Help with TV/radio stations?
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Friday, 28 January 2011
P
Pete3:00 PM
RE 160 DAB TRANSMITTERS When you say DAB will cover the same parts of the country as FM, are you taking into account areas where FM is weak but FM sound can still be heard, albeit with a bit of hiss ? In the case of DAB, however, when the signal dips, you hear absolutely nothing, thus losing the programme altogether in those areas, or worse that horrible squelchy noise. Even inside a specific buiding DAB has trouble using a telescopic aerial needing a fixed aerial to get a decent signal in a significant number of already established regions covered by DAB, making radios much less portable than FM. This is also the case when out with pocket DAB radios in rural areas. I live in a very good reception area (North Macclesfield) but the DAB signal even for BBC channels using a telescopic areas varies from 100% to 47%, depending on which room I'm in (the ground floor being the worst). To overcome this I have a good directional DAB external aerial on the roof, which picks up quite a few regional multiplexes outside my local area including Stoke, Lancashire and Liverpool (as well as Manchester, which is my local region), but not BBC Cymru/Wales which booms in on FM (104.3MHz and 95.4MHz).
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Saturday, 29 January 2011
M
michael10:19 AM
This is a fundamental issue. It looks as if coverage maps will ultimately "demonstrate" meeting the target. De facto received signal strength would, however, be the criterion of choice. If reception on a portable or incar is not as good as "historical FM", it will be too late to riot in the streets ...
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Monday, 31 January 2011
N
Nedbod2:28 PM
If actual coverage doesn't match predicted I for one will be rioting !! EGYPT ain't seen nothing yet if this is the case.
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michael: Being a digital service, the "received signal strength" is of little concern. It is the "received signal quality" that is the main issue.
The COFDM service is designed to provide full service to the very edge of the service area, and nothing beyond it, the famed "digital cliff".
As with digital TV, the service will be the same everywhere within the service area, you don't get the reduction of quality you get with analogue.
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Tuesday, 1 February 2011
M
michael9:32 AM
DAB SIGNAL QUALITY is obviously more significant than signal strength. However just as with the DTT predictor maps, only signal strength predictions are feasible, not quality. For this reason I referred to signal strength. Given the unreliability of DAB reception on a portable (or car) radio where there is a reasonable signal, as here, coverage, theoretical and real, is a valid issue to discuss. Also, there must be good reasons for the current vhf DRM+ experiments to go ahead. Maybe as a future complementary option in view of the limitations of DAB? The electorate might be unenthusiastic to have to buy yet another radio, but maybe we are getting used to the idea...
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michael: So, all these plots that I have seen that provide the quality information don't really exist then?
Forget about DRM or DRM+, these will never be used for UK services.
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S
steve5:35 PM
You can't riot on your own but you can run amok or go beserk; depending if you are inclined more to SE Asia or Scandinavia.
Signal strength/quality - how about integrity, or interpretability?
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steve: The words integrity or interpretability do not really work in the context.
"integrity" is used in data processing to indicate the probablility that the data is uncorrupted. As DAB uses FEC (forward error correction) the "integrity" issue is standard to the whole of the broadcast, it does not change over the coverage area.
When you type "interpretability" do you mean "can be interpreted"? As DAB is a digital multiplex, there isn't anything to interpret, only demux.
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