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

Heikki Hannikainen hessu at hes.iki.fi
Sun Sep 23 22:32:14 UTC 2012


Yes, agreed - dead reckoning's benefits come from the visualisation of the 
probable error in the displayed position ("how far would have the vehicle 
gotten at the speed it was doing at the time it transmitted the position") 
as much as from the indication of a possible current position. I find it 
easy to make a guess where the station is based on the shown range (given 
that often I'm aware of the station's intended destination).

On Sun, 23 Sep 2012, Robert Bruninga wrote:

> 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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   - Hessu




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