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[aprssig] New Twist on APRN!

Stephen H. Smith wa8lmf2 at aol.com
Sat Apr 3 00:16:39 UTC 2010


I have been implementing APRN - Automatic Picture Reporting Network 
(combined SSTV and APRS) using various hardware TNCs to decode the Mic-E 
position burst, following the SSTV transmission decoded by the PC sound 
card running mmSSTV.    This has meant various messy forked audio cables 
to supply the same RX audio to the TNC and to the computer sound card.   
(Of course the lazy but expensive way to do this would be to tie up a 
D700 so that it's internal TNC, and computer sound card via the mini-DIN 
"data" jack,  can hear the same RX audio. But you would still need a 
serial port on the PC.)

I just redid my Ham "Super Server" software that runs three instances of 
UIview for my personal APRS webserver, mmSSTV and another instance of 
UIview for the APRN system on UHF, and Echolink on UHF.     Details here:

    <http://wa8lmf.net/EPIAserver> 

The APRN gateway and the Echolink node have always shared a single radio 
and UHF RF channel.  However, in the past I was running TWO sound 
systems (one for mmSSTV and a second one for Echolink) -AND- a KPC3+ for 
the APRN packet bursts.

During the upgrade of the operating system from Windows 2000 to WinXP 
SP3, I accidentally discovered that unlike Win 2000, XP can allow MORE 
THAN ONE APPLICATION TO USE THE SAME SOUND CARD AT THE SAME TIME!

I now am running a totally software-based APRN  setup.  I have a radio 
connected to the sound system LINE input and LINE output of a Dell L866r 
mini-tower PC. [This is a 866 MHz Pentium III PC running WinXP SP3 in 
512K RAM; i.e. not a bleeding-edge super-screamer maxed-out 
machine.]       The same RX audio from the same sound card input is 
being used simultaneously by mmSSTY, the AGW Packet Engine soft TNC for 
packet, -AND- Echolink ! 

It really works!    The transmitted SSTV pics show up in mmSSTV.  The 
packet bursts decoded by AGWpe show up on the UIview map.  The Windows 
Task Manager shows only about 10-15% CPU utilization and only about 320K 
RAM in use.  And NO serial ports or pain-in-the-neck USB<-->serial 
dongles required!


Running Echolink was the ultimate torture test of this sound card 
sharing.  In actual use, for the receive-only APRN setup, I will be 
running a Bearcat 760 scanner's "tape recording" output into the PC 
sound system with "just" AGW  and mmSSTV sharing the single sound card 
as a turnkey ready-to-go APRN package. 

------------------------------------------------------------------------

-- 

Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

NEW!    Universal HF/VHF/UHF Antenna Mounting System
 http://wa8lmf.net/mobile/UniversalAntMountSystem.htm

"APRS 101"  Explanation of APRS Path Selection & Digipeating
 http://wa8lmf.net/DigiPaths

Updated "Rev H" APRS            http://wa8lmf.net/aprs
Symbols Set for UI-View,
UIpoint and APRSplus:








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