Author Topic: Interference and Noise  (Read 36517 times)

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Offline Cutty Sark Sailor

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Interference and Noise
« on: October 10, 2013, 02:15:27 PM »
'Interference': Any undesired signal that tends to interfere with reception.

I thought it time to start a thread that brings all our noise knowledge into one place, especially to help those living with frustration and those who may be less experienced and knowledgeable. Perhaps we could bring our troubleshooting, isolating, and resolution tips here, along with any screen captures we might grab.

Qualification: June 3 2014 Please Note that this looks at H field only, Amplifier 1, channels A (red) and B (green).  Among other difference between E and H fields amps: You CANNOT DISABLE E-field signals by checking "don't send" on the settings page. The server wants to see all three channels. Best you can do is set gains to 1x1, thresholds to "0". You can adjust gains. E field signals look different, and interference location is a different process.

We all want the clearest signal at the maximum distance that supports the network, and - for myself - there is some 'pride' and curiosity involved. We have healthy servings of those, or we wouldn't get involved it this! Contra-wise, we also want to avoid hindering the network efficiency by ignoring 'nearby' signals... especially as more stations come online in the USA. Our 'long range'  capability becomes less a factor, and clean signals become more important... not ignoring the heavier load on the servers due to mucho 'noise' signals.

The first phase would be to identify, if we can, the type and source of interference. And that becomes quite a chore sometimes.


Addenda, May 2015
...these thoughts:
While communicating with some operators, I developed a sense that some of us might be
confused when we speak of "interference" and "interference".... :D
We might be using "interference" as 'a disturber or noise that degrades communication or data, or a system's operation'.
But we might also simply be referring to "a system going into 'interference' ".

System RED (and BLUE will likely operate in a similar manner) will go into one of two types of "Interference Modes" from time to time.  "Burst" or "Normal"
The System is designed this way, generally,
1. Because nearby active cells produce so many signals, so rapidly, that they cannot normally be recognized separately... and matter of fact, one "paradigm" of the developers might be phrased as "detected signals <30km are generally useless to the network"  with the current design, anyway.
So when you go interference because of nearby storms.... accept it, let 'er ride, and let the network do its net work.  :D
2. Unless you have a perfect location, sporadic 'disturbers' such as an arcing power line, may produce conditional interference that swamps the controller similar to nearby cells, such are useless anyway.  But they're sporadic, and when they cease, you'll come out of interference.
3. Repeating, identical, signals that might be caused by someone standing nearby with walkie-talkie, burst of repeating  power line noise... weird stuff.

Now, while Interference Modes can be triggered by non-lightning signals,  it is based on the "number of signals sent" within certain time frames.
Except for the limited 'repetition and recurring' algorithms for "Burst Mode", it has no recognition of "types of signals" and doesn't care.
Interference mode can be activated due to signals on all channels, or one single channel, or a combination if you're running 5 channels including both H and E field.

It also is one 'controller parameter' that is monitored over time and varied by the server/controller! 
In other words, the server/controller can lower or raise those limits depending on what it sees from your station! 
You only have "indirect control' of this response: your operating mode, gains and thresholds, etc.
The 'basic' purpose is to avoid sending "too many signals" or "EM noise pulses" from your station.

These "interference parameters" operate no matter what mode you're in -Auto or Manual: 

If you look at your 'status' page when you access your controller web interface, down under "other parameters', you see something like this:
Interference Mode
   Burst        When > 80sig/s in 3s average. Disable when 50% below threshold
   Normal     When > 70sig/s in 60s average. Disable when 30% below threshold

...and if too many signals are actually sent under certain conditions,
that will 'back that down' to, for e.g. 30sig and 15sigs.... until
you can come out of interference, and the limits will rise again after some period of time.

So if over "some period of time" you've averaged over 70sigs/minute, you'll go into "Normal" interference, and stay there until it drops below 70sigs average.... which can be a long time... especially if the /controller has lowered the max limit temporarily for your controller to 15...! And if you are in Auto mode it could take even longer under certain conditions, as the controller may continuously cycle on and off and in and out of the mode.

For Burst mode... (short periods of repeating signals) it'll come out of interference much quicker.. a few seconds). It can be longer, again, if your limits have been temporarily lowered...

