Radio Interference to 648kHz AM Radio Caroline.

[telstar]

Hi. I am a regular listener to 648 AM (Radio Caroline, of course) on my Roberts RT1 radio. The reception has been quite good up to now where I live, but recently some ugly phone mast has been built a few hundred yards down the road. Initially, this was not the problem, until some additional structures were added more recently. The reception on 648 is now marred by a noisy background (hash).
Has anyone experienced a similar situation where they live, and how did they resolve it?
Sorry, if I have posted on an incorrect section.

[Station X]

Radio Caroline has been on reduced power since Monday after suffering lightning damage.

https://radiocaroline.co.uk/#home.html

[raditechman]

Slightly going of topic so moderators remove if necessary.
I noticed on the Caroline link that they have stopped their Freeview service.
This is the second radio station to vacate Freeview recently (TWR being the other) I wonder why.

John

[Bazz4CQJ]

Originally Posted by telstar

The reception on 648 is now marred by a noisy background (hash).Has anyone experienced a similar situation where they live, and how did they resolve it?
.

I listen to Caroline on my internet radio (which feeds the pantry Tx).

B

[telstar]

I recently read that they did have issues with some mobile phone operators causing problems with reception, not sure how they got to resolve the matter.
Mike

[agardiner]

Back on full power according to their website after transmitter repairs.

Has the problem gone telstar?

[1955APREN]

Just over the last few days I have one button on my car radio tuned to 648am. In the day time very weak signal not clear enough make out . After dark it is better but only just good enough to listen . North Shropshire is as long way from north sea
Derrick

[paulsherwin]

Indeed, it's essentially a local station. Once you're outside East Anglia reception is very difficult with typical domestic radios.

[telstar]

Originally Posted by agardiner

Back on full power according to their website after transmitter repairs.

Has the problem gone telstar?

Hi. The reception has improved slightly, but it does get better as the day goes on. There seems to be a background hash, where there was not such hash before.

[smiler411]

Are you sure its not something more local, do you have any new products in the house?. Mobile phone signal itself won't interfere with the am signal as the frequency is so much higher, its electronics could possibly cause interference I suppose but as it is a couple of hundred yards away and its connecting cables etc likely buried would have thought it unlikely to be the cause of your interference. Any interference at am frequencies would normally be from the power leads etc as the parts within the equipment are usually too small to be good antennas except when really close by and a couple of hundred meters would be quite some distance for a signal to travel

[Stuart R]

Sounding OK on my kitchen Sobell, but that's fed from a Wellgood loop. The Twente WebSDR has a bit of noise on it. There's a carrier around 644KHz visible that seems to have a bearing on the noise received there. Whilst I was watching something else originally at 657KHz swept around in frequency and then appeared to land right on top of 648, wiping it out on the SDR for a bit.....

All interesting to watch, but I'm not really sure what it all is.....

SR

[telstar]

Originally Posted by smiler411

Are you sure its not something more local, do you have any new products in the house?. Mobile phone signal itself won't interfere with the am signal as the frequency is so much higher, its electronics could possibly cause interference I suppose but as it is a couple of hundred yards away and its connecting cables etc likely buried would have thought it unlikely to be the cause of your interference. Any interference at am frequencies would normally be from the power leads etc as the parts within the equipment are usually too small to be good antennas except when really close by and a couple of hundred meters would be quite some distance for a signal to travel

No, there is nothing new in the house that would possibly cause any problems. I keep the radio well away from anything else like television power supplies (usually switched off anyway). The good news is that the signal output on 648 suddenly increased on Friday (for no apparent reason) and now it is the same level as it was before. I mentioned to Radio Caroline about the reduction in output before the transmitter had been struck by lightning, but they denied that there was any reduction. The signal from Caroline seemed to be very low and nearly under or just over the s/n level during the day, but it got better in the evening.

[Radio Wrangler]

Interference can be formed in so many ways. A rusty joint on fencig w8re can act as a diode and mix the carriers of two perfectly legitimate transmissions together, yielding the difference frequency. Harmonics can mix together and also do this. A lighting storm can spoil the impromptu diode, zapping it apart or welding it across.

