Radio Shack VoxBox TRS-80 Service Manual
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TRS-80
TM
RECOGNITION
Catalog
Number 26-1181
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CUSTOM
MANUFACTURED
FOR
RADIO
SHACK^A
DIVISION OF
TANDY
CORPORATION
1. Introduction
This
manual provides the
serviceman
information
necessary
to repair the
Radio Shack
TRS-80 VOXBOX
Speech Recognition
peripheral.
The
hardware
involved in
the device is
fairly simple;
most of the complex
task of
speech recognition
is
accomplished
by the
TRS-80 computer,
which
executes a software
algorithm
on the raw
data
provided
by
the
speech recognition
hardware. The
hardware itself
simply
extracts
four bits of
information
from the
speech waveform
and presents it
to the computer.
The
recognition
program
samples this data
approximately
every 10
ms.
In
addition,
two BASIC
test programs
are available
to help
debug the
board. The
first
program tests the
board by training
and recognizing
the ten digits
zero
through nine. The
second program plots the
information
gathered
by
the
board
on the
video monitor
where it may
be compared
to known
patterns
to help isolate
the
problem.
2. Troubleshooting
The
VOXBOX
This product
is easy
to
troubleshoot. It
has a serial analog signal
path which
starts at the
microphone
and
terminates at the
voltage comparators. Thus the
signal may
be
traced from
beginning
to
end
to determine where the problem lies.
Use the
test programs
to
help
isolate the trouble.
Test equipment required is as follows:
•
TRS-80 computer
with
Level 11 BASIC
•
Oscilloscope
There are no adjustments to be made.
Test Programs
The first
step
in troubleshooting
the board is
to run the programs
to verify
improper
operation.
Listings
for Program 1 and
Program 2 are
contained in this
section.
PROGRAM 1
Load the speech assembly language
routines using
the "system"
command
and load the
BASIC program "Test
1
".
Run
the program,
train the system
on
the
ten digits
by speaking
clearly,
and try the unit
out.
The
unit should
respond with at least
80% to
90%
correct
results. If
the
unit
does not operate at all,
go to the hardware
tests in Section
2-B,
and
particularly
inspect the power
supply, mike preamp,
and addressing
logic.
If the unit
responds but operates poorly, load the
second BASIC
test
program
"Test
2".
PROGRAM 2
Run the second
program and say the
word "six" loudly
and clearly. You
should
see roughly
the
same
shaped
plots as shown in Figure
1.
If any of these lines are constant
across the
screen with no variation
at all, then the
corresponding
area of the circuitry
is at fault.
The
top line is a plot of low
band energy,
which corresponds
to the
rectifier/
averager
output
from low band on the block
diagram
and is the
output from IC4-1
on the
schematic.
The
second
line
from the
top
is
high band
energy, from the
high band
rectifier/
averager
on the
block diagram,
or from IC4-2
on the
schematic.
The next line is the
high band
zero-crossing
rate, from
the high
band zero-crossing
detector
on
the block diagram,
or from IC4-1
3
on the
schematic. Finally,
the
bottom line
is the low
band zero-crossing
rate, from the low
band
zero-crossing
detector
on the block
diagram, or from IC4-14
on the
schematic.
Test Program
1
can
be run,
if
desired,
before
disassembling
the unit
to
verify customer
trouble
complaints.
Disassembly
Procedure
Place the unit upside
down
on a clean
surface and
remove the
6 screws
which hold
the
top and
bottom half of
the plastic enclosure
together. Remove
the board
from
the box
by
lifting
it
out and place the
board on a clean
non-conducting
surface.
VOXBOX
BOARD (IN
BOX) TOP
COVER REMOVED
FIGURE 1
-3-
L
>
"AMPLITUDES'
>
"FREQUENCIES'
TYPICAL
PLOT
OF WORD
"6"
AS
SEEN ON TRS-80
VIDEO
DISPLAY
FIGURE
2
-4-
TKST PROGRAM 1
DIGITS
10
REM SET
UP CALLING
PARAMETERS
20
REM
MS=MEMORY
SIZE
IN
K-BYTES
30
AD=112
40
GOTO
80
80
POKE
16526,6
90
POKE
16527, AD
100
X=USR(0)
200
REM
TRAIN
210
REM
TR= INDEX;
W$=STRING
ARRAY
220
DIM
W$
(32)
230
W$
(0)="0"
240
W$
(1)="1"
250
W$
(2)="2"
260
W$(3)
="3"
270
W$
(4)="4"
280
W$
(5)
="5"
290
W$
(6)
="6"
300
W$
(7)
="7"
310
W$
(8)
="8"
320
W$
(9)
="9"
330
W$
(10)
="10"
3
40
FOR TR=0 TO
10
350
PRINT "SAY.
.
."
;W$ (TR)
360
GOSUB
1000:
REM
TRAIN
370
NEXT
TR
400
REM GET VOICE
INPUT
410
POKE 16
5
26,3
420
POKE 16527, AD
430
PRINT "SPEAK.
.
.
"
440
X=USR(0):REM CALL
RECOGNITION
450
W=PEEK (TX)
460
IF
W>31 THEN
GOTO
500
470
PRINT "YOU
SAID
";W$(W)
480
GOSUB
900:
REM
DELAY
490
GOTO
400
500
REM
ERROR
510
PRINT "PLEASE REPEAT
THAT"
520
GOSUB
900:
REM
DELAY
530
GOTO
400
900
REM DELAY
FOR
BETTER
USER
INTERACTION
910
FOR
1=1
TO
300
920
NEXT
I
9
30
RETURN
1000
REM
CALL TRAINING
SUBROUTINE
1010
TX-256*AD+1018
1020
if TX >
32767 THEN TX
=
TX-65536
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