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<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>I am testing the
viability of using APRS in a non-fixed station environment - eg. no established
digipeaters and no base stations. The intention is to use a number of
lightweight, portable radios such as the TH-D7a to create an ad hoc mesh that is
survivable even if some radios fail. I have worked with trying to create a
mesh network - in one case with nine radios using WIDE7-7 to ensure that as many
radios copied the signal as possible. My reasoning for this was that if
each radio was almost in the fringe area of its neighbor radios and the radios
were in a line, for N radios it would take N-2 hops for an end radio's data to
traverse the network to the other side. Obviously, this creates many
unneeded duplicate packets in less extreme cases, and I am wrestling
with ideas on how to solve that issue. One method I have come up with
would be rather more software intensive:</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>1. Remember
your immediate neighbors.</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>2. For a given
packet, choose a random wait time. If you haven't heard every neighbor
digipeat the packet after a given wait time, digipeat.</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>3. Maintain packet
in memory for a fixed, user settable amount of time to ensure that you do not
digipeat it again.</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>I still see problems
with the above protocol, although it would cut down some on
packets.</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>I have tried
researching the spec to see if the meshing concept is covered, but all I have
seen so far assumes that there are fixed stations and digipeaters. Is
there a part of the spec I have missed that addresses this? Has anyone
else worked on a similar experiment? Thanks for your
help.</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial
size=2>73,</FONT></SPAN></DIV>
<DIV><SPAN class=725554604-05012006><FONT face=Arial size=2>Richard Clement
(AE6QE)</FONT></SPAN></DIV></BODY></HTML>