In message 06013AA10880459380352E3FB29C4B5C@pc52, "Tom Van Baak" writes:

The first input you need is the exact longitude/latitude of the
lightning bolt.

The easiest way to do that is with a set of GPS synchronized receivers,
aaaand we're back to sqare one!

The next issue is that lightnings are seldom vertical, they can
trivially wiggle many hundred meters sideways, so at absolute
best your jitter is going to be no better than the microsecond
domain, and probably much worse, increasing with distance.

But there's a workaround:  if you have the right kind of "pregnant"
thundercloud overhead, a plain firework rocket trailing a thin
grounded wire will, on your command, get you a lightning strike.

Not only are these lightnings almost always entirely vertical, they
are also particular sharp and potent (for that very reason).

So if you live in the right kind of place, you could implement
a daily clock synchronization service much more spectacular
than a mere "ball-drop".

I belive the US electrical grid industry runs a joint research
center somewhere in northern Florida, using this method to test
lightning protection of the power grid components.

I suspect they ignite their rockets using remote control.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

That's true for ultimate accuracy. But notice how each strike is seen by dozens of observers and each observer knows their (fixed) position and has their own local (approximate) clock.

So it seems to me it's not unlike how GPS works: with enough samples, it should be possible to solve for latitude, longitude, and time of each strike. Like running GPS in 3D mode rather than position hold (zero D) mode.

Now the accuracy is clearly not going to be at the nanosecond level. Maybe not even microsecond level, since as you mentioned, there are biases and jitter and who know what propagation variations.

But over time, you should be able to converge on differential local clock measurements. What I'd like to see is the TDEV of this as a common view time transfer method. A couple of hops and we could compare UTC(PHK) with UTC(TVB), for example.

Perhaps another side effect of their lightning project is that it could create dynamic propagation maps using the residuals in their massive database. When I first owned WWVB gear I thought I had accurate time. After I got GPS, I realized that my WWVB receivers now became accurate Colorado-to-Seattle weather stations. As they say, one man's error is another man's signal.

/tvb

as, ahem, one of the early experimenters of lightning detection, gotta tell
ya, the return stroke risetime is on the order of 1 us. Also, the very
beginning of the waveform, that is the first part of the spike, is connected
with the beginning of the breakdown, hence the location on the ground.
Subsequent parts of the waveform are due to higher portions of the channel.
Also, there are two polarities of discharge, and the "positive" discharge
gives a waveform that looks like a cloud discharge that does not strike ground
at all. Those seriously interested should get hold of a copy of "Lightning" by
Martin Uman; this is bby now old, but is available inexpensively and will get
you started. The original detectors used wideband crossed loops to get
direction and no time of arrival; well before GPS timing. I hadn't looked into
the "amateur" network!
Vaisala corp has the best USA net, otherwise there is one in Boston and TOA
enterprisesin Florida. U of Washington has a network as well.
Enjoy!  I can tell you after 50 years of dinking with it, Lightning is fun if
ya ain't too close.
Don

Tom Van Baak

--
"The power of accurate observation is commonly called cynicism by those who
have not got it."
-George Bernard Shaw

Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
Huson, MT, 59846
mail:  POBox 404
Frenchtown MT 59834-0404
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com

I suspect this is quite common. You don't have to get into precise time very deep before you realize that all your timing gear is just pile of environmental sensors in disguise. Before time-nuts began, the first timing guy I met was Doug Hogarth (www.niceties.com) and he was seriously into weather measurement. He later got into the world of ultra-precise weight (mass) measurement. So I guess time-nuts is just a subset of measurement nuts.

A quartz oscillator makes a good thermometer and sometimes a hygrometer and barometer too. An OCXO is a sensitive anemometer (just ask anyone who uses a PWM fan for TBolt temperature control). Quartz also makes an excellent accelerometer, gravimeter, tiltmeter, or even seismometer. An OCXO with EFC is a good voltmeter. Atomic clocks are superb magnetometers. And as Einstein predicted, atomic clocks make good altimeters and speedometers too.

So everything we play with is a sensor. It's no wonder we are preoccupied with environmental sensing. Maybe Time is just what's left over after you shield or attenuate or compensate for everything else.

