Propagation... why do I miss some signals?

[cutty]

Here's one set of theories that can explain how Blitzortung Systems interact with the environment,...




Special acknowledgment to Dupreezd  for assistance with these two graphics...

[allsorts]

Like those, espeically the first showing why one station will see a strike but one not that far away won't.

One comment decide if it's going to be and Air/Earth capacitor or an Earth/Air one.

[cutty]

Like those, espeically the first showing why one station will see a strike but one not that far away won't.

One comment decide if it's going to be and Air/Earth capacitor or an Earth/Air one.

Heh...  Good point, Dave... I'll update, and 'standardize'.... with something...
There's a 'concept' called the Earth Ionosphere Capacitor (EIC) ... but it doesn't account for or disregards many of the effects of atmospheric charge...
So the "Atmospheric Capacitor"  is a bit more valid.... and I do not think there is a 'standard' name for this affect.... best way I've discovered
is to call lit the "Earth-Atmosphere Capacitor"... since the actual 'upper plate' is really not defined and probably can't be, more or less a 'virtual' plate.....
since so many variables determine it' content, height, thickness', position...appear to determine its 'structure'...  etc.... So I tried to use all three 'variations' within
the graphic... Earth-Atmosphere, Earth - Air, Air-earth ,,, Since E Probe uses 'earth' as 'plate, I may go with "Earth-Atmosphere" to distinguish dramatically from the
"Earth Ionosphere Capacitor' hypothesis....

For me, the important part is that the Probe tends to act as a 'mini-duplicate' of the instantaneous Ion, proton, electron,whatever,  'charges'  within that 'virtual' capacitor, rather than as a VLF antenna...
... even using the term "mirror" could be misleading, since the 'image' isn't a 'mirror' necessarily (reversed), more of a 'copy'...


ADDENDA:  Modified  using "Earth / Atmosphere" as ref.
Thanks, Dave...

Mike

[dupreezd]

Thanks Mike, even though I have been a member for some time, these pictures are very informative and provide a good picture how those bouncy waves work.
The E-field picture provides a clear view regarding the working of the Earth-Atmosphere capacitor.

Thanks again.

Dries

[cutty]

Thanks Mike, even though I have been a member for some time, these pictures are very informative and provide a good picture how those bouncy waves work.
The E-field picture provides a clear view regarding the working of the Earth-Atmosphere capacitor.

Thanks again.

Dries

And I thank You.. for your input developing those.... I overlooked giving you the kudo, but have added it to the first post....

[vk2him]

Nicely done Mike and Dries - one pedantic point though sticks out with the E Field - Are you sure the probes at different locations sense these changes instantaneously? - I'd think sensing is delayed by propagation though our atmosphere due to the speed of light through our atmosphere. I know Quantum mechanics allows for instantaneous transmission over an unlimited distance due to Quantum entanglement, however I don't think the E/A capacitor falls into that category?

[cutty]

.,.. one pedantic point though sticks out with the E Field - Are you sure the probes at different locations sense these changes instantaneously? - I'd think sensing is delayed by propagation though our atmosphere due to the speed of light through our atmosphere. I know Quantum mechanics allows for instantaneous transmission over an unlimited distance due to Quantum entanglement, however I don't think the E/A capacitor falls into that category?

Without all the advanced physics possibilities, ... which I've no understanding, .... like, "how fast is gravity?"
... let's just assume propagation at C, ... then it's more about this... which I can wrap my teeny old brain around:
....at the location of the device (antenna or probe) the probe responds instantaneously to it's environmental charge,  as opposed to antenna 'delays'...
as in  E Charge H Magnetic  with E also, in a manner of speaking,  reflecting a better 'energy content' image of the impulse, especially in 'pre-discharge' time

[vk2him]

.,.. one pedantic point though sticks out with the E Field - Are you sure the probes at different locations sense these changes instantaneously? - I'd think sensing is delayed by propagation though our atmosphere due to the speed of light through our atmosphere. I know Quantum mechanics allows for instantaneous transmission over an unlimited distance due to Quantum entanglement, however I don't think the E/A capacitor falls into that category?

