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#13
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On Sun, 25 Jan 2004 21:20:31 GMT, Telamon
wrote: In article , (Sidchase3) wrote: Has anybody built or bought a DRM capable receiver? I printed out a schedule of broadcastng times from the DRM website. It appears that there are test transmissions going on from participating broadcasters a good part of the day. One station transmits for an hour or two and then passes off to another. Has anyone heard these broadcasts? How was the clarity? As I mentioned in Future of shortwave, I think there is tremendous potential for digital shortwave particularly concerning the transmission of text. The ability to interface these receivers with a computer (PC, laptop, palm) coupled with the relatively high coverage to cost ratio would enable a greater variety of thought (political, social) from marginalized groups to the reach the public. As far as the FCC banning domestic broadcasts, the law could be challenged in court--I admit I don't know what the cost would be. But more importantly, I think the ban needs to be challenged in the court of public of opinion. Given the ridiculous situation today in which businesses can own multiple stations in one locality and enormous corporations control all the programming for those stations the FCC's rationale for the ban falls flat on its face. Ironically, domestic shortwave would represent the kind of programming diversity that the FCC claims it wants to promote. I strongly disagree that DRM in its current form will create over all improved radio reception than analog. DRM reception will be different and could be judged "better" at times but over all different conditions and situations reception will be no better off than analog. I believe that DRM can never be mertely "no better than analog". Provided you can receive the signal in the first place, you can't possibly get the usual background noise, fading, and limited bandwidth as you get with analog, because you re receiving an MP3 compressed digital signal, which is practically FM broadcast quality. On the other hand, if you can't receive the signal with the required threshold signal-to-noise ratio, you will hear nothing. Not even noise, just pure silence. Besides being no better than the current analog regime DRM brings several new negatives along with it like some of the codexes are still proprietary. The radios will consume more power and cost more money. If the codec is a proprietary HCMOS chip, the extra 20mA or so won't make much difference to the battery life. With software-based PC receivers like the Winradio G303, this point does not apply. The cost issue will depend on economy of scale. If there are millions of users (as DRM obviously must anticipate), the chip will cost just a few dollars, and may also integrate other existing receiver functions, for example a conventional AM/FM demodulator, so it won't add significantly to the cost of the radio. Other negatives are the ability to control where broadcasts are heard and by whom. What is going to stop a consortium of radio manufactures and broadcasters if the broadcasters want certain broadcasts to be heard only on certain continents similar to what is done with DVD's as an example of potential abuse of a digital system? This is potentially true, but it would be much harder to police than with DVD (where the so-called "zoning" was a failure anyway and in most countries you now get multi-zone DVD players as a matter of course, no questions asked). Whether anyone likes it or not the change to DRM means that shortwave will no longer be a world wide medium. The DRM consorcium must make it a world-wide medium in order for the standard to succeed in the first place. George |
#14
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I am using a custom receiver/dsp software radio that I connected using
a soundcard to the PC running Dream 1.0. I can receive the US directed and 1 or 2 other DRM broadcasts. I had problems with dropout prior to fully understanding the bandwidth settings, sidebands, and signal placement in the receiver IF passband. Overall, I am not pleased with the sound of DRM. There is an annoying distortion related to the compression. It sounds marginally better than internet broadcasts, if at all. I struggle to equate the sound quality to mono FM as others due. The dynamic range and signal/noise ratio might be there, but the objectionable artifacts (most noticeable in speech, but masked in music) make listening tiring. Setting aside the carrier fades, there is no comparison to analog AM through my radio when I set the IF passband to a bandwidth around 11k. I recommend that anyone that is considering a new receiver for DRM purchase a bare-bones receiver with I/Q outputs and use PC based software for decoding DRM, AM, narrow FM, sideband, and other future digital modes. I think DRM is going to evolve. (Sidchase3) wrote in message ... Has anybody built or bought a DRM capable receiver? I printed out a schedule of broadcastng times from the DRM website. It appears that there are test transmissions going on from participating broadcasters a good part of the day. One station transmits for an hour or two and then passes off to another. Has anyone heard these broadcasts? How was the clarity? As I mentioned in Future of shortwave, I think there is tremendous potential for digital shortwave particularly concerning the transmission of text. The ability to interface these receivers with a computer (PC, laptop, palm) coupled with the relatively high coverage to cost ratio would enable a greater variety of thought (political, social) from marginalized groups to the reach the public. As far as the FCC banning domestic broadcasts, the law could be challenged in court--I admit I don't know what the cost would be. But more importantly, I think the ban needs to be challenged in the court of public of opinion. Given the ridiculous situation today in which businesses can own multiple stations in one locality and enormous corporations control all the programming for those stations the FCC's rationale for the ban falls flat on its face. Ironically, domestic shortwave would represent the kind of programming diversity that the FCC claims it wants to promote. -Bill |
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