[cma-l] DAB trials

[tlr at gairloch.co.uk]

Pete: We know what software and modulator they will probbaly be using, but one
of the key features of Ofcom's proposals for low-cost DAB broadcasting is
avoiding the use of the conventional large and expensive DAB mask filters
(typically 6-cavity high power devices) on th efinal output.
 
This can be achieved by a combination of tactics, including a very under-run
driver stage (eg 100mW stage running at only 5mW) and relatively underrun RF
amplifiers (eg maybe using an amplifier potentially capable of say 250-500W
continuous carrier power to produce a DAB signal of less than 100W), so that
there are fewer spectral regrowth components to be filtered. Plus with the whole
kit running at relatively low ERP anyway, the filtering is not as critical as it
would be for a high-power transmitter because the absolute level of spurious
products is low relative to neighbouring high-power signals and aeronautical
limits.
 
Alex

> On 09 March 2015 at 20:18 Pete <peter at engineeringradio.co.uk> wrote:
>
>
> It's obvious what type of exciter they will be using if you have been
> following them. It's obvious it will be SDR based. The amps may be a different
> matter. I don't think it is clear what they would be using. They would
> probably use filtering to the spec set out for DAB.
 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.commedia.org.uk/pipermail/cma-l/attachments/20150309/babd6723/attachment.html>