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Digital radio mondiale!
- Thread starter blackgold
- Start date
I'm sure that someone will disagree but it's my understanding that there isn't a significant difference between fully digital AM IBOC and DRM. Both have slight advantages and disadvantages.
I think the issue here is the idea that shortwave can be revived at all. There is little left on SW except for religious broadcasters and extreme propaganda with everyone else from the BBC to CBC to VOA reducing or eliminating services.
DrM requires exclusive use of the channel. That means that the analog service would come to an end. That also means that the station would have no listeners until they bought new radios. You cannot run DRM on the same channel as HD radio.
Something like two-thirds of Canadian AMs have moved to FM, and seldom does a month go by that another couple don't also make the move. There are entire provinces with no AM any more.
Keep an eye on India for the possible future of DRM. The country has an aggressive program to implement the digital format on mediumwave, shortwave, and even the FM band. It could really accelerate the move to digital...or it could be a massive flop. Supposedly the Indian government is pushing hard to make DRM capable receivers easily available, which will be the acid test.
Brazil is in the very early stages of trying out DRM for mediumwave and shortwave. Apparently part of the plan is to push for the conversion of existing domestic shortwave operations to DRM, thus reviving a dying medium. The national public broadcaster is supposedly conducting some tests at the current time. Of course Brazil is also expanding the FM band down to 76 MHz, so what actually might happen is that most existing AM and shortwave stations simply move into that expanded band, which might solve reception issues...and make DRM irrelevant.
It will certainly be interesting to see what comes out of those two national efforts.
On the negative side, several high powered international shortwave broadcasting facilities in the Americas have tried DRM in the past decade or so. And, as part of the overall demise of shortwave broadcasting, each of those sites has been completely closed in the past two years.
Brazil is in the very early stages of trying out DRM for mediumwave and shortwave. Apparently part of the plan is to push for the conversion of existing domestic shortwave operations to DRM, thus reviving a dying medium. The national public broadcaster is supposedly conducting some tests at the current time. Of course Brazil is also expanding the FM band down to 76 MHz, so what actually might happen is that most existing AM and shortwave stations simply move into that expanded band, which might solve reception issues...and make DRM irrelevant.
It will certainly be interesting to see what comes out of those two national efforts.
On the negative side, several high powered international shortwave broadcasting facilities in the Americas have tried DRM in the past decade or so. And, as part of the overall demise of shortwave broadcasting, each of those sites has been completely closed in the past two years.
Are there even any DRM-ready shortwave receivers on the market? I am not too deep into shortwave anymore since it became the all-preaching band, but the few demos of DRM I've seen have been PC/computer based decoding programs.
If there were any English language DRM-encoded broadcasts I could decode, I'd be willing to pay a reasonable amount for a radio that could decode that format.
If there were any English language DRM-encoded broadcasts I could decode, I'd be willing to pay a reasonable amount for a radio that could decode that format.
There are a few DRM receivers out there. Usually the DRM organization's website at www.drm.org has some pages on available receivers, but I was getting 404 errors when I checked a moment ago. If you google "DRM receivers" quite a bit of info comes up, including online retailers.
Virtually all of the reports/forums about DRM reception that I have seen involve Software Defined Radios (SDR's.) The technology does work, but you need a solid signal to get 100% decoding. On shortwave DRM appears to work best for local/regional groundwave coverage, or skywave reception of one or two hops. At greater distances you will still get the datastream, but useable decoding is iffy unless you happen to have a great signal (there was a recent report of a North American listener getting full decoding on Radio New Zealand International's DRM stream.)
Problem is that there are no longer any DRM transmissions aimed at North America as all the facilities that used the format have shut down as part of the overall demise of shortwave broadcasting. Some of those transmitters put very strong DRM signals into Texas.
I do not have any DRM receiver capability, but have heard audio files of other listeners' reception. Quality at best is similar to mono FM minus the highest audio frequencies.
One interesting aspect of DRM is the ability to send text and video images (similar to webpages) along with the audio stream.
