MAN page from Mandrake Other ax25-utils-2.1.42a-3.i386.rpm
SOUNDMODEM
Section: Kernel Reference Guide (9)
Updated: 2 October 1996
Index 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 donein software, so you definitely do not want to use it on a 386SX classmachine.
KEYING THE TRANSMITTER
Soundcards do not have a DC coupled output that could serve as aPTT signal. So there are basically for possibilities forobtaining 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 ofthe soundcard can be used, especially as it can be built with a singletransistor plus a few passive components and typical soundcards havestrong 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 theDATA1 line.
Serial Port
A standard serial port (8250, 16450, 16550) can also be used to outputPTT. 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 andthus cannot output a straight DC level, however it may be used ifconnected through a retriggerable monoflop with about 15ms pulseduration. Note that only newer SoundBlaster models have a genuineMPU401 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, WSS1200or WSS9600)
- SMCTL_SETMODEMTYPE
- sets the modem type. Only superuser can do this.
- SMCTL_GETMIXER
- returns the mixer type and the contents of the specifiedmixer register.
- SMCTL_SETMIXER
- sets the specified mixer register, if the specifiedmixer 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 bysmdiag 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, (sailerAATTife.ee.ethz.ch).
Index
- NAME
- SYNOPSIS
- DESCRIPTION
- KEYING THE TRANSMITTER
- VOX circuitry
- Parallel Port
- Serial Port
- MPU401 MIDI Port
- IOCTL CALLS
- SEE ALSO
- AUTHOR
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