People spend a lot of time near multichannel transmitter sites looking for rusty bolt effects in nearby fences. It's not unknown for mixer products between a couple of broadcast carriers to wreck the sensitivity of VHF repeaters on the same site, sometimes the repeaters belonging to blue flashing light type people.

David

[Rich Woods]

Originally Posted by raditechman

Slightly going of topic so moderators remove if necessary.
I noticed on the Caroline link that they have stopped their Freeview service.
This is the second radio station to vacate Freeview recently (TWR being the other) I wonder why.

John

Cost apparently vs limited use

[Rich Woods]

Originally Posted by Bazz4CQJ

I listen to Caroline on my internet radio (which feeds the pantry Tx).

B

Snap. If I want though I can get reasonable AM reception using a loop aerial in West Wales just south of Aberystwyth at night.

[music-centre]

I was listening to Caroline a couple of days ago and the presenter said the engineers have found the recent transmitter problem making them go on reduced power was due to a fault in the transmitter rather than a lightning strike as they originally said.

Its a pretty good signal here in Essex but the presenter this afternoon said they are working with Ofcom about hopefully being allowed an increase in transmitter power, don't expect that will be any time soon though.

[trh01uk]

What's been said indicates that this hash is local to telstar. I haven't experienced this specific problem - and am never likely to, being located on the border with Wales.

But the clue is in telstar's statement "...some additional structures were added..."

It would be useful to know the precise nature of these additional structures, but in the absence of that, lets note the coincidence in time of these going up, and hash appearing across 648kHz, which points to a potential causative effect. I'd put my money on computer noise being output from this mast (with the additional structures) being the source of the hash, with a likely cause being faulty EMC components or no EMC components at all.

The next step to take is find a portable radio with a ferrite rod aerial, and go on the hunt for the source of the hash. The null in the antenna pattern (along the length of the rod) will point you to the hash source. Walk down the road homing in on it. It will get stronger as you get near the source. If you are then standing under this telecomms mast at the strongest point, you have all the proof you need.

Your next step after that will be to complain to the telecomms company who put the mast up. They will be obliged to fix the problem.

Richard

[Rich Woods]

I completely agree with this assessment. For my sins I used to work for a certain very large telecommunications company dealing with the reverse issue, sources of interference that disrupted the frequency that ADSL broadband synchs at in the UK. This frequency is very close to Caroline’s 648kHz and so it follows that accidental retransmission of broadband noise would give exactly the effect you are describing.

[telstar]

Originally Posted by trh01uk

What's been said indicates that this hash is local to telstar. I haven't experienced this specific problem - and am never likely to, being located on the border with Wales.

But the clue is in telstar's statement "...some additional structures were added..."

It would be useful to know the precise nature of these additional structures, but in the absence of that, lets note the coincidence in time of these going up, and hash appearing across 648kHz, which points to a potential causative effect. I'd put my money on computer noise being output from this mast (with the additional structures) being the source of the hash, with a likely cause being faulty EMC components or no EMC components at all.

The next step to take is find a portable radio with a ferrite rod aerial, and go on the hunt for the source of the hash. The null in the antenna pattern (along the length of the rod) will point you to the hash source. Walk down the road homing in on it. It will get stronger as you get near the source. If you are then standing under this telecomms mast at the strongest point, you have all the proof you need.

Your next step after that will be to complain to the telecomms company who put the mast up. They will be obliged to fix the problem.

Richard

Hi. I may just try that with my Roberts RT1 radio.
Cheers
Mike

[Graham G3ZVT]

Originally Posted by Rich Woods

I completely agree with this assessment. For my sins I used to work for a certain very large telecommunications company dealing with the reverse issue, sources of interference that disrupted the frequency that ADSL broadband synchs at in the UK. This frequency is very close to Caroline’s 648kHz and so it follows that accidental retransmission of broadband noise would give exactly the effect you are describing.

There was this idea around that there is a "special" frequency in the MW range that affected ADSL. The frequency most often quoted was 612KHz, and while it's certinly within the range of the "bins" of both ADSL and VDSL and a strong (or not so strong) transmission could indeed disrupt xDSL, there is nothing particularly significant about 612KHz, or any other frequency.

I think someone picked 612KHz as a quiet spot on the dial for hunting down ADSL interference, and a myth grew up around it.