Not quite DRM but the VOA is experimenting with text transmissions out of their 250 kW transmitter in Greenville. The signal can be decoded with a laptop and a sound card and one of several free programs (I use NBEMS).
Link with the program schedule is .... http://voaradiogram.net/
Link with the program schedule is .... http://voaradiogram.net/
DRM is a lead balloon just like IBOC and all the other digital modes which have been tried. Shortwave is not as bad as every one here says either. I listen to it quite a bit along with AM radio. In fact we are going backwards, AM and shortwave can and does sound great on my 20 watt 13 tube 120 lb RCA 13K. Build AM and shortwave receivers which perform like that again (obviously smaller and lighter with today's technology) and there goes the problem of lousy AM sound. Amplitude Modulation is simple, goes quite far intelligibly, is wireless and most of us have receivers which pick it up, what is better than that? Why fix something that doesn't need fixing?
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Well I don't keep the frequencies in my head but 49 meters seems to be good on Saturday night, (Saturday night seems to be the best night for shows) there are several DX programs on. I have caught Glen Hauser's program on that night, there are also some rock n roll shows, pirates etc. I just tune around to see what I can find. Daytime SW is not too good, that's when all the religious broadcasters dominate the airwaves. Wish I could be more helpful with specific frequecies but it's out there if you tune around with patience. Certainly isn't like 30 years ago though.
6180 & 11780 -- Radio Nacional Da Amazonia has great musical programming. It's all in Portuguese, but the music is worth it.
Radio Rebelde on 5025 plays a lot of good music also.
Early evenings on the West Coast Radio Australia and RNZI both come in well on 25 and 21 meters. Their programming is always interesting. Sometimes they're the only good signals on those bands.
Radio Rebelde on 5025 plays a lot of good music also.
Early evenings on the West Coast Radio Australia and RNZI both come in well on 25 and 21 meters. Their programming is always interesting. Sometimes they're the only good signals on those bands.
Rebelde, from Cuba? That's interesting. They and Radio Havana both boom in where I live since I'm right on the gulf coast. Some of the most solid signals around.
Yes, Radio Cuba also booms in here on the 49M and 31M bands, 6000 and two other frequencies on 49.
Anybody here into consoles? I just got an RCA 13K from 1937, it's a 13 tube hifi radio covering 150kHz all the way up to 60 mHz, has a tuned RF stage and has two 6L6 output tubes for 20 clean watts. Also has a selectivity control along with bass and treble controls, AM 740 out of Toronto sounds great on it, anyone who thinks AM radio sounds like krap should listen to this thing, it makes AM sound great, strong AM stations sound as good as FM if not better.
Anybody here into consoles? I just got an RCA 13K from 1937, it's a 13 tube hifi radio covering 150kHz all the way up to 60 mHz, has a tuned RF stage and has two 6L6 output tubes for 20 clean watts. Also has a selectivity control along with bass and treble controls, AM 740 out of Toronto sounds great on it, anyone who thinks AM radio sounds like krap should listen to this thing, it makes AM sound great, strong AM stations sound as good as FM if not better.
I've always been curious, how does local shortwave reception work? Say you're close to a 2KW or 50KW shortwave station, is the signal stable like MW or is it still fade-prone and weird like in distant reception?
Speaking of DRM; I have actually done some transmission experiments using DRM like HD Radio (Two 20khz channels on either side of FM, and 96khz DRM signal split and placed at either side) With the Opus audio codec, it actually works incredibly well. Reception seems about the same as IBOC.
Problem? No receivers will ever be made for something like that--especially the "split" version. Though it is cool to play around with.
Speaking of DRM; I have actually done some transmission experiments using DRM like HD Radio (Two 20khz channels on either side of FM, and 96khz DRM signal split and placed at either side) With the Opus audio codec, it actually works incredibly well. Reception seems about the same as IBOC.
Problem? No receivers will ever be made for something like that--especially the "split" version. Though it is cool to play around with.
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