;-----------------------------------------------------------------------;
; README                                                                ;
; (C) 1993                                                              ;
; Walla Walla College                                                   ;
; By: Fred Christensen                                                  ;
;                                                                       ;
; Operating Instructions for the DSP Voice Frequency Companding System  ;
;-----------------------------------------------------------------------;

INTRODUCTION
------------

These are instructions for the use of the DSP Voice Frequency 
Companding System using TI's DSP Starter Kits (DSK).  Note that 
this setup is just a demonstration of what could be possible	
possible with this compandoring technique.  With closer observation
you will note that you must recompile or reload new code in order
to switch between TRANSMIT and RECEIVE modes.  It is possible to 
have this done automatically, but then an input of some kind from
the PTT on the transceiver would need to be made to the DSK.  This
would most likely require some hardware modification which we have
not done yet.  

The following hardware will be needed:
	IBM compatible computer with serial port
	TI's TMS320 DSP Starter Kit (with TMS320C26 DSP)
	Microphone (can use mike on radio)
	Audio Amplifier (maybe depending on mic output)
	Radio Transceiver

The following software files will be needed:
	COMPAND.ASM (Main program code for DSP)
	COEF.ASM (FIR Filter coefficients)
	EXP.ASM (cosine & sine lookup tables)
	DSKA.EXE (Assembler - comes with DSK Kit)
	DSKD.EXE (Debugger Interface - comes with DSK Kit)

These are available via anonymous FTP from ftp.wwc.edu:/pub/compandor or via
gopher from gopher.wwc.edu under Available Code.

PLEASE NOTE:  These files are in UNIX format (no CR).  Also included is a file
called compand.zip which is a pkzip(v2.0) format archive of the same files in
DOS format.  If for some reason you need the DOS format files seperately please
drop a note to ftp@wwc.edu.

HARDWARE
--------

The DSK board should be setup with power and a serial connection to the 
computer as per the DSP Starter Kit instructions.  


Transmit Mode:

Plug the microphone into an audio amplifier.  Run the output of the 
amplifier to the RCA input jack on the DSK board.  The amplifier is
usually needed so that 0-3 volt audio levels are obtained.  Run a cord then 
from the RCA output on the DSK board to the audio/mic input on the
transceiver.  You may need to also connect up the PTT from the mic
to the transceiver, unless you wish to do this manually.  

Receive Mode:

Run a cord from the audio output of the transceiver to the RCA input
jack on the DSK board (check the output levels of the transceiver to
make sure they are in the 0-3 volt range... you may need an amplifier 
if they are not).  Now run a cord from the RCA output on the DSK board
to a speaker (an amplifier is usually needed between the DSK board and 
the speaker unless your speaker system has one built in).  


SOFTWARE
--------

The compand program was written to run within the DSKD debugger interface.
To change between the receive and transmit modes simply modify the 
TR_DEFAULT constant within COMPAND.ASM to be either RECEIVE or TRANSMIT.
Next assemble COMPAND.ASM using DSKA.EXE (i.e. type: DSKA COMPAND.ASM).
Now run DSKD.EXE (i.e. type: DSKD -M2).  When inside the debugger program
type LD and then enter the file name COMPAND.DSK and press enter.  Once
the file has been loaded into the DSP, simply press F5 to execute it.

Note:  When compiling COMPAND.ASM, make sure that the two files
       EXP.ASM and COEF.ASM are in the same directory.  

OPERATION
---------

Transmit Operation:

Hook up the hardware as described in the hardware transmit section and
then run the software within the debugger (make sure the TR_DEFAULT is 
set to TRANSMIT within COMPAND.ASM).  Now talk into the microphone.
If you have the output of the DSK board hooked up to a speaker you should
here what you say except that it should sound a bit distorted and have
a base sound (lower frequencies) to it.  If you have it hooked up to
a transceiver then just start transmitting.

Receive Operation:

Hook up the hardware as described in the hardware receive section and
then run the software within the debugger (make sure the TR_DEFAULT is
set to RECEIVE within COMPAND.ASM).  Now have someone transmit a 
companded signal to your receiver.  The person transmitting should
be using the same code and DSK setup except in the TRANSMIT mode. 
Listen to the audio on a speaker.  The audio should now sound normal
again except for slight distortions.  As with the Transmit mode, you could 
simply run a microphone to the input of the DSK board through an amplifier
and listen to the output of the DSK board on a speaker.  In this case
the audio should sound higher than normal (more high frequencies than
normal due to shifting up).  


CONCLUSION
----------

Have fun and we hope this works for you.  The file TABLES.M is a matlab
file that we used to generate the filter coefficients and sine/cosine
lookup tables.  This may help you if you want to play with the filter
coefficients.  If you have questions we can be reached at the following
email addresses: 

John Ash, IV (KB7ONG)
email: jash@eecs.wsu.edu

Fred Christensen (KA6PNW)
email: chrifr@wwc.edu

Rob Frohne (KL7NA)
email: frohro@wwc.edu