Without all the advanced physics possibilities, ... which I've no understanding, .... like, "how fast is gravity?"
... let's just assume propagation at C, ... then it's more about this... which I can wrap my teeny old brain around:
....at the location of the device (antenna or probe) the probe responds instantaneously to it's environmental charge,  as opposed to antenna 'delays'...
as in  E Charge H Magnetic  with E also, in a manner of speaking,  reflecting a better 'energy content' image of the impulse, especially in 'pre-discharge' time

I think I follow what you're saying, this is interesting as it's not how I understood it worked and I'd like to learn more ... using the graph in your post as an example, are you saying that since the magenta E signal appears before the M Green signal, then it's because the M antenna takes longer to display the signal (due to antenna 'delays')?

My understanding of how e-probes and antenna work in transferring the energy they receive is a bit different- assuming equal internal processing delays by the BO receiver regardless of E or M inputs, a Magnetic impulse hitting the antenna at the exact same instant the eProbe senses the charge from the same lightning source should have identical start points in time on the graph. This is because a magnetic impulse and E signal travel at the speed of light - the rise in the graph shows the increase in the energy received by both sources (M and E). Therefore, if the E displays before the M then it can only be cause the E arrives before the M ... To my thinking there is only two possibilities of why the E arrived before the M in your graph 1) The E component of the strike was "created" before the M signal - I'm not 100% sure of the physics involved in a lightning strike, what "part" of the strike creates the M and E and is one "made" before the other? and 2) the E signal took a more direct route than the M which was delayed slightly due to reflection, ie, the M signal travelled a slightly further distance and was therefore displayed behind the E.

As an aside and if you're interested ... gravity travels at the speed of light - if the sun suddenly disappeared by magic right now, the earth would continue to orbit where the sun used to be until the exact same time that we saw the sun's light "disappear" - the earth would then shoot off into space in a straight line at the exact same time.

Cheers

[cutty]

It's easy to 'mix' theories, here... one reason I posted these was to provoke discussion!  I'm not sure anyone knows Exactly what happens here... but my limited research and background has led to these thoughts... let me fumble my way through them...
Assume Vertically polarized EM signal, wave (planar) explanation:

One cannot exist without the other. They are in phase, one supports and produces the other. An EM wave can be produced either with a changing Voltage Signal, or a changing Current. Whichever, it will cause the creation of it's "partner".  The H signal plane (magnetic field) energy, exists at right angles to the E plane (energy field)

An antenna must be of construction type,  physical length, and mount orientation to receive the the specific field 'plane'.
EM travels inside the Earth Ionosphere wave guide, as surface (subsurface also if ELF), space, or skywaves. and in a vacuum propagate at the speed of light. They are created by man, or by nature.

The impulses we are interested in are produced by nature, through sudden changes in the electrical charge environment of the atmosphere, (charge, discharge, steady state) caused by build up or decrease in charges, such as protons, electrons, ions, what-have-you.  A discharge, cascade, etc. can be triggered, for example, by a cosmic wave, change in earth''s magnetic field... jet plane, meteor,.... etc....or exceeding the 'voltage breakdown' potential of the 'envelope' that contains the charge.

The H field loops  detect the magnetic portion of this 'EM impulse' wave.  If strong enough, it will also detect some of the E wave components.  for our purposes, we use a long wire constructed in a loop.... if it were a true wavelength long, for an impulse with energy centered at 15 kHz  would be about 20,000 meters in length (20 Km or 12.4 Mi).... Our loops don't have to be that long, because of some  funky characteristics of EM signals, and fancy mathematics... heh...

An E probe of 150mm length would be fantastic for detecting the Vertical E field signal in the 2 GHz band... but iis much too 'short' for an E 'wave field' at 3-300 Khz... unless the field was very intense... It is virtually immune to H(magnetic) influences since it is NOT a coil. ... sure, it will 'feel' E 'plane' 2GHz RF, but our systems cut off at around 300 KHz..

Instead, the probe surface area mimics the CHARGE content, and changes in the environment around itself at any given instant.  In effect, a 'capacitor' plate.    this charge  in the virtual capacitor between the probe and earth is impedance matched to the receiver's amplifier chain. The Common plate for the virtual EA capacitor, and the E probe capacitor is Earth.

This charge field is NOT an EM wave field.  It will produce an EM field of whatever polarity and strength is proportional to that total charge, and its strength,   depending on the amount and speed of the content change. It is the progenitor of, not an artifact of, the EM impulse wave.

A person might say that the EM impulse we detect with a loop is therefore initialized  by the atmospheric content changes of the required intensity, at that location and in that environment, and its E plane partner rides along with it.

