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[aprssig] APRS traffic collection

Scott Miller scott at opentrac.org
Sun Apr 20 00:05:24 UTC 2008


A while back, WA8LMF went to a lot of trouble capturing and editing some 
  great real-world traffic samples from 144.39 in the LA area during 
rush hour.  The resulting TNC test CD has been extremely useful to me 
and a number of other software and hardware developers, as well as end 
users who just want to know how well their equipment is working.

The CD represents only one area, though, and one radio.  I'd like to get 
samples from more locations and with different hardware, so I'm asking 
for the help of the APRS community.

If you're interested in helping out, you can use your favorite recoding 
software, or try a piece of freeware like Vox Recorder 
(http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3985) - I haven't used 
that one myself but it's designed for scanner monitoring and should be 
able to exclude periods of silence.  I'm not sure what the sample rate 
is, but as long as it's at least 16 kHz it should be OK.  Recordings 
should be at least 10 minutes of traffic, but check with me first if you 
want to upload more than about 1 GB at a time.

Hardware setup can be as simple as a patch cord between a scanner's 
earphone jack and your PC's line in.  Just as long as it's a good 
hardwired connection and not a mic held up to the speaker!

I'll take open squelch recordings too, but squelched samples have the 
benefit of being easy to condense down to just the actual traffic.  If 
you feel like manually editing open squelch recordings to cut out dead 
air, that's great.

You can upload recordings (in WAV or AIFF format, please, no lossy 
compression) by FTP to n1vg.net, username 'aprs', password '14439'.  Tag 
the filename with your callsign so I know who to credit, and be sure to 
use binary file transfer mode.  It'd also help to know if it was 
recorded from a 'flat' source (no de-emphasis, e.g. service monitor or 
9600 baud output) or from a regular speaker output.

I'll freely publish everything usable that I get.  A larger set of 
sample data should let all of us developers better tune our stuff to 
work with real-world signals, and it'll probably be useful for any 
researchers who want to analyze aspects of network performance that 
don't show up on the APRS-IS.

And just to give everyone a little incentive to contribute, I'll collect 
submissions through 5/1/2008 and randomly pick one contributor who'll 
get a new PX-777 HT 
(https://www.argentdata.com/catalog/product_info.php?products_id=74), or 
Tracker2 if they prefer.

Thanks everyone!

Scott
N1VG





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