/tvb

See also:

Quartz Resonators vs Their Environment: Time Base or Sensor?
http://dev.quartzdyne.com/pdfs/quartzresonators.pdf
http://www.paroscientific.com/

Oh man does this bring back memories of 12au7s and loop antennas pre
internet 1970 as I recall. A QST magazine article. I built it and it used a
crt for readout.
There wasn't really a way back then to share the data.
But will say this is quite a nice setup.
Regards
Paul
WB8TSL

On Tue, Jun 24, 2014 at 3:35 PM, Tom Van Baak tvb@leapsecond.com wrote:

This one is/was run by the Neveda Test Site. I don't know if NOAA took
it over. When you get strikes, it give the lat/lon.

At the moment, all is quiet on the western front.

However, I have to say that near real time website is more impressive.

I have been watching the blitzortung system in the US for a few days now
and really like the clean and simple display. Very nicely done.
Also downloaded the information package.
Oddly it does not use any 12AU7s in the design.
Regards
Paul
WB8TSL

On Wed, Jun 25, 2014 at 2:24 AM, nuts nuts@lazygranch.com wrote:

Quite true.

One of my other interests is the ionosphere and propagation. This of course has an effect on GPS and other time related receiving systems. In support of my monitoring and trying to measure such things I monitor on a more or less continuous basis CHU on 7850 KHz. This in itself may not seem that unusual except that I am about 20 miles from the CHU transmitters and I monitor this transmission with the idea of creating a dopplergram of it's signal. As we know, HF radio signals are reflected and refracted by the various layers of the ionosphere. In doing so the signal can exhibit apparent changes in frequency due to the continual movement of these refracting and reflecting layers.

My advantage being so close to the transmitter is that I also receive the ground wave of these signals which are not reflected or refracted in any way. I have a receiver set up which feeds Spectrum lab running in a long integration mode and displaying a very narrow bandwidth of just over 3 and half Hz.

I publish my dopplergrams to a dropbox web page here:

https://www.dropbox.com/sh/9dakbbrrn2ju3hc/TIIKrDY-Iu

usually stored by month

these:

https://www.dropbox.com/sh/9dakbbrrn2ju3hc/AAA7FLx2nZuEZzBayIqyMAUza/20140320

are for April 20 this year. The solid line more or less in the center of the image is the ground wave from the CHU transmitter on 7850 KHz, everything else is the Doppler shifted signal as it has been reflected and refracted by the various continuously moving layers of the ionosphere. You will note that sometimes there is more than one predominate Doppler shifted signal.

Variations in the  more or less solid line in the middle of the images is the result of drift in the local oscillator in my receiver. It is not currently locked to GPS. However, as Tom has suggested it makes a good thermometer as it is a relatively high stability oscillator but temperature variations in my lab show as minor changes in these images. I have in fact done a reasonable calibration and I can tell at glance the approximate temperature of my lab near this radio as well as when the furnace has started in the colder months or when the air conditioner starts in the warmer months.

There is a group in Czech Republic doing something very similar:  http://ok0eu.fud.cz/

They are using their own network of GPS disciplined transmitters on 80M and monitor their signals in a similar fashion. They describe their studies as also studying the effects of gravity waves.

Along the lines of trying to measure and study the ionosphere using these dopplergrams, I have also toyed with the idea of trying to make my own passive sounder. There is a network of ionospheric sounders in the Canadian Arctic called CHAIN - Canadian High Arctic Ionospheric Network. They use GPS receivers to measure characteristics of the ionosphere such as total electron count (TEC) by monitoring phase scintillation of the GPS signals. They are using modified GPS's with high stability reference oscillators.  I don't know yet if any of my GPS receivers would provide any useful data even with a high stability reference but the thought occurs that there might be another way indirect way. DGPS beacons transmit corrections for GPS users and something I stumbled across on another web site suggested that some of this data may be buried within the corrections provided by these DGPS beacons. And it so happens that I have a DGPS nearby which I can receive easily and reliably 24 hours a day but I just haven't got round to doing much more than brainstorming and trying to understand just what I need to do to connect the dots.

