Hein ten Horn wrote:

craigm wrote:
Hein ten Horn wrote:

(..)
Now read the following about a possible DRM-future...

[quote]
In an ideal world it would also be possible to transmit both an analogue
and a digital signal within the same channel (9 or 10 kHz) so that the
analogue service could be received, without interference from the
digital signal, on any analogue receiver.
[unquote]

With only one transmission there would be no interference,
so in the real world anno 2007 interference may arise and
DRM is not IBOC.
The statement "DRM is not IBOC" is also apparent from
some other quotes from page 20:

[quote]
(..) promising proposals for a SCS (Single Channel Simulcast)
option are currently being evaluated (..)
Even if single channel simulcast may prove a difficult goal to
achieve (..)
[unquote]

DRM is not IBOC,
correct me if I'm wrong.

Look at page 19 of the document.

Thanks, craigm.
To be honest, by and by it occurs to me that this document is
intending to make DRM-IBOC-things look better than they are.

[quote, page 19]
The system is flexible in other ways as well, in that the broadcaster has
the facility to vary the occupied bandwidth of the signal to meet the
spectrum requirements of different frequency bands in different regions
of the world. This can include the ability to provide services often
described as IBOC (In Band on Channel).
[unquote]

What is meant by "This"?
If that is "a set of requirements", then the IBOC remark says nothing
about DRM.
If it is "the system flexibility", then why hasn't been written
"This includes..." instead of "This can include..."?
In that case the answer is quite simple: nowadays there's no DRM
in band on channel available, as is stated on page 20 (see above)
and on page 19 (below).

[quote, page 19]
A number of promising proposals have also been made for a single
channel simulcast option (SCS), whereby an analogue and DRM
signal together occupy a single 9 or 10 kHz transmission channel.
These proposals offer the possibility of a signal which is compatible
with reception on both analogue and digital receivers. Work is still
actively in progress to determine which of the proposals would
provide the best way of meeting this requirement.
[unquote]

Promises, promises...
So, until further notice DRM provides no IBOC-ability.

gr, Hein


I suppose it matters what you define IBOC to really mean. In Band On
Channel, just by looking at the words, may only mean "In Band" as between
the highest and lowest frequencies of the band, 530-1710 kHz for the US AM
broadcast band, and "On Channel" by being centered on a one of the common
transmitting frequencies (a multiple of 10 kHz for AM broadcast in the US).

Ideally it would would also require less bandwidth than the channel spacing,
but that is not the case for HD Radio in the US. However it is "On Channel"
if you consider that an analog station could use the same bandwidth if it
was broadcasting 15 kHz audio bandwidth.

So, depending upon the definition of "channel" On Channel may also imply
fitting within the channel.

To relate this to DRM and shortwave, if a DRM signal is broadcast within the
bounds of one of the shortwave broadcast bands, and its central frequency
is the same as an analog broadcast would use then it may be appropriate to
call it IBOC. If the DRM signal is using 10 kHz bandwidth, then it would be
using the same approximate bandwidth as many(most?) analog shortwave
stations.

In the US, IBOC may be used as if it were synonymous with HD Radio. (HD
Radio being what Ibiquity is promoting.) I would consider HD Radio to be a
specific form, or implementation, of IBOC. (Here, my definition of IBOC is
only what I describe above.)

While I might consider DRM to be a form of IBOC, I consider DRM and HD Radio
to be significantly different.

If anyone has a a reference to the 'official' definition of IBOC, I'd like
to see it.

It would also be interesting to see what folks consider a "channel" to be.
Specifically, how many kHz wide is a channel?

craigm