Re: [HCDX] DRM DIGITAL RADIO MONDIALE AND ITS ONGOING PROBLEMS

["Prof. Arnaldo Coro Antich" <coro@xxxxxxx>]

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

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