[aprssig] Why do we not use APRS 9600?

Jason Rausch jason at ke4nyv.com
Wed Feb 16 16:49:22 EST 2022

In short, it would be a monumental task.  What you might not be aware of is, prior to the first Kenwood D7 being shipped, EVERYONE was using a TNC and radio cabled together through in most case the speaker//mic jack of an HT or the mic and external speaker jack of a mobile.  Some of us were starting to use radios with dedicated 6 pin mini DIN packet ports, but those have always been rare, even on higher end mobiles.  That also required you to set the levels for both transmit (deviation) and receive.  At 1200 baud, this can be done reasonably well just by ear.  Even slightly off, it's forgivable and usually works.
When you move to 9600, it's a whole different world.  The TNC's double in price.  You cannot simply use the mic/speaker connections.  You have to directly modulate the transmitter and receive at a minimum has to come off the discriminator stage, prior to any filtering.  Then adjustment is quiet precise and cannot be done by ear because while 1200/2200 Hz tones are audible to the human ear, 9600 baud sounds like static.  You can't just adjust the audio from the front panel and call it "good enough".  This added complexity of setup scares a lot of guys away from even trying it or get frustrated and give up.
In Virginia, we had several setups where the VHF 1200 baud digipeaters were "backboned" by 9600 baud UHF links.  I'm pretty sure they are all gone now, but it was pretty cool to see that up and working.  Doesn't mean we can't do it again.
My friend Remi VE2YAG and I are dusting off some ESP32 model designs now that we're thinking could potentially be good for 1200 and 9600 baud, but no promises just yet.
Jason Rauschwww.ke4nyv.com 

    On Wednesday, February 16, 2022, 04:37:58 PM EST, Jonathan Delaney <kb3osp at gmail.com> wrote:  
  The  discussion  this  past  week  has  made  me  wonder  on  why  APRS  9600  is  not  used.  To  my  knowledge  most  if  not  all  APRS  mobile/ handheld enabled  radios  have  a  TNC  capable  of  9600  bps  however  we  still  set  them  to  1200.  Is  this  because  most  of  the  digis  and  igates  still  use  1200?  What  would  it  take  to  get  everyone  to  change  to  9600?
 Jon  KB3OSP
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