> out there that are fascinating to watch.  It doesn't take a very
> sophisticated receiver to receive the signals from a variety of
> ionosonde transmitters.
>
> Juha Vierinen has a variety of interesting software:
> http://www.sgo.fi/~j/gnu_chirp_sounder/
>
> Juha also has done stuff with measuring the frequency of beacon
> satellites
>
> http://www.sgo.fi/~j/jitter/web/
>
>
>
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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[jimlux]

On 12/7/17 1:29 PM, Bill Hawkins wrote:





So yes, this could be interesting for a hobbyist, but it won't add
anything to Science.
A MASER is overkill. Heck, so are Rubidium and Caesium.
A naked crystal will be rock solid compared to received WWV.

OTOH, NTP has marvelous mathematical tricks to reduce Internet
propagation delay.
A scheme to reduce varying atmospheric delay would be useful, if there
weren't much better ways to get a standard frequency.



What you are talking about is "better ionosphere modeling", which is 
something that a lot of people have spent a lot of time and effort on, 
without a lot of success.  That said, there are some real time ionograms 
out there that are fascinating to watch.  It doesn't take a very 
sophisticated receiver to receive the signals from a variety of 
ionosonde transmitters.


Juha Vierinen has a variety of interesting software:
http://www.sgo.fi/~j/gnu_chirp_sounder/

Juha also has done stuff with measuring the frequency of beacon satellites

http://www.sgo.fi/~j/jitter/web/



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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Hal Murray]

martin.burni...@burnicki.net said:
> Hm, this file is part of the standard NTP source code package available
> here: http://support.ntp.org/bin/view/Main/SoftwareDownloads 

Argh.  Good catch.  Thanks.

I knew that it came from the ntp package.  I thought it was stand alone but 
it seems to use some of the ntp package.

If anybody is having trouble building it, let me know and I'll try to figure 
out the recipe.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Martin Burnicki]

Hal Murray wrote:
> 
> kb...@n1k.org said:
>> To get the accuracy into the 1 ms range on WWV, you would need a pretty good
>> idea of the path length between you and WWV. 
> 
> Dave  Mills has a program to compute delays.
> 
>  * By default it prints out a summer (F2 average virtual height 350 km) and
>  * winter (F2 average virtual height 250 km) number.  The results will be
>  * quite approximate but are about as good as you can do with HF time anyway.
>  * You might pick a number between the values to use, or use the summer
>  * value in the summer and switch to the winter value when the static
>  * above 10 MHz starts to drop off in the fall.  You can also use the
>  * -h switch if you want to specify your own virtual height.
> 
> What's the height difference between night and day?
> 
> This was google's first response.
>   https://opensource.apple.com/source/ntp/ntp-136/clockstuff/propdelay.c

Hm, this file is part of the standard NTP source code package available
here:
http://support.ntp.org/bin/view/Main/SoftwareDownloads

Martin
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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Hal Murray]

kb...@n1k.org said:
> To get the accuracy into the 1 ms range on WWV, you would need a pretty good
> idea of the path length between you and WWV. 

Dave  Mills has a program to compute delays.

 * By default it prints out a summer (F2 average virtual height 350 km) and
 * winter (F2 average virtual height 250 km) number.  The results will be
 * quite approximate but are about as good as you can do with HF time anyway.
 * You might pick a number between the values to use, or use the summer
 * value in the summer and switch to the winter value when the static
 * above 10 MHz starts to drop off in the fall.  You can also use the
 * -h switch if you want to specify your own virtual height.

What's the height difference between night and day?

This was google's first response.
  https://opensource.apple.com/source/ntp/ntp-136/clockstuff/propdelay.c


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Mark Goldberg]

I have done some frequency measurement testing of WWV transmissions against
a not that great reference. Results are shown on

https://sites.google.com/site/perseusmods/home/performance

They are pretty awful even compared to a not that great reference. The
Ionosphere is not friendly.

