[aprssig] daft UI-PATH's

[Steve Dimse]

On May 30, 2005, at 11:13 AM, Jack Cavanagh wrote:

> John, EI7IG asked:
>
>> I was wondering if anyone had looked at an automated method of  
>> grabbing
>>
>
> these packets and trying to do an 'after the fact' analysis of the  
> propogation paths.
>
> Yes, they have
> www.propnet.org
> this uses PSK31 for Hf and APRS for VHF.
>
Sorta. The data on all bands is an APRS compatible format, the link  
layer varies. Some PSK31 happens on 6 meters, but most is AX-25 like  
APRS uses. There is some AX-25 on 10 meters, but most is PSK31, and  
all PropNet activity below 10 meters is PSK31.

There is a separate internet hub called Live-X, and findU has support  
for propnet here:

http://propnet.findu.com/

The animated GIFs are especially cool, if a little large (roughly 2 MB).

There is another site that claims to extract this info from the APRS  
Internet System, I don't have the URL handy, but having designed the  
APRS Internet System, I can say that it is ill-suited to propagation  
studies. Path information and duplicates are deliberately removed to  
lower bandwidth requirements, and it is this data that is needed to  
draw any sort of conclusion about propagation. His charts are pretty  
though, so people tend to believe them. Unfortunately he does not  
include any discussion on his site about the problems with  
interpreting the APRS Internet System data the way he does, he  
presents it as fact, which it certainly isn't.

PropNet avoided this pitfall by taking those parts of APRS which  
worked for propagation and developing an independent network that is  
designed correctly for propagation studies.

Steve