|
|
Band I, II and III
|
What is actually every digital system developped or in developping to
broadcast on band I, II and III
In my head, I have
Band I :
DRM
Band II :
DRM
IBOC
FMeXtra
Band III :
DAB
|
Sounds about rite.
DRM+ will work up to 120Mhz,
so yes it could be used on Band-I or Band-II.
IBOC/FMeXtra, as far as I understand are systems that work with FM, so
yes, I presume that they would have to be Band-II.
|
Will IBOC work in Europe? Each FM station in the US operates analog ±75kHz
with the digital IBOC carriers operating beyond that out to ±200kHz. In
theory this works but in the US it's not unusual for reception of 102.7 to
have 102.5 and 102.9 come in to spoil any IBOC reception you may have
gotten.
|
It may work in some countries. The commercial broadcasters in
Switzerland would like to use it and -over there- the mountains do
provide for a very good "seperation" of the FM-transmittors.
I do wonder however how well it will work in the border-areas where they
have to take account of FM-radio-stations of other countries and some of
those areas are not that mountainous. (Like the Basel area).
Cheerio! Kr. Bonne.
|
|
DAB will probably be used mostly on Band-III. It is also capable of
using L-Band, which is a much higher frequency band. However it is
looking less likely that this will be used, due to the much higher cost
L-Band of transmission.
|
Why not?
L-band does work great for local coverage in big urban centers.
It's used in Canada for DAB and CHUM's own system.
There have been new assignment for DMB mobile video-broadcasting in some
of the German Länder in L-band.
In theory, DAB is designed to work at any frequency between 30 MHz en 3
Ghz, so it can also work at other frequenties. One of the proposals for
S-DMB in France proposed the range around 2.1 Ghz currently assigned for
the satellite segment of UMTS.
|
OK. I may have been a little quick to dismiss L-Band, it may well have
it's uses. I was however simply saying that DAB uses mostly Band-III.
Richard E.
|
|
I'd also add DVB-H (and DVB-T) which could use Band-III as well as Band-IV.
|
But finally, I can see that frequencies for broadcasting is very important.
Band III, seems to be a very big bandwidth, near 50 MHz, and with
frequency around 200 MHz, is easier to put small antenna.
I think, it can be developped a system, without mux using band III, no ?
With a modern system like DRM, to have the same offer of programs, we
need only 14 MHz, so only two channels in band III ! In considering, we
use only one channel of 100 kHz of two
|
The man made noise and fading are very important in band I and band III,
|
Man made noise is unimportant, because it's only 1 - 2 dB and can be
compensated by increasing transmitter powers.
|
if the channel is inferior to 1.4 MHz, it is not working well. It's
research results since a few years now.
If you want ot minimeze flat fading, you need large channels...
|
Flat fading is dealt with by using time-interleaving and FEC coding.
And presumably you're trying to suggest that you shouldn't use DRM+ and
you should use DAB instead, but this figure shows how amazingly
expensive DAB is to distribute:
Nobody should *ever* choose to use DAB.
|
Preliminary tests of DAB had been made in France on band I
Nicolas Croiset VDL
http://www.vdl.fr/
|
100kHz
|------|------|------|------|------|------|------|------|
Radio free radio free radio free radio
|
Richard E.
|
|
|