For reference, this is the web site and blog posting were I stumbled across the idea of using DGPS correction data:

http://goughlui.com/?p=1071

I have not been able to connect all the dots between all these subject but I am getting there.  At least it is fun and educational trying. After all, it's the journey which is brings the greatest rewards, not the destination.

Cheers, Graham ve3gtc

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Tom Van Baak
Sent: June-24-14 3:35 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing

I suspect this is quite common. You don't have to get into precise time very deep before you realize that all your timing gear is just pile of environmental sensors in disguise. Before time-nuts began, the first timing guy I met was Doug Hogarth (www.niceties.com) and he was seriously into weather measurement. He later got into the world of ultra-precise weight (mass) measurement. So I guess time-nuts is just a subset of measurement nuts.

A quartz oscillator makes a good thermometer and sometimes a hygrometer and barometer too. An OCXO is a sensitive anemometer (just ask anyone who uses a PWM fan for TBolt temperature control). Quartz also makes an excellent accelerometer, gravimeter, tiltmeter, or even seismometer. An OCXO with EFC is a good voltmeter. Atomic clocks are superb magnetometers. And as Einstein predicted, atomic clocks make good altimeters and speedometers too.

So everything we play with is a sensor. It's no wonder we are preoccupied with environmental sensing. Maybe Time is just what's left over after you shield or attenuate or compensate for everything else.

/tvb

See also:

Quartz Resonators vs Their Environment: Time Base or Sensor?
http://dev.quartzdyne.com/pdfs/quartzresonators.pdf
http://www.paroscientific.com/

This electronic message, as well as any transmitted files included in the electronic message, may contain privileged or confidential information and is intended solely for the use of the individual(s) or entity to which it is addressed. If you have received this electronic message in error please notify the sender immediately and delete the electronic message. Any unauthorized copying, disclosure or distribution of the electronic message is strictly forbidden. NAV CANADA accepts no liability for any damage caused by any virus and/or other malicious code transmitted by this electronic communication.

Le présent message électronique et tout fichier qui peut y être joint peuvent contenir des renseignements privilégiés ou confidentiels destinés à l’usage exclusif des personnes ou des organismes à qui ils s’adressent. Si vous avez reçu ce message électronique par erreur, veuillez en informer l’expéditeur immédiatement et supprimez le. Toute reproduction, divulgation ou distribution du présent message électronique est strictement interdite. NAV CANADA n’assume aucune responsabilité en cas de dommage causé par tout virus ou autre programme malveillant transmis par ce message électronique.

I think it would be perfectly appropriate to design an LF amplifier with 12AU7s considering the high signal levels when the storm does get close.

I have been thinking of building a system myself since I already have an STMicro Discovery board and several GPS receivers I could use.

One potential problem is that the preamps obviously must remain connected to the antennas when the storm gets close, while my ham radio gear is normally disconnected when not in use. I have had so much lightning damage over here (North West Florida) over the years that I am concerned about pissing off the Gods for good...

Didier KO4BB

On June 25, 2014 1:54:19 PM CDT, paul swed paulswedb@gmail.com wrote:

--
Sent from my Motorola Droid Razr HD 4G LTE wireless tracker while I do other things.

In message 16957e54-f6d5-4c0a-9068-6f0c772d2082@email.android.com, Didier Jug
es writes:

Somewhere, sometime, I saw an homebrew article for a lightning detector
which was based on some obscure valve/tube that had grid on the top
terminal.

A wire from the grid electrode ran to a porcelain isolator and from
there to the wire antenna, in order to get the highest possible
imput impedance.

