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 [EMAIL PROTECTED], again [EMAIL PROTECTED], 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: [EMAIL PROTECTED], again [EMAIL PROTECTED], and VIA AIR MAIL send a postcard or letter 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@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/hard-core-dx http://www.hard-core-dx.com/ _______________________________________________ THE INFORMATION IN THIS ARTICLE IS FREE. 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