Author Topic: Interference and Noise  (Read 100326 times)

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Offline uhf

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Re: Interference and Noise
« Reply #175 on: October 14, 2014, 10:09:46 PM »
Another one, this is more typical.
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Offline W3DRM

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Re: Interference and Noise
« Reply #176 on: October 15, 2014, 01:02:25 AM »
Just got my November issue of QST and it has a nice article in it about RFI (Radio Frequency Interference) on HF. In the article there is a reference to some information on power-line noise. It can be found at http://www.arrl.org/power-line-noise-faq. NOTE: This link is good for anyone whether you are an ARRL member or not. If you are a Ham and a member of the ARRL, you can see the article in the Nov 2014 issue of QST starting on page 33. The article also describes the design, building and usage of a direction finding system. ARRL members with on-line accounts may access the November issue of QST at the following link: http://www.nxtbook.com/nxtbooks/arrl/qst_201411/index.php. Non-ARRL members will not be able to see this article - sorry.

If I can find some free time (ha-ha) I may just try to build one of these myself and see how it works.
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Offline W3DRM

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Re: Interference and Noise
« Reply #177 on: October 16, 2014, 07:40:00 PM »
Well, I just found the perfect place for an Ortunger to live - Green Bank, West Virginia - it is within the National Radio Quiet Zone. Watch the video for details.
This would drive some folks nuts not being able use all of their electronic gadgets but Blitzortung would be quite at home there...
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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #178 on: October 16, 2014, 07:49:38 PM »
Another one, this is more typical.
Yep;... buncha line freq interference... check for old, ageing street lamps. dimmer switch, household appliance, nearby motors....
 


Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #179 on: October 16, 2014, 08:01:21 PM »
Well, I just found the perfect place for an Ortunger to live - Green Bank, West Virginia - it is within the National Radio Quiet Zone. Watch the video for details.
This would drive some folks nuts not being able use all of their electronic gadgets but Blitzortung would be quite at home there...
Yep, the "black hole'... would you believe that KFFT apparently has reactivated a NDB just over the hill from me?  Sheesh... talk about dark ages....  yeah,
 


Offline miraculon

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Re: Interference and Noise
« Reply #180 on: October 16, 2014, 09:52:44 PM »
Either there or the VLA on the Plains of San Agustin in New Mexico. We visited there in 2000. It is also a NRAO http://www.vla.nrao.edu/ site. It is out in the middle of nowhere.

Greg H.


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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #181 on: October 16, 2014, 10:09:44 PM »
Meditating line freq is part of the fun of this thing.. first, make sure ONLY the controller block has a good "cold water" ground.... finding that "sweet spot" took me some time........  get an AM radio, tune it off station.... somewhere 530 -645 kHz... and find a location where it's minimum.... try your antennas there... my 'sweet spot' is about 2 meters high and 2 meters wide... it can be that critical in locations like mine !...and I've a tough M component environment! If I can mitigate it, anybody can, 'cause I'm not that bright! But even a blind hog finds an acorn if he roots long enough... .
 
« Last Edit: October 16, 2014, 10:12:39 PM by Cutty Sark Sailor »
 


Offline uhf

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Re: Interference and Noise
« Reply #182 on: October 16, 2014, 10:23:26 PM »
Another one, this is more typical.
Yep;... buncha line freq interference... check for old, ageing street lamps. dimmer switch, household appliance, nearby motors....
Dishwasher is making a lot of the noise, as are two dimmer switches. The dimmers are going bye-bye. Don't know what I'm doing about the dishwasher, but I have some ferrites that I might try on the power leads. My antenna is also located fairly close to the electric meter, which probably isn't the best spot, but at times it's very quiet there and it's the perfect spot convenience wise for me to mount the antenna, so I'll leave it there if I can.
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Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #183 on: October 16, 2014, 11:18:41 PM »
Another one, this is more typical.
Yep;... buncha line freq interference... check for old, ageing street lamps. dimmer switch, household appliance, nearby motors....
Dishwasher is making a lot of the noise, as are two dimmer switches. The dimmers are going bye-bye. Don't know what I'm doing about the dishwasher, but I have some ferrites that I might try on the power leads. My antenna is also located fairly close to the electric meter, which probably isn't the best spot, but at times it's very quiet there and it's the perfect spot convenience wise for me to mount the antenna, so I'll leave it there if I can.
Great!  You're on the way,,, the network and you both can survive the dishwasher at it's odd times... the dimmers are a different matter...  you might even find a 'sweet spot' to minimize the dishwasher,........ just  takes some trial and error,..   might have to move it away from the 'mains' meter, if possible... my location isn't the most 'convenient'... but it's the best... and it is a PITA but it's all I've got  ](*,) at least for H field...  my e field fairly comfortable/.....
« Last Edit: October 16, 2014, 11:20:29 PM by Cutty Sark Sailor »
 