The E probe monitors and reflects that atmosphere content instantaneously as it is 'felt' at the probe. Whereas an EM receiver must 'wait' until the change is strong enough to create a 'wave front'. ... so the E probe signal in theory should be just a tiny bit 'faster' on a display device for example, and considerably 'faster' depending on the number of reflections the EM might make from a distant impulse.

If you should take a passive CB or similar vertical antenna, disconnect it from the receiver, and connect a volt meter across the connector, you can watch the 'field' value change as a storm cloud passes overhead.

Note that the EA capacitor charge content DOES NOT reflect off the Earth Ionosphere Wave guide, as an EM wave does.  It is felt WITHIN that capacitor formed by Earth Atmosphere in it's entirety, as fast as the 'charges' can propagate. Since it doesn't reflect, it has a 'shorter' path to a more distant receiver. And theoretically could be detected by all... no "skip"....  Unfortunately, this can't occur in our reality...the actual propagation is affected,  e.g.  more intense local field changes near any specific receiver obscure, variable changes in the air dielectric, etc....

So, if the above is some 'rough' thinking, as a 'starting point'..... we can evolve a real hypothesis that explains everything,  publish a paper, win a Nobel Prize, and become rich and famous...
Have at it....

[vk2him]

That's a terrific explanation Cutty, thanks for taking the time to describe it - I'm sold

[cutty]

There is another reason you might miss strokes... even if its recognized as a 'stroke', you might "lose out" as being a 'locator'...
for sure, it can affect the overall network 'location' accuracy...

Observe:

(Graphic should refer to the "third DECIMAL digit")
....with that much error, the server may even discard the signal...


Yet...


More in depth explanation in the INTERNAL forum for Operators: HERE
Not posting more explanation here...

[cutty]

There are some 'Hidden' "Gotchas"  that may result in 'missed signals'... when looking at your stats..

The 'trigger' threshold level must be at least twice your noise level... any triggered channel signal failing that will be ignored by the server.  That sometimes may change, but most of the time the baseline is 'twice the noise level'. The 'best' channel for any given station, for any given impulse, will be selected, and compared with others, beginning with the timestamp and trigger point... (TOA) then such tricky things as 'Zero Crossings' i, etc...(TOGA)

Both H channels and E channels have KNOWN inherent time delays.  Each Filter setting has KNOWN time delays.  Each antennas type has expected or computed time delays.... This is why it is extremely important to configure your station properly on your owner's page on BT... especially as regards antenna type, and dimensions.

as an example,
We are going to use the RED's E channels to illustrate delays, because they're much more obvious than H channel Antenna differences... :
Here would be the KNOWN and EXPECTED time delays and frequency responses of a System RED which has three E channels available:
Filters:
     The coax and it's shielding is effectively part of a High Pass filter network  >5 KHz System RED)
(preamp, coax, amp combined) (This is also true for system BLUE expect ± 8 KHz )
These numbers are specific to RED, but basic principle is similar for Blue:    
First stage HP filter is in Pre-Amp, third stage in amp.
     50,100,150,200,250 Hz is effectively attenuated
     Similar with 60Hz and harmonics
This is specific to RED channel design:
18 KHz cutoff
44 KHz cutoff
>50 KHz
± effective channel selectivity
A =    5KHz ±  ——  23KHz ±
B =  18KHz ±  ——  44KHz ±
C =    5KHz ±  —— > 50KHz ±

Again the below is a RED's  E channels signal.


On E channels, the 'Probe delay' is virtually 'zero', but the surface area of the probe (from dimensions) affects both the 'type of charge' content, it's amplitude, and the 'capacitance' value of the 'circuit'... In effect, a primary component of the above mentioned 'high pass' filter. Therefore it's 'response'  can affect both BW and delay, especially in the TOGA chain computations. The Server Knows this 'designed' delay, for each selected channel, and that is factored into the 'TOA and TOGA computations. 
The exact same thing is true for BLUE, except there is only ONE wide band E channel with optional filtering variations....  The delays in the designed and optional filter settings are KNOWN by the server. And computed 'surface area' of the probe can be factored in if the station's configuration data is correct

APPLY SIMILAR LOGIC to H channels on either system, RED or BLUE... but equate the E Channels Above to different antenna types and construction, That info must be entered correctly in your station configuration,... otherwise you may 'miss out' on best effectivity and efficiency.

example: Here are two identical FERRITE core antennas... with one difference: the faster response has an experimental core wrap modification...   (which I now use as my 'standard' H antenna, in two build designs.)

