DAB - suddenly almost zero reception

[Nick Armstrong]

Yesterday I noticed that the DAB radio (which usually has full-strength reception) was on next to zero reception… Slightly better this morning but still minimum ‘bars’ indicating reception and unlistenable-to with all the squelchy interference…

Anyone else? Any idea why? Is it atmospheric? (it hasn’t happened for ages… but can particular climatic conditions cause it?)

[Dave2002]

Are you listening on a portable radio [with an included aerial] or via a tuner? Maybe your aerial has become disconnected.

Climatic conditions can cause slight disturbances, but DAB shouldn't generally be affected in the way you've described.
Are you sure you are listening to DAB - not accidentally switched to FM? Some sets might switch automatically between bands or to alternate stations depending on reception conditions.

[Cockney Sparrow]

Checking the transmitter you use might turn up an explanation?

https://www.bbc.co.uk/reception/check-for-transmitter-faults/#/undefined

[Nick Armstrong]

Definitely DAB, on a portable with aerial attached & which wasn’t touched between maximum & minimum reception levels… And the transmitters all seem problem-free (thanks for the link, CS). Plus I’ve ‘rebooted’ the radio to clear its tubes, to no avail.

A puzzle

[smittims]

I've found that the weather, especially the air pressure , affects the DAB signal strength where I live. When I can, for speech radio I often prefer Long Wave,as I have a little LW radio which seems to accept that signal very well: I use it nearly every day for Woman's Hour and The Archers. Sadly, Radio 3 is not on LW!

[antongould]

Yesterday I noticed that the DAB radio (which usually has full-strength reception) was on next to zero reception… Slightly better this morning but still minimum ‘bars’ indicating reception and unlistenable-to with all the squelchy interference…

Anyone else? Any idea why? Is it atmospheric? (it hasn’t happened for ages… but can particular climatic conditions cause it?)

probably because you’ve criticised the new super easy listening spin off station

[Andrew Slater]

It could be that the 'front end' of your radio is being affected by a local source of radio frequency radiation - either because the radio's front end is 'wide open' (insufficient filtering) or the local source is 'dirty' (insufficient control of the bandwidth of the emitted signals). Are you aware of any new equipment (e.g. a router) which has been switched on or moved recently? (Could be your own or a neighbour's.) Alternatively the signal might be being shaded by a new structure - is any building work going on nearby?

It would be interesting to know whether the effect is common to both BBC and commercial multiplexes, as they use different frequencies, which could be affected differently in the two scenarios. Also on some transmitters the multiplexes are of different strengths. If you tune to a commercial station do you get the same effect?

[Serial_Apologist]

It could be that the 'front end' of your radio is being affected by a local source of radio frequency radiation - either because the radio's front end is 'wide open' (insufficient filtering) or the local source is 'dirty' (insufficient control of the bandwidth of the emitted signals). Are you aware of any new equipment (e.g. a router) which has been switched on or moved recently? (Could be your own or a neighbour's.) Alternatively the signal might be being shaded by a new structure - is any building work going on nearby?

It would be interesting to know whether the effect is common to both BBC and commercial multiplexes, as they use different frequencies, which could be affected differently in the two scenarios. Also on some transmitters the multiplexes are of different strengths. If you tune to a commercial station do you get the same effect?

The problem I have is with my TV signal having recently been seriously affected, with frequent cut outs necessitating shifting my indoor aerial or hanging it out of my window to try and recover the signal (unfortunately living in a district where rules forbid external or roof sited aerials). This possibly has in the past been a consequence of large tree canopies in full leaf close to my building. I am also within shouting distance of the Crystal Palace mast, and it has been argued that such proximity also affects quality of transmission, necessitating extra care with angling and positioning of the aerial, and, in my case, the height and positioning also of the building, in which I am on the ground floor, acting as an obstruction. Also, people moving around upstairs, passing aircraft, and use of motorised garden implements, electric drills and so on in the vicinity. It's a nuisance, but would be something I would have to live with, except for the suspicion that the signal power from the transmitter may have been reduced for some reason.

[Andrew Slater]

The problem I have is with my TV signal having recently been seriously affected, with frequent cut outs necessitating shifting my indoor aerial or hanging it out of my window to try and recover the signal (unfortunately living in a district where rules forbid external or roof sited aerials). This possibly has in the past been a consequence of large tree canopies in full leaf close to my building. I am also within shouting distance of the Crystal Palace mast, and it has been argued that such proximity also affects quality of transmission, necessitating extra care with angling and positioning of the aerial, and, in my case, the height and positioning also of the building, in which I am on the ground floor, acting as an obstruction. Also, people moving around upstairs, passing aircraft, and use of motorised garden implements, electric drills and so on in the vicinity. It's a nuisance, but would be something I would have to live with, except for the suspicion that the signal power from the transmitter may have been reduced for some reason.

I'm very surprised that if you're close to the Crystal Palace transmitter you're having problems with the TV signal. It's a main transmitter, with a huge power output. Although indoor aerials are frowned upon, in your case even a piece of wet string should pull in a good signal! More seriously, if you're in urban conditions, buildings could shade you from the transmitter. You mention angling the aerial: with a main transmitter it's important that the aerial elements are horizontal. (Generally vertical for relay transmitters.) If you continue having problems, it's worth finding an odd end of wire about 2 to 3 feet long and poking one end of it in the central terminal of the aerial socket, instead of using the indoor aerial, and moving the wire around: it might just work better than the indoor aerial, as it won't be at all directional.

While you're experimenting it would be useful if you could find the signal strength indicator in the TV's menu to help find the best position to place the aerial / piece of wire. With digital signals it's difficult to judge the signal strength by looking at the picture as generally it will either work or not, with the picture breaking-up when the signal becomes very poor.

[Dave2002]

We seem to have had a shift to discussion of TV reception with msgs 8 and 9. The technology is broadly similar, but not absolutely the same. Up here in the frozen north we can get DAB signals using a very simple aerial - as supplied with the Denon unit we had a year ago, and simply attached to a wall with a couple of drawing pins. OTOH we have never managed to get any kind of reliable digital TV signal, despite many attempts, so now we do all the TV via internet - and radio is split between internet and live broadcast feeds. If we have power failures we have to switch back to FM - or possibly a battery powered DAB set. Under power fail conditions, TV reception is not possible for us. Satellite TV is possible, but not worth installing as the internet based feeds are much cheaper to set up. I believe some good aerial installers can get a Freeview signal from one of the local relay transmitters, but it requires very careful alignment and is just not worth the cost and bother involved. In another house about 10 miles away I did adapt the installed satellite dish which came with the house purchase with a quad LNB to pull in several channels, but even there I think most reception is now via the internet.

It's difficult to know what to do in the London area with either DAB or DTV if one fails. Directional aerials may help though probably aren't going to work in locations where installing any remotely good antenna is not permitted. If things don't improve and calls for help to the technical help lines don't solve the problems satisfactorily, then I can only suggest switching to internet based delivery as a potential solution. We have several gadgets for that, such as Roku streaming sticks, and there have been some devices for digital radio too - such as the earlier Chromecast audio units - now not supported or generally available.

The good thing about TV and radio via internet is that time shifting/on demand viewing and listening is more or less built in. The only downside compared with previous generations of technology, such as digital recorders, is that programmes do get "lost" over time, as they get taken down by the broadcasters, so if you really want to keep a recording of a radio or TV programme for the future you have to make recordings when they are available. I also suspect - but can't prove - that the quality of some of the replay/repeat versions may be lower - particularly with radio or TV concerts - but it is only a suspicion.

[Serial_Apologist]

I'm very surprised that if you're close to the Crystal Palace transmitter you're having problems with the TV signal. It's a main transmitter, with a huge power output. Although indoor aerials are frowned upon, in your case even a piece of wet string should pull in a good signal! More seriously, if you're in urban conditions, buildings could shade you from the transmitter. You mention angling the aerial: with a main transmitter it's important that the aerial elements are horizontal. (Generally vertical for relay transmitters.) If you continue having problems, it's worth finding an odd end of wire about 2 to 3 feet long and poking one end of it in the central terminal of the aerial socket, instead of using the indoor aerial, and moving the wire around: it might just work better than the indoor aerial, as it won't be at all directional.

While you're experimenting it would be useful if you could find the signal strength indicator in the TV's menu to help find the best position to place the aerial / piece of wire. With digital signals it's difficult to judge the signal strength by looking at the picture as generally it will either work or not, with the picture breaking-up when the signal becomes very poor.

Thanks for this advice, Andrew - I'll try your suggestion.

[Ein Heldenleben]

I'm very surprised that if you're close to the Crystal Palace transmitter you're having problems with the TV signal. It's a main transmitter, with a huge power output. Although indoor aerials are frowned upon, in your case even a piece of wet string should pull in a good signal! More seriously, if you're in urban conditions, buildings could shade you from the transmitter. You mention angling the aerial: with a main transmitter it's important that the aerial elements are horizontal. (Generally vertical for relay transmitters.) If you continue having problems, it's worth finding an odd end of wire about 2 to 3 feet long and poking one end of it in the central terminal of the aerial socket, instead of using the indoor aerial, and moving the wire around: it might just work better than the indoor aerial, as it won't be at all directional.

While you're experimenting it would be useful if you could find the signal strength indicator in the TV's menu to help find the best position to place the aerial / piece of wire. With digital signals it's difficult to judge the signal strength by looking at the picture as generally it will either work or not, with the picture breaking-up when the signal becomes very poor.

good advice . That close to Crystal Palace an indoor aerial should be fine .
To give you some idea of the power of that transmitter, This might be urban myth but I certainly heard a BBC rumour that licence fee payers were reporting reception troubles on the west side of the transmitter. It turned out a local in the shade of the transmitter had wrapped coils of cable in his roof space and was using the induced current to reduce his electric bills. A very hazardous procedure and not recommended.(also illegal)

[Old Grumpy]

good advice . That close to Crystal Palace an indoor aerial should be fine .
To give you some idea of the power of that transmitter, This might be urban myth but I certainly heard a BBC rumour that licence fee payers were reporting reception troubles on the west side of the transmitter. It turned out a local in the shade of the transmitter had wrapped coils of cable in his roof space and was using the induced current to reduce his electric bills. A very hazardous procedure and not recommended.(also illegal)

[Dave2002]

Probably urban myth. . Yes - it may be possible to get a current flow, but hardly likely to power anything significant.

Perhaps more likely - though still very "suspect" would be if someone put sheets of insulating material with metal foil up in their loft. I don't buy either of these possibilities though.

[Ein Heldenleben]

Probably urban myth. . Yes - it may be possible to get a current flow, but hardly likely to power anything significant.

Perhaps more likely - though still very "suspect" would be if someone put sheets of insulating material with metal foil up in their loft. I don't buy either of these possibilities though.

I’m not sure it would work . But a large illegal “aerial” would affect signal strength and might be successful in terms of heating the cable. You certainly wouldn’t want to be standing next to a major tv transmitter aerial.