[aprssig] APRS RFID apps? (MAP list)

Bob Bruninga bruninga at usna.edu
Thu Feb 11 09:13:27 CST 2010

> I think fudging coordinates at the source 
> is just asking for trouble....

> You will have no control over where this 
> lands for programs using zoomable, scrollable 
> maps such as UIview, APRSplus or APRSpoint, 
> findu or aprs.fi .  If the user happens to 
> have their zoom level one step out, the 
> calls will overlap and be unreadable. 

Not at all.  It solves all those problems.  The table list is built on the surface of the earth.  It has nothing to do with any particular map, zoom, resolution or anything. It is built at a location that is chosen by the person placing the HotSpot to not interfere with any other posits near-that-site.  

Anyone with any client can see it with any map, or zoom to any scale and see it.  Yes, they will have to zoom to a certain level before the calls will be distinct, but heck, if one wants to see who is in the arena, then it only makes sense to zoom to a scale where the arena is visible.  And that is the scale where it will appear distinct on any client.

>Bob Bruninga wrote:
>>> Therefore for APRStt and RFID I think it best 
>>> to clearly show up on the map as a distinct 
>>> vertical table located in a logical place 
>>> on the map.
>> So what APRS application can do this?    
>>> All of them.    
>>> The list formation is done at the transmit site 
>>> by incrementing the latitude by 0.01 from an 
>>> origin location and that way the list shows 
>>> up on all clients of all kinds.  You can see what
>>> it looks like as implemented in APRStt at Dayton 
>>> last year.  See he APRSdos map (3rd image down on)
>>> www.aprs.org/aprstt.html
>>> The APRStt PC is located at the red X in the 
>>> middle of the buildings.  But any DTMF user that 
>>> did not send a position, just his call, was 
>>> placed on the map on the left edge.  Uview and 
>>> any other client would have displayed the same 
>>> thing.  That left edge location was chosen 
>>> because it is a grove of trees where no one 
>>> would normally be.
>>> The next image on that page shows how such a 
>>> list is made by an APRStt in a larger area at  
>>> the 147.105 rpeater.  There, DTMF callsigns 
>>> are incremented by 0.1 mile because the range 
>>> of that APRStt is much larger and people will 
>>> be looking at that area on a larger scale.
>> Bob, Wb4APR

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