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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.
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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.
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Alex
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<br />> On 09 March 2015 at 20:18 Pete <peter@engineeringradio.co.uk> wrote:
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<br />> 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.
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