DAB radios out of synch .. how come?

[Rupert]

We have three DAB radios in our house and I've noticed that, if they're all tuned to the same station, when you walk from room to room they don't seem to be perfectly in synch with each other. There's a sort of echo effect between two of them and a distinct half second delay on the third one.

Can anyone explain why this should be, please? Also, if we rely on the pips for perfect time, how can we be sure that the pips we actually hear are the same pips that represent the exact correct time?

 

[hammill]

The DAB signal has to be processed before playing. How long it takes to process the signal depends on how powerful the radio's processor is, so different radios will have different delays. If you compare with an FM radio, all the DAB radios will be delayed. If you need to be accurate to the second, only an FM radio will do for the pips.

 

[Rupert]

Thanks hammill, that seems to make sense.

Is this the same phenomenon that we notice between our two televisions? The kitchen unit (7-year old non-HD set) might have BBC1 on, but when we go through to the living room where the main set is tuned in to BBC1 HD, we notice that they're not in synch with each other.

I wonder if this is more to do with the way that standard and HD broadcasts are carried on the airwaves, than the ability of the TVs to process the signals.

What do you say?