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Data is transferred from the microprocessor to
peripheral circuits in 5-bit data units to control -
sensitivity,
medium
frequency
equalization,
high frequency
equalization
and
bias in this
sequence.
The data passes through the logic
circuit to control the functioning of the record-
ing
circuit.
Fixed
equalization
values
are
ATRS program
The ATRS
program can be broken down