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Re: [HCDX] Dxers Unlimited's script for 19-20 December 2006
Radio Havana Cuba
Dxers Unlimited's mid week edition for
By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados around the world and in space also at the
present time... this is the mid week edition of your favorite radio
hobby program. I am Arnie Coro, radio amateur CO2KK,and here is item
one...HF propagation related item... seems like the big active ,
magnetically complex solar active region activity is going down...
something that can bedemonstrated by the lower solar flux figures... but
solar scientists do insist in the possibility of more flares .... Item
two: back to the DRM poll results and their analysis, plus many comments
received from now thirty five countries and territories... It seems like
people that heard Dxers Unlimited or have read the scripts made
avaialable on several Internet mailing lists and websites do want to
make their opinions about DRM known, and above all, I notice a great
concern for what can best
be described as a total lack of respect for the short wave international
broadcast listeners by stations placing their DRM transmission right
next to others that are then terribly affected by the excessive
bandwidth generated by the DRM broadcasts.
I have received here well documented examples of what can best be
described as poor transmitter adjustment, in case the basic DRM
generator is working properly...
Stay tuned, so that you can hear several of these well documented
opinions that accompained many of the answers to the DRM Digital Radio
Mondiale poll launched by Dxers Unlimited a week ago...
.......
Si amigos, you are listening to Radio Havana Cuba,
the name of the show is Dxers Unlimited and here are more details about
our item two of today: DRM poll and comments by listeners and readers of
our scripts...
>From Professor Jose Angel Amador of the School of Telecommunications
Engineering at Havana's Technical University... He has read the poll and
answered in great detail, even making a phone call to me in order to
further discuss the topic. He is very much against the ongoing practice
of placing DRM broadcasts on the same international short
wave broadcast bands as the regular analog AM transmissions, for a great
number of reasons, among them, Professor Amador says, is the fact that
so far not one station that he knows is using a transmitter
specifically designed from scratch, to handle Digital
Radio Mondiale type of digital transmissions, and he adds that all
stations broadcasting DRM are using standard AM transmitters that in
some cases may be of a very old technology, not designed to have the
extreme linearity and peak power capability required by DRM signals.
Professor Amador agrees with the criteria that in its present form DRM
for short wave broadcasts is doomed to failure, and also that after
listening to those transmissions, if the managers of the stations
involved could listen to them, they will not authorize
one single more cent of their budgets to broadcast DRM signals !!!
Another regular listener and contributor to Dxers Unlimited, amigo
Robert from Montreal, writes in his addemdum to the DRM poll , that he
has seen the spectrum analyzer's display of the 49 meters band, and the
31 meters band when DRM broadcasts that were not even targeted to his
CIRAF zone were on
the air, and the pictures he sent me, are very , very good proof that
the DRM broadcasts were exceeding the 10 kiloHertz bandwidth regularly
used by AM short wave broadcast stations.
Another regular listener, Troy, from Nigeria, says that his friend in
Europe, listening to the AM broadcast band where DRM transmssions are
taking place , are horrorized with the noise generated by those
transmitters, and he adds, that it was obvious tha the transmitters were
not brand new ones , specifically designed to provide the required
extremely linear amplification of signals, and the very demanding peak
power to average power ratio.
Troy adds that using a computer , a nice Racal professional receiver and
decoding software he is able to pick up DRM signals at his Lagos,
Nigeria location, but that so far, everytime he listens, the very
annoying total dropout effect is present... making listening , and here
I quote " a very discouraging experience, that prompts one to quickly
disconnect everything and go back to listening to a standard AM short
wave broadcast" ,end quote.
More about the controversial DRM Digital Radio Mondiale technology that
is not only affecting regular short wave broadcast transmissions but
there is also now evidence that AM medium wave band signals in Europe
are been severely interfered by the hash generated by the 460 closed spaced
carriers used for DRM transmissions... AND yes, it was not a mistake,
the DRM technology in its present form makes use of 460 very close
spaced carriers that are in the opinion of many senior engineers the
cause of the sometimes very severe interference to adjacent frequencies
caused by poorly adjusted
transmitters broadcasting DRM...
