RadioBanter - View Single Post - Europe's digital radio sector is a not a happy place, as consumersvote with their wallets

Richard Evans[_2_]

d wrote:

You'd think , but DAB isn't that simple. I'm sure people more in the know
can correct me but AFAIK it doesn't simply send 2 channels of data for left
and right. I think like FM it sends mono data then some sort of difference
data which uses up much less bandwidth so a 128K DAB signal has a mono
component of something like (I'm guessing) 100K. I think this is why a lot
of people complain about the stereo image of DAB being very flat.

You're on the right lines, but I'll correct you :-)

Mid side is not available in mp2, instead is has a intensity stereo, and
it only uses it in the higher frequencies. The lower frequencies are
still in discrete stereo. The Intensity stereo as the name suggests, is
basically mono, with a parameter to select the difference in volume
between left and right channels. As far as I understand each audio sub
band would have it's own intensity stereo parameter.

A lot of the reason for the poor stereo image is that intensity stereo
doesn't preserve any of the phase information between the channels. Or
then again, perhaps it just that whole system is cr*p. :-o

Richard E.