FM Radio interference

I get it in E London if I have RDS traffic announcements enabled. One or more pirates seem to trigger them - on purpose (though why given it's just a second or 2?) or through incompetence. If you have TA on you could try turning them off and see if the interruptions go.

Mind you, don't blame me if Sod's law then means you get stuck in a jam for 2 hours for lack of the news :)

Quite probably, they abound everywhere these days. Havyou been in hibernation? Most are supported by drug money and bricked in at the top of tower blockes operated remotely via uhf/vhf and even microwave feeds from other locations, enabling quick switching if the fuzz find the installation.

You say that no sane person would listen to it, but its not meant to be listened to, its mostly trance dance stuff as often heard in what we used to call raves, where the dealers make their sales. Brian

1. Could be one of those gadgets that send the output of a music-playing device to the radio via RF. The radiation from them can pass to other vehicles.
2. When it happens, try to remember the music and then tune through the band to see if you can find a continuous transmission.
3. Could be triggered by RDS.

Bill

This ^

Almost certainly.

One reason DAB is so good in the car. No pirates and excellent reception round London. Much better reception on R4 than FM.

I suspect that it's the result of the little low-power FM transmitters that you can get to plug into iPhones. They allow you to play the music from your phone through any FM radio receiver, in a car or at home, without having to bother about a lead or a special stand. The car versions plug into the lighter socket to keep the iPhone charged. There are millions in use.

/I suspect that it's the result of the little low-power FM transmitters that you can get to plug into iPhones. They allow you to play the music from your phone through any FM radio receiver, in a car or at home, without having to bother about a lead or a special stand. The car versions plug into the lighter socket to keep the iPhone charged. There are millions in use. /q

All with very short ranges...?

Jim K

A lot of pirate stations are just community stations carrying ads for services and playing music mainstream stations rarely play, such as soul and reggae. I often listen to those local to me, especially reggae, of which I'm a fan.

E.

What's the typical separation of two vehicles passing each other on a narrow road. A couple of meters maybe?

I was very surprised when these Band II transmitters were legalised.

Having said that I don't think I have ever had my listening interfered with by one.

Years ago you used to be able to hear carriers at around 100Mhz as you drove along residential streets, some had speech and music faintly audible. These were the local oscillators of radios tuned to Radio 2

I don't seem to hear them now, partly I think because there are so many stations above 100MHz these days, and also it is quite possible these were valve radios emitting fairly high levels of RF.

I suppose it is one duty of society to cater for those of limited intelligence.

Bill

No. RDS, as others have said - but not Traffic Announcements.

Data is transmitted which tells the radio the frequency of adjacent transmitters carrying the same programme. If the signal level/quality drops, the radio looks for a strong transmission on one of them and then switches to it.

In London there are relays of the main transmitter (Wrotham) at Crystal Palace and my car radio will switch seamlessly back and forth between the two as I drive around. Unless I look to see which of the two frequencies it is tuned to, I won't even know it has happened in the majority of cases.

However, if a pirate uses one of the stored frequencies, the radio will switch to that but will find the data stream doesn't match and promptly switch back again.

In this neck of the woods, I find that pirates camping out on Classic FM alternative frequencies are the worst problem.

Traffic Announcements rely on the receiver being instructed via the data stream that a Traffic Announcement is being currently carried on another frequency - to which the radio briefly switches. If the signal is there, the radio switches to it but if it is not, because the distance to the local radio station is too great, for example, it switches back. This causes a brief gap of silence during the process.

In article , Terry Casey scribeth thus

What some pirates do is to transmit the "Traffic Flag" or TA all the time this causes your radio to lock onto their transmission.

Expressly prohibited on the Ofcom regs but as there're Pirates;!...

Yes, Tony, but your radio won't be monitoring every transmission in Band II to see if any have raised the flag!

Your radio will only know that a TA is available because of data received with the transmission it is tuned to at the time. When it switches to the TA it uses the other station's flag - or rather the loss of it - to signal that it is time to return to the previous transmission ...

That could well explain why I still get some interruptions with TA disabled. But I get more with TA enabled. So - perhaps unsurprisingly - the pirates* could be causing maximum bother.

Or bad taxi service breakthrough at close range. Also these dongles that rebroadcast iPads on close range FM in passing vehicles.

That isn't much use to the majority of us who do not live in London.

Last night DAB radio in parts of North Yorkshire was decoding as "service unavailable" an error I have never previously seen before.

No course not, but I haven't seen it myself but these buggers have got some way to trigger off in some radios a "scan" and then once on that frequency it stays there...

Pushes "auto tune" on DAB set "NO SERV"

Then you're not so likely to suffer interference on FM from pirates.

Wonder how good your aerial is? My aftermarket DAB car radio was useless with the original car aerial. The expensive one I bought has a built in head amp for DAB. Despite being a 1/4 wave for that frequency.