[OZAPRS] WIFI for events

[Mark Cheeseman]

Andrew Rich wrote:
> We are considering using WIFI 2.4 GHz for a horse enduro next year.
> 
> Has anyone used wifi for such events ?

Hi Andrew,

I've often thought it would be nice, but the topography of most of our 
events doesn't lend itself to 2.4GHz paths. But if you can do it, it 
makes the whole project little more than a basic web dev job.

> We are also working on traditional 1200 baud packet.
> 
> The base will be running a LINUX based database.
> 
> http://vk4tec.no-ip.org/horse_enduro/

Looks interesting. It could probably extend to any number of events 
where tracking competitors is needed. Car rallies, horse enduoros, boat 
races, fun runs. The basic requirement is pretty much the same. The 
challenge I've found is keeping channel traffic down to such a level 
that even with unexpected peaks in traffic, you don't get the sort of 
congestion that quickly brings a connected AX.25 channel to its knees.

> I understand you can also surf over 1200 baud packet ?

I wouldn't bother. The overheads would quickly clog up the channel if 
things get even moderately busy. A better approach IMO (which we've 
half-tried) is some intelligence on the client machines, so that data 
entry and validation is done at the checkpoint and then it just sends a 
short AX.25 packet to the server, where a little script takes care of 
the database insert. The challenge then is you also need to write an 
interface for every platform people want to run in the field.

You also need a way to query the database - a web/PHP interface is easy 
for WiFi, but again, minimising overhead is critical on busy packet 
links. So it needs some intelligence on the client so that verbose menus 
and responses aren't sent back and forth.

I'd interested in collaborating on something like this if I can find the 
time. It's similar to some stuff a few of us in VK2 have been thinking 
about on and off for a few years.

Cheers,
Mark VK2XGK

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