Remembering that you have only indirect control over 'Interference Mode" ... each channel's 'gain and threshold' settings.
If you're in "Automatic" mode, you have no access to your gains and threshold settings. Unless you desire to wait until the sources vanish on their own, you'll have to return to "Manual" mode, and reapply gain/thresholds settings under each specific amp, (the actual gains /thresholds have been set by "Auto", and they are NOT visible under the AMP settings... that shows you your settings so you must hit apply to reset the "Auto" parameter.
It follows, then, that if H channel A is the one causing the interference, you could back down channel A to 'just under noise trigger level, it will now come out of interference, and channel B  continues its merry way, and A now is of some use also.
You can take it from here.

(This is duplicated at http://sferics.us/bo1/index.php?topic=130.0 for cross searching )


I'll kick it off with the following posts....

Mike

Links to explore:
RFI GUIDE From New Zealand, a PDF... pages 1 through 9 have good info!
Radio Jay Allen's Web Page or Download as PDF A thorough, simple look-see, although aimed at AM broadcast, it's very applicable, and not technical.
« Last Edit: June 23, 2015, 06:35:52 AM by Cutty Sark Sailor »

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Offline Cutty Sark Sailor

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The cleanest signals we can obtain?
« Reply #1 on: October 10, 2013, 02:16:06 PM »
Idealized Waveforms:


System Red Received Examples:





And if we've constructed well, are fortunate, in a good location, with adequate antennas, we should acquire strokes and signals similar right from the start.

But not always....

-more-
« Last Edit: October 11, 2013, 07:40:18 PM by Cutty Sark Sailor »

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Offline Cutty Sark Sailor

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That Power Line Stuff
« Reply #2 on: October 10, 2013, 02:16:47 PM »
Our good old American 60hz:


And it often has other noise mixed with it, in this case from an Acer desktop:


Also signals ride in on it:



And now, we have 60hz, computer leakage, and signals...

But wait!   There's more!   

Moving on to computer noise!

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Offline Cutty Sark Sailor

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Computer Noise
« Reply #3 on: October 10, 2013, 02:17:32 PM »
When we first combine our antennas, amp, and controller, into 'The System',  we may in fact be sitting right next to our pc, laptop or whatever...and our new Blitzortung system  immediately goes into interference, with a signal screen that looks similar to this:

Or the noise might be a lower level, with signals visible:

The above 2 images result from an HP Laptop 5 and 10 feet distant from the antennas.

The below contain interference from a leaky ACER desktop, in another room, 25' away! About 5' from the controller and it's cables:

And here's a signal riding in on it:


Now, take a piece of wire, connect it to the computer case (metal, hopefully) and ground it to the controller!

Well, that was simple enough. Now it may be tolerable.

Now what is this?

At the far right, what appears to be a signal from a streetlight!  Sodium or Mercury vapor?... and they'll put you in interference in a jiffy!


Possible Quick Resolutions: 1) Have you grounded the Controller per the documentation? 2) Move the antenna and amp well away from the computer room if possible! 3) Try grounding the metal PC case. Measure any voltage difference between case and the controller's ground first! Use a high impedance meter...

-more-
« Last Edit: October 10, 2013, 04:06:20 PM by Cutty Sark Sailor »

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Offline Cutty Sark Sailor

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External Utility Noise, Possibly
« Reply #4 on: October 10, 2013, 02:18:08 PM »
Power Lines and stuff (anything that arcs, for example, an insulator, transformer, etc) might look like this:

a flurry of spikes, and that slow '60Hz' or even '120Hz curve'...  probably intermittent... if it's a street light, you'll note it just at dusk when it tries to fire, and sporadically throughout the dark hours, until sometime after sunrise...

It may be riding on other noise:


Any arcing device may look similar... power drills, sanders... etc  etc


Possible Quick Resolutions: 1) If you've isolated it to a street light, the power company, city, or other utility or factory is responsible. In some areas the Property Owner has to make the complaint. Tell 'em there's a street light/security light failing. Could also tell 'em it's interfering with your late night A.M. Talk Radio program reception... You've got the FCC on your side. But not necessarily for lightning detector interference! More importantly, tell 'em if you're pretty sure it's a transformer or insulator... you don't won't to be powerless during cold weather! (Or hot, for that matter)... .