Offline dwmatt

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Re: Interference and Noise
« Reply #184 on: October 17, 2014, 11:25:04 AM »
I found one of my sources of interference.  I have an E-Wave detector from HobbyBoards that would go off every day about 8am, and I couldn't figure out why.  Then, setting up my Blitzortung H-Wave, I'd see the same interference at the same time.  This morning, I was getting tons of signals (8-40 a second), and started looking around.  Everything was in the 10kHz range.  Opened up the door and heard the school next door giving a fairly long PA announcement.  Every time the speaker would stop and clear the mike, the signal would stop, then would start back up the moment he would start speaking.  The bells don't seem to set off the detectors, just the announcements.  Attached is one of the waveforms I am seeing.

Argh!  Luckily, it only goes of predictably every morning, so I can set up a cron job to disable sending at 7:55am and re-enable it about 8:30am.


Offline 92merc

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Re: Interference and Noise
« Reply #185 on: October 17, 2014, 11:33:19 AM »
Where did you get the E-Wave detector?  I wouldn't mind getting one to track down some intermittent interference I see.
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Offline miraculon

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Re: Interference and Noise
« Reply #186 on: October 17, 2014, 11:38:22 AM »
I found one of my sources of interference.  I have an E-Wave detector from HobbyBoards that would go off every day about 8am, and I couldn't figure out why.  Then, setting up my Blitzortung H-Wave, I'd see the same interference at the same time.  This morning, I was getting tons of signals (8-40 a second), and started looking around.  Everything was in the 10kHz range.  Opened up the door and heard the school next door giving a fairly long PA announcement.  Every time the speaker would stop and clear the mike, the signal would stop, then would start back up the moment he would start speaking.  The bells don't seem to set off the detectors, just the announcements.  Attached is one of the waveforms I am seeing.

Argh!  Luckily, it only goes of predictably every morning, so I can set up a cron job to disable sending at 7:55am and re-enable it about 8:30am.

This is an interesting one. I suspect that the noise is the audio radiating from either the speakers or building wiring for the speakers. I worked for "famous maker auto company" years ago. We had an issue where 610KHz AM noise was coupling from the speaker voice coil to the AM antenna in the rear defroster grid. It was a harmonic of the DSP subsystem.

It might be harmonic distortion from the voice clipping into our band. 3rd/5th order harmonics from voice could fall right where it could be picked up.

Greg H.


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Offline dwmatt

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Re: Interference and Noise
« Reply #187 on: October 17, 2014, 11:59:49 AM »
Where did you get the E-Wave detector?  I wouldn't mind getting one to track down some intermittent interference I see.

HobbyBoards Lightning Detector, http://www.hobby-boards.com/store/products.php?product=Lightning-Detector.  Only counts signals it receives, so probably not helpful for tracking down interference.

Offline miraculon

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Re: Interference and Noise
« Reply #188 on: October 17, 2014, 01:02:02 PM »
I have the H-B lightning detector, not currently connected. It is a "One-Wire" unit that requires a computer side interface and supporting software. (Weather Display supports it, and some Linux-based applications like OWW).

I wouldn't think this would be practical as a detector/sniffer for noise sources. Mine had to be grounded to a cold-water pipe ground to work at all, even with local lightning. The range was somewhat limited, which is not a surprise since it is not tuned and is a simple Darlington transistor-pair circuit. I ran it for several years prior to getting into Blitzortung, and when we moved I decided to retire it.

I have a variety of EMI "Smog" meters, etc. but the most effective E-field sensor I have is the "Natural Radio" receiver. I bought it primarily to find noises, but it's intended purpose is listening to "whistlers". It is not cheap, but works very well. I bought a pair of Stanton headphones with a HPF that minimizes 60Hz pickup, which is filtered out by the E-Field amplifier quite well.

Here is a link to the radio: http://www.auroralchorus.com/wr3gx2.htm I see that Stephen how has an H-Field receiver in the works as well. http://www.auroralchorus.com/ This H-Field one doesn't seem to be portable enough to use as a noise sniffer though.

There is also this one, but I don't have any experience with it. http://theinspireproject.org/

Greg H.


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CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
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Offline uhf

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Re: Interference and Noise
« Reply #189 on: October 17, 2014, 10:07:20 PM »
Would something like this work to find interference?
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en
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Offline miraculon

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Re: Interference and Noise
« Reply #190 on: October 18, 2014, 11:34:55 AM »
Would something like this work to find interference?
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en

Interesting, I wonder if it is really used for some kind of noise cancellation for phone calls. Would a tablet/pad also have this sensor? I might try loading it. If I don't get anything, I would conclude that the pad doesn't have the sensor.

