[aprssig] APRSIS32 sending conflicting position reports
Eric H. Christensen
eric at aehe.us
Sat Nov 7 21:01:04 EST 2020
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, November 7th, 2020 at 8:28 PM, Lynn W Deffenbaugh (Mr) <KJ4ERJ at arrl.net> wrote:
> On 11/7/2020 7:35 PM, Eric H. Christensen via aprssig wrote:
>
> > I think I just found a flaw in APRSIS32 (but it may not be limited to that software).
>
> It's not a flaw, it's a feature.
:D Well, that might be true, but...
> > Having never run APRSIS32, I'm wondering if this is a setting somewhere in the software to include the grid in the status text. I've seen so many of these stations sliding across my screen it would seem to be odd that it is an individual effort.
>
> It is a mis-configuration by the operator who doesn't understand the effects s/he is causing in other clients. Yes, there is a checkbox in the status configuration of APRSIS32 that includes the GridSquare in the status report. But status reports are not enabled by default, nor is this box checked by default. The option is there for someone that doesn't want to beacon positions but only do Status Reports with GridSquare included. Anyone that enables both, again, doesn't understand what they are doing.
Shouldn't this be an either-or situation? It seems bad to let the user select both cause, you know, users will do both.
> So, if you want the station to stop doing that, contact the operator and educate them. Tell them that they are beaconing two different positions and to disable one or the other. They can keep the Status Report, but just don't include the GridSquare within it. And point them to the wiki page
>
> http://aprsisce.wikidot.com/menu:configure-status-report
I'll do that.
>
> that even says:
>
> > GridSquare- If checked, the current GridSquare will be included in the Status Report. Use this with caution if you are also transmitting position beacons as the position resolution between the GridSquare and Lat/Lon coordinates is significantly different, possibly resulting in a station that ping-pongs between two locations depending on which packet was heard most recently.
That's pretty clear.
Thanks for your quick answer here.
73,
Eric WG3K<blockquote class="protonmail_quote" type="cite">
<div><br>
</div>
<div class="moz-cite-prefix">On 11/7/2020 7:35 PM, Eric H.
Christensen via aprssig wrote:<br>
</div>
<blockquote type="cite">
<pre wrap="">I think I just found a flaw in APRSIS32 (but it may not be limited to that software).
</pre>
</blockquote>
<p>It's not a flaw, it's a feature.</p>
<blockquote type="cite">
<pre wrap="">I've been seeing stations slide across my screen over the past few weeks. I couldn't quite put my finger on it until tonight. Here's what I'm seeing:</pre>
</blockquote>
<p>It's helpful if you supply specific examples so that we can
adequately research the details. Especially what software you are
using that shows "stations slide across my screen".<br>
</p>
<br>
<blockquote type="cite">
<pre wrap="">A non-mobile station will suddenly relocate itself a distance away only to move back to where it came from a short time later. After working with one station, and looking at the packets being sent directly to the IS, I noticed two things: 1) the position reports are not changing, and 2) the status reports (of which I've never found to be useful) contain a properly formatted status report *with Maidenhead Grid Locator*.</pre>
</blockquote>
<p>If a station is reporting two different locations with different
precision and/or different center locations, then yes, some
software will display them ping-ponging between the two
locations. APRSISCE/32 remembers the most precise coordinate
received and will ignore the less precise coordinate (typically
the grid square) to avoid this issue.</p>
<br>
<blockquote type="cite">
<pre wrap="">So, what I think is happening is my client is seeing the position report and plotting the station as expected. It is then seeing the grid locator in the status text and moving the station to the middle of the grid, as it should per the APRS spec[0].</pre>
</blockquote>
<p>Again, I'd be curious as to what client you are running. The
author of that client might be able to implement the same approach
that APRSIS32 uses.<br>
</p>
<br>
<blockquote type="cite">
<pre wrap="">Having never run APRSIS32, I'm wondering if this is a setting somewhere in the software to include the grid in the status text. I've seen so many of these stations sliding across my screen it would seem to be odd that it is an individual effort.</pre>
</blockquote>
<p>It is a mis-configuration by the operator who doesn't understand
the effects s/he is causing in other clients. Yes, there is a
checkbox in the status configuration of APRSIS32 that includes the
GridSquare in the status report. But status reports are not
enabled by default, nor is this box checked by default. The
option is there for someone that doesn't want to beacon positions
but only do Status Reports with GridSquare included. Anyone that
enables both, again, doesn't understand what they are doing.</p>
<p>So, if you want the station to stop doing that, contact the
operator and educate them. Tell them that they are beaconing two
different positions and to disable one or the other. They can
keep the Status Report, but just don't include the GridSquare
within it. And point them to the wiki page</p>
<p><a href="http://aprsisce.wikidot.com/menu:configure-status-report" target="_blank" rel="noreferrer nofollow noopener">http://aprsisce.wikidot.com/menu:configure-status-report</a></p>
<p>that even says:</p>
<p>
</p><blockquote type="cite"><strong style="color: rgb(0, 0, 0);
font-family: verdana, arial, helvetica, sans-serif; font-size:
12px; font-style: normal; font-variant-ligatures: normal;
font-variant-caps: normal; letter-spacing: normal; orphans: 2;
text-align: left; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color: rgb(221,
221, 238); text-decoration-style: initial;
text-decoration-color: initial;">GridSquare</strong><span style="color: rgb(0, 0, 0); font-family: verdana, arial,
helvetica, sans-serif; font-size: 12px; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: left; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color: rgb(221,
221, 238); text-decoration-style: initial;
text-decoration-color: initial; display: inline !important;
float: none;"><span> </span>- If checked, the current
GridSquare will be included in the Status Report. Use this
with caution if you are also transmitting position beacons as
the position resolution between the GridSquare and Lat/Lon
coordinates is significantly different, possibly resulting in
a station that ping-pongs between two locations depending on
which packet was heard most recently.</span></blockquote>
<p></p>
<p>Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and
Win32
</p>
<blockquote type="cite">
<pre wrap="">73,
Eric WG3K
[0] <a href="http://www.aprs.org/doc/APRS101.PDF" target="_blank" rel="noreferrer nofollow noopener">http://www.aprs.org/doc/APRS101.PDF</a> (pages 8, 27, and 81-82)
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</pre>
</blockquote>
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</blockquote>
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