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(Short-, Medium-, Long)wave Radio Meets Digital Stereo
cryptec writes "Today shortwave radio will have some new life pumped into it as the German broadcaster Deutsche Welle will be the first full time shortwave broadcaster of DRM (Digital Radio Mondiale). DRM is a full stereo fully digital broadcast system. The quality of the broadcasts are close to that of FM radio. For samples check out this link." Akai adds this link to an article in the San Francisco Chronicle with some more information, like the involvement of the BBC and Voice of America in this undertaking.
Obviously, you will need special gear to receive this - they are using COFDM so your normal shortwave rig is unlikely to give you anything meaningful.
I suppose IF you had a single-sideband rig with a wide enough filter set, and IF you then used your computer, you COULD decode this, but the usual means is going to be a dedicated receiver.
(Hmmm. Have to see if I can get the spec, and see if I can write a decoder for it....)
www.eFax.com are spammers
The British Broadcasting Corp., Voice of America and other international broadcasters launched digital short-wave radio service Monday, promising to provide near-FM quality in the place of static-filled signals.
Digital broadcasts don't increase a station's range, but they eliminate static and let broadcasters transmit text, such as news updates and song information, with the audio signal. For now, digital radio receivers are considerably more expensive than analog radios.
The Digital Radio Mondiale consortium launched its digital service at a global radio meeting in Geneva.
"DRM's introduction will forever alter the course of radio broadcasting," said Peter F. Senger, chairman of the consortium, which has more than 80 members.
The initial signals were transmitted from a nearby mountain in France shortly after 8 p.m., when Senger gave the word during a ceremony in conjunction with the World Radiocommunication Conference in Geneva. The conference is held every few years to decide airwave issues such as the sharing of radio and satellite frequencies.
Simultaneously, other short-wave broadcasters started using digital transmitters in different parts of the world. The transmissions received at the reception featured voices in Chinese, French, English, German, Russian and Spanish, followed by static-free music.
For the foreseeable future, broadcasters will use both traditional analog systems alongside the digital transmissions so people with traditional radios will still be able to tune in. At first, broadcasts will be aimed at Europe, North America, the Middle East, Australia and New Zealand.
Digital radio signals are duplicated enough so that even if some are lost from interference, the receiver is able to put the transmission back together so it can be heard correctly. And Senger said the system uses much less electricity than analog, which will save broadcasters considerably on their biggest cost item.
Although the Federal Communications Commission has approved a different digital standard for U.S. domestic broadcasters, Senger said the new system is meant to be universal and could eventually be used in the United States.
Other broadcasters in Europe, Asia and Canada have been using digital transmissions for several years. That system, known as Eureka 147 or DAB, uses a different set of frequencies than traditional AM, FM or short-wave bands.
My potato gun was confiscated by the United Nations. They said I wasn't allowed to have weapons of mash destruction.
This isn't interesting, it's funny.
I'm suddenly starting to wonder just how much modern digital techniques bring to the party. For example, remember the technique of bounding signals off of meteor trails? I believe they recorded audio at normal speed, then waited for a meteor trail and squirted it out at many times normal speed... that sort of thing would be trivial and cheap to do with digital technology.
Maybe a LOT of old, low-fi, unreliable radio broadcast technologies can have useful new digital life. It could be very handy as a backup for satellite-based communications.
"How to Do Nothing," kids activities, back in print!
Does anyone still listen to shortwave? By the way, there's an interesting history of shortwave I picked up one day at the library and couldn't put down. It's called "On the Short Waves, 1923-1945: Broadcast Listening in the Pioneer Days of Radio", by Jerome S. Berg.
Harold
Hmm... not so sure about your P2P dream.
Its one thing to stream digital data and have it picked up by a device and spat out via a DAC.
Its another thing altogether to have to co-ordinate lossless data transmission. You are going to need a protocol that handles retransmission CRCs etc... i.e. some sort of transmission control protocol maybe?
People have been getting all sorts of stuff. Digital stuff over SW for a long time now, bouncing packets of meteor trails containing e-mail and shit.
Good idea... bit late
"what's the point ? maybe I missed something ?"
Well, here in the UK, there's a point. Already the BBC has squeezed so much into it's limited DAB multiplex, that it can only pump out BBC Radio 7 at 80kbps MONO. It's World Service, which sometimes broadcasts music, has an output of 64Kbps MONO, as does it's Asian Network.
If it shifts these services to (ugh) DRM, then the they can be output in stereo, probably at better rates. The remaining services can go up in quality (BBC 6 Music, currently at 128Kbps on DAB, could go up to 160, etc.)
More bandwidth, at better quality. I would guess that that's the point.
Corporation, n. An ingenious device for obtaining individual profit without individual responsibility. - Ambrose Bierce
There are in the US people who actually live so far out in the middle of nowhere that shortwave is the only option for radio unless they want to put up a huge antenna.