Greg H.


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CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
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Offline corwyyn

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Re: Interference and Noise
« Reply #191 on: October 19, 2014, 12:55:06 AM »
Would something like this work to find interference?
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en

Interesting, I wonder if it is really used for some kind of noise cancellation for phone calls. Would a tablet/pad also have this sensor? I might try loading it. If I don't get anything, I would conclude that the pad doesn't have the sensor.

Greg H.
Greg I know my galaxy tablet has the magnetic sensors because every time I  start up one of my planetarium programs it tells me there are unusually strong magnetic fields present if I'm say sitting in my car.  Might download it and try it at home this weekend.
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Offline miraculon

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Re: Interference and Noise
« Reply #192 on: October 19, 2014, 12:36:28 PM »
When I installed it on my El Cheapo tablet, it complained about the missing sensor. So, I guess that it is not an option for me, unless I eventually upgrade my mobile....

Greg H.


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Offline Silversword

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Re: Interference and Noise
« Reply #193 on: October 19, 2014, 03:22:03 PM »
Would something like this work to find interference?
https://play.google.com/store/apps/details?id=com.superphunlabs.emf&hl=en

Hi All,

I installed both this one and the Ultimate one on my Motorola Xoom table.  It seems to be working but I don't understand what is going on with the readings.  It does change when I move around the house but too significantly.

No chance to go outside with it as Hurricane Ana was passing by and there were some lightning activity around my location.  Guess no one from the West picked it up as I did not see anyone getting a line over here.

Survived the storm without any issues at my location.

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Offline W3DRM

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Re: Interference and Noise
« Reply #194 on: October 20, 2014, 11:10:12 PM »
I tried to download the app onto my Android phone but I received a warning saying it was "Adware" so I aborted the download. Did anyone else get such a warning?
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Offline corwyyn

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Re: Interference and Noise
« Reply #195 on: October 21, 2014, 02:20:27 AM »
I tried to download the app onto my Android phone but I received a warning saying it was "Adware" so I aborted the download. Did anyone else get such a warning?
I noticed that, decided to try it anyway.  When it first opened up it mentioned that it would also place an icon on the phone to link you to more of the company's apps.  When closing it out every time it would ask if I wanted more of their apps so after the 3rd time using it I decided to uninstall it - I went with this one instead: https://play.google.com/store/apps/details?id=com.codebros.emffree&hl=en  Note that this one is also 'adware' but it isn't nearly as annoying as the one from superphunlabs (A division of Venture Industries no doubt  :roll: ) and if it seems to work OK then I'll spring for the two bucks for the full version.
Kevin
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Offline uhf

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Re: Interference and Noise
« Reply #196 on: October 21, 2014, 05:36:05 PM »
Sorry, guys. I didn't install the app before posting about it, and I should have tested it first. My bad.
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Offline W3DRM

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Re: Interference and Noise
« Reply #197 on: October 22, 2014, 01:47:22 PM »
I've been poking around looking for some Android apps that handle EMF measurements and have come across a couple items that may be of interest to the group.

I have an app on my Samsung Galaxy S5 named CPU-Z. It lets you view all kinds of information about the cpu. It can be found in Google Apps as follows:
While looking through the various CPU-Z tabs that are loaded with info, I stumbled on two fields under the SENSORS tab. They are AK09911C Magnetic field Sensor and AK09911C Magnetic Sensor UnCalibrated. The readings shown are 44.3 µT and 55.1µT respectively. µT stands for micro-Teslas. These readings match what I see on another EMF app named EMF Sensor Free which is also available free in the Google Apps store.
Unlike the EMF Meter by SuperPhunLabs, I don't get any warnings or apparent issues while running EMF Sensor Free. There is a paid version available that gives you additional options and ad-free viewing. The ads are on the bottom of the screen and are not too intrusive.
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Offline Einar

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Re: Interference and Noise
« Reply #198 on: October 24, 2014, 03:16:36 PM »
The data sheet for that sensor suggests max sampling speed is 100s/s. Maybe enough for hunting ghosts, but not EMI.

Offline Cutty Sark Sailor

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Re: Interference and Noise
« Reply #199 on: October 24, 2014, 10:20:47 PM »
Here's the deal... if you can't find it with an AM radio for H field,. . why waste all this time with these '''apps"""   why not get a TriMeter, http://www.amazon.com/gp/product/B00050WQ1G/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1, or professional system, and be done with it???? You'll  never mediate it in any auto mode, or with "what's causing this" anyway... you'll have to do like us old timers.... find it, mediate it, or live with it.... ///

How 'bout no more PHONE APPS of doubtful efficiency in this thread????
« Last Edit: October 24, 2014, 10:28:25 PM by Cutty Sark Sailor »
 


 

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