Mark
W7MLG



On Thu, Dec 7, 2017 at 6:48 AM, Patrick Barthelow 
wrote:

Hello Friends,
>
>>
> I am picking up locally a couple of vintage analog Radio Shack SW time cube
>
>> radios, 70s vintage, 3 switchable SW frequencies.  Two types, the one
>
>> pictured and a Radio Shack model also that has WWV and Weather channel VHF
>
>> frequencies.
>
>> I am interested in an accurate bench test to compare the analog shortwave
>
>> radios time reporting
>
>> hopefully UT-1 against other available references.
>
>
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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Scott McGrath]

The timecube radios were simple superheterodyne AM receivers.   I suspect the 
group delay of the timecubes will be small and fairly consistent due to the low 
component count,   

Yet because of the low quality components performance variability between units 
will be quite high.

A more interesting test would be with a heathkit 'Most Accurate Clock' GC-1000 
which was effectively a HFDO since it used HF WWV signals to discipline its 
timebase.



On Dec 7, 2017, at 3:05 PM, paul swed  wrote:

Pat
Way back in the 90s I measured the color subcarrier frequency of
geostationary satellites. That aren't actually stationary.
I knew the quality of the subcarriers for a number of the networks since we
originated the signals. CBS was Cs others were Rb and still others various
Xtals. I had direct access to the references.
I used an HP5360 and homebrew interface collecting the data on a computer.
I was using a wide variety back then.
No matter. I actually could see over long periods the orbital day to day
and seasonal behaviors. By gosh physics and such in action. The reference
was the 5360s oven oscillator that was quite good. I know times have
changed. The reason to do it was simply because I could.
All of that said I will believe the doppler shifts are your biggest impact
so not sure orders of magnitude really help and may actually confuse. You
will have the effects of earth, the moon and the satellites orbit. Now
thats some serious math and thinking. Some place along the line other great
stuff will work to mess with you.
Regards
Paul
WB8TSL

On Thu, Dec 7, 2017 at 8:48 AM, Patrick Barthelow 
wrote:

> Hello Friends,
> 
> I am picking up locally a couple of vintage analog Radio Shack SW time cube
> radios, 70s vintage, 3 switchable SW frequencies.  Two types, the one
> pictured and a Radio Shack model also that has WWV and Weather channel VHF
> frequencies.
> I am interested in an accurate bench test to compare the analog shortwave
> radios time reporting
> hopefully UT-1 against other available references.  For accuracy, and
> repeatability.   Could eventually add an SDR to the mix, too.
> The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
> propagation distance delays, somewhat calculable, and the vagaries of
> Ionospheric propagation, and, propagation delays between the antenna and
> the measured tap point to the seconds ticks of WWV.   I have some friends,
> microwave professionals, who are also hams here in Auburn who may enjoy
> doing a bench test, with published results, etc.  But wonder if anyone else
> would be interested in borrowing a RS Timecube radio (and/or use an SDR)
> and designing an accurate bench test against available modern standards?
> We are talking probably HUGE  UT-1 errors compared to what this group plays
> with, and that is OK but I think still a worthwhile test, especially if the
> errors using available and cheap equipment are predictable, and repeatable.
> https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/
> 
> Another question:  Re precision frequency measurements of spacecraft
> carriers at earth ground stations.  I have found a number of MASER labs,
> willing to help measure a 70 cm UHF carrier of a satellite planned mission,
> circling the moon.  Fun, and overkill yes .   But I would like to know if
> the MASER extra 3 orders of magnitude precision frequency measurement (over
> Rubidium, Cesium)  is useful, or utterly wasted in measuring a lunar
> orbiting spacecraft frequency over as long a period as a month, in a coming
> satellite mission?   Or, are Rubidium and Cesium and GPS disciplined
> references  plenty accurate for accurate spacecraft orbit determinations?
> 
> 
> Best, 73,   Pat Barthelow AA6EG
> apol lo...@gmail.com
> 
> 
> *"The most exciting phrase to hear in Science, the one that heraldsnew
> discoveries,  is not "Eureka, I have found it!"but:*
> "That's funny..."  Isaac Asimov
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
> 
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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Bob kb8tq]

Hi

If you happen to pick 5 or 10 MHz as your target frequency, all sorts of 
interesting 
things come into play. The first is that any 5 or 10 MHz local standard 
distribution 
may well get into your receiver. That can create all sorts of odd effects as 
the signal
fades. Next is that you aren’t just on a channel for two stations. There are a 
number of 
standard broadcasts that pop up. Depending on propagation, they may be strong 
enough to notice. 

