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1995-01-16
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DTMF decoder DEMO version
Shima-nized Advanced Utilities - J.M. Shima
Copyright (c) 1994-95 by James Shima
All Rights Reserved
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▐▐▐▐ R E F E R E N C E M A N U A L ▐▐▐▐
» Type DTMF_D at the DOS prompt for a summary of options «
INTRODUCTION
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* This program is capable of post processing DTMF tones and decoding the
numbers from a given input sound file. The sound file has to be sampled
at a 8kHz sampling rate. One application where DTMF tones are used
is in the standard American telephone dialing system. The standard
DTMF tones represent the numbers 1,2,3,4,5,6,7,8,9,0,*,# on a standard
keypad interface.
* The source sound file has to be binary or a Soundblaster 8-bit .VOC file.
* This program accepts COMMAND-LINE ARGUMENTS that are passed to the
DTMF decoder.
* For a list of the arguments, type DTMF_D at the DOS prompt.
* The DEMO only decodes a maximum of 5 numbers. Interested
persons can purchase the full-blown REGISTERED version with no limitations.
* An example of the input arguments are:
Usage: DTMF_D <in_file> <thresh> <sblast>
<in_file> --> input sound file name.
<thresh> --> The threshold that the DTMF tones must exceed over the
noise floor for detection (in dB). Typically, strong
DTMF tones will be 20-40 dB stronger than the noise
in the signal. However, noisy signals lower this
signal-to-noise (S/N) ratio. The threshold parameter
allows the user to set the S/N threshold for detection.
NOTE: If nothing is entered, then the default thresh value
is 20dB.
<sblast> --> Set to this to a 1 for a Soundblaster .VOC file, else set
it to 0. NOTE: If nothing is entered, the default is 1, i.e.
a .VOC file is selected.
IMPORTANT NOTES BEFORE USE
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** For the DEMO program, your input .VOC or binary file * MUST BE SAMPLED *
at a 8kHz rate (no exceptions) for correct results.
The industry standard for DTMF sampling is 8kHz, and this demo program
uses that sample rate in its calculations!!
** A binary file consists of samples that are stored as 2's complement
numbers. In other words, the samples take on values from [-128, 127].
EXAMPLES OF RUNNING DTMF_D
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DTMF_D dtmf800.voc 25 1 --> input file is dtmf800.voc, threshold S/N
ratio is 25dB, soundblaster .VOC file type is
selected.
DTMF_D dtmf800.voc --> input file is dtmf800.voc, threshold DEFAULTS
to 20dB S/N ratio, soundblaster file type
is selected by DEFAULT.
DTMF_D junk.dat 20 0 --> input file is junk.dat, thresh=20dB, binary
file type is selected.
INCLUDED FILES
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DTMF_D.EXE --> DTMF demo decoder.
DTMF800.VOC --> DTMF number 1-800-555-1212 stored in a .VOC file.
DTMF_1.VOC --> DTMF number 1 stored in a Soundblaster .VOC file.
DTMF_7.VOC --> DTMF number 7 stored in a Soundblaster .VOC file.
DTMF_D.DOC --> This file.
REGISTER.DOC --> Registration form.
REGISTRATION
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** For registration, please fill out REGISTER.DOC and see the DEMO screen.
Specify media dispersement.
The enhanced REGISTERED version of this program allows unlimited decoding
of numbers, and offers many other features INCLUDING:
1) File types supported include: .VOC, .WAV, and raw signed binary files.
Input file types are auto detected.
2) Fast detection mode, which doubles the speed of decoding.
3) Flexible sampling rate. The program adapts to sample rates other than
the standard 8kHz.
4) Automatic logging of the resulting decoded numbers to a log file.
5) Multiple-file input mode, so uninterrupted decoding and logging happens
without user intervention.
** REGISTERED users will also receive a DTMF generator program. This is
a DTMF tone generator which allows you to create any DTMF sequence
you wish. The program allows you to specify a DTMF number sequence,
the sampling rate, and how long you want the pulses to be (in samples).
SOFTWARE LICENSE
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The DEMO version of the DTMF decoder is shareware, and is free to be
used for personal use only. This is true as long as the DEMO is
not alterted in any fashion. Registered users will receive the enhanced
version of the DTMF decoder and will receive documentation stating such.
I have thoroughly tested this code and am not responsible for any mishaps
that may happen when launched on your computer. The code was tested on
a IBM compatible 25MHz 386DX PC with a Soundblaster Ver. 1.5, 8-bit sound
card, running DOS 5.0. For optimal performance, DO NOT run this program
while under Microsoft Windows.
Every action has been taken to ensure an error-free program.
Use this program at your own risk, as I assume no responsibility in your
actions while you are using this program. Invoking the program is your
compliance to this statement.
Good luck!
For more information,
email: James Shima
shima@eel.ufl.edu
TRADEMARKS
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Soundblaster and Creative Voice File are trademarks of Creative Lab's Inc.
Microsoft Windows and DOS are trademarks of Microsoft.