On 15/01/2012 14:17, J G Miller wrote:


The question listeners and radio stations should be asking is, what
digital system could be developed for future use, rather than
continuing with the present failures of DAB and HD(tm) radio.

Agreed.

We did have high hopes for DRM+, and what they developed was a pretty
good narrow band broadcasting standard, although not as good as it could
have been, mostly due to not using the best error correction. Also I
think they should have extended it's frequency range up to Band III.
That would allow one DAB channel to be used for many small local radio
stations.

For wider band multiplexes, we appear to have got exactly what we needed
with DVB-T2-Lite. The problem now is whether it ever actually gets used
for radio.

I'm also thinking, perhaps they ought to come out with a version of DVB
to rival DRM+. Basically a narrow band version of DVB-T2-Lite. Perhaps
they could call it DVB-TN or something like that. Basically use any
relevant techniques used for T2-Lite but designed for much narrower
channels. Perhaps a choice of 100Khz or 200Khz bandwidth. (The reason
why I included 200Khz is for situations where a broadcaster can not use
Qam64, in which case a wider bandwidth would be required to achieve a
good bit rate).

I would also suggest that a narrow band standard should also be designed
to be able work well in SFN mode. The problem here would be signals from
different TX sites being out of phase and so cancelling each other out.
I think this problem could be solved by allowing the phase of the
transmission to be changed randomly at regular intervals. Different TX
sites could then change their phase in different ways, so if the signal
cancels at one moment in time, the phases would soon change, and then it
would no longer cancel.

Richard E.