-more-

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Offline Cutty Sark Sailor

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Automobiles, Power Tools, Other Noisy Stuff.
« Reply #5 on: October 10, 2013, 02:19:04 PM »

May resemble a 60Hz line noise, depending on engine etc!


What a hodge-podge!

Possible Quick Resolutions: 1) Patience, it'll drive off, ...or run out of fuel.

Then your neighbor fires up his electric drill, or similar:


Or your energy conscious Green spouse replaces the last 100W incandescent light bulb in the US
with a 13 W fluorescent:


Yes, resembles computer and other similar interference, doesn't it?

Possible Quick Resolutions: 1) Borrow your neighbor's drill. Forget to return it.  2) Paint your face green and claim extreme fatigue and nausea resulting from Mercury radiation poisoning due to the fluorescent, and replace it with a 75 watter...



Hope these initial blurbs help.... post your experience, screen grabs and tips!

Couple of folks had some issues with those robot lawn mowers.... the 'perimeter' radio guidance.  Solutions varied from waiting till grass out of season, giving wife a non-motorized reel mower, ... and I suggested a herd of sheep instead, since they're self-supporting, self-replicating, keep the grass cut short, fertilize it, and provide warm snuggly stuff for cold weather....

Same is true for those electronic "pet fences". Seems like both resemble the 'computer interference' images somewhat.

Mike





« Last Edit: October 11, 2013, 08:39:50 PM by Cutty Sark Sailor »

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Offline Timay

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Re: Interference and Noise
« Reply #6 on: October 10, 2013, 02:49:48 PM »
Take a shot of the signal after someone turns on a plasma TV...I think you will be amazed.  I had a plasma TV for about a week and then took it back.  When the TV was on, it completely wiped out my HF ham radio.

Tim
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Offline i_fiorentino

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Re: Interference and Noise
« Reply #7 on: October 10, 2013, 02:59:12 PM »
Wow Mike, thanks for sharing this!

Please, Could you give me an eye to my signal to verify if it's apparently ok?

Here it is: https://www.dropbox.com/s/9gikltg3lpj6383/Signal1.PNG

I also posted the image below.....what meaning this message near the captured strike?

https://www.dropbox.com/s/3vixc4afjizu6ie/Strikes.PNG

Many thanks,



Alessandro

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Re: Interference and Noise
« Reply #8 on: October 10, 2013, 03:04:15 PM »

'Interference': Any undesired signal that tends to interfere with reception.

I thought it time to start a thread that brings all our noise knowledge into one place, especially to help those living with frustration and those who may be less experienced and knowledgeable. Perhaps we could bring our troubleshooting, isolating, and resolution tips here, along with any screen captures we might grab.

We all want the clearest signal at the maximum distance that supports the network, and - for myself - there is some 'pride' and curiosity involved. We have healthy servings of those, or we wouldn't get involved it this! Contra-wise, we also want to avoid hindering the network efficiency by ignoring 'nearby' signals... especially as more stations come online in the USA. Our 'long range'  capability becomes less a factor, and clean signals become more important... not ignoring the heavier load on the servers due to mucho 'noise' signals.

The first phase would be to identify, if we can, the type and source of interference. And that becomes quite a chore sometimes.


I'll kick it off with the following posts....

Mike


Mike, I think this is a fantastic idea.

I know it will help me.

Joe
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Re: Interference and Noise
« Reply #9 on: October 10, 2013, 03:06:41 PM »
I like it. Kind of a "rogues gallery" of noises.

I'll post my bad ones here when they occur.

Greg




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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #10 on: October 10, 2013, 04:38:45 PM »
Wow Mike, thanks for sharing this!

Please, Could you give me an eye to my signal to verify if it's apparently ok?

