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#1
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DRM transmissions from Sackville NB, Canada on 9.800MHz, had no drops today.
Starting with Deutsche Welle (Germany) on to Radio Sweden's 60-degrees North, finally followed by BBC World Service. In addition, DRM from Radio Kuwait on 11.675MHz was very readable with quite a few drops. The quality of audio of the DRM transmissions was excellent. Musical pieces were as though they were coming from a local source. No static crashes, no fading, just clean sounds. I use both the Dream software as well as the Merlin DRM decoders. This isn't conclusive but I believe the Dream software has less drops than the Merlin software, and it's free. I'm hoping for more stations using DRM transmission modes. It makes SWLing a pleasure. Al KA5JGV San Antonio, Tx. |
#2
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In article ,
"Al" wrote: DRM transmissions from Sackville NB, Canada on 9.800MHz, had no drops today. Starting with Deutsche Welle (Germany) on to Radio Sweden's 60-degrees North, finally followed by BBC World Service. In addition, DRM from Radio Kuwait on 11.675MHz was very readable with quite a few drops. The quality of audio of the DRM transmissions was excellent. Musical pieces were as though they were coming from a local source. No static crashes, no fading, just clean sounds. Snip You mean you thought the sound quality was good in between the drops. Taken all together though would you call the reception from Kuwait good? How long were the drops in time? How often was the signal dropped? -- Telamon Ventura, California |
#3
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"Telamon" wrote in message
... In article , "Al" wrote: DRM transmissions from Sackville NB, Canada on 9.800MHz, had no drops today. Starting with Deutsche Welle (Germany) on to Radio Sweden's 60-degrees North, finally followed by BBC World Service. In addition, DRM from Radio Kuwait on 11.675MHz was very readable with quite a few drops. The quality of audio of the DRM transmissions was excellent. Musical pieces were as though they were coming from a local source. No static crashes, no fading, just clean sounds. Snip You mean you thought the sound quality was good in between the drops. Taken all together though would you call the reception from Kuwait good? How long were the drops in time? How often was the signal dropped? One of the neat features of both the DRMrx and DReaM software DSP decoders for DRM is the logging of SNR and rate of successful audio decoding. Using another software, DRMcalc, you can view the logs graphically. There are many of these graphs posted in the DRM Software Radio Project web site in either the Analysis Area or in the Forums at http://www.drmrx.org/ . Have a look to see what dropout rates and durations are being encountered. With hf skywave propagation, experience one day is no predictor of performance for the next. You may have an incredibly strong signal but the multipath scattering could be so great that the decoder mutes - I often see that on Sackville transmissions in Toronto. OTOH, the signal may be relatively weak but less scattered and the audio will be reliable. I sometimes see that on long distance paths, e.g., from Kuwait. Sackville is now experimenting with 2-channel stereo transmission on its TDPradio relays on Saturdays. Don't believe anyone's claims that this is near CD quality - you aren't going to get that at 20 kbps. But the stability of the audio frequency response (absence of the effect of selective fading that we are so familiar with for SW-AM) and the absence of heterodynes while perceiving an audio spectrum greater than 5kHz is a remarkably different SW listening experience. When propagation is favorable, you forget you are listening to SW! The problem is getting close to 100% successful audio decoding for extended listening periods, day after day.... Tom |
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