[aprssig] Aeronautical Mobile Best Practices?

[Heikki Hannikainen]

On Tue, 31 May 2011, Joe Dubner wrote:

> Heikki Hannikainen <hessu at xxx> writes:
>> Mic-E generally works fine - I would not make such a recommendation!
>
> For terrestrial, sure, but I can't agree in the case of aeronautical mobile 
> due to its limited usage vs. the ease of troubleshooting ASCII.
>
> Please help me see the attractiveness of Mic-E.  Assuming a Mic-E packet is 
> about 20 characters shorter (1/6th second at 120 characters per second), 60 
> packets per hour would cost 10 seconds of additional bandwidth for each hour 
> of flying time.  With so few airplanes and flying so few hours, isn't this 
> just "lost in the noise level".  There are much bigger gains to be had with 
> proper beacon rate, path, etc.

The gained channel time could be small when compared to tuning rates and 
paths, but it comes cheap, just a flip of a switch to enable mic-e. You 
can multiply the 10 seconds by the area your transmitter is getting heard 
at to figure out the true amount of saved channel time. When you save 10 
seconds at your flying altitude, the saving happens at a very large 
geographical area when compared to a terrestial transmitter.

Also, I don't see much problem in debugging mic-e packets, just look up 
http://aprs.fi/?c=raw, flip the switch from "Normal" to "Decoded" and 
you'll see what's in there according to the Ham::APRS::FAP decoder. You 
only need to actually decode the packets in your head when you're 
developing software to encode or decode the packets, which I admit can be 
tricky.

http://aprs.fi/?c=raw&call=OH7LZB-8&limit=5&view=decoded

   - Hessu