A 2 to 4 Microsecond time difference can refine a 'deviation' error by 0.5 to 1.2 kilometers!
(600-1200 meters)

So ensure your station antenna and probe configurations are correct... Yes, the 'dimensions' should be metric.
System BLUE.. and tick the  shielded, or transformer boxes as appropriate. E SHOULD HAVE NO Ticks..

0-2 are for H field antennas
The server and the rest of us   would expect HA=0, HB=1
If using HC = 2, if not, undefined, skip it...
E Field ALWAYS begins at 3 regardless of system - undefined if NO E connected
4,5 ALWAYS undefined for BLUE's single channel.  Red has 3 channels which should be defined if E is utilized.

[mwaters]

Which layer of the ionosphere do 16 kHz signals bounce off of?

Also, the idea of a skip zone at such low frequencies is new to me! They are almost unheard of at 2 MHz, and more common as you go up in frequency, depending on the time of day and solar activity.

[cutty]

Which layer of the ionosphere do 16 kHz signals bounce off of?

Also, the idea of a skip zone at such low frequencies is new to me! They are almost unheard of at 2 MHz, and more common as you go up in frequency, depending on the time of day and solar activity.

Any layer or height it wants to.. I suppose.. what does your research show?  Lower freqs bounce. Higher Freqs escape.
You could assume D layer... E maybe at times... I'm an operator, Jim, .. not a physicist.... but, conditionally, the others also have some say about it.  maybe 40-80 miles, whichever is currently 'in charge'... pun intended.

Also do NOT forget:  THE EARTH is the other 'wall' of the wave guide! It makes stuff bounce too.

Unheard of?   You've never listened to a distant am radio station fade in and out?

[mwaters]

Fair enough. As for an AM station fading in and out, that most often called selective fading. Remove the carrier (SSB) and it's greatly reduced.
See https://en.m.wikipedia.org/wiki/Fading

[readbueno]

Hi Mike and Cutty, During the night time there is no "D or E Layer," only "F" Layer.
During the Daytime it is possible, due to ionisation density variations, to have Sky wave signals at VLF and ELF from all three and possibly four ionised layers ("D, E, F, or F1 and/or F2,) simultaneously or at varying intervals.
Theoretically it is possible to have Sky wave propagation without contact with the ground for considerable distances, especially where there is a transition from day to night, night to day, Chordal Hop and Grey line effects.
Neither the Ionosphere nor the Earth are smooth flat surfaces, nor perfect curves, so there are various forms of Diffraction, Refraction, Absorption and Scattering etc., and other natural phenomenon, (Aurora? Non Great circle paths, due to ground wave becoming sky wave or vice-versa) that may account for fading or enhanced propagation at varying distances and for the different frequencies in the bandwidth of a stroke of lightning. 
There possibly could also be considerable time differences for the same stroke, if there is long path and short path propagation, at the same time, or multiple around the world paths, as in near antipodal situations.
While this probably does not make things much clearer in regards to our case, there have been many studies done with ELF propagation for submarines.
Kindest regards,
Brian.

[mwaters]

I found this ELF propagation link from sferics.com and plan on studying it a little. The goal is to find out whether a skip zone exists at ~16 kHz.
https://www.semanticscholar.org/paper/Mo...0ac651cd46

[cutty]

I found this ELF propagation link from sferics.com and plan on studying it a little. The goal is to find out whether a skip zone exists at ~16 kHz.
https://www.semanticscholar.org/paper/Mo...0ac651cd46

While you're absorbing the link you posted...
(here's direct link to paper:  WAVE GUIDE }

You might add these two additional factors... as 'starter' papers....
Impulse Earth Surface
Coupling Mechanism




There's a point where I become very enamored with the basic 'light switch' theory... throw the switch, stuff happens... hopefully.

[mwaters]

Thanks, Mike. I've studied the first one and did brief searches through the other two just now.

One thing to consider is that diagrams imply that there is a single takeoff angle from a strike. The reality is different.

[mwaters]

Right or wrong, https://en.m.wikipedia.org/wiki/Skip_zone seems to imply that there is no skip zone at LF.

"A method of decreasing the skip zone is by decreasing the frequency of the radio waves. Decreasing the frequency is akin to increasing the ionospheric width. A point is eventually reached when decreasing the frequency results in a zero distance skip zone. In other words, a frequency exists for which vertically incident radio waves will always be refracted back to the Earth. This frequency is equivalent to the ionospheric plasma frequency and is also known as the ionospheric critical frequency, or foF2."