Its also a fairly widespread hobby. Starting cost can be as low as $10 for a garage sale world band radio up to several thousand for the latest in equipment.
Its pretty fun being able to hear programs from austalia, india, or wherever someone can muster a few kilowatts to bounce a signal off the ionosphere.
here's a website I found in the UK that gives a very detailed explanation.
Wrap your brain around this.
I tried to digest all of it...
Now my head hurts.
Even if a man chops off your hand with a sword, you still have two nice, sharp bones to stick in his eyes.
>> Does anyone still listen to shortwave?
Yes.
SW is the only communication you can get in certain poor rural zones, because:
- telephone lines are too expensive to install;
- same for optic fiber & microwave links;
- FM&AM&TV are't close enough;
- satellite receiving equipment too expensive;
- internet requires one of the above;
- etc.
People really use SW, because they need general news, government announcements and entertainment.
Of course, this idea will only work if someone can come up with an inexpensive enough apparatus.
Now that I come to think of it, this is like Vorbis streaming thru internet, over amateur radio.
Hey, Cringely, do you want cheap internet access? (ok, your project was way cooler, but then, not that cheap...)
One could use a range of frequencies to get more bandwidth (duh). Is this spread-spectrum?
These wavelengths aren't so great for reliable transmissions. They tend to come in and go out depending on the weather, time of day, solar activity and every other variable. Sometimes nearer transmitters get lost but nuch more distant ones can be tuned in.
I suppose if you had a reciever and a transmitter, with a lot of bands open, and can "hunt" bands, it might work but those are big ifs. You'll be able to transfer data, but my guess is that bandwidth and latency are still big issues, but still secondary to connection reliability.
(Hmmm. Have to see if I can get the spec, and see if I can write a decoder for it....)
If you really want the spec visit the European Telecommunications Standards Institute (ETSI) website, search for Digital Radio Mondiale, register for free and download the system specification.
In the Harris booth they weren't even running it in stereo. They were using mono voice and it sounded just awful - full of really bad artifacts that made the speaker sound like he was gargling liquid while speaking.
A German fellow came up and was listening to the audio on a second headphone. he commented at how awful it sounded. Turns out that he does DSP for a living - perceptual coding in particular. he had done some work on the coser used and was embarrassed at what he was hearing on the headphone.
By contrast, the DRM samples I hear here sound just great! ...and this with dual (dueling?) bit rate conversions (analog > DRM > MP3 > analog).
FM DAB sounds somewhat better...but then again is's using a 96K bit rate - even Windows Media sounds good at that high a bit rate!
What I'd like to hear is OGG at both the 32k bit rates of AM DAB and the 96k bit rates of FM DAB... My guess is that it would sound great!
Well thank God it's not based on WM9. Unfortunately some DAB radio solution manufactures are looking into WM9 instead of MP1 layer II. I can only conclude they are mad and want their company (and the world) to be ruined like Sendo.
It is an amazing coincidence, but I was at the sales pitch for DRM last Friday. Well, apart from things being rehashed here on /. some insider information:
DRM is going to be certified by ITU (International Telecomms Union), basicaly the body that gives the certs for these kind of things.
Most of the digital radio concepts failed because they were able to produce a small run of say 10,000 receivers that would cost an arm&leg when they hit the streets. Well, it seems that DRM will not share this fate, since China, having poor radio coverage in rural areas (FM not viable, shitty AM/SW reception) has chosen DRM as their new standard. Starting run will be ~14mil receivers, so from start they will be able to produce them dirt cheap. Basically the deal is that the West will supply the transmitters, and China will flood the market with cheap receivers.
Otherwise the test rig shown at the pitch sounded really good.
There's nothing wrong with digital over AM/SW. It's just that these experiments are in NO way relevant to the current operation of the BBC world service, or any other radio station. It will takes some years to develop this technology further AND, most importantly, it will take *decades* before the installed base reaches any sort of critical mass. Before that happens this is a play thing.
With regard to your comments about satellite being expensive - already companies are selling satellite tuners that connect to your regular FM radio's antenna so you can use your regular radio as a satellite receiver.. In Africa. Satellite is already being used by the BBC world service (and the world services of many other countries).
You might want to check out a little thing called 'context'.
The original poster's comment was like saying "Wow! Now the BBC can switch to online streaming audio!" when the very first streaming audio was sent over the ARPAnet in 1973 (RFC 508).
SCO employee? Check out the bounty
Confess I don't know anything about DRM but lower frequency generally means lower bandwidth. It's simple, at 500kHz, 50kHz of bandwith represents 10% but at 5MHz it only represents 1%
Art is the mathematics of emotion
Modems use ~3khz of bandwidth to get >48kbps. HF channels have more than twice that bandwidth available, and if you are using a digital front end there's no reason at all you can't use more than channel at the very same time. Use two VHF channels (say, on the also-unregulated 49mhz band) and it's not at all unreasonable to expect >200kbps - on a packetized multichannel service with no line-of-sight issues.
This is NOT "packet radio."