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[aprssig] News from DCC (5) better Views - AVMAP Dead-Reckoning!

Steve Noskowicz noskosteve at yahoo.com
Tue Sep 25 04:11:55 UTC 2012


  I think a correct interpretation of a DR circle or line is that it's a 'worst case' (or would that be 'best case') indication of where the station may have moved to... (As well as the simple age indication).  If people don't know how to use the information, that's another problem, perhaps training.  There are already way too many things in ham radio that many hams don't understand, but that shouldn't make it invalid to have.
  It seems to me that it is only useful in limited situations so it should 
be 'turn-offable'.

  Perhaps a different name would help prevent misunderstanding. 
ET - Estimated Travel
EUoP - Estimated Uncertainty of Position
DOA - Dilution of Accuracy
PPU - Potential Position Uncertanty
DR - Determined Radius (of potential travel) (;-)

73, Steve, K9DCI  USN (Vet)  MOT (Ret)  Ham (Yet)

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--- On Mon, 9/24/12, Dave B <dave at g8kbv.demon.co.uk> wrote:

> YAAC does have by default an Age
> counter next to each object.  That is 
> very useful indeed I find.
> 
> DR objects going "Off Road" could be very misleading in some instances, 
> where a true "Off the Road" situation could indeed be true.  It has it's 
> uses, but for many I think it's best left disabled.
> 
> I never advocated a "Snap to Road", or "Folow Road" mode for DR, what 
> would you do in the event a mobile stopped short of a junction, where 
> would the DR go then?
> 
> 73.
> 
>     Dave.
> 
> 
> On 24 Sep 2012 at 0:12, Andrew P. wrote:
> 
> > So there is no interest in trying to do Snap-to-Road?
> Good thing;
> > that's hard work and depends on high-precision map data
> and GPS fixes.
> > 
> > Andrew Pavlin, KA2DDO
> > Sent from my Verizon Wireless BlackBerry
> > 
> > -----Original Message-----
> > From: Robert Bruninga <bruninga at usna.edu>
> > Date: Sun, 23 Sep 2012 16:12:41 
> > To: <aprssig at tapr.org>
> > Subject: Re: [aprssig] News from DCC (5) better Views -
> AVMAP
> >  Dead-Reckoning!
> > 
> > 
> > I fear you may be misinterpreting Dead Reckoning.  No
> one should
> > expect a DR line to stay on the road.  The function of
> the DR line is
> > to show the passage of time and distance visually since
> the last known
> > update.  Of course it is probably off the road.  But
> that is not what
> > DR is trying to convey.  It is trying to convey the
> age of the
> > position in time and the growing error of the position
> in distance in
> > an instantly visual way.
> > 
> > Hope that helps.  It is really great to see it on
> APRS.FI and now on
> > the AVMAP GPS display when pluggedin to a D72 or D710
> radio as well as
> > most of the modern clients.
> > 
> > Bob, WB4APR
> > 
> > -----Original Message-----
> > From: aprssig-bounces at tapr.org
> [mailto:aprssig-bounces at tapr.org]
> On
> > Behalf Of Dave B Sent: Sunday, September 23, 2012 9:45
> AM To:
> > aprssig at tapr.org
> Subject: Re: [aprssig] News from DCC (5) better Views
> > - AVMAP Dead-Reckoning!
> > 
> > The only problem with DR Bob, is it only realy works
> with straight
> > roads and constant speeds, or in marine/aironautical
> environments etc
> > (where it came from of course.)
> > 
> > In mountain regions, or other countries (UK/EU) where
> few of the roads
> > are straight (except those made by the Romans many
> 100's of years ago)
> > it rapidly turns into a comedy feature.
> > 
> > In such cases, mobile objects stray off the road/track
> for quite a
> > distance, before coming back on track when the next
> posit is sent (if
> > it's picked up.)   If a few posits are missed, then
> the object is
> > stranded in the wilds for quite some time.   Somehow,
> I think it's
> > worse with DR than without.
> > 
> > I know you dislike Smart Beaconing, but that works
> better in varied
> > terrain than DR in my view.   Others may disagree,
> it's a free world
> > (alegedly.)
> > 
> > 73.
> > 
> > Dave G0WBX.
> > (sort of using YAAC as a creaky satnav while in the
> US.  Not made it
> > talk to my D7 successfully yet, one or the other seems
> to get p'd off
> > with something.)
> > 
> > 
> > On 22 Sep 2012 at 11:18, Robert Bruninga wrote:
> > 
> > > Don W6GPS demonstrated a beta test of the next
> release of AVMAP GPS
> > > display software that can now display all of the
> APRS stations on
> > > the GPS map but with all moving stations DEAD
> RECKONED IN REAL TIME.
> > > Meaning, now you can see where people really
> probably are, and not
> > > where they were minutes ago.
> > >
> > > Traveling in parallel with other APRS mobiles and
> using many
> > > existing clients is a joke.  THe ICONS pop up on
> the map, but then
> > > are stuck there as time continues to move on, and
> the ICON stays
> > > stuck on the road a few miles back, until it again
> snaps ahead and
> > > again is obsolete seconds after it was
> transmitted.
> > >
> > > WIth DR, the DR indication moves smoothly down the
> road, so you can
> > > always see where he is relative to where you are.
> > >
> > > Dead Reckoning of live moving symbols on APRS was
> FUNDAMENTAL to
> > > APRS 2 decades ago but was ignored by many
> clients.  Fortunately now
> > > AVMAP, YAAC and APRS.FI and most newer clients
> (APRSIS32) are
> > > including this as the default.
> > >
> > > Everyone can see how DR works, by just zooming
> into a moving mobile
> > > on APRS.FI.  The track leads the symbol in real
> time.  Though this
> > > is not my ideal choice of display (I prefer to see
> the symbol move
> > > along with its CSE/SPD leader with an anchor back
> to last known
> > > position) but it still lets you see where he
> really is...
> > >
> > > Bob, WB4A
> > >
> > >
> > >
> > 
> > 
> > 
> > 
> > _______________________________________________
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> > 
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> > 
> > 
> > 
> 
> 
> 
> 
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