1SOUNDMODEM(9)               Kernel Reference Guide               SOUNDMODEM(9)
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NAME

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

9       #include <linux/soundmodem.h>
10       #include <linux/hdlcdrv.h>
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DESCRIPTION

14       The  driver  currently  supports  both 1200 baud AFSK and 9600 baud FSK
15       (G3RUH compatible) using a standard SoundBlaster compatible or Windows‐
16       SoundSystem  compatible  soundcard. The whole decoding is done in soft‐
17       ware, so you definitely do not want to use it on a 386SX class machine.
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KEYING THE TRANSMITTER

21       Soundcards do not have a DC coupled output that could serve  as  a  PTT
22       signal.  So  there  are basically for possibilities for obtaining a PTT
23       signal.    Sample    schematic    diagrams    can    be    found     on
24       http://www.ife.ee.ethz.ch/~sailer/pcf/ptt_circ/ptt.html.
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26   VOX circuitry
27       A simple VOX circuitry that detects output signals at the output of the
28       soundcard can be used, especially as it can  be  built  with  a  single
29       transistor  plus  a  few passive components and typical soundcards have
30       strong output signals.
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32   Parallel Port
33       A parallel port line can also be used to signal PTT. If  selected,  the
34       PTT  signal  is output on the DATA0 line and DCD is output on the DATA1
35       line.
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37   Serial Port
38       A standard serial port (8250, 16450, 16550) can also be used to  output
39       PTT. PTT is output on RTS and TxD, while DCD is output on DTR.
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41   MPU401 MIDI Port
42       The  MIDI  port  is basically an asynchronous serial interface and thus
43       cannot output a straight DC level, however it may be used if  connected
44       through  a  retriggerable monoflop with about 15ms pulse duration. Note
45       that only newer SoundBlaster models have a genuine  MPU401  MIDI  port.
46       The older SB MIDI port cannot be used.
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IOCTL CALLS

50       The ioctl calls follow the implementation in the hdlcdrv.
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53       SMCTL_GETMODEMTYPE
54              returns  the  modem  type  (i.e.  SBC1200,  SBC9600,  WSS1200 or
55              WSS9600)
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57       SMCTL_SETMODEMTYPE
58              sets the modem type. Only superuser can do this.
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60       SMCTL_GETMIXER
61              returns the mixer type and the contents of the  specified  mixer
62              register.
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64       SMCTL_SETMIXER
65              sets  the  specified mixer register, if the specified mixer type
66              matches the mixer type of the soundcard. Only superuser  can  do
67              this.
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69       SMCTL_DIAGNOSE
70              returns  the  contents  of the diagnose buffer, which is used by
71              smdiag to display the eye and oscilloscope diagrams.
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73       SMCTL_GETDEBUG
74              return some debugging values. Not always available.
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SEE ALSO

79       baycom  (9),  soundmodem  (9),smdiag   (8),smmixer   (9),   linux/driv‐
80       ers/net/hdlcdrv.c,
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AUTHOR

84       soundmodem    was    written    by    Thomas    Sailer,   HB9JNX/AE4WA,
85       (t.sailer@alumni.ethz.ch).
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89Linux 2.1.x                     2 October 1996                   SOUNDMODEM(9)
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