*If* you can get WWV to give you sub 1 ms timing accuracy (or even low ms), 
that’s better 
accuracy (as opposed to jitter) than NTP can do with a normal home internet 
connection.
Internet modems have some pretty nasty timing asymmetries built into them. On 
top of that
you may have asymmetric routing. Up stream and downstream routing is a “two 
pipes” 
process  in a lot of head end installations.  Again, we’re talking about 
internet and not
some sort of GPS based system. 

To get the accuracy into the 1 ms range on WWV, you would need a pretty good 
idea of the path
length between you and WWV. If you are looking at  ground wave, that is a bit 
easier than 
if you are bouncing off the ionosphere. Just as with WWVB, there probably is a 
“best time
of day” to run your comparison. 

Since you get a lot of ticks, there is no real need to just use one. Feed the 
audio into a computer and
let it sum them up. Monitoring for 10 minutes does not seem to be overly crazy. 
That’s still a lot
of ticks.  If you dig into the archives, there are some good posts from PHK 
about doing this 
sort of thing  with Loran-C. 

Bob

> On Dec 7, 2017, at 4:29 PM, Bill Hawkins  wrote:
> 
> One way to compare any WWV receiver to a local standard is to use the
> PPS output of a standard against the PPS tick modulated on WWV. The tick
> is five cycles of a one KHz signal derived from the master frequency.
> See
> https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-a
> nd-wwvh-digital-time-code-and-broadcast-format
> 
> It will be a bit tricky to determine the onset of the first cycle amid
> the noise on shortwave radio. A computation that determined that there
> were just 5 cycles and worked backwards to determine the timestamp of
> the beginning or middle of the tick could then allow calculation of the
> offset between the standard PPS and the tick. Limit of accuracy might be
> 100 microseconds. 
> 
> Years ago, I had a standard calibrator made by Lavoie that had a vacuum
> tube WWV receiver. IIRC, the WWV carrier caused a circular sweep on a 2
> inch CRT. The sine wave from a standard modulated the intensity of the
> circular trace, so that a bright half moon appeared on the CRT and
> rotated at the error rate between the two frequencies. On several
> evenings the dominant signal varied between WWV and WWVH (identified by
> the voice broadcasts). Here in Minneapolis the phase difference between
> the two stations was about 180 degrees, causing the bright arc on the
> CRT to change sides.
> 
> So yes, this could be interesting for a hobbyist, but it won't add
> anything to Science.
> A MASER is overkill. Heck, so are Rubidium and Caesium.
> A naked crystal will be rock solid compared to received WWV.
> 
> OTOH, NTP has marvelous mathematical tricks to reduce Internet
> propagation delay.
> A scheme to reduce varying atmospheric delay would be useful, if there
> weren't much better ways to get a standard frequency.
> 
> Bill Hawkins
> 
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Patrick
> Barthelow
> Sent: Thursday, December 07, 2017 7:48 AM
> 
> Hello Friends,
> 
> I am picking up locally a couple of vintage analog Radio Shack SW time
> cube radios, 70s vintage, 3 switchable SW frequencies.  Two types, the
> one pictured and a Radio Shack model also that has WWV and Weather
> channel VHF frequencies.
> I am interested in an accurate bench test to compare the analog
> shortwave radios time reporting hopefully UT-1 against other available
> references.  For accuracy, and
> repeatability.   Could eventually add an SDR to the mix, too.
> The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
> propagation distance delays, somewhat calculable, and the vagaries of
> Ionospheric propagation, and, propagation delays between the antenna and
> the measured tap point to the seconds ticks of WWV.   I have some
> friends,
> microwave professionals, who are also hams here in Auburn who may enjoy
> doing a bench test, with published results, etc.  But wonder if anyone
> else would be interested in borrowing a RS Timecube radio (and/or use an
> SDR) and designing an accurate bench test against available modern
> standards?
> We are talking probably HUGE  UT-1 errors compared to what this group
> plays with, and that is OK but I think still a worthwhile test,
> especially if the errors using available and cheap equipment are
> predictable, and repeatable.
> 

Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Bill Hawkins]

One way to compare any WWV receiver to a local standard is to use the
PPS output of a standard against the PPS tick modulated on WWV. The tick
is five cycles of a one KHz signal derived from the master frequency.
See
https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-a
nd-wwvh-digital-time-code-and-broadcast-format

It will be a bit tricky to determine the onset of the first cycle amid
the noise on shortwave radio. A computation that determined that there
were just 5 cycles and worked backwards to determine the timestamp of
the beginning or middle of the tick could then allow calculation of the
offset between the standard PPS and the tick. Limit of accuracy might be
100 microseconds. 

Years ago, I had a standard calibrator made by Lavoie that had a vacuum
tube WWV receiver. IIRC, the WWV carrier caused a circular sweep on a 2
inch CRT. The sine wave from a standard modulated the intensity of the
circular trace, so that a bright half moon appeared on the CRT and
rotated at the error rate between the two frequencies. On several
evenings the dominant signal varied between WWV and WWVH (identified by
the voice broadcasts). Here in Minneapolis the phase difference between
the two stations was about 180 degrees, causing the bright arc on the
CRT to change sides.

So yes, this could be interesting for a hobbyist, but it won't add
anything to Science.
A MASER is overkill. Heck, so are Rubidium and Caesium.
A naked crystal will be rock solid compared to received WWV.

OTOH, NTP has marvelous mathematical tricks to reduce Internet
propagation delay.
A scheme to reduce varying atmospheric delay would be useful, if there
weren't much better ways to get a standard frequency.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Patrick
Barthelow
Sent: Thursday, December 07, 2017 7:48 AM

Hello Friends,

I am picking up locally a couple of vintage analog Radio Shack SW time
cube radios, 70s vintage, 3 switchable SW frequencies.  Two types, the
one pictured and a Radio Shack model also that has WWV and Weather
channel VHF frequencies.
I am interested in an accurate bench test to compare the analog
shortwave radios time reporting hopefully UT-1 against other available
references.  For accuracy, and
repeatability.   Could eventually add an SDR to the mix, too.
The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
propagation distance delays, somewhat calculable, and the vagaries of
Ionospheric propagation, and, propagation delays between the antenna and
the measured tap point to the seconds ticks of WWV.   I have some
friends,
microwave professionals, who are also hams here in Auburn who may enjoy
doing a bench test, with published results, etc.  But wonder if anyone
else would be interested in borrowing a RS Timecube radio (and/or use an
SDR) and designing an accurate bench test against available modern
standards?
We are talking probably HUGE  UT-1 errors compared to what this group
plays with, and that is OK but I think still a worthwhile test,
especially if the errors using available and cheap equipment are
predictable, and repeatable.
https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/

- %< - [snip of microwave stuff]

Best, 73,   Pat Barthelow AA6EG
apol lo...@gmail.com

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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[paul swed]

Pat
Way back in the 90s I measured the color subcarrier frequency of
geostationary satellites. That aren't actually stationary.
I knew the quality of the subcarriers for a number of the networks since we
originated the signals. CBS was Cs others were Rb and still others various
Xtals. I had direct access to the references.
I used an HP5360 and homebrew interface collecting the data on a computer.
I was using a wide variety back then.
No matter. I actually could see over long periods the orbital day to day
and seasonal behaviors. By gosh physics and such in action. The reference
was the 5360s oven oscillator that was quite good. I know times have
changed. The reason to do it was simply because I could.
All of that said I will believe the doppler shifts are your biggest impact
so not sure orders of magnitude really help and may actually confuse. You
will have the effects of earth, the moon and the satellites orbit. Now
thats some serious math and thinking. Some place along the line other great
stuff will work to mess with you.
Regards
Paul
WB8TSL

On Thu, Dec 7, 2017 at 8:48 AM, Patrick Barthelow 
wrote:

