[aprssig] APRS return to basics (DR) (new images)

[Randy Allen - KA0AZS]

Some of it might be user education.  I've trained myself (and, somewhat, CINCHOUSE and Darlin' Daughter) to wait for our D700s to zero out in speed and then send a beacon before shutting down when arriving at a destination.

73

Randy


-----Original Message-----
>From: "Andrew P. " <andrewemt at hotmail.com>
>Sent: May 24, 2012 1:31 PM
>To: Bob Bruninga  <bruninga at usna.edu>, "aprssig at tapr.org " <aprssig at tapr.org>
>Subject: Re: [aprssig] APRS return to basics (DR) (new images)
>
>Hi, Bob.
>
>Here's an interesting observation on DR. 
>
>In my area, I find a large number of "hanging" DR's, because a mobile station didn't send a final "I have stopped moving now" beacon (with speed=0) before powering off. Whether this is because the software I am using infers speed and course from the last few position reports for stations not reporting CSE/SPD, or because Smart Beaconing doesn't work well upon deceleration (as was noted in someone else's post a month or so ago), I do not know, but I have hanging DR's all over my map most of the time.
>
>I'm not sure what to do about this problem, except wait for this misleading station information to expire off the real-time display.
>
>Any ideas?
>
>Andrew Pavlin, KA2DDO
>author of YAAC (Yet Another APRS Client)
>http://www.findtheater.com/ka2ddo/YAAC.html
>------Original Message------
>From: Bob Bruninga
>To: aprssig at tapr.org
>Sent: May 24, 2012 9:32 AM
>Subject: Re: [aprssig] APRS return to basics (DR) (new images)
>
>
>> I've never used a system that used dead reckoning, 
>> but I don't think I would like the feature. 
>
>That's what they said about the telephone, the car, the telegraph and
>facebook.  It also shows why I had asked all authors to have DR enabled by
>default.  SO that people would get a taste of what real-time tactical
>awareness really looks like when they came into APRS.  If it got too messy,
>they could turn it off.  But if it is messy, then it is really telling you
>something important about the latency of your data!  Hiding it is hiding
>that important element.
>
>Again,  DR is fundamental to all military and aviation and other tracking
>systems.  If something is moving then it has FOUR dimensions.  LAT, LONG,
>COURSE and SPEED.  TO ignore CSE and SPD in the display is like looking at a
>Black and white TV and it hides the age of the position.
>
>> but my feeling is that I would rather know what is fact... 
>
>The last known position is always clearly shown with the circle and the
>line.  The length of the line from that last known position to the estimated
>DR'ed position shows the passage of time and the age of the "fact".
>
>> if they kept moving, completely missing the next bend in the road...
>
>A symbol DR'd at 70 MPH off the interstate because the road turned still
>conveys exactly the same information.  He is that far along his route.
>Looking at the map you can easily see where the road went with him still on
>it and can visualize where he is.  If the DR is very long, such as 5 or 10
>miles, then clearly he can be 5 or 10 miles from that last known position
>and so its "factual" value is vanishing to practically nothing.
>
>In fact at 60 MPH, the error in that "fact" is more than a mile off after
>even just a minute.  Hence, the DR'ed position is always more factual than
>the old stamp on the road just getting older and older.
>
>Bob, WB4APR
>

Randy Allen, KA0AZS