I have no idea where I saw that article, but some HAM magazine or
possibly Elector about 10-20 years back is a good guess.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

I am currently using a 12AX7 as a ELF preamp and have for years.
A note in the coldest part of winter preheat the tube low filament voltage.
They tend to fracture.
It sits 200 ft from the house as far away in the woods as possible.
That said and back to the thread. At these frequencies tubes do work. The
12AX7 can be found on vlf.it and numbers of tubes will work. They run 12 V
on the plate. They also stand up to nearby lightning very well.
So Diddier now you have no excuse. I can't wait to implement your design on
one of my stm boards. Not sure how to get this back on time-nuts topics
Regards
Paul
WB8TSL

On Wed, Jun 25, 2014 at 4:44 PM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:

On Wed, Jun 25, 2014 at 1:24 PM, Didier Juges shalimr9@gmail.com wrote:

It could be 100% safe if there were no wires leading back to the house.  A
battery powered receiver that connected back to the house over WiFi would
be safe.  Use a solar panel and a lead/acid battery for power.  The only
trouble is the added cost and a direct hit would still cost you a few
hundred $$.  Less  risk is to expose only some minimum portion of the
system to lightening then run fiber optic cable back to the house.

--

Chris Albertson
Redondo Beach, California

On Wed, Jun 25, 2014 at 4:42 PM, paul swed paulswedb@gmail.com wrote:

Try a 6DJ8 instead of the 12AX7. It has a higher GM and a LOT more
bandwidth. What kind of risetime are we talking about for a lightning
strike? And why not a loop antenna? That should provide plenty of signal
but not destructive voltages.

I know you are talking about measuring lightning strikes but if you get the
impedance high enough, you can actually measure the earth's electric field.
(It is about 200V/m if I recall properly.) Interestingly it is affected by
the solar flux and solar wind.

--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067

Is anyone using a field mill?
I have always been going to make one.
It consists of a horizontal metal plane with a conducting button on the surface
which is insulated from the ground plane.
A metallic maltese cross driven by a motor alternately covers and uncovers the electrode
exposing/not exposing it to the sky.
The electrode button has capacitance to ground which drops its impedance,
but across that impedance is an AC voltage proportional to the ambient static field.
A typical field in fine weather is 300 Volts/metre  so the signal is not trivial.
You should be able to make a field mill that works continuously except when
actually shorted by rain.
This is not a very high impedance device, and should show many marvellous things
as the clouds float over you.
You can calibrate it with a metal plate, say 12 inches above it with 50 volts on it.
That should produce a uniform field on the mill.
cheers,
Neville Michie

As I recall, the Boonton 535A isn't specially made at all,
but rather a selected 2A6 triode/twin diode.  The tube is
selected for having an especially clean vacuum, and being
capable of running with a really high grid leak resistor (100M).

-Chuck Harris

Bill Hawkins wrote:

Charley Wenzel made it very safe: here is
http://www.techlib.com/electronics/lightning.html,
I used cross-correlation to identify the "right electrical noise"
Alex
On 6/25/2014 8:22 PM, Brian Lloyd wrote:

Lightning risetimes are slow enough that back-to-back zener diode limiters can
protect the input circuitry for a 1-meter probe. Nothing will stop a direct
strike, even a 12ax7 :-). A series resistor on the input helps.  Actually, a
well-designed active probe antenna, even (shudder) one made by MFJ will be
quite adequate for vlf-ulf phenomena. May have a lo-pass filter that needs
attention.
Measuring the earth/s fair-weather field, 100 v/m or so, or even a field under
a thunderstorm, 5000v/m or higher, would require input impedance in excess of
10^15 ohm. Better is to raise a sharp point, say a sewing needle on a nice
protected teflon or better kel-f insulator, and measure the small current of
around 10 fA. Needs a small breeze to work right. Clean off the spider webs
and wasp nests as needed.
Better is to build a device called a field mill (q.v.) that essentially chops
the field into an AC signal.
Getting too far from time nuttery and into atmospheric electric nuttery :-)

Don

Brian Lloyd

--
"The power of accurate observation is commonly called cynicism by those who
have not got it."
-George Bernard Shaw

Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
Huson, MT, 59846
mail:  POBox 404
Frenchtown MT 59834-0404
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com

How fast does the maltese cross turn?

Regards.

Max.  K 4 O DS.

