Admin at 11:01, 8 November 2014

2014-11-08T11:01:54Z

New page

<pre>
/etc/ax25/soundmodem.conf
</pre>

Soundmodem is a technique to use an ordinary sound card as an analogue-to-digital converter like a TNC does.

<pre>
<?xml version="1.0"?>
<modem>
<configuration name="AX25">
<chaccess txdelay="1000" slottime="100" ppersist="40" fulldup="0" txtail="100"/>
<audio type="alsa" device="plughw:0,0" halfdup="1" capturechannelmode="Mono"/>
<ptt file="none" gpio="0" hamlib_model="" hamlib_params=""/>
<channel name="sm0">
<mod mode="afsk" bps="1200" f0="1200" f1="2200" diffenc="1" inlv="8" fec="1" tunelen="32" synclen="32"/>
<demod mode="afsk" bps="1200" f0="1200" f1="2200" diffdec="1" inlv="8" fec="3" mintune="16" minsync="16"/>
<pkt mode="MKISS" ifname="sm0" hwaddr="VK2HAQ-1" ip="44.128.0.2" netmask="255.255.255.0" broadcast="44.128.0.255" file="/dev/soundmodem0" unlink="1"/>
</channel>
</configuration>
</modem>
</pre>

Noteworthy in this file are the following parameters:

* txdelay -- set this to be long enough for the radio to open on transmit (default is 250ms)

* plughw:0,0 -- points to the first sound card (1,0 would point to the second), make sure the order is configured properly (see here (page missing))

* ifname -- this needs to match the network interface and is also referenced in [[Rpi-aprs-axports]]

* hwaddr -- set to the callsign (including the SSID) as seen in [[Rpi-aprs-axports]] and [[Rpi-aprs-aprx.conf]]

* ip, broadcast -- use same network settings when starting [[Rpi-aprs-soundmodem]]

* file -- points to the /dev/soundmodem character device, even though the system will not show it in /dev (do not use the sm0 interface)

Rpi-aprs-soundmodem.conf - Revision history

Admin at 11:01, 8 November 2014