This is copied directly from the DRM User Guide:

"For ionospheric propagation, the most severe Doppler spread is
observed in the case of Near Vertical Incidence Sky-wave (NVIS)
propagation. Because the path lengths between transmitter and
receiver are quite short for NVIS, the distances between the
ionospheric layers represent a larger proportion of the total path
length. The several reflections can also have similar energy levels.
This gives rise to significant values of Doppler spread.

"To counter the effects of Doppler shift and Doppler spread the
frequency separation between the OFDM carriers in the DRM signal is
progressively increased (e.g. the carrier spacing in Mode D is more
than 2.5 times that in Mode A). This ensures that the frequency
spread experienced is kept to a sufficiently small fraction of the
carrier spacing to allow correct demodulation."

wrote:


"To counter the effects of Doppler shift and Doppler spread the
frequency separation between the OFDM carriers in the DRM signal is
progressively increased (e.g. the carrier spacing in Mode D is more
than 2.5 times that in Mode A). This ensures that the frequency
spread experienced is kept to a sufficiently small fraction of the
carrier spacing to allow correct demodulation."

better than IBOC ??


--
--
Shortwave transmissions in English, Francais, Nederlands, Deutsch,
Suid-Afrikaans, Chinese, Dansk, Urdu, Cantonese, Greek, Spanish,
Portuguese, ...
http://shortwave.blogsite.org/ Updated every month or so ....

On Oct 1, 1:42 pm, Ratata wrote:
wrote:
"To counter the effects of Doppler shift and Doppler spread the
frequency separation between the OFDM carriers in the DRM signal is
progressively increased (e.g. the carrier spacing in Mode D is more
than 2.5 times that in Mode A). This ensures that the frequency
spread experienced is kept to a sufficiently small fraction of the
carrier spacing to allow correct demodulation."

better than IBOC ??



Digital Radio Mondiale *is* IBOC. (Like HD Radio, it sits right next-
door to the AM signal, widening the channel by a few more kilohertz)

I wish I was young again.I used to be a hound dog boy,,,, gittin at the
gals,,,,, now I am a pussycat.Doggy, she humps my right leg every
day/night and she slurps me face all over too.If that isn't Love, I
don't know what is!
cuhulin

On Tue, 02 Oct 2007 04:26:10 -0700, wrote:

Digital Radio Mondiale *is* IBOC. (Like HD Radio, it sits right next-
door to the AM signal, widening the channel by a few more kilohertz)

A few kilohertz here, a few kilohertz there, pretty soon you have
"real money" -- channel overlap a.k.a. harmful interference as
defined in communications law.
--
Phil Kane
Beaverton, OR

On Oct 2, 4:26 am, wrote:
On Oct 1, 1:42 pm, Ratata wrote:

wrote:
"To counter the effects of Doppler shift and Doppler spread the
frequency separation between the OFDM carriers in the DRM signal is
progressively increased (e.g. the carrier spacing in Mode D is more
than 2.5 times that in Mode A). This ensures that the frequency
spread experienced is kept to a sufficiently small fraction of the
carrier spacing to allow correct demodulation."

better than IBOC ??


- Digital Radio Mondiale *is* IBOC. (Like HD Radio, it sits right
next-
- door to the AM signal, widening the channel by a few more kilohertz)

SFTV -aka- "Hybrid Digital" Man,

DOH ! - You had beeter go back and re-do your
DRM 101 and IBOC 101 Classes again. ~ RHF

Digital Radio Mondiale (DRM)
http://en.wikipedia.org/wiki/Digital_Radio_Mondiale
Unique Digital Broadcast Signal Mode {Non-Analog AM}

In-Band On-Channel (IBOC) so called "HD" Radio
http://en.wikipedia.org/wiki/IBOC
Combined Analog and Digital Broadcast Signal Modes
http://en.wikipedia.org/wiki/HD_Radio

DRM is All Digital Mode of Shortwave (HF) Radio Transmission
http://www.eiinfo.fh-konstanz.de/dow...rm/image35.jpg

DRM Digital Signal at 13,790 kHz with AM Analog
http://shortwaveradio.org/drm_13_Af_010511_2100.jpg
Signals at 13770 kHz; 13800 kHz; and 13810 kHz.
* Clearly you can see that DRM requires at least
15 kHz of Channel "Spacing" for it not to interfere
with any 'adjacent' DRM or Analog Radio Broadcast.

