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[hfsig] Re: [Flexradio] The final nail in the coffin of Morse ?

Trevor AKA m5aka at yahoo.co.uk
Mon Jul 25 17:42:54 UTC 2005


Back in the late 1970's the original FCC proposals (bitterly opposed at the
time by the ARRL) called for the Amateur Bands to be divided by bandwidth
rather than mode.

At the time the FCC proposed 4 seperate bandwidths for HF:

  0.350 kHz
  3.500 kHz
  7.500 kHz
 15.000 kHz (above 29.5)

These seem to me to be sensible bandwidths to adopt today.

73 Trevor M5AKA

--- DuBose Walt Civ AETC CONS/LGCA <Walt.DuBose at RANDOLPH.AF.MIL> wrote:

> Ant,
> 
> 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.
> 
> 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.
> 
> However, with a 3.5 KHz bandwidth limit being recommended by the ARRL, this
> just isn't going to happen.
> 
> Walt/K5YFW
> 
> PS we've migrated from CW to bandwidth and perhaps now to Digital Voice as
> the subject of this thread.
> 
> -----Original Message-----
> From: hfsig-bounces at lists.tapr.org
> [mailto:hfsig-bounces at lists.tapr.org]On Behalf Of
> Anthony.N.Martin at seleniacomms.com
> Sent: Friday, July 22, 2005 10:28 AM
> To: TAPR HF Modes SIG Mailing List
> Subject: RE: [hfsig] Re: [Flexradio] The final nail in the coffin of
> Morse ?
> 
> 9kHz AM is the standard for shortwave broadcast AM and in
> theory gives us compatability with the sets SWLs use.
> 
> Broadcast SSB never took off, although it looks like change may
> be happening with DRM.
> 
> There is an arguament that amateur digital voice should also aim
> to retain compatability with SWL's receivers.
> 
> The DRM standards allow several bandwidths, not just 9kHz.
> 
> SWLs form some part of the membership of amateur radio societies.
> They are also a source of future amateur operators.
> Building and operating receivers is a perfectly valid form of amateur
> radio that doesn't need a licence and is the only choice in countries
> where licences are impossible to aquire.
> 
> Ant M1FDE
> 
> > _______________________________________________
> hfsig mailing list
> hfsig at lists.tapr.org
> https://lists.tapr.org/cgi-bin/mailman/listinfo/hfsig
> 


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