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Author Topic: Power Line Noise ?  (Read 456 times)

EI3IBB

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Power Line Noise ?
« on: January 24, 2021, 12:44:38 PM »

Hi everyone, I have this noise that is quite annoying and when I go outside with my portable radio it's very loud when I stand under the 10Kv line going over my garden, I followed this last night on foot through a field in the dark for some distance and it's the same doesn't increase or decrease.

Tonight I went out in the car with the radio and passed a house with an incredibly noisy LED flood light.

The noise is audible from around dark and I don't know when it stops because I'd most likely be in bed so I'm wondering if this LED noise can travel from this light through the Persons house wiring and through the transformer on the pole and back out on this same 10 Kv line ? this house is around 1.5-2 miles away, surely the LED light can't emit noise this far ?

Listen to it on my Kiwi here http://emeraldsdr.proxy.kiwisdr.com:8073/ and tell me if this sounds like power line noise , QTH is Ireland, so power frequency is 50 Hz. Tune to 6920 Khz and you will hear the Noise I'm talking about, it can be heard at different frequencies.

Sounds similar to the noise emitted from the LED floodlight 1.5-2 miles down the road but yet if I stand under the 10kv line it's really loud on the portable.

And why would it be only after dark ?
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W7CXC

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Re: Power Line Noise ?
« Reply #1 on: January 24, 2021, 01:06:45 PM »

Not to me. Expected a "buzzzzz" 73's david
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K6AER

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Re: Power Line Noise ?
« Reply #2 on: January 24, 2021, 02:53:45 PM »

Does the noise have a 50 Hz component to the sound?

Normally on site noise does not travel back out the power lines away from the source.

Does the suspected site have any high power light sources such as high intensity lights?
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W4MDP

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Re: Power Line Noise ?
« Reply #3 on: January 24, 2021, 02:56:49 PM »

I'm sorry I can't help you in Ireland but here in the US The FCC will respond to interference complaints from power companies and private individuals.  Generally they first send a letter to the offender asking them to get rid of the devise creating the noise.  If that does not work they do follow up with details of potential legal action and fines. When I worked in the utility industry part of my job was tracking down these complaints against our  company.
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W6QW

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Re: Power Line Noise ?
« Reply #4 on: January 24, 2021, 03:08:25 PM »

Hi Mark - here's an easy way to determine if the 10KV distribution line is the root cause of your noise.  I see that you have an IC-7300 so the test is easy.

1. If the power line is producing arc-faults, you will find that the noise pulses will be continuous across most of the HF spectrum - deteriorating as the RX frequency is increased. LED-produced interference may manifest itself in less than a contiguous radiation so you may notice frequencies where the noise is dominant but less-so on other portions of the HF spectrum.

2.  Arc-faulting of your 50Hz power line will manifest itself as an impulse frequency of 100Hz.  Using the time-domain display feature of your IC-7300 (the audio oscilloscope feature), change the radio's mode to AM and observe the inter-pulse time of the interfering impulse.  If that interference is from arc-faulting of your HV distribution line, you will observe a repeating short duration pulse every 10 milli-seconds.  The pulse waveform may also look like a ringing pulse (follow-on deteriorating pulses from the primary pulse).  But you should be able to measure the inter-pulse duration.

3.  LED RFI will manifest itself as impulse noise that is not necessarily a repeating 10mS time-domain event.

Hope that helps you..
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EI3IBB

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Re: Power Line Noise ?
« Reply #5 on: January 25, 2021, 06:43:01 AM »

Hi Mark - here's an easy way to determine if the 10KV distribution line is the root cause of your noise.  I see that you have an IC-7300 so the test is easy.

1. If the power line is producing arc-faults, you will find that the noise pulses will be continuous across most of the HF spectrum - deteriorating as the RX frequency is increased. LED-produced interference may manifest itself in less than a contiguous radiation so you may notice frequencies where the noise is dominant but less-so on other portions of the HF spectrum.

