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<div class="moz-cite-prefix">Robert Bruninga wrote:<br>
</div>
<blockquote type="cite"
cite="mid:e610c97fce1e70710f56c14d0d467c38@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">I'd love to hear if any system in APRS actually implemented the Precedence
bit?
<a class="moz-txt-link-freetext" href="http://aprs.org/aprs12/precedence-bit.txt">http://aprs.org/aprs12/precedence-bit.txt</a>
Basically it is making the Table-Overlay character a lower case character.</pre>
</blockquote>
<p>I was about to process all of April's APRS-IS through
Ham::APRS::FAP.pm but was suspicious when there were *NO*
lowercase symbols.</p>
<p>Then I found in the code:</p>
<p> if ($symboltable !~ /^[\/\\A-Z0-9]$/) { _a_err($rethash,
'sym_inv_table'); }</p>
<p>... which basically means it accepts / \ A-Z (upper) or 0-9
(lower) or considers it to be INVALID :-D</p>
<p>I believe aprs.fi is based around this library, but possibly a
newer version of it?<br>
</p>
<p>So re-parsing myself, and looking at the entire APRS-IS for
April, I see</p>
<p></p>
<pre>148019309 packets parsed with symbols for the month
147998954 packets parsed with GOOD symbols ("approx ASCII")
90278050 use table "/" (which obviously can't be upper/lower case
4944477 use alternate "\" (ditto)
50955070 use UPPERCASE symbol table overlay
1717233 use 0-9 as an overlay
72662 use LOWERCASE symbol table overlay
28403 use bad (8-bit / control-char / corrupt) symbol tables
23414 use ASCII symbol table overlays like ~@#$%^&*() (ASCII but non-alphanumeric)
20355 use bad symbols (not the table, the actual symbol is non-ASCII)
</pre>
<p>So... lowercase symbols DO happen, but less than 0.05% of the
time. Hard to tell how many of those might be deliberate
"precedence" vs "Just didn't know and thought lower-case was fine"
vs "data corruption" but they are quite a bit higher than (ab)use
of 8-bit.<br>
</p>
<p>For comparison, the upper/lowercase of the LatLon N/S/E/W chars:<br>
</p>
<pre>129128571 NS=N (Notable bias toward Northern hemisphere as well)
7279962 NS=S
77838643 EW=E (E/W a bit closer but bias to E, yes I was surprised)
58559906 EW=W
77842 NS=n
11534 NS=s (Still a notable N bias, but notably less - interesting?)
18753 EW=e
80607 EW=w (... but much more westerly bias in the lowercase - WAT?!?)
</pre>
<p>I see (from the same doc) there's also a standard to use an
overlay of "O" for "Operator Present".</p>
<p>I've seen that used far more on repeater objects to mean OFFLINE!
This is almost but not quite the opposite of "Operator present"!
:-D<br>
</p>
<p>They'll use I0 for idle/IRLP, C0 for Connected, B0 for Busy, O0
for Offline (not Operator Present)<br>
</p>
<p>Nick VA3NNW - self-declared APRS "big data statistician" nosing
around APRS data ;-)</p>
<pre class="moz-signature" cols="72">--
"Nosey" Nick Waterman, VA3NNW/G7RZQ, K2 #5209.
use Std::Disclaimer; <a class="moz-txt-link-abbreviated" href="mailto:sig@noseynick.net">sig@noseynick.net</a>
Men still remember the first kiss after women have forgotten the last..
</pre>
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