No Noise Is Good Noise! (Medium Wave)

Noise and interference issues?
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simbeav
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Re: No Noise Is Good Noise! (Medium Wave)

Post by simbeav » 05 Sep 2017 14:50

What are you complaining about ?
You can just about make out your loacal stations can't you ?
Stop being a luddite and buy yourself a DAB radio so we can fleece you again when DAB+ comes along.
Sign up to iplayer so we can "get to know you better"
We've got to keep the economy going by selling cheap Chinese electronics at below cost prices.
If we can't be bothered to send a policeman out to your burglary, why should we bother policing the airwaves...........

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John Faulkner, Skegness
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Re: No Noise Is Good Noise! (Medium Wave)

Post by John Faulkner, Skegness » 05 Sep 2017 16:37

You are absolutely right Simon.

I already bought a DAB radio. There's no decent DAB reception around here. Should I spend more money and buy a better one?

I pay my TV licence, which I think is worth every penny - in fact I would happily pay twice as much for their excellent and politically unbiased programming.

I already have an account with the BBC, so I will be able to listen to BBC Radio Lincolnshire live on their web stream after they switch off my local medium wave and, eventually, my FM outlet.

The noise can buzz away all it likes!

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John Faulkner, Skegness
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Re: No Noise Is Good Noise! (Medium Wave)

Post by John Faulkner, Skegness » 03 Oct 2017 12:35

Medium wave DX is almost impossible lately with yet more noise destroying the band. It's time to do some tests, but I doubt there's anything I'll be able to do about this.

The middle of the band is now continually awash with signal-killing hash, but there is a much more general increase in noise now across the whole band.

If I use the Perseus to see how severe the noise is, the constant mid-band noise reads -90 dB. This wipes out 890 - 1130 kHz. Either side of this, the noise doesn't go lower than -120 dB, which can be OK for stronger transatlantic signals, but the hash can still be heard. Nothing 'weak' will get through.

Then there's the daily sunrise and sunset noise periods, which are severe and wipe the whole band. These last between one and two hours and vary slightly in their timing. The 0600 - 0700 noise period has now slowly migrated to 0700 - 0800. The 1800 - 1900 noise period has stayed around the same time, but I remember this lasting around 1500 - 1800 at times last winter. It was not every day then. There is also an additional severe noise period around midday, but I am rarely tuned in to see that. These three severe noise periods give -75 dB across the band, rendering even my semi-local transmitters unlistenable.

None of the noise is coming from my property. I have done numerous tests, listening to medium wave on both my desktop and laptop computers, using a leisure battery while switching off the main supply to the property.

https://www.youtube.com/watch?v=s6WD_HOycz4 Hmm. The similarlty is striking!

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John Faulkner, Skegness
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Re: No Noise Is Good Noise! (Medium Wave)

Post by John Faulkner, Skegness » 13 Oct 2017 22:53

After several days of hardly any noise at all, solid, band-killing noise is now wiping out all nearby transmitters on MW. This has been affecting MW continually since late afternoon.

I am baffled. I took a portable around the bungalow, around the garden, around the neighbour's property and on nearby streets. The only noise I heard was when the portable was close to the bungalow or inside it. Strangely, there was no noise when I put the portable near my desktop computer! If I put the portable where the flag is, there is no noise at all!

Next, I switched off the electricity supply at the mains box and ran my computer and Perseus from my leisure battery. The noise was still there, though slightly reduced. Still bad though.

Baffled.

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John Faulkner, Skegness
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Re: No Noise Is Good Noise! (Medium Wave)

Post by John Faulkner, Skegness » 27 Nov 2017 19:33

At last! I found the source of at least 'some' of my local noise. I knew it was going to take me a while to track this down. I also half expected that the noise would be coming from something really obvious that I had overlooked. It was!

After going around the streets with a portable radio the other evening, I discovered that the noise was everywhere around my property, yet the further I moved away from the property, the weaker the noise became and it disappeared completely by the time I had reached neighbouring properties.

As previously mentioned, I had already run my computer from a leisure battery and switched off the house mains, so I thought I had tested everything I had, only I hadn't tested the computer itself!

Did I even have any need to test my computer as the noise appeared to be quieter when my flag antenna was closer to the part of the property where my computer sits. That seemed to rule out the PC. The noise has been variable too, and even disappears completely at times, roughly once a month on average.

I hit on the idea only yesterday that my main PC could be the cause of the noise so I tried swapping the Perseus over to the laptop and immediately noticed a huge reduction in noise levels. Probably about 20-25 dB, according to signals levels in the Perseus control software. Only a slight buzz can be heard on the laptop. With my Perseus connected to the laptop, switching my PC on and off makes no difference at all to the slight amount of noise I am getting with the laptop setup, so I am assuming the noise is somehow being induced into the system on the PC, as opposed to it being received by the antenna directly. This might explain why the noise varies a little when moving the flag around the garden. Maybe there is some kind of phase cancellation effect, i.e. the noise being induced and then fed again by the flag.

So where exactly is the noise coming from? I guess it's something to do with the motherboard, but I am not absolutely certain. I had a new motherboard about a year ago as the original one failed. It was only cheap. The power supply was also replaced at the time, but that is a good quality Corsair brand which I don't think causes any noise. I researched this at the time, but not the motherboard as I had an enormous amount of difficulty getting one.

So, I am looking for suggestions as to how I can find out which component/s is/are causing the problem and how I might be able to stop this.

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John Faulkner, Skegness
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Re: No Noise Is Good Noise! (Medium Wave)

Post by John Faulkner, Skegness » 29 Nov 2017 18:00

Spoke too soon. Egg ... face ... etc.

There is equally as much noise when using Perseus on the laptop as there is when using it on my main desktop PC. I hadn't checked the Perseus waterfall settings. They were vastly different on both machines. Once I had matched them I could see exactly the same noise levels on both machines.

I really thought I had found out something. It was not to be.

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