> Hello Friends,
>
> I am picking up locally a couple of vintage analog Radio Shack SW time cube
> radios, 70s vintage, 3 switchable SW frequencies.  Two types, the one
> pictured and a Radio Shack model also that has WWV and Weather channel VHF
> frequencies.
> I am interested in an accurate bench test to compare the analog shortwave
> radios time reporting
> hopefully UT-1 against other available references.  For accuracy, and
> repeatability.   Could eventually add an SDR to the mix, too.
> The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
> propagation distance delays, somewhat calculable, and the vagaries of
> Ionospheric propagation, and, propagation delays between the antenna and
> the measured tap point to the seconds ticks of WWV.   I have some friends,
> microwave professionals, who are also hams here in Auburn who may enjoy
> doing a bench test, with published results, etc.  But wonder if anyone else
> would be interested in borrowing a RS Timecube radio (and/or use an SDR)
> and designing an accurate bench test against available modern standards?
> We are talking probably HUGE  UT-1 errors compared to what this group plays
> with, and that is OK but I think still a worthwhile test, especially if the
> errors using available and cheap equipment are predictable, and repeatable.
> https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/
>
> Another question:  Re precision frequency measurements of spacecraft
> carriers at earth ground stations.  I have found a number of MASER labs,
> willing to help measure a 70 cm UHF carrier of a satellite planned mission,
> circling the moon.  Fun, and overkill yes .   But I would like to know if
> the MASER extra 3 orders of magnitude precision frequency measurement (over
> Rubidium, Cesium)  is useful, or utterly wasted in measuring a lunar
> orbiting spacecraft frequency over as long a period as a month, in a coming
> satellite mission?   Or, are Rubidium and Cesium and GPS disciplined
> references  plenty accurate for accurate spacecraft orbit determinations?
>
>
> Best, 73,   Pat Barthelow AA6EG
> apol lo...@gmail.com
>
>
> *"The most exciting phrase to hear in Science, the one that heraldsnew
> discoveries,  is not "Eureka, I have found it!"but:*
> "That's funny..."  Isaac Asimov
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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[time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Patrick Barthelow]

Hello Friends,

I am picking up locally a couple of vintage analog Radio Shack SW time cube
radios, 70s vintage, 3 switchable SW frequencies.  Two types, the one
pictured and a Radio Shack model also that has WWV and Weather channel VHF
frequencies.
I am interested in an accurate bench test to compare the analog shortwave
radios time reporting
hopefully UT-1 against other available references.  For accuracy, and
repeatability.   Could eventually add an SDR to the mix, too.
The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
propagation distance delays, somewhat calculable, and the vagaries of
Ionospheric propagation, and, propagation delays between the antenna and
the measured tap point to the seconds ticks of WWV.   I have some friends,
microwave professionals, who are also hams here in Auburn who may enjoy
doing a bench test, with published results, etc.  But wonder if anyone else
would be interested in borrowing a RS Timecube radio (and/or use an SDR)
and designing an accurate bench test against available modern standards?
We are talking probably HUGE  UT-1 errors compared to what this group plays
with, and that is OK but I think still a worthwhile test, especially if the
errors using available and cheap equipment are predictable, and repeatable.
https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/

Another question:  Re precision frequency measurements of spacecraft
carriers at earth ground stations.  I have found a number of MASER labs,
willing to help measure a 70 cm UHF carrier of a satellite planned mission,
circling the moon.  Fun, and overkill yes .   But I would like to know if
the MASER extra 3 orders of magnitude precision frequency measurement (over
Rubidium, Cesium)  is useful, or utterly wasted in measuring a lunar
orbiting spacecraft frequency over as long a period as a month, in a coming
satellite mission?   Or, are Rubidium and Cesium and GPS disciplined
references  plenty accurate for accurate spacecraft orbit determinations?


Best, 73,   Pat Barthelow AA6EG
apol lo...@gmail.com


*"The most exciting phrase to hear in Science, the one that heraldsnew
discoveries,  is not "Eureka, I have found it!"but:*
"That's funny..."  Isaac Asimov
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