[aprssig] Marrying APRS & Doppler - Was: aprssig Reading APRS beacons w/Dopplers?

[Robert Bruninga]

Yes, APRS DF formats include a quality field and also
a Distance field.  The distance field is important to
limit the bearing lines to only that area of interest
and not infinitly long.  If you are zoomed into the
8 mile range, then the vectors are only 8 miles long.
If you are down to the final mile and on the 1 mile
range, then your DF vectors are only 1 mile long.

This vastly improves the visibility of the maps that
others are seeing no matter what scale they are on.
Without this, an observer looking at a 128 mile
range scale map would see total gyberish, with DF
bearings in ALL directions as the DF unit circled into
the source.  But with the vector lengths limited to
only the range scale of the SENDER, then these
vectors are no longer than the best info available
as to the location of the signal.

de WB4APR, Bob

>>> noskosteve at yahoo.com 03/16/06 6:05 PM >>>
  Bob,
   
  I'm also aware of the interpretation issue and would not consider a non-human button pusher (see below).  I'm referring to automatically reporting the (human selected) bearings from the hound(s) to a central location (or any hunter) to do the triangulation for the best estimate fox lat/Lon.  Each time a bearing is reported by a hound, it is reported via APRS.  Anyone can grab them (thanks to APRS) and put them on the map and the SW will do the triangulation.  One can drive around and do the pushing, or several hounds can do the pushing and the "system" will give the best estimate Lat/Lon.  My code does up to five fixes. Neat and very possible (with the required software).
   
  That being said, however, I can imagine that looking at the last so-many bearings from the Doppler, one could define a quality factor and consider automatically sending a bearing only when the quality is 'good', or sending the quality factor and including it in the calculation. This is something I already have in my code because even with manual bearings, each hound will have a confidence factor in his bearing and that can be put into the calculation.   I borrowed the concept from computer generated curves and surfaces so common in in the modern CG films, so that part is a piece of cake.  Getting all the boxes to talk is beyond me right now.
   
  Dave, 
     As I said, I fully understand that the Doppler is not the ideal tool.  It doesn't do everything, all the time, the best way.  There are also very easy ways to mess up an otherwise good concept.  I have been involved / interested in DF since the Navy around '65, and have some ideas I want to try which I think can improve the Doppler, but until I have one running, I can't brag; just try these ideas and either do good, or say it was fun trying.
   
  Do you know what (brand) Dopplers have you seen that have so much trouble with FSK?  This makes perfect sense and is precisely why I asked about the affect of APRS Squawks on them.  I have the Greany board and the design looks pretty good.  Without going into a full resume, I also have access to some pretty good test gear and a full understanding of what's going on inside and out (vagarious nature the RF ocean in which we live).
   
  Out of curiosity, what's your weapon(s) of choice?
  Which Doppler is in your basement?
  73, Steve, K9DCI
  ==========================================
  Date: Thu, 16 Mar 2006 09:23:06 -0500
From: "Robert Bruninga" <bruninga at usna.edu>
Subject: Re: aprssig Reading APRS becons w/Dopplers?

  ...  it is best to interrupt that interface with a push button.
Only the human eyeball and brain has the sense to interpret the data ...
  ...  having it garbage up the entire APRS display with garbage, I finally put a push button on the front panel ...
  
This worked beautifully..  de Wb4APR, Bob
==============================
  Date: Thu, 16 Mar 2006 09:50:00 -0500
From: "David  Odom" <dodom at mindspring.com>
Subject: Re: aprssig Reading APRS becons w/Dopplers?

  ...  I have found being able to listen to the receiver output will help in determining what is useful date and what is garbage.
I have participated in a fox hunt almost every month for 3 years and my 
Doppler is still in the basement.  So far I am first to the fox as 
often as anyone without the hassle of setting up the Doppler.  By the way you can forget using Doppler with digital signals such as posag paging.  True FSK confuses the Doppler big time.    Dave   W4VOR 
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