[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [HCDX] DRM DIGITAL RADIO MONDIALE AND ITS ONGOING PROBLEMS
Dxers Unlimited DRM Opinion Poll + answers
and comments
Lots of answers coming in from all over the
world regarding the questions I asked during the most recent mid week
edition of Dxers Unlimited about DRM , Digital Radio Mondiale... and I
will review some of them in detail and add some comments from my own
tests and detailed observations...
.....
Here is now the first part of the results of the opinion poll launched
here during this past mid week edition of Dxers Unlimited about DRM,
Digital Radio Mondiale system.
Let's start with the first statistical analysis of the
answers so far received , all via e-mail , because
replies to the poll sent by AIR MAIL are going to take a little more
time as expected.
Well, so far one hundred and ninety seven e-mail messages received from
twenty three nations and territories, of which one hundred percent, yes,
, all, each and every one of them were critical of the Digital Radio
Mondiale system, and to this I must add, that some of the messages
received contained very angry and well documented comments about how the
present DRM broadcast transmissions are producing heavy interference to
standard analog international short wave broadcast transmissions, an
issue that I think deserves a lot more of attention from the Engineering
Departments of the stations involved in the use of the DRM technology.
Another important fact about the comments coming from listeners from
five continents is that not a single person has been able to find a
commercially built working DRM receiver that can pick up those
broadcasts reliably.
I emphasize reliably, because one of the main objections to the DRM
technology is precisely that it is not reliable for everyday listening
because of its characteristic sudden drop outs, when the sound of
the station you are picking up simply vannishes, and nothing is heard
for a certain period of time... then listeners explain in their e-mail
answers to the poll, that the audio suddenly
comes back with a plop or click sound, and you loose whatever was on the
air during the DRM drop out.
Just to give you an idea of how the replies that came in to arnie@xxxxxx
read, here is an example
From a listener in the US state of Virginia, who is also
a ham radio operator:
Arnie,
1. "Have you ever listened to Digital Radio
Mondiale, DRM broadcast transmissions on short
wave?".
Answer. Yes with receiver, computer and software.
2. "And in case that your answer is yes: again, in
case your answer is yes, give your impressions about
those DRM broadcasts regarding quality and
reliability of reception."
Terrible and useless. Broadcast was Radio Sweden
via Sackville, Canada. So many dropouts and signal
not locking that program was useless. Analog signal
from Sackville, Canada is usually very strong.
As we know a digital signal is either received or
not. There is nothing in between.
We need a new Q code for DRM. I propose QRD (as in
crud. Crud is English slang for rubbish).
DRM also causes hash to analog broadcasts making
analog broadcasts often useless.
Unsure how people will receive DRM broadcasts
without affordable receivers.
And he continues by making a comment that I fully
agree with, regarding the present use of DRM transmissions
If DRM continues, specific out-of-band frequencies
should only be used for DRM.
Signed Kraig, from Virginia
Another answer to the DRM poll came from the United
Kingdom, where listener Alan has experimented with
a very expensive commercial version of a receiver
that is advertised as fully DRM capable. Alan says that
he has very carefully evaluated DRM reception from
different transmitting stations, and notice he makes
a very good reference to transmitting stations , and not
to the program source, something that speaks highly
about the excellent analytical job Alan has done for
more than a year now. He comes forward with a one
sentence opinion that I fully endorse:
Arnie, DRM, Digital Radio Mondiale, is doomed to
failure, because it the technology is simply not good
for short wave broadcasting applications. The drop
outs, those black holes during the reception of
DRM broadcasts are horrible, making the reception
of stations using DRM very annoying to say the least.
Now more about DRM, its problems, difficulties
and its very bad impact on analog short wave broadcasts
that are operating legally near the frequencies of the
DRM transmissions that are generating so much unwanted
interference, that is certainly producing a lot of problems
on the international high frequency broadcast bands
where DRM transmission are taking place on
frequencies adjacent to analog broadcasts.
According to several senior broadcast engineers that
yours truly has asked for opinions about DRM, the
problems of this technology are divided into three
main areas:
One: the technical characteristics of the transmitter
used for DRM and how the actual DRM signal
to be broadcast is adjusted to comply with the
bandwidth regulation in effect on the HF bands
Two: The lack of "memory", that is according to one
of Cuba's most prominent broadcast engineers and
university telecommunications engineering professor
Jorge Inclan Artze, who unfortunately passed away
recently, the DRM technology is fundamentally wrong
for short wave broadcasting, because those who
designed it , according to Inclan and I quote from my
notes of an interview about this topic " they simply
forgot that short wave propagation via the ionosphere
is totally different from the ground wave propagation
used by daytime AM broadcast band and FM broadcast
band stations" And Inclan added that the basic idea
of digital broadcasting is good, but that it must
be combined with sophisticated computer hardware
and software in order to make it a viable and reliable
option. He then asked his wife Aida, to draw for me
some of his ideas, because Inclan had lost his eyesight
many years ago. Aida, also a senior broadcast engineer
drew a block diagram in which the role of a buffer
memory and a redundant transmission of signals
system were integrated so that the extremely annoying
dropouts will simply dissapear if, and they both Inclan
and Aida underscored, if, a time window long enough
to compensate for deep fading was included in the
software that will handle this digital broadcasting
technology that would be capable of dealing with the
typical short wave ionospheric propagation conditions.
Now amigos, another of the answers to the DRM
poll that came from a long time listener in the USA...
And before reading it, let me add that due to the great
impact that this topic has had, I will be continuing to
review it on our upcoming mid week edition, where I
will also repeat the DRM poll's questions for those of you
that have now become interested in this controversial
topic...
Amigo Randall, from the USA, a long time listener wrote
and says: Dear Arnie, DRM in its present form simply
doesn't work...and it is a nuisance to analog signals
that otherwise could be well heard by listeners...
DRM transmissions MUST be entered at the ITU
as experimental, and they MUST be moved away from
the internationally assigned short wave broadcast bands
until the DRM or other new technology that is better
are fully compatible with existing 10 kiloHertz wide
analog A3 Double Side band plus carrier broadcast
transmissions...
More about DRM and your opinions that are reaching
me here from all over the world in upcoming editions
of Dxers Unlimited, and if you want to send your
points of view about DRM, send them to arnie@xxxxxx
of VIA AIR MAIL to Arnie Coro, Radio Havana Cuba
Havana, Cuba
---[Start Commercial]---------------------
Preorder your WRTH 2007:
http://www.hard-core-dx.com/redirect2.php?id=wrth2007
---[End Commercial]-----------------------
________________________________________
Hard-Core-DX mailing list
Hard-Core-DX@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/hard-core-dx
http://www.hard-core-dx.com/
_______________________________________________
THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at
http://www.gnu.org/licenses/dsl.html