Note - That the DRM Shortwave Radio Broadcasts are
independent and separate from the older Analog "AM"
Radio Transmission Mode Broadcasts.
* International, National and Local DRM Broadcasts
Underway in Markets Worldwide
http://www.drm.org/livebroadcast/livebroadcast.php

From what I have read and heard DRM appears to work
best as a Directed Beam Radio {Audio} Delivery System
up to 1000 Miles and out to 2500 Miles.
* DRM Tropical Band {With-In-Country} Omni-Directional
Radio Broadcasting best up to 300 Miles and out to 1000
Miles.

Analog "AM" And DRM Can Not Co-Exist On The Same
Channel {Frequency} At The Same Time [.]

As with all Shortwave Radio Broadcasting the Coordinated
Scheduling of Broadcast Time and Frequency is important
for DRM Broadcasters since they take up Four Times (4X)
the Bandwidth as the Analog "AM" Broadcasters.

High Frequency Co-ordination Conference (HFCC)
HFCC = http://www.hfcc.org/

drm ain't iboc -and- iboc ain't drm ~ RHF

On Oct 2, 6:17 pm, RHF wrote:

drm ain't iboc -and- iboc ain't drm ~ RHF
.




You are dumb. DRM has a hybrid digital/analog mode. See this manual,
page 20. Notice how the DRM sits "in-band on-channel" same as the HD
Radio works.

www.drm.org/pdfs/Broadcast_Manual.pdf

THIS DISCUSSION IS OFF-TOPIC FOR REC.AUDIO.TECH
(AND REC.AUDIO.CAR, FOR THAT MATTER)
PLEASE DROP REC.AUDIO.TECH FROM THIS DISCUSSION

On Oct 3, 5:02 am, wrote:
On Oct 2, 6:17 pm, RHF wrote:



drm ain't iboc -and- iboc ain't drm ~ RHF
.


- You are dumb. DRM has a hybrid digital/analog mode.
- See this manual, page 20. Notice how the DRM sits
- "in-band on-channel" same as the HD Radio works.
-
- www.drm.org/pdfs/Broadcast_Manual.pdf

yo, Yo. YO ! - SFTV - Dumb I May Be . . .

But presenetly the majority of DRM Broadcasting on the
Shortwave Radios is Pure {100%} DRM "Digital" and it
Trashes 20 kHz of Bandwidth around it and makes good
old AM Analog Shortwave Broadcasting very hard to Hear.

SFTV - Your Such A Gooder "Hybrid Digital" Man ! ~ RHF

wrote
On Oct 2, 6:17 pm, RHF wrote:

drm ain't iboc -and- iboc ain't drm ~ RHF

You are dumb. DRM has a hybrid digital/analog mode. See this manual,
page 20. Notice how the DRM sits "in-band on-channel" same as the HD
Radio works.
www.drm.org/pdfs/Broadcast_Manual.pdf

No, the manual does not state
"DRM has a hybrid digital/analog mode".
A simulcast is not necessarily hybrid.
I also cannot find any affirmation on your statement
Notice how the DRM sits "in-band on-channel".

RHF dumb?
Don't think so.
Take a good look on that page 20 of the manual.

[quote]
DRM supports a number of different simulcast options. Currently the
supported simulcast modes require the use of additional spectrum outside
an assigned 9 or 10 kHz channel (Multi-Channel or Multi-frequency
Simulcast, MCS). The DRM signal can be located in the next adjacent
upper or lower channel and can occupy a half or whole channel
depending on the bandwidth option chosen.
[unquote]

So far nothing about IBOC.
In general, a simulcast is a simultaneous transmission of the same
programme. Here, both transmissions are located in two adjacent
channels, the DRM transmitter operating with less power than the
analogue signal transmitter.

[quote]
(..) a satisfactory compromise can be obtained when the DRM power
level is around 14-16 dB below the adjacent analogue signal.
[unquote]

Unfortunately, operating on two adjacent frequencies (channels) may
give rise to interference problems. With IBOC no such problems
would occur, isn't it?
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.

gr, Hein