This isn't really the fault of the in-car receiver, it is rather a fault with the exceedingly limiter coverage of the DAB broadcast transmitters.
The whole point of DAB might work quite happily in, say, the Netherlands. But, when you introduce 'obstructions' (mountains, hills, tall buildings, short buildings, trees, tall grass, clouds, etc.) then all bets are off.
Inlike FM (and AM) radio - in the 'analogue' - you just receive on long continuous stream of 'signal'. If there is a signal dropout (fading in the old AM days, hiss - or a loss of 'stereo' - in the not so old FM days) then you, as the listener, just put up with it.
In the ;digital' world of DAB, just like the world of BSkyB, when you 'lose' the signal, the electronics tries to 'do something'. On your TV, you see the signal 'freeze', usually in chunky blocks. In the world of DAB, there is a memory buffer that stores the recent data stream, some of which will have been 'played back' to you already, some of which is 'yet to be played'. So long as the buffer is kept full (i.e. it does not 'under-run') then you don't hear any interruption as new data arrives to keep the buffer filled.
But, when signal reception os poor, the buffer 'under-runs' and the software then has to decide what to do next. Now, it may be that there is also data being received from a different transmitter, and so that data can be streamed to the listener - but the problem is where to 'make the change'. Sometimes there will have been enough signal information to tell the software where in the data buffer to make a 'seamless change' from one transmitter to the other. But if the signals from one or other transmitter are sufficiently poor, then that 'seamless' transition cannot be made - hence you hear data being 'repeated'
The basic problem is that our terrestrial broadcast network is cr4p - in many cases far worse than even 'third world' networks - all because we are over-regulated, as well as being under-funded. We are not ready for DAB, but consumers are being herded into buyig receivers (by any and all means) because there is an income stream in the sale of receivers that can be used to subsidise the expansion of the transmitter network.
It is no different from the mobile phone network. Your 'ownership' of your phone helps pay for cellular operators to set up new base stations (or to repair/upgrade stations that have probably been on the go for more than twenty-five years now). But, the income stream doen't always get channeled to the correct destination (just like the tax on fuel doesn't get associated with the road network in most cases).
Bottom line: think of DAB as the same as 3G or videocalling on your mobile. Yes the technology exists, yes it maybe works in Central London. But, do you really want to have to live there in order to take advantage of it?? If you don't, and choose to live in the 'real world', then you have to accept that the DAB network is just not really ready for use, not everywhere (and in many cases, like 3G and videocalling, not 'anywhere').
Where I live - inside the city limits of the third largest city in Scotland, we have NO cellular 3G coverage. We also have NO terrestrial digital TV reception, and we certainly do not have DAB radio reception (unless I stand on the roof!!). Heck, on the daily 20-mile commute round the outskirts of Aberdeen, I barely even get 25% signal strength as far as FM reception is concerned, and I know of plenty of areas between here and Manchester where there is actually NO signal reception, of any kind, whatsoever.
DAB, in my opinion, is still a fledgling technology - and willremain so for the next ten years (until ALL other forms of 'analogue' terrestrial broadcasting have been turned off). Even then, be prepared to encounter somewhere between 10 to 20% of the UK (by land area) where DAB signal reception will simply not be available (because broadcasters only have to reach a 'target audience by percentage', not a 'target area by percentage').
Cheers,
Niall
