[aprssig] "no sym yet" icon + compressed packets?

Stephen H. Smith wa8lmf2 at aol.com
Sat Feb 15 00:14:48 CST 2014


On 2/14/2014 11:07 PM, Paul Bramscher wrote:
> Forgot to add -- my station, and the others that get 'no sym yet', seem
> to all be passing compressed-format packets.  So maybe that's a factor
> also.  It's unclear to me how to turn off compression on my D710, as an
> experiment, so see if that's his issue.
>
> -Paul
>


1)   The symbol set in use by another station has NO effect on the symbols YOU 
see.   All that is transmitted is a two-character control code that tells the 
other station(s) what symbol position in his symbol set to select and display.

What you see in response to that control code is entirely dependent on the 
graphic images stored on YOUR computer or device.

If your station symbol is coming up wrong, then somewhere along the 
transmission path (ISS digipeater, igate station, etc), the symbol control 
characters in your packets are getting mangled.



2)   The ONLY format used for position transmissions by the Kenwood radios in 
their stand-alone "APRS" mode is the highly-compressed Mic-E format, that 
yields very short transmit bursts.

There is no way to override Mic-E transmit mode in stand-alone operation of the 
Kenwood radios.   If you want to send plain-text posits, you will have to have 
some external program controlling the Kenwood's TNC in "PACKET" mode instead.



3)   Mic-E format is notorious for getting mangled by some out-dated igate 
software that attempts to convert it to plain-text before passing it to the 
APRS-Internet System.  (Rather than just passing the Mic-E packet as-is to the 
APRS-IS.)

Are the "raw packet" displays on findu or APRS.fi showing the typical Mic-E 
gibberish, or are you seeing something that looks like plain-text lat/long 
values in your igated packets?

If you are transmitting natively with a Kenwood, but you are seeing plain-text 
lat-long in the Internet packets, then someone is ineptly trying to translate 
Mic-E to plain-text format.

Igate software translating Mic-E is a vestige of another era, decades ago, when 
not all APRS client software knew how to decode Mic-E. Today, there is NO 
reason for igates to be translating packets, since all current APRS software 
now knows how to deal with Mic-E packets.

__________________________________________________________________


--

Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
EchoLink:   14400  [Think bottom of the 2-meter band]
Home Page:          http://wa8lmf.net


  Long-Range APRS on 30 Meters HF
     http://wa8lmf.net/aprs/HF_APRS_Notes.htm

High Performance Sound Systems for Soundcard Apps
    http://wa8lmf.net/ham/imic.htm
    http://wa8lmf.net/ham/uca202.htm

"APRS 101"  Explanation of APRS Path Selection & Digipeating
   http://wa8lmf.net/DigiPaths








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