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<TITLE>RE: [hfsig] Re: [Flexradio] The final nail in the coffin of Morse ?</TITLE>
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<P><FONT SIZE=2>Ant,</FONT>
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<P><FONT SIZE=2>I agree that we should look carefully at what DRM and other digital voice modes are doing and advance the art in ham radio. DRM and the other digital voice modes being used by hams today aren't particularly robust...they take quite a large SNR to produce a good, clean sounding signal. When used at low SNRs (weak signals levels) there quality and performance is poor and the overall communications quality is not much better than SSB.</FONT></P>
<P><FONT SIZE=2>To make them more robust, considering that they all use OFDM types of modulation, the best way to make them more robust is to increase the number of tones and use this increased throughput capacity for heaver FEC.</FONT></P>
<P><FONT SIZE=2>However, with a 3.5 KHz bandwidth limit being recommended by the ARRL, this just isn't going to happen.</FONT>
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<P><FONT SIZE=2>Walt/K5YFW</FONT>
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<P><FONT SIZE=2>PS we've migrated from CW to bandwidth and perhaps now to Digital Voice as the subject of this thread.</FONT>
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<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: hfsig-bounces@lists.tapr.org</FONT>
<BR><FONT SIZE=2>[<A HREF="mailto:hfsig-bounces@lists.tapr.org">mailto:hfsig-bounces@lists.tapr.org</A>]On Behalf Of</FONT>
<BR><FONT SIZE=2>Anthony.N.Martin@seleniacomms.com</FONT>
<BR><FONT SIZE=2>Sent: Friday, July 22, 2005 10:28 AM</FONT>
<BR><FONT SIZE=2>To: TAPR HF Modes SIG Mailing List</FONT>
<BR><FONT SIZE=2>Subject: RE: [hfsig] Re: [Flexradio] The final nail in the coffin of</FONT>
<BR><FONT SIZE=2>Morse ?</FONT>
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<P><FONT SIZE=2>9kHz AM is the standard for shortwave broadcast AM and in</FONT>
<BR><FONT SIZE=2>theory gives us compatability with the sets SWLs use.</FONT>
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<P><FONT SIZE=2>Broadcast SSB never took off, although it looks like change may</FONT>
<BR><FONT SIZE=2>be happening with DRM.</FONT>
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<P><FONT SIZE=2>There is an arguament that amateur digital voice should also aim</FONT>
<BR><FONT SIZE=2>to retain compatability with SWL's receivers.</FONT>
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<P><FONT SIZE=2>The DRM standards allow several bandwidths, not just 9kHz.</FONT>
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<P><FONT SIZE=2>SWLs form some part of the membership of amateur radio societies.</FONT>
<BR><FONT SIZE=2>They are also a source of future amateur operators.</FONT>
<BR><FONT SIZE=2>Building and operating receivers is a perfectly valid form of amateur</FONT>
<BR><FONT SIZE=2>radio that doesn't need a licence and is the only choice in countries</FONT>
<BR><FONT SIZE=2>where licences are impossible to aquire.</FONT>
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<P><FONT SIZE=2>Ant M1FDE</FONT>
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