<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Joe,<br><br>I don't know if it will help you much, but last year sometime I wrote a VB.net application that will convert a raw KISS packet to the "human readable" version. I wrote it more of a see if I could do it project. I never added in direct serial input, so you have to copy/cut and paste a KISS packet into the program to convert it. Basically in the process of converting the packet, it breaks down the packet byte by byte in some tables and even parses out the converted packet to show the different elements.<br><br>Anyways, if it could be helpful, I have it for free download on my webpage at:<br><br>http://www.ke4nyv.com/software.htm<br><br>See the bottom program "KISS Packet Analyzer".<br><br>Jason Rausch - KE4NYV<br>RPC Electronics, LLC<br>www.rpc-electronics.com<br><br>--- On <b>Tue, 9/20/11, Stephen H. Smith
<i><wa8lmf2@aol.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Stephen H. Smith <wa8lmf2@aol.com><br>Subject: Re: [aprssig] The APRS AX.25 Frame<br>To: "TAPR APRS Mailing List" <aprssig@tapr.org><br>Date: Tuesday, September 20, 2011, 3:35 PM<br><br><div id="yiv804918550">
On 9/20/2011 3:09 PM, Joseph M. Durnal wrote:
<blockquote type="cite">
<pre>I'm trying to explain an APRS packet to many non-APRS users and I want<br>to get it right, but I've confused myself<br><br>Here is a basic packet<br><br>NE3R>APX200,WIDE1-1,WIDE2-1:=3925.63N/07726.00WxPHG3000Frederick ARC APRS Demo<br><br>The AX.25 frame is defined<br>Flag(1) Dest(7) Src(7) digi(0-56) ctrl(1) PID(1) info(1-256) FCS(2) flag(1)<br><br><br>I'm assuming that there are bits in the frame that aren't translated<br>to text on the TNC, what confuses me is the source, I obviously see<br>the source on the TNC, but it comes before the destination. I'm also<br>not sure what defines the : between the path and position.<br><br>My explanation will look like this<br><br>"NE3R>" = The source of the packet<br>"APX200," = The destination, in practical application, it isn't really<br>the destination, but it identifies the APRS software generating the<br>packet<br>"WIDE1-1,WIDE2-1" = the packet path, 3 hops in this case,
once<br>dilapidated looks like N3KTX-2*,WIDE1*,KV3B-1*,WIDE2*<br>":" = not sure exactly what this is, found between the path and the<br>rest of the APRS info field</pre>
</blockquote>
<br>
<br>
The display you see in a TNC monitor window is already considerably
"sanitized" relative to the actual raw packet that contains binary
headers, sync bits, checksums, packet type codes, etc. Viewing a
raw packet will show considerable binary "gibberish before and after
the recognizable text payload. <br>
<br>
":" is the delimiter added by the receive TNC, for display purposes,
to separate the path data (itself already reformatted from the raw
packet) from the packet "payload". This will be the same for any
kind of AX.25 packet, either APRS or "classic" connected packet.
<br>
<br>
Everything beyond this is "just payload text" as far as AX.25 is
concerned. Any further delimiters are purely APRS constructs and
have nothing to do with the low-level AX.25 "shipping container". <br>
<br>
<br>
<blockquote type="cite">
<pre>"=3925.63N/07726.00WxPHG3000Frederick ARC APRS Demo" = the APRS<br>information, which I'll break down further below<br>"=" = APRS datatype, this one represents an APRS position without a<br>time stamp from a messaging capable station<br>"3925.63N/07726.00W" = the position data, but the / is important to<br>the APRS symbol definition<br>"x" = the second part of the symbol, combined with /, the x displays<br>an X for XAPRS/Xastir (linux software), symbols for cars />, trucks<br>/k, houses /-, etc can be used<br>"PHG3000" = optional power height & gain info, important for<br>digipeaters and fixed stations (your software should calculate this)<br>"Frederick ARC APRS Demo" = A free-form comment<br><br><br></pre>
</blockquote>
<br>
<br>
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