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[aprssig] 9600 APRS

Herb Gerhardt hgerhardt at wavecable.com
Thu Apr 2 03:52:08 UTC 2009


Yes, the 9600 baud APRS network would work just fine.  It has been done in
the Seattle Area for several years as an experiment on 440.800 MHz, 223.600
and on 145.550 and it has worked very successfully!  Bob King K7OFT is the
one who pioneered the 9600 baud experimentation in our area and would be a
good person to contact in helping you set up a similar 9600 baud network in
your area.  Bob uses special paths on this network in order to minimize the
ping-pong effect since all those signals are retransmitted on the main
network of 144.390 at 1200 baud via the internet.

Recently we also have a second 9600 baud network in our area spearheaded by
N7FSP on 440.875 and 144.350 since Scott did not agree with the special
paths.

So, yes 9600 baud APRS works well but it requires people to get together and
set up a network to make it all work well and as we all know, it is next to
impossible to get everyone to work together to accomplish a common goal
.......
Herb, KB7UVC
NW APRS Group, West Sound Coordinator
Our WEB Site:  http://www.nwaprs.info


  -----Original Message-----
  From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org]On Behalf
Of Wayne Sanderson
  Sent: Wednesday, April 01, 2009 7:43 PM
  To: aprssig at tapr.org
  Subject: [aprssig] 9600 APRS


  My increasing involvement in Emergency Management in NJ has gotten me back
into APRS with a vengeance, and my Kenwood rigs are running hot. Running
slow 1200 baud with random packet intervals and packet collisions seems kind
of static. The newer rigs will run 9600 APRS, but there is no 9600 network
for them.

  We have better features built into the Kenwood radios than we actually get
to use because the network at 144.39 is still 1200, hence very little 9600
ops- mostly satellite spotting. Since we allow these features to languish
unused or at least under used, no other radio manufacturers seem to feel the
need to incorporate them in their product lines. Now we have lost the
TH-D7s. ( I don't really believe that decision was made because of toxic
chemicals in the PCBs... Do you?)

  How about something a bit different? Suppose, as an experiment, here in
Central NJ where there is a pretty dense signal cluster, we were to set up a
440 UHF 9600 APRS digi at as high a point as we can get, running as much
power as we can manage.

  Instead of having a conventional digi, have a computer hooked to 2
radios/TNCs, one running at 1200 on 144.39, the other at 9600 on 440 UHF.
Have the computer APRS application record all the received packets over a
three minute period of monitoring 144.39 1200 operations, compile them into
one long data stream and at the end of that 3rd minute transmit that three
minute take from 144.39 1200 onto the 440 UHF band 9600 channel in one long
burst. In the intervening minutes between that digi-burst and the next, 9600
UHF APRS units can transmit position packets, which will not be digipeated
immediately but will be scooped up by the computer and incorporated into the
next data burst, and can be cross banded to 144.39 at 1200 as well.

  If I am correct, this will cut packet collisions way down, and on the UHF
9600 channel the air will be clear, allowing for greater distance RX and TX
in between digi-bursts, at least until a large number of people start
running APRS at 9600 on UHF and we eventually get QRM. And even if a large
number of people eventually do run 9600 on UHF, the capacity of the channel
is as much as eight times that of 144.39 because of the speed increase. That
gives us room for more content, larger packets, longer messages, in short-
More room to play with.

  I am not a programmer, and so I can't make this happen by myself. All I
have is some money for equipment and the desire to see this happen. One of
the talented APRS programmers out there would have to get interested in
this. Any takers?


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