bionic (9) soundmodem.9.gz

NAME

       soundmodem - amateur (AX.25) packet radio network driver for soundcards

SYNOPSIS

       #include <linux/soundmodem.h>
       #include <linux/hdlcdrv.h>

DESCRIPTION

       The  driver  currently supports both 1200 baud AFSK and 9600 baud FSK (G3RUH compatible) using a standard
       SoundBlaster compatible or WindowsSoundSystem  compatible  soundcard.  The  whole  decoding  is  done  in
       software, so you definitely do not want to use it on a 386SX class machine.

KEYING THE TRANSMITTER

       Soundcards  do  not have a DC coupled output that could serve as a PTT signal. So there are basically for
       possibilities  for  obtaining   a   PTT   signal.   Sample   schematic   diagrams   can   be   found   on
       http://www.ife.ee.ethz.ch/~sailer/pcf/ptt_circ/ptt.html.

   VOX circuitry
       A simple VOX circuitry that detects output signals at the output of the soundcard can be used, especially
       as it can be built with a single transistor plus a few passive components  and  typical  soundcards  have
       strong output signals.

   Parallel Port
       A  parallel  port line can also be used to signal PTT. If selected, the PTT signal is output on the DATA0
       line and DCD is output on the DATA1 line.

   Serial Port
       A standard serial port (8250, 16450, 16550) can also be used to output PTT. PTT is output on RTS and TxD,
       while DCD is output on DTR.

   MPU401 MIDI Port
       The  MIDI  port is basically an asynchronous serial interface and thus cannot output a straight DC level,
       however it may be used if connected through a retriggerable monoflop with about 15ms pulse duration. Note
       that  only  newer  SoundBlaster  models have a genuine MPU401 MIDI port. The older SB MIDI port cannot be
       used.

IOCTL CALLS

       The ioctl calls follow the implementation in the hdlcdrv.

       SMCTL_GETMODEMTYPE
              returns the modem type (i.e. SBC1200, SBC9600, WSS1200 or WSS9600)

       SMCTL_SETMODEMTYPE
              sets the modem type. Only superuser can do this.

       SMCTL_GETMIXER
              returns the mixer type and the contents of the specified mixer register.

       SMCTL_SETMIXER
              sets the specified mixer register, if the specified mixer type  matches  the  mixer  type  of  the
              soundcard. Only superuser can do this.

       SMCTL_DIAGNOSE
              returns  the  contents  of  the  diagnose  buffer,  which is used by smdiag to display the eye and
              oscilloscope diagrams.

       SMCTL_GETDEBUG
              return some debugging values. Not always available.

SEE ALSO

       baycom (9), soundmodem (9),smdiag (8),smmixer (9), linux/drivers/net/hdlcdrv.c,

AUTHOR

       soundmodem was written by Thomas Sailer, HB9JNX/AE4WA, (t.sailer@alumni.ethz.ch).