[Elecraft] Free DV (digital voice as reported in QST-Aprilissue)

[Richard Fjeld]

FreeDV uses about one-third the bandwidth of many of the SSB signals seen on the bands.  (1100 Hz)

We have tried it on 75 meters during heavy QRN and QRM while using low power.  We were surprised to find that we were able to work well, (but not perfect).  We had occasional loss of sync, but worked noise free due to it being digital. 

It will not replace SSB, but it will be useful.

As for DSSTV; what a great way to send a .jpg drawing or picture to someone.  As they say, 'a picture is worth a thousand words'.  DSSTV pics are amazing clarity.  But, I guess the internet has spoiled us.  With that thought, why bother with radio?

Rich, n0ce

  ----- Original Message ----- 
  From: MontyS 
  To: ab2tc ; elecraft at mailman.qth.net 
  Sent: Wednesday, April 03, 2013 11:46 AM
  Subject: Re: [Elecraft] Free DV (digital voice as reported in QST-Aprilissue)


  Digital slowscan uses tones, just like AFSK, PSK31, or any other 
  soundcard-based mode.  It does not use analog, continuously variable tones, 
  like original slowscan, but discrete tones, like AFSK.   It does not use a 
  bandwidth wider than a standard SSB signal, about 2.5 - 2.8 khz.  In fact 
  when I receive digital slowscan I narrow the bandwidth to remove 
  interference.

  The worst "our frequency" offenders are the daily social nets found 
  throughout the phone allocations.  One frequency on each band does not 
  strike me as frequency hogging, and it does allow the few users of a mode to 
  find one another.  In the case of PSK31, it allows many times more QSOs to 
  be possible in the approximately 3khz segment used.

  Monty K2DLJ


    I am concerned with the creepage into our phone bands of wide digital 
  modes with
  their raw audio when tuning in SSB mode. The occupants of these frequencies
  are also typically very protective of "their" frequencies and tend to be
  intolerant of "intruders".

  AB2TC - Knut