Author Topic: Electric fence?  (Read 542 times)

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Offline Jim-Bob

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Electric fence?
« on: November 11, 2018, 11:06:27 AM »
I'm seeing some very strong signals on my Blue. (0.2-0.4v on red and green channels with 200mm ferite antennas)
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I believe this is an electric fence (or two)

Is there anything that I can try to overcome this?

p.s. I hope this post is OK as I can't preview attachments?

Offline Cutty Sark Sailor

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Re: Electric fence?
« Reply #1 on: November 11, 2018, 02:28:56 PM »
It may be... if that is your normal threshold setting, simply adjust it higher till that doesn't trigger the system.. looks like it's predominate on B... I have something similar at times, and have never bothered to track it down....but it's not a fence.
With the current rebuild on the servers, cannot observer your signals,

Progress is being made there, however...
 

Offline Jim-Bob

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Re: Electric fence?
« Reply #2 on: November 11, 2018, 02:58:21 PM »
Is this more like how it should be triggering?
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Offline Jim-Bob

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Re: Electric fence?
« Reply #3 on: November 11, 2018, 03:09:24 PM »
Or this
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Offline dupreezd

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Re: Electric fence?
« Reply #4 on: November 11, 2018, 03:46:50 PM »
Out of curiosity, how many ferrite antennas do you have, 2 or 3?
WS-1200-IP | ObserverIP | Meteobridge
WU, PWSWeather - KTXCONRO61
CWOP - FW0717
Blitzortung 2100

Offline Jim-Bob

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Re: Electric fence?
« Reply #5 on: November 11, 2018, 03:54:17 PM »
Three.
2 at 90 degrees horizontal, 1 vertical (Yellow) and 1 E field, which does not produce much at the moment.

Offline Cutty Sark Sailor

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Re: Electric fence?
« Reply #6 on: November 11, 2018, 03:56:46 PM »
Ok... here's what:
Calculations within the controller for the gains, etc... something called 'relative' gain'  shown on the status page, not on the signals page.
             10 * 5 * 40 = 2000   relative gain :1666
It is calculated on a reference standard, used by all systems, and the server...  baseline trigger threshold0 of 100MV. 
This relative gain figure influences a whole lot of processing and comparisons on the server and is the first paradigm for quality...
In  theory, everybody would have a threshold setting of 100, the same exact antenna, etc... .  That is not possible, of course.The threshold actually is a DIGITAL function, not an ANALOG function. And the Relative Gain Computation is what the ADC uses to reference the 'signal' characteristics, along with frequency components, etc..
Gain settings work on Analog chain... and only affects the output amplitude to the ADC...


Now, to keep thing simple, all you need do, is set the digital 'threshold', so that any signal lower than some  voltage, at the analog output, will NOT trigger the ADC...You may see them on your signals display, if a different channel triggers the ADC, but THAT channel DIDN"T.. follow me?The 'Triggered' channel will probably be sent to the server... once ADC is triggered, all signals within the threshold  restrictions will be sent.  (see the 'setting' "ignore signals below threshold percentage"... those normally aren't sent.

Regardless, the server will only select the 'best' channel info from your station for analysis.  Just one. The Best....and the first thing server does is query "IS this signal threshold greater than twice the receiver's noise floor?"  If "NO"... it immediately drops the signal, and won't process it. That assumes it made it to the server, and the controller itself allowed it to be sent.
So, however you set things, whatever your average noise level, ambient, no signals or junk, your trigger should be at LEAST twice that voltage.

 You can rais or lower gains all day, and mess with your average operation, but it's the threshold setting that's critical.Automatic mode plays hell with this, especially in certain environments like mine. If you're running an average noise floor 40mv or lower, you're in good shape, and a trigger of 85 is fine... UNLESS you've got these noise pulsed sending junk... and theyr'e triggering at 110MB for example... set that channel to 115... voila, no junk, and you won't affect your 'quality' ,... yeah.. if you're detecting some strokes at 5000Km you might drop to 4000km... so what. ... you're signals probably aren't used for location at that distance, anyway ... and that's the goal of Blitzortung... Locating strokes... an am radio can 'detect' a stroke... heh....

So.. if you've got, like me, sporadic noise makers..... automatic may not be your friend... 

