White Noise/Hissing Interference on 80 Metres

[Aub]

Hi all,

For the past few months, I have been getting a loud hissing/white noise type of interference on the 80 metre Amateur Radio band. It starts at around 2Mhz on the receiver, and gradually increases in volume until it peaks at around 3.6Mhz. It then cuts off, quite sharply, at 3.710Mhz.

I've turned all the power off in our bungalow and the interference is still there on my portable. What I've recently discovered, is that it seems to be being radiated by the phone line, which is the old style wire from a pole in the street. The interference can hardly be heard at the other end of the house from where the phone line enters and, if I go outside, it disappears within walking a few yards away from the phone line side of the house. This is the same with everything disconnected from the main phone socket.

Is it possible that the there is some kind of noise coming down the line from the exchange, perhaps generated from the ADSL equipment there?

Has anyone else experienced this? I've already listened to some of the interference clips on You Tube, but cannot see anything similar.

Thanks

Aub, G4KQL

[G8HQP Dave]

Do you have broadband?

[Aub]

Yes we do Dave. That's why I'm wondering if something's wrong in the exchange.

[G8HQP Dave]

Maybe they have changed/upgraded the line equipment. A sharp cutoff suggests a filter is still working, but perhaps at too high a frequency?

My guess is that to get BT to play ball you will need to involve OfCom.

[Paul Adams]

If you have BT’s infinity, you could try turning off the wireless in BT’s ‘Home Hub’ to access it you need to type in:
http://192.168.1.254/

And then go into settings, it’s password protected enter your password (you should have this on your home hub 3) and then click on ‘Wireless’ you should then be able to disable it.

User name is normally Admin.

I had similar problems and had to disable mine, I now have my PC hard wired to the Hub.

Paul.

[G8HQP Dave]

How can Wi-Fi at 2.4GHz on the 'home' side of the router affect 80m interference from the 'line' side? Is it digital hash getting into places it should not go?

[Aub]

Thanks for the replies.

The interference still happens even when all power is off in the house, including the router and all phones and extensions are disconnected from the main phone line socket. I've also removed the faceplate to no avail.

Looks like I'll need to phone Orange ( now EE ) as they provide my phone and broadband service. I had to call their support line a few weeks ago,about a different problem and they were quite good, but how do I explain all this to someone who, most likely, will not even know what Amateur Radio is. As you say, I may need to involve Ofcom.

Cheers

Aub

[dsergeant]

Normal ADSL/ADSL2 only uses up to 2MHz, there will be nothing at all from the ADSL signal in your frequency range. If however you have BT Infinity or Orange's equivalent that uses VDSL which will have outputs in that range. But I guess you would know if you had fibre broadband....

Electrical noise is hard to trace as it gets picked up by all the nearby wiring. I rather doubt it has anything to do with your telephone service. Do you get any noise if you test next to mains wiring, if so it could be coming from quite a way away?

However the usual cause of all these noises is switch mode power supplies and increasingly solar panel installations. You have (probably) eliminated your own house, but it could still be a neighbour's and you are seeing a resonant point where your phone line enters the house.

Dave G3YMC

[Peter.N.]

I had this problem a few years ago and it turned out to be a fault on an 11kv pole about a mile away. I could just hear it on the car radio and managed to locate the approximate position then pinpointed it with a low band mobile and an vhf beam.

Peter

[arjoll]

Originally Posted by dsergeant

If however you have BT Infinity or Orange's equivalent that uses VDSL which will have outputs in that range. But I guess you would know if you had fibre broadband....

Fibre? VDSL is delivered over copper - it's enabled on most urban exchanges and cabinets here as a faster alternative to ADSL, at least until the UFB rollout (Government-funded fibre). https://myaccount.snap.net.nz/signup/home

[jjl]

BT's Infinity is a fibre to the cabinet (FTTC) product, with VDSL2 over copper from the street cabinet to the customer's premises. Fibre to the premises (FTTP) is available in a few areas but is not common at present.
UK ISPs refer to many products as "fibre broadband".

VDSL2 can use higher frequency OFDM carriers than ADSL and ADSL2+ so could cause the interference that Aub is experiencing.

John

[real2real]

A friend of mine has had increasing levels of this type of interference for about 3 years now. The local electricity board has been investigating the solar panels that have been fitted on many houses at his location and have found some do indeed radiate broadband noise. Early tests indicate that some installations use Sine wave invertors and some Square wave ones, it is showing that the Square wave units are causing the problem, (generating many harmonics) and of course the cables between the panels and the control boxes are unscreened so make a good aerial. Apparently the electricity board is quite concerned as it is possible some installations do not meet EMC regulations (not from experience that makes a lot of difference!).

My broadband speeds are 10meg DL and 1.2Meg UL and I get no interference from the telephone lines that are running parallel with my long wire aerial about 20 feet away, from 160-10M.
Andy

[Aub]

Hi All,

An update to this.

I eventually got round to reporting the problem to Ofcom. After lots of tests, they concluded that the noise is probably due to ADSL signals, from one or more modems, communicating with the exchange or street cabinet. This is then being radiated by the overhead phone wires. They closed the case as it was too difficult. I had a letter about this published in Practical Wireless.

I have contacted the RSGB's EMC team, who said they may come out and do some tests.

Cheers

Aub

[G8HQP Dave]

It is nice to know that 'too difficult' is now a valid reason for ignoring the law.

A case of 'Vox Pop', my internet is more important than all of the shortwave. Try a loop for receiving, for transmitting on your current aerial the weeny signal from the interferer won't matter.

[Aub]

Originally Posted by G8HQP Dave

It is nice to know that 'too difficult' is now a valid reason for ignoring the law.

They did confiscate a laptop power supply that was causing interference on the 5mhz band. I guess that's easy to do though. Pity they didn't confiscate the DSLAM!

Aub

[Aub]

A further update.

In April last year, the RSGB EMC team came to my house and made a load of measurements, to gather evidence to put before BT. They confirmed that the noise was 10dB above the residual noise level. Since then I've carried on listening, by using the web enabled SDR sites such as Hack Green.


Then a few weeks ago, my broadband service kept dropping out and gradually got worse. This was accompanied by severe crackling on phone calls. I called my provider ( EE ) who sent me a new router but this, as I expected, did not fix the problem. They then arranged for Openreach to call round. The engineer installed new wiring from the junction box on the front gable end of our bungalow, down through the wall to the phone socket, which is now situated at the front of the house. This has done away with the original copper pair , which had ran over the roof and down to the side of the house. The new wiring is about the same thickness as thin co-ax but I don't know if there is a shield under the outer plastic. This means that the length of the wiring, from the junction box to the phone socket, is less than half its previous length and all the wiring is now at the front of the house, further away from my 80 metre dipole than before.

This has had two benefits. One is that the white noise interference is considerably better than before. The other is that I can now operate the transmitter without knocking out my broadband.

Since then, the EMC guys came back and took some more measurements. They are doing this in different parts of the country. They confirmed the improvement ( now 5db ).

I can now hear weaker stations, on my AR88, that I couldn't hear before, so I can go on the air again. It could still be better, but I'll guess I'll have to wait for what eventually gets decided by the powers that be

73

Aub, G4KQL

[AlanC]

Very interesting Aub, thanks for the update. It occurs to me that if the telephone copper pair becomes unbalanced due to leakage or a high resistance joint it will both radiate and be affected by radiation; maybe this was what was happening until it suddenly got worse! Be interested to hear any developments.

Alan