Email: max@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe@yahoogroups.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe@yahoogroups.com

To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe@yahoogroups.com

----- Original Message -----
From: "Neville Michie" namichie@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, June 25, 2014 10:46 PM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing

Hi,
the maltese cross is a chopper to interrupt the lines of electrostatic force.
The cross could have a hundred legs, as long as it alternately blocks
and unblocks exposure to the electric field.
The cross spins in a horizontal plane, maybe half an inch above the sensor
electrode which is flush or just above the ground plane.
The idea is to get the output signal up to a frequency where the time constant
of the sensing electrode can be quite short.
If you can get it up to 400 Hz it only needs a 2.5mS time constant.
Even then, since you can calibrate it you can have the signal below the time constant.
A 12 legged "cross" spinning on a 4 pole motor gives a chopping frequency of 360 hertz,
(in America), quite convenient for amplification and processing.
If the motor is synchronous, or you put a sensor on the motor shaft you can run a phase
sensitive detector and get polarity as well as magnitude.
cheers,
Neville Michie

On 27/06/2014, at 1:59 AM, Max Robinson wrote:

The tube was probably the FP-54

http://frank.pocnet.net/sheets/141/f/FP54.pdf

No luck on finding the article - it is not in the Handbook of Projects for
the Amateur Scientist by C.L. Stong

http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti
st.pdf

I thought it might be as I remember there was a project to detect sferics
but this one used plain 12AU7s and 6AU6s

On Thu, Jun 26, 2014 at 9:08 PM, DaveH info@blackmountainforge.com wrote:

When I was a kid this may have been my favorite book. I did build the MRS
when I was 12. Sucker actually worked too! I was amazed. I have built
several things from this and used many of the projects with modern
electronics as projects for my students in middle school.

--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
brian@lloyd.com
+1.916.877.5067

I have never seen an article using exotic special tubes. I understand that
benefit but common tubes do a fine job. I still believe it was a QST
article. Maybe 73 magazine. It was a long time ago. When I started using
the 12AU7s again for the vlf pre-amp they were $1 or so 7 years ago. Now
audiophiles have driven them into the silly range especially on the
websites. I scrounged 4 at really good prices $2 recently. But the
audiophiles were on the hunt as I noticed.
Bottom line a tube frontend is easy to build for this application. Even if
we want to make it seem hard. Its simply not the front end. Its the other
parts of the solution that should be the focus. How to make a sub $$
solution. The European solution is several hundred Euros. $$$$
Regards
Paul
WB8TSL

On Thu, Jun 26, 2014 at 10:50 PM, Brian Lloyd brian@lloyd.com wrote:

I think the QST article being referred to in this thread is one that I
remember rather clearly.  I kept the issue for a long time but it got away
from me somewhere along the line.  It was a lightening direction finder
using a display much like a radar PPI.  It used two crossed untuned loops
and a vertical.  All three signals were amplified using tubes and one of the
loops was fed to the horizontal deflection plates of a CRT and the other
loop's signal was fed to the vertical plates.  The signal from the vertical
was fed to the control grid of the CRT.  The project was essentially an XY
scope built from the ground up.  He suggested figuring out the polarity of
things by waiting for close lightening that was visible and correlating
sightings with the display on the CRT.  You wouldn't use a general purpose
scope because the fair weather condition would burn a spot in the center of
the screen.  One more thing.  He wound the loops in hula hoops he had cut
open.  I still have two hula hoops awaiting the project.  The bandwidth of
his amplifiers was low audio to about 100 kHz.  I suspect that in today's
radio environment some tuned traps would be necessary to notch out some of
the strong signals in that frequency range.  You now have all the
information I have and I am sure I could build one if only I could find the
time.

Regards.

Max.  K 4 O DS.

Email: max@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with transistors group send an email to.
funwithtransistors-subscribe@yahoogroups.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe@yahoogroups.com

To subscribe to the fun with wood group send a blank email to
funwithwood-subscribe@yahoogroups.com

----- Original Message -----
From: "paul swed" paulswedb@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Friday, June 27, 2014 8:10 AM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing

It was QST and Max is right. I built it. There was a e-field antenna for
amplitude and the crossed antennas the XY access. I guess the old brain has
somethings correct.
Now can I remember the tube line up. Heavens no. :-) The CRT was a little
mil surplus 3p...
But enough of that. Whats the chance of finding the article that would be a
kick.
Regards
Paul
WB8TSL

On Fri, Jun 27, 2014 at 12:28 PM, Bob Stewart bob@evoria.net wrote: