DAB aerial

[nospam]

Hello,

I hope this is not considered off-topic. I have read other posts here about TV aerials and I hope to fit the aerial myself, so I think it falls into the category of DIY.

I know you can get FM aerials for your radio and you can get a multiplexer so that you can combine the TV aerial and fm aerial (in your loft) into one cable and then use a demuiltiplexer at the other end (in your lounge) to separate the TV and radio. This saves lying another cable.

So far so good. But I have now upgraded to a DAB radio. What aerial should I use for this? I presume a special DAB one. But can I use the multiplexer option with that? I don't want to be lifting floorboards etc. to lay a new cable if I can help it. I haven't seen any TV/dab multiplexers or have I? I have seen uhf/vhf multiplexers; is this what these are? If not, what are they?

Thanks,

[Andy Burns]

yes e.g.

But can I use the

Plenty around, I use a blake "loft box" which multiplexes UHF+SAT TV with FM+DAB radio

'll need a di/triplexing faceplate at the outlet too, I might as well keep all the links to one site!

[Dave Plowman (News)]

You are indeed best to have an external aerial for DAB unless in a very high signal area, as a poor signal produces unpleasant noises - some describe it as mud boiling.

In many areas a simple vertical dipole will suffice - although Yagi arrays are available at from around the 20 quid mark.

As regards the diplexer I tend to avoid them since cable isn't that expensive, but I'd imagine one designed for VHF will be ok for Band III as well as Band II.

[Andy Hall]

Correct. There are single element ones which may be enough if you live in a reasonable signal area or 4 element ones if not. These are more directional but not so much so that they are not useful for signal from the sides. I had a 4 element one fitted and directed towards the weaker of two transmitters. This results in good and approximately equal signals from each and a good selection of programmes.

There are multiplexers for introducing a DAB signal into a mix of others.

The way I did it (which is the typical one, I believe) was to combine the FM antenna signal with the DAB one. There is a diplexer to do that (Google for DAB diplexer).

I then have a launch amplifier for my house cable system which has separate inputs for UHF and VHF (means FM and DAB).

Otherwise, the VHF and UHF can be combined via a VHF/UHF diplexer and the lot fed to a distribution amplifier.

[The Natural Philosopher]

Actually really you don't.

The input sage of what you plug in makes a pretty good demux in itself.

I've got simple paralelled sockets running off muxed FM/TV feeds from the dis amp, and no problems at all to date.

Sure its a bit of an impedance mismatch, but the signal is high enough after the amp to make this a non issue.

[Dave Plowman (News)]

You may get away with it, but in strong signal areas adding the rubbish signals from the 'wrong' aerial may cause problems and should be avoided. But far better to keep them separate anyway.

[Andy Burns]

Where possible, but the OP was keen to avoid laying new cables.

[Dave Plowman (News)]

Indeed. However in this strong TV signal area I found diplexing didn't work too well at all. I had picture ghosting caused by pickup on the FM circuit. Nor did the FM side work well. I tried the state of the art filters (of the time) without success too. I'm sure modern satellite co-ax would have helped but it wasn't around at the time - or at least not readily available.

[tony sayer]

In article , [e-mail] writes

Hardly worth bothering with IMHO, as the piss poor audio quality on DAB as it stands in the UK makes listening to anything bigger than a Mono portable unit a real pain!.

I'd hardly call it upgrading!....

[Dave Plowman (News)]

Hmm. You really saying you can tell the difference on R3 and R4?

And the possibly better reception will sound much better than multipath on FM on the average portable.

FWIW I'd love to set up some proper testing for those who say DAB sounds terrible. I did do a quick test on a pal who is 'into' Hi-Fi using Capital Radio with the FM delayed to match the DAB and levels carefully matched. He failed. ;-)

[Andy Hall]

I had a similar problem trying to mix the signals from two transmittters. In the end, the solution was band pass filters for the individual TV channels.

[tony sayer]

In article , Dave Plowman (News) writes

Yes Dave, I can as it happens..

Just because you live in the nastiest bit of London for multipath it doesn't mean every other person in the UK does..

Well not too surprising seeing the way these chains are setup. When your up this way lets do a CD-v-FM then shall we:)

[The Natural Philosopher]

well don't mux them down one cable then! All signals are weak here.

[Dave Plowman (News)]

You *say* you can. As do others. Plenty claim to hear differences between cables too. The problem is that the treatment applied to R3 is different between DAB and FM which rather muddies the waters.

All of London is nasty for all FM in the car. Likewise most of the country with a portable radio unless you fiddle with the aerial and don't move anywhere near it. VHF requires diversity reception to get round this - which is why it's used on radio mics and some cars. Dunno any portable that has it, though. VHF can be very good with a good fixed installation. Which 99.9% don't have for every receiver in their home.

[tony sayer]

In article , Dave Plowman (News) writes

Yes.. as do quite a few others who are bothered by the noise the MP 2 codec makes when its been used at bitrates it was never intended for. This was supposed to be the 21st century system that was to replace FM but in effect is a lot worse than FM. Hopefully they'll see sense and that a big mistake was made and do what other countries are now looking to do and that is use a modern codec ACC+ which works much better at the bitrates that DAB can handle.

Some can but that is a whole new argument Dave and you well know it is!..

Yes it does but much was promised with DAB that hasn't materialised.

Multipath isn't that much of a problem for the rest of the country Dave not everyone lives where you do!..

Well I don't have any real problems apart from Pirate interference but that isn't the fault of the system..

Hollyhocks.. We don't have any problems here and neither do a lot of other people over the country.. there are quite a few places that don't have Dabble reception as yet Dave and well you know it!..

A lot don't need them but as you say they are rather good;)

>

[Mark]

This problem seemed to be repeated with other digital broadcast media. Digital has the potential to be 'better' than analogue, but in practise, it's all over-compressed to fit in too many channels. This defeats the whole purpose of using the technology IMHO.

M

[tony sayer]

In article , Mark writes

Quite agree!. The analogue piccy on our 10 Y/O B&O still knocks the spots off digital on most all programme materiel especially on definition and colour rendering:-)

Hope proper HD is here before I have to get a 3view box!...

[Dave Plowman (News)]

When DAB was introduced with 'better' bit rates it was near totally ignored by everyone - true possibly due to the high cost of the hardware - but even by enthusiasts happy to pay through the nose for other high end hardware. It was only when the choice of stations was increased that it took off - and of course the availability of cheaper hardware. Now those same audiophiles who didn't bother with it earlier are those who complain about the quality - the average punter *seems* happy enough.

My view is that for many purposes and casual listening - portable radios and in car use - it sounds far better than either FM and definitely AM. Where you want to sit down for some serious listening you still have FM and of course now Freeview which gives most of the radio services too with very cheap hardware.

For car use I'm sold on DAB - even the pop stations - which is about the only time I listen to them.

The public appear to want choice - even if it's shopping or quiz channels that many here never watch. They are commercial operations and can't survive without viewers. If there genuinely was an overall desire for 'quality over quantity' they simply wouldn't exist.

[Dave Plowman (News)]

I'll bet it doesn't beat my DLP for resolution...

[tony sayer]

In article , Dave Plowman (News) writes

Name your source!..