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.TH MINIMODEM 1 "July 15, 2011"
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.SH NAME
minimodem \- software audio Bell-type or RTTY FSK modem
.SH SYNOPSIS
.B minimodem --tx
.RI [ options ]
.I {baudmode}
.br
.B minimodem --rx
.RI [ options ]
.I {baudmode}
.SH DESCRIPTION
.B minimodem
is a command-line program which generates (or decodes) audio
modem tones at any specified baud rate, emulating an old Bell-type or
radio-teletype FSK modem.  The tones can be played to (or recorded from)
the PulseAudio system or to an audio file.
.PP
.B minimodem
can be used to transfer data between nearby computers using an audio
cable (or just via sound waves), or between remote computers using radio,
telephone, or another audio communications medium.
.SH "TX/RX MODE"
.TP
.B \-t, \-\-tx, \-\-transmit, \-\-write
transmit mode: generate audio tones
.TP
.B \-r, \-\-rx, \-\-receive,  \-\-read
receive mode: decode audio tones
.SH OPTIONS
.TP
.B \-a, \-\-auto-carrier
automatically detect mark and space frequences from carrier
.TP
.B \-c, \-\-confidence threshold
set receive confidence threshold (0.0 to 1.0, default 0.6)
.TP
.B \-8, \-\-ascii
ASCII  8\-N\-1
.TP
.B \-5, \-\-baudot
Baudot 5\-N\-1.5
.TP
.B \-f, \-\-file filename.wav
encode or decode an audio file (extension sets audio format)
.TP
.B \-b, \-\-bandwidth {rx_bandwidth}
.TP
.B \-M, \-\-mark {mark_freq}
.TP
.B \-S, \-\-space {space_freq}
.TP
.B \-T, \-\-txstopbits {m.n}
.TP
.B \-q, \-\-quiet
Do not report CARRIER / NOCARRIER or signal analysis metrics.
.TP
.B \-V, \-\-version
print program version
.SH {baudmode}
The required \fI{baudmode}\fR parameter may be any floating-point value to
specify a baud rate, or the string "rtty".
The \fI{baudmode}\fR also implies certain other parameter defaults
depending on the rate, including standard (or at least reasonable)
default mark and space tone frequencies.
.TP
.B    1200
	: Bell202  1200 bps \-\-ascii
.TP
.B     300
	: Bell103   300 bps \-\-ascii
.TP
.B    rtty
	: RTTY    45.45 bps \-\-baudot \-\-txstopbits 1.5
.TP
.B  {any floating point value N}
	: Bell-like   N bps \-\-ascii
.SH EXAMPLES
.TP
.B minimodem --tx 100
Transmit 100 baud tones from one computer ...
.TP
.B minimodem --rx 100
and receive 100 baud tones on another nearby computer.
.TP
.B minimodem --rx --auto-carrier rtty
Decode amateur radio RTTY signals (listen near 14.085 MHz).
.TP
.B minimodem --tx 0.5
Experiment with very low baud rates (works in noisy conditions).
.TP
.B minimodem --tx 12000
Experiment with very high baud rates works (works with audio files).
.SH NOTES
.B minimodem
does not decode AX.25 framed packets.
.PP
.B minimodem
does not support modem control ("AT") commands, nor does it produce
DTMF telephone dialing tones.
.SH VERSION
This page documents
.B minimodem
version 0.8.1.
The latest version is available at <http://www.whence.com/minimodem>.
.SH AUTHOR
.B minimodem
was written by Kamal Mostafa <kamal@whence.com>.
.SH COPYRIGHT
Copyright \(co 2011 by Kamal Mostafa <kamal@whence.com>.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
.br
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.