2.  Arc-faulting of your 50Hz power line will manifest itself as an impulse frequency of 100Hz.  Using the time-domain display feature of your IC-7300 (the audio oscilloscope feature), change the radio's mode to AM and observe the inter-pulse time of the interfering impulse.  If that interference is from arc-faulting of your HV distribution line, you will observe a repeating short duration pulse every 10 milli-seconds.  The pulse waveform may also look like a ringing pulse (follow-on deteriorating pulses from the primary pulse).  But you should be able to measure the inter-pulse duration.

3.  LED RFI will manifest itself as impulse noise that is not necessarily a repeating 10mS time-domain event.

Hope that helps you..

Hi Donald,

Thanks for that detailed information, you obviously know a lot more about this than I do.

I will see what I can see on the 7300 tonight and I'll take a few photos, it might mean more to you than me.

I do know for certain though that the noise is coming from the 10 Kv line, and it seems to travel at least the 1.5-2 miles that I checked yesterday evening and the noise gets much worse at the LED flood light at a house 1.5-2 miles away then I drive past and it gets quieter again, so whether this is the same noise or not I have no idea but it seems to only happen after Dark so if it is this LED lights I find it absolutely amazing that it can travel this far and through a transformer on to the 10 Kv line.

Anyway, thanks for the info I'll see what I can see on the 7300 tonight.

Mark
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EI3IBB

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Re: Power Line Noise ?
« Reply #6 on: January 25, 2021, 06:53:45 AM »

Does the noise have a 50 Hz component to the sound?

Normally on site noise does not travel back out the power lines away from the source.

Does the suspected site have any high power light sources such as high intensity lights?

Yes it does have a 50 hz kind of sound and it's definitely radiating from the 10 Kv line that's running over the bottom quarter of my Garden because when I walk under it the noise on the radio is most intense and less and less the further I walk away.

I drove around yesterday evening and at this LED Flood Light 1.5-2 miles away was the only thing that greatly increased the intensity of the noise which sounds similar maybe and it's weird because the noise only occurs after dark and appears like something on a timer and every time I pass that house in the dark the light is on, no such thing as being on a sensor.

I remember this noise last year when I was working night shifts, it uses to come on around the same time and go off around 2 or 3 am so does sound like something on a timer but why on earth something like this could leak in to the grid is beyond me, it's not like I'm in a built up area where I'd be connected to the same line as the neighbours, all the houses in the country have their own transformer, the only common thing is this 10 Kv line.
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EI3IBB

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Re: Power Line Noise ?
« Reply #7 on: January 25, 2021, 07:13:22 AM »

I'm sorry I can't help you in Ireland but here in the US The FCC will respond to interference complaints from power companies and private individuals.  Generally they first send a letter to the offender asking them to get rid of the devise creating the noise.  If that does not work they do follow up with details of potential legal action and fines. When I worked in the utility industry part of my job was tracking down these complaints against our  company.

We have here COMREG which is probably the closest thing to the FCC, they have enforcement power but of course the question is will they have the people and skills necessary to locate such noise ? I have no idea and I'd like to be pretty confident as to the source of the noise before I contact them because I fear they might only come out admit there's an issue and say nothing they can do.

The other issue is that the Power company is half owned by the state and they might not want to cause issues for them, I fear they might just have a friendly word and not take further action.

I don't think such a thing exists here such as a time limit to fix issues.
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W6QW

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Re: Power Line Noise ?
« Reply #8 on: January 25, 2021, 08:37:27 AM »

Hi Mark - If you would like to, email me a screen-shot of the display and I'll help you interpret the pictorial information.  The most important information will be from the audio waveform display segment.  You can freeze the audio display so keep trying the freeze-frame process until you can clearly view/measure the inter-pulse time. 
My email is: W6QW@YMAIL.COM

Don / W6QW
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EI3IBB

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Re: Power Line Noise ?
« Reply #9 on: January 25, 2021, 01:24:35 PM »

Hi Don, thanks a lot, Yes I will try tonight or tomorrow night and email it to you.

Mark
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