Here it is: https://www.dropbox.com/s/9gikltg3lpj6383/Signal1.PNG

I also posted the image below.....what meaning this message near the captured strike?

https://www.dropbox.com/s/3vixc4afjizu6ie/Strikes.PNG

Many thanks,



Alessandro
I don't know for sure, Alessandro, those signals look pretty clean... for the error message, you might check the 'settings' 'sampling' for 'tracker'...
the settings should be  512   128  and some percentage... mine's set for 30%, and under 'A/D Converter'  56   28  12bits  and 2.   That might be what's happening.
Mike

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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #11 on: October 10, 2013, 04:43:45 PM »
Take a shot of the signal after someone turns on a plasma TV...I think you will be amazed.  I had a plasma TV for about a week and then took it back.  When the TV was on, it completely wiped out my HF ham radio.

Tim
Yeah, Tim. I had a recent spurt of interference that looked very similar to the computer interference. I think was about 55-56Khz. Neighbor next door had just moved their big plasma to an outside wall, facing my garage. Negotiated a slight movement of the TV to the corner of their room, now minimal interference, but still some on rare occasions.

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Offline NeverDie

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Re: Interference and Noise
« Reply #12 on: October 10, 2013, 05:02:31 PM »
'Interference': Any undesired signal that tends to interfere with reception.

I thought it time to start a thread that brings all our noise knowledge into one place, especially to help those living with frustration and those who may be less experienced and knowledgeable. Perhaps we could bring our troubleshooting, isolating, and resolution tips here, along with any screen captures we might grab.

We all want the clearest signal at the maximum distance that supports the network, and - for myself - there is some 'pride' and curiosity involved. We have healthy servings of those, or we wouldn't get involved it this! Contra-wise, we also want to avoid hindering the network efficiency by ignoring 'nearby' signals... especially as more stations come online in the USA. Our 'long range'  capability becomes less a factor, and clean signals become more important... not ignoring the heavier load on the servers due to mucho 'noise' signals.

The first phase would be to identify, if we can, the type and source of interference. And that becomes quite a chore sometimes.


I'll kick it off with the following posts....

Mike

Links to explore:
http://radiojayallen.com/combatting-am-and-sw-interference/ A thorough, simple look-see, although aimed at AM broadcast, it's very applicable, and not technical.


Thanks for the helpful info.  What is it that you're using to capture the signals and make those nice signal and noise graphs?

Offline Cutty Sark Sailor

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Building Structure and Antenna Placement
« Reply #13 on: October 10, 2013, 05:06:45 PM »
I posted a link, and guess we can post more, to a page regarding intereference... maybe move all the links to the first post as you post 'em.  Anyway, he mentions building structure, and discusses the blocking of signals.

I have the opposite issue in this dwelling. The home is covered with (real) foil covered insulation. The encapsulation seems to act as a 're-radiator' for noise... matter of fact, I've only found one 'sweet spot' in the garage where the generated fields are weakest... and one spot only!...

A few weeks ago, I rolled up a couple of 300mm ferrites per Don F's 250mm design, and replaced my 120mm, shielded kit ferrites with them. Possibly because of the increased gain, this longer pair has a better S/N than the 120s overall. And they perform better unshielded.

Antenna type, placement and orientation is important for some types of interference. For e.g. If I only had one source of street light interference, instead of three right now, with this TOA system not directionally critical, I could 'null' one antenna by pointing its 'core' end directly toward the light. However, with the current trinary source and the radiating home shell, that has very little effect. The stronger fields are pretty much detected from 'all directions'.  
« Last Edit: October 10, 2013, 05:11:24 PM by Cutty Sark Sailor »

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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #14 on: October 10, 2013, 05:09:36 PM »
What is it that you're using to capture the signals and make those nice signal and noise graphs?
Those are just screen captures of the signals display of the web interface for the Blitzortung controller. Nothing dramatic or fancy at all.

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Offline miraculon

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Re: Interference and Noise
« Reply #15 on: October 10, 2013, 08:56:19 PM »
OK, here is one that I just captured. I see this all the time. I call it the Two-Horn noise because it looks like it has horns (or maybe ears).

This is one of the nasty ones, it just started all of a sudden.

Greg




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Offline Jumpin Joe

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Re: Interference and Noise
« Reply #16 on: October 10, 2013, 09:03:29 PM »
OK, here is one that I just captured. I see this all the time. I call it the Two-Horn noise because it looks like it has horns (or maybe ears).

This is one of the nasty ones, it just started all of a sudden.

Greg

Greg, I see this occasionally too!
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Re: Interference and Noise
« Reply #17 on: October 10, 2013, 09:49:47 PM »
OK, here is one that I just captured. I see this all the time. I call it the Two-Horn noise because it looks like it has horns (or maybe ears).

This is one of the nasty ones, it just started all of a sudden.

Greg
That looks like a sodium/mercury light! If I can catch one of mine acting like that, we can compare. On both antennas, out of phase! Check the diagonal directions. Weather's cooler, it's having trouble starting.
« Last Edit: October 10, 2013, 09:53:30 PM by Cutty Sark Sailor »

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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #18 on: October 10, 2013, 10:28:35 PM »
OK, here is one that I just captured. I see this all the time. I call it the Two-Horn noise because it looks like it has horns (or maybe ears).

This is one of the nasty ones, it just started all of a sudden.

Greg
That looks like a sodium/mercury light! If I can catch one of mine acting like that, we can compare. On both antennas, out of phase! Check the diagonal directions. Weather's cooler, it's having trouble starting.
Here ya go...

5 mins apart, virtual twins, not as strong as yours, and not as much 60Hz rollout, but that's a 10 yr old utility pole sodium security light 200' SE of my antennas....

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Re: Interference and Noise
« Reply #19 on: October 11, 2013, 09:59:38 AM »
Great thread.  Thanks, guys.  This is an essential primer for analyzing and defeating those pesky noise problems we can all experience.  I just noticed a streetlight interference pattern on one of my strikes, and I still have 60 Hz interference coming and going on channel B.  I need to go over that side of my amplifier board again...
Regards, Jerry Wilkins
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Interference and Noise - added resource link to Post 1
« Reply #20 on: October 11, 2013, 11:32:21 AM »
Resource Summary to date... see Post #1 for most up to date additions/changes

Links to explore:
RFI GUIDE From New Zealand, a PDF... pages 1 through 9 have good info!
Radio Jay Allen's Web Page or Download as PDF A thorough, simple look-see, although aimed at AM broadcast, it's very applicable, and not technical.
Mike
« Last Edit: October 11, 2013, 11:36:26 AM by Cutty Sark Sailor »

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Offline schwab

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Re: Interference and Noise
« Reply #21 on: October 11, 2013, 05:13:51 PM »
I have an ungrounded and unshielded ferrite antenna 6.8 system.

Is the attached image a reasonable signal profile?

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Re: Interference and Noise
« Reply #22 on: October 11, 2013, 06:00:34 PM »
I have an ungrounded and unshielded ferrite antenna 6.8 system.

Is the attached image a reasonable signal profile?

Something doesn't look right. I'm not familiar w/greens, but:
Is 256 the default sampling rate for Green systems, not 512???, and  0 sample before trigger?  Zero Gain???

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Perfect Signals?
« Reply #23 on: October 11, 2013, 07:36:33 PM »
For comparison, added drawings of 'idealized' signals to post #2 above
Mike
« Last Edit: October 11, 2013, 07:43:12 PM by Cutty Sark Sailor »

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Offline miraculon

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Re: Interference and Noise
« Reply #24 on: October 11, 2013, 08:23:10 PM »
I have an ungrounded and unshielded ferrite antenna 6.8 system.

Is the attached image a reasonable signal profile?

Something doesn't look right. I'm not familiar w/greens, but:
Is 256 the default sampling rate for Green systems, not 512???, and  0 sample before trigger?  Zero Gain???

The Green (6.8USB) uses a "dumb" amplifier. The gains are set by jumpers (a pain, believe me) and not PGA (Programmable Gain Amplifier). The windows-based tracker program has no idea about the gain setting. The threshold on a stock "green" is fixed at +/-417mV, although my modded unit is adjustable. The tracker doesn't know what this is set to either, the "green" controller uses a simple analog comparator that triggers based on a reference voltage.

Also the scope-like trigger window is different hence the different trigger points. I believe that the buffer can store the pre-trigger data in "red".

Here is a web page where I have both of my stations "red" and "green". I also have the FFT plots for both systems.

http://www.miraculon.net/signals.html

Greg





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