You cannot mitigate this in Automatic Mode... you must set things in manual first, or automatic will drie you nuts.
when the offender is present, set the threshold high enough so that it just barely WILL NOT trigger that channel... if it's triggering more than one, set them also...
Now your system will hum along pretty well on average, much of the time, in this manual setting.   If you go back to automatic, it's going to play games turning the gains up and down... enjoy it, I guess...or stay manual...You may be a new member of the Cutty Sark Sailor All Manual Mode Network.
« Last Edit: November 11, 2018, 04:05:08 PM by Cutty Sark Sailor »
 

Offline Jim-Bob

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Re: Electric fence?
« Reply #7 on: November 11, 2018, 04:12:58 PM »
Thank you for that.
Basically I should concentrate on the thresholds in manual unless the system is clipping or 100mV peak is never reached during a real event?
All the time bearing in mind the two times noise floor validation from the servers?
Do i understand correctly?

Offline Cutty Sark Sailor

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Re: Electric fence?
« Reply #8 on: November 11, 2018, 04:51:24 PM »
Thank you for that.
Basically I should concentrate on the thresholds in manual unless the system is clipping or 100mV peak is never reached during a real event?
All the time bearing in mind the two times noise floor validation from the servers?
Do i understand correctly?

You might look at this WIKI entry
If you're clipping, that's caused by gains in the amplifier chain... the ADC is just reproducing them as a 'square wave' with 'unlimited odd harmonics'... junk in other words...
On a 'perfect' ground wave stroke, the trigger could be said to be at the 80% level of the 'discharge' portion of the stroke amplitude out of the Analog chain... that would be your 'time stamp' in a perfect world... Now, this is actually a 'power' representation, you're seeing it as a 'voltage' when in effect it is more properly a 'current' derivation,.. they are 'presented' to us in something we can relate to visually....
« Last Edit: November 11, 2018, 04:55:40 PM by Cutty Sark Sailor »
 

Offline Jim-Bob

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Re: Electric fence?
« Reply #9 on: November 11, 2018, 06:00:35 PM »
I thought this would happen, but for anyone that reads this thread, this is what clipping looks like.
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I will drop the first gain number a lot, followed by the second number somewhat less.

Offline Cutty Sark Sailor

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Re: Electric fence?
« Reply #10 on: November 11, 2018, 08:13:18 PM »
That is one humongous signal...  :twisted: :twisted: ...almost 2 volts clipped!
how big are your antennas?  :D   The 470v trigger level is absurd... ????
and not possible for the system to work correctly...
I would suggest that's a helluva 'near field' source, or

 

Offline Jim-Bob

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Re: Electric fence?
« Reply #11 on: November 12, 2018, 03:11:15 AM »
That is one humongous signal...  :twisted: :twisted: ...almost 2 volts clipped!
how big are your antennas?  :D   The 470v trigger level is absurd... ????
and not possible for the system to work correctly...
I would suggest that's a helluva 'near field' source, or

I've been gradually reducing gain by small factors, like 10%, but after another strike that saturated the ADC again, I've halved all channel gains.
That will be my first aim, to stop it clipping, then play with the thresholds.
I'm using 3 200mm ferites and a 100mm E-field.
I'm not too sure about the screening on the CAT 6 cable so I will have to swap that out, if I can locate another one.

Offline Jim-Bob

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Re: Electric fence?
« Reply #12 on: November 12, 2018, 02:47:20 PM »
New 1m foil screened RJ45 cable and a few tweaks.
It may still need the gain knocking down a bit.
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« Last Edit: November 12, 2018, 02:50:21 PM by Jim-Bob »

Offline Jim-Bob

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Re: Electric fence?
« Reply #13 on: November 12, 2018, 03:27:37 PM »
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Offline Jim-Bob

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Re: Electric fence?
« Reply #14 on: November 24, 2018, 10:03:20 AM »
The electric fence fence mysteriously disappeared last weekend, along with the wooden fence that it was attached to.
I now need to get my stats registering properly on Blitzortung.org.

Offline Cutty Sark Sailor

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Re: Electric fence?
« Reply #15 on: November 24, 2018, 12:00:28 PM »
The electric fence fence mysteriously disappeared last weekend, along with the wooden fence that it was attached to.
I now need to get my stats registering properly on Blitzortung.org.

,,, heh... Elephant herd??? Buffalo Stampede???? Tornado???? 

Stats won't be possible or accurate until the servers are back in full swing... so don't put much faith there for awhile...
In addition to the 'restoration',,,, there are new processing and computation programs being installed gradually...
 

Offline Jim-Bob

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Re: Electric fence?
« Reply #16 on: November 24, 2018, 01:49:35 PM »
Quote
,,, heh... Elephant herd??? Buffalo Stampede???? Tornado???? 

Stats won't be possible or accurate until the servers are back in full swing... so don't put much faith there for awhile...
In addition to the 'restoration',,,, there are new processing and computation programs being installed gradually...

The fence was rotten which is why there was an electric fence was erected in the first place. It is now being replaced with a new one.

Thank you for the updates with the servers.

 

anything