Amateur Radio Interfering With ADSL

Sorry for the length of this, I'm looking for some advice, over the last 6 to 8 weeks I've been receiving rather low adsl speeds, usualy I can get a nice stable 4.85MB but recently I've been as low as 0.13MB.

Numerous calls to my ISP led nowhere, BT engineers have been out and the line is ok, I've replaced routers and filters and I'm wired into the test socket, my ISP has even suggested that it could be down to an increase of broadband users in the area

With the help of Router Stats, I've eventually worked out the source of the problem, my next door neighbour broadcasts on various amateur radios an it seems that whenever he broadcasts on HF radio I get disconnected, if my router then tries to resync, while he is still chatting to somebody, I then get assigned a really low profile by the exchange, which takes 3+ days to build back up to full speed again, if my neighbour broadcasts during this time I'm knocked back down to 0.13MB again and the process starts over.

When my neighbour realised it was him he sold his radio and for a week everything was back to normal but then he decided he couldn't live without it and bought a new HF transmitter (a more powerful one) so I'm back to square one.

He seems willing to help when I'm chatting to him, for example on Saturday past there he said he wouldn't broadcast at all until I was back to full speed, then he would start at 10 watts and increase his power over a few days until I cut out, in the hope we could find an acceptable level but I just checked Router Stats and the noise graph has went crazy again this morning and I've been resynced at 0.5MB... it has taken me a week to climb to 1.5MB and now I'm back down to 0.5MB!!

I'm dunno what else I can try, I phoned Ofcom and they said all they can do is identify the source but can't stop it.

I've also been chatting to another amateur radio enthusiast and he thinks it's likely the fact that my neighbour is notorious for botching together his own aerials rather than spending money on proper equipment. I know nothing about radios all I know is for the week that he sold the HF radio he was still broadcasting on FM and that didn't affect me so it's whatever this HF radio is that's causing the problem, I only know it's HF because my neighbour calls it HF

I've put 7 bits of ferite on the end of my phone cable to try and catch the RF but they aren't helping.

Anyone any ideas?

Thanks for your time
Stu

what frequencies does the guy use ?

Tried an iPlate ? - the common mode choke may help if the signal is coming in on the phone line, but not if it's direct pickup by the modem.

Can you relocate your kit to the furthest pouint away from him, or shield it with some earthed metal foil ?

It's a bit of a difficult one.

As a licensed amateur (he IS licensed, right?) he is supposed to take steps to ensure that any interferance if dealt with. However, (and it's been a few years since I was into radio and I never went as far as getting licensed) I don't know to what extent he has to go to to ensure this.

As for the "botched aerials rather than buying equipment" - that was the whole point of amateur radio, to build you own kit from scratch or surplus parts, but obviously not the botched part of it.

If he was on FM, that was likely to be 2m or 70cm, which is VHF and UHF, HF is 10m and under (as the frequency gets lower, the wavelength is longer). The 160m is 1.8-2Mhz and sits just above the top end of the frequency ranges used by ADSL. A badly operated 200w SSB transmission into a nearby phone line could bleed all over ADSL band and completely destroy your sync.

As for possible ways forward, it might be an idea to look at the RSGB website (www.rsgb.org) and see if there is anything helpful on there.

Sorry that you are in this predicament and I hope you can find a way around it.


Pete

@yarwell - I haven't tried an iPlate but I will certainly get one ordered, anything is worth a try I already have my phone line and router running down the wall furthest away from his house so I can go any further

@pete_thomson - he is licensed, I'm not sure if you get any different types of licenses but he definitely said he was licensed

I know he has a separate transmitter for FM and it doesn't affect things

I'm not sure about frequencies he's been chatting about 40m? I know he keeps saying he stays away from 10m as that is notorious for interfering with everything. He also talks about 18m.
I know the new transmitter he bought goes to 150W because he was telling how his old system only went to 100W and this new system is so much better sa it went 150W (I was thinking that would explain why I can now hear you on my surround sound louder than every).

He works off what he calls an inverted aerial if that makes any difference?
When I look at the side of his house he has 2 wires making a triangle with the point at the peak of his roof and then a 2m pole on top of that.
He had installed a second inverted aerial right beside the first around the same time as I started having problems, he thought the second aerial was scattering the RF at 10m so he brought the new aerial down but things haven't changed. I'm wondering if the new transmitter is just to strong or something?

I also should add that my estate is using overhead telephone cables

Thanks for your help guys
Stu

Edited by Stu1983 (Mon 24-Aug-09 15:40:13)

Frequency in kHz = 300000 / wavelength in m

hence 1500m LW Radio 4 = 200 kHz

40m = 7500 kHz = above ADSL frequency so anything shorter is well above it.

Other thoughts - use a twisted pair RJ11 cable rather than flat to feed modem. Put router in an earther biscuit tin for a short period (may get hot) to see if it helps.

If the worst comes to the worst, what your neighbour is doing may constitute a statutory nuisance, since his activities are interfering with your enjoyment of your home life.
I don't know whether your council can help, or whether you could try the CAB.

Regards,

Felix

You said you get disconnected when your neighbour is transmitting, so presumably you can see your line stats, particularly the DS SNR take a dive at that point. Are you plugged permanently into the test socket?

If your NTE5 socket has been wired correctly, then with the filter plugged into the test socket, no other phones in the house are connected, right? That would at least eliminate your house wiring as acting as an aerial.

At the point when he transmits, observe your DS SNR with modem/router in the test socket, and no telephone plugged into the filter. Does that make any difference?

If not, then his transmitted signal is being induced into the external phone lines. You could try lengthening your telephone lead between NTE5 socket and modem/router. This would have the effect of making the line length no longer resonant to the frequency of his transmitted signal.

What sort of ferrites are you using? You could try a couple of good quality ferrite rings and wrap an extension lead through the ferrites at least half a dozen times. Place the ferrites on the lead where it is closest to the modem/router.

The other thought that occurs to me is to establish, with the help of your neighbour , exactly which frequency bands are causing the trouble. The most likely ones are Top Band (1.8MHz) or 80 metres (3.7MHz). Perhaps a quarter wave stub could be attached to your modem/router cable connection?? The idea being the stub is tuned to the unwanted frequency and would absorb the RF. Not tried it myself, as I normally only run low power these days...

G0AOZ - licenced operator.

As regards being a statutory nuisance, I think you'd need to establish the field strength of his signals. If they exceed so many volts per metre at your premises, then he could be instructed by Ofcom to run at a reduced power level on certain frequency bands. I suggest you contact Ofcom who should be able to give you advice on this...

I wonder if BT's SFI team would take an interest?

Get him to transmit into a dummy load instead of his aerials. Regardless of what frequency comes out of the aerial, most transmitters start by generating a lower frequency and then multiplying it - because that's a simpler way of being able to transmit on several bands. That's why the amateur bands tend to be multiples - 3.5, 7, 14, 21, 28 MHz.

If he's causing interference when transmitting into a dummy load, it's likely that it's getting back into the mains supply.

The problem is that ADSL doesn't meet the same specifications with regard to immunity from unwanted signals as does, say, a basic radio receiver. OfCom will test his gear if requested but it could well be that his equipment does reach the required standard. Not sure what the answer would be then but it's definitely better to work with the guy rather than laying down the law...

John.