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[aprssig] OBJ engine on APRS-IS (Naming)

Heikki Hannikainen hessu at hes.iki.fi
Fri Feb 24 15:28:14 UTC 2012


On Fri, 24 Feb 2012, Charles Blackburn wrote:

> Ok so, object names are case sensitive, so you can (using your example) have
> LEADER-1, leader-1, LeadeR-1 as three individual objects ?

I guess that's not a very popular implementation. Might be worth checking 
how others do it (mine is case insensitive, so they're the same object). I 
also think that case sensitivity like that would be unfriendly to the end 
users.

> The problem I have with the co-ordinates is that hessu's library only
> supports decimal degrees for lat/long. So everything has to be in that
> format. While I personally prefer dd.mm.ss those pesky euros have to 
> have it different :P so I'm contrained to that.

Umm, it's not just us europeans, it's programmers everywhere in general. 
Storing coordinates internally in decimal degrees allows them to be stored 
in a single numeric variable (floating point or integer), instead of a 
string or a set of numeric variables for degrees, minutes, maybe seconds. 
It also makes it easy to do calculations (distance, bearing...) between 
coordinate pairs, avoids the work of converting a dd.mm.ss string to 
degrees every time before such calculations.

You're not constrained by the API of the library when doing your user 
interface. Simply convert on input/output according to the user's 
preferences.

> I guess I could convert to dms, but as far as the actual packets goe, I 
> am limited to that.

Um, what? The library uses APRS standard coordinates (degrees and decimal 
minutes, DDDMM.MM) for the actual packets it transmits, and the respective 
magic encodings for mic-e and compressed formats. The software API just 
uses degrees internally for convenience, consistency and performance.

   - Hessu




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