Author Topic: Identifying E-Field Interference  (Read 1731 times)

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Offline Baobab

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Identifying E-Field Interference
« on: January 20, 2015, 11:57:01 PM »
Hello Everyone,

I just finished setting up and configuring my system - Station 1270. I am currently running an e-field antenna only. The controller is running on manual mode with quite conservative gain settings. Even so, it seemed to have picked up a good proportion of the strikes down in the Gulf of Mexico last night - +3200km away. When looking at the signal viewer I consistently see the signal in the attached screenshot - it's amplitude occasionally increases but the frequency (13kHz) seems constant. Signal analysis and interpretation is not something I have ever done so am hoping that someone with more experience can have a look and perhaps suggest what may be responsible. Any other suggestions on how to configure and set up the system are welcome and I am always eager to learn something new.

Thanks and what a fun project to be part of!!

Phil

Offline miraculon

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Re: Identifying E-Field Interference
« Reply #1 on: January 21, 2015, 09:19:00 AM »
The fact that the amplitude is not constant is interesting and perplexing.

Is there some "periodicity" to this amplitude peak, in other words what is the time between these peak amplitude periods? (from when it grows to this "bulge" in the waveform until the next time it happens)
Is it several seconds, or is it in the millisecond range?
There are some recommendations in the noise thread for hunting down noise. You could try an AM radio as a noise sniffer, or shutting off circuits in your house until the noise stops.

Greg H.


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Offline Cutty Sark Sailor

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Re: Identifying E-Field Interference
« Reply #2 on: January 21, 2015, 09:40:37 AM »
Here... watch it awhile:  http://frankfortweather.us/BoStaSig/station_index.php?station=1270
Just added you recently... monitor and follow the various resolutions...
You actually look quite good.... Noise is 'ignored' by the server... and if it's "troublesome" the
controller will go into either "Burst" interference, or "normal" interference where too many signals are
received.... it's a pretty smart system.  What you do, is establish a baseline during this quiet season....
Don't run AUTO... stay in Manual!!!  Auto and those extra filters you can click in, is/or still experimental
and / or only for specific locations, like Europe.  Let the server "get to know you"... This coming year,
a lot of emphasis is going to be placed on "quality".... not 'range'... And quality is NOT inherent in
long distance reflected skywaves... necessarily. Some of your "noise" isn't "local",.,. it may be
coming from something 500 miles away!
Cheers!

Mike
 


Offline scarecrow93

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Re: Identifying E-Field Interference
« Reply #3 on: January 26, 2015, 12:12:31 PM »
IMHO, auto amplitude has it's place.

I use manual gains and auto amplitude filter because I have a neighbor with something that throws a 60Hz signal at me from dusk to about 10pm and again for a few hours in the morning.  Been running the auto amplitude filter for the last 6 months or so.

Sure, when I'm getting "jammed" by my neighbor, I lose about half of the strikes I should be getting.  Biggest benefit is most of the jammed signals get filtered at my level and never sent to the server.  I very rarely get into interference mode anymore.  Maybe the filtered signals don't count toward your limit before getting pushed into interference?  When he shuts off his jamming, I'm back in the ballgame.

Just my .02

Lance
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Offline W3DRM

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Re: Identifying E-Field Interference
« Reply #4 on: January 26, 2015, 03:24:33 PM »
I agree with Cutty that your basic signals don't look that bad at all. However, I am wondering if you are getting some ringing (oscillations) in the circuitry when a signal gets detected? Check over your solder joints for all of the op-amps and associated circuitry in both the pre-amp and amplifier PCBs.


Also, you mention you are using manual gain settings. What do you have your gains set at? And, did you follow Cutty's E-field Startup and Operation thread (http://www.wxforum.net/index.php?topic=22710.0)?
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Offline Baobab

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Re: Identifying E-Field Interference
« Reply #5 on: January 26, 2015, 11:56:31 PM »
I tried to follow Cutty's guide but ran into a couple of issues. First, and I hate to admit, it it is a bit over my head at this point. Second, I am still having issues with the signal viewer being very very jerky. It rarely flows smoothly and often freezes up for seconds or minutes at a time.

I currently have the gains set as follows:

2A = 10 * 5; Threshold = 120
2B = 10 * 5; Threshold = 120
2C = 10 * 5; Threshold = 120

Noise adaption and amplitude filter are enabled.

Looking at the signal viewer screen it appears that the majority of times the gains and thresholds are adjusted to the values in the attached screenshot.

I chose the setting with the idea of keeping an eye on how the station performs relative to other zone 3 stations and then adjusting accordingly. So far when I compare my station to the others in zone 3 it seems to be performing well especially given that so far the majority of lightning activity has been over 3000km away. If I can track down and eliminate the 13kHz signal that is always present I am hoping that the performance of my station will increase. If there is a faulty solder joint does the signal pattern provide any clues as to which op-amp may be responsible? Thank you.

Offline Cutty Sark Sailor

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Re: Identifying E-Field Interference
« Reply #6 on: January 27, 2015, 12:20:39 AM »
You have looked great every time I've checked....

A 13kHz signal is right in the middle of critical stroke energy.  Now, if you're watching your signals on the 'signals' page we rigged up, you should see pretty good signals.. they should update from the BT server every 2.5 seconds if you've sent a signal. Your signals look fine.
You are also perhaps in error comparing with stations that are detecting signals 3000km away.  Those signals tell the servers very little, since they are reflections of "something"... maybe not even lightning... an A bomb maybe? A meteor path? A jet contrail causing an atmospheric discharge?  Who knows?
Concentrate on the cleanest, best performing 'overall' structure... might be to catch that 13kHz and set stuff so it's just under the level that the 13kHz triggers.

Perhaps this is also a good time to remind all that the E field is going to be more efficient and reliable at distances <600km or so... that was the design thinking!
(Gosh, I've had so many discussion on this stuff I probably get my numbers all screwed up)

Cheers!
Mike