More radio hobby related information, and some of your own valuable
contributions to the program after a short break...
....
You are listening to Radio Havana Cuba, the nameof the show is Dxers
Unlimited, and even when the sunspot count is ZERO, as it is today, HF
propagation conditions still support the narrow band communications
modes like standard run of the mill CW radiotelegraphy, and of course,
the much more advanced digital keyboard to keyboard modes, like the
extremely effective PSK31 ...
By the way, I had a nice time Monday evening, that was Tuesday UTC day
making two way CW QSO's with several amateur radio stations under very
difficult propagation conditions... accepting the challenge of making
contacts when propagation is very poor, is an excellent practice to
prepare yourself when an emergency situation has to be dealt with under
poor propagation... If you get some training on how to make a succesful
two way contact under very poor propagation conditions, then when the
real life situation is there, you are much better prepared to provide
those even live saving communications that amateur radio can provide
even under the most difficult circumstances, when commercial services
fail due to overloads or simply because their facilities are damaged. As
a good friend of mine likes to say: every radio amateur has the duty to
keep a well prepared emergency communications kit, with everything
required to move ahead and install your station anywere it may be
required, or to provide a vital link from your home QTH to remotely
located field emergency stations...
.....
Now a bit more about our main topic today... more well documented
opinions about DRM broadcasts reception and collateral damage to other
short wave stations using standard AM A3 double sideband plus carrier
mode... From South America, amigo Alberto near Buenos Aires is using a
nice fast computer, and a very good receiver that he has modified with an
additional conversion to extract a low frequency IF that is then fed to
the computer. Alberto is not only a long time radio amateur operator,
but also a sort of computer guru, and he knows how to write computer
programs. He writes that using the standard software that is sold for
DRM , and at a very steep
and rather unreacheable price, decoding is not very good at all, even
when propagation conditions are so good that he can pick up analog
stations broadcasting to his CIRAF zone using a portable radio with a
telescopic whip. Alberto says , and I quote: " I can't see any advantage
to using DRM over standard analog AM, if DRM doesn't incorporate any
real , efficient, storage and read
later type of signal processing, that is , in my opinion Alberto says,
the only way to be able to make those very annoying silences to
disappear" end quote.
Alberto is obviously making reference to a completely different approach
to digital audio
broadcasting that will require a system design that will contemplate
that the received signal be sent several times, and then, that it be
recorded on a fast computer memory, so that it can be read once the
dropouts and errors are not present..and that amigos
is certainly a very different approach to Digital
Radio Mondiale...
Your opinions about DRM are most welcome, send them to arnie@xxxxxx,
again arnie@xxxxxx, and maybe they can be made available to some of the
world's most well known radio engineers for them to see "the other side
of the picture" , that is what the
real short wave listeners really pick up , and also how they feel about
the terrible interference to AM analog broadcasts that is now damaging
reception of otherwise perfectly useable signals...
With an upcoming World Radio Communications Conference organized by the
International Telecommunications Union to take place during 2007, the
use of DRM on the short wave international broadcast bands, could become
an important issue to discuss, and maybe a solution may be found... for
example, as many Dxers Unlimited's listeners have suggested, set aside
segments of the
HF spectrum outside the presently used bands , so that DRM broadcasts
will be all alone and by themselves, so that if they generate adjacent
channels interference, they will damage the reception of other DRM
stations !!!
See you all at the weekend edition of the program, and don't forget to
send me your opinion about DRM Digital
Radio Mondiale broadcasts, if you have heard them and also if you have
not... because one of the challenges is exactly trying to find a
moderately priced short wave receiver capable of picking up DRM
broadcasts... send your e-mail message to:
arnie@xxxxxx, again arnie@xxxxxx, and VIA AIR MAIL send a postcard or
letter to Arnie Coro
Radio Havana Cuba, Havana, Cuba.
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