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[aprssig] SSID for RF only Station with backup power

Joel Maslak jmaslak-aprs at antelope.net
Mon Apr 9 23:26:03 UTC 2007


On Apr 9, 2007, at 4:17 PM, Robert Bruninga wrote:

> * Being there are less than 7 APRS symbols left
> * Being that there are many many more ideas to go
> * Therefore, APRS must expand its symbol set by using OVERLAYS
> * We need concurrence from all authors on receipt of an overlay:
>   - Receipt on all existing "overlyable characters works"
>   - Receipt on any other symbol will not break anything
>   - Eventually receipt of the overlay may be displayed somehow
>   - An overlay on a base symbol can trigger a different symbol


Maybe the idea of symbols is wrong?

I have no desire to know whether or not someone is using solar  
power.  Very likely someone else does.  When mobile, I don't care  
about anyone but other mobile stations generally.

It APRS had a faster signal rate (maybe 1200 is enough now that we've  
decided 500 ms is an okay tx-delay...), you could have an "icon  
packet" that included the bitmap.  A 16x16 bitmap is 256 bits - if  
you had 8 bit clear channel, you could send that in only 32 bytes.   
Of course APRS isn't 8 bit clear, so it's going to be more like 40  
bytes (base-91).  That is .26 seconds or so additional traffic...you  
could even tack it on after whatever the length of the comment that  
the Kenwoods truncate is (since long comments have become useless  
with the introduction of the D7/700 radios).  And if someone  
complains about the extra traffic, shortening the Kenwood TX-delay a  
bit might offset the increased bandwidth).  In addition, the icon  
might only need to be sent once per net-cycle time or maybe even less.

For internet-connected displays (probably a good chunk of them) you  
could even bounce that 40 byte icon off of some public web service  
that returns the icon made to look pretty - color, higher resolution,  
etc - which the client could then cache for offline use.  Maybe even  
provide a way of updating your icon list before you take a machine  
out to the field.  Then so long as people used a registered icon,  
you'd be able to display it pretty, and if it wasn't a registered  
icon it would still display, just not in high resolution or color.

The reality is that a large number of icons is not useful.  Does the  
station move?  That's important to know sometimes.  Is it  
infrastructure or is there a human near it - that's important but is  
impossible to determine from the current use of icons.  That's pretty  
much what I need to know.  90% of the time, if I was doing something  
where I needed to track things, I already know the callsign or  
tactical call.  Certainly there is a "gee-wiz" part of making the  
ambulance look like an ambulance, but only if I care about the  
ambulance or I am *not* doing anything on APRS of any importance (so  
I'm playing, not doing an exercise or something).

The other problem is that we could have 60,000 icons and someone will  
come up with "Well, that bicyclist is riding an upright bike and I  
ride a recumbent" while the next person will say "and I have a  
trailer behind my upright bike", etc.  And thus most programs will  
end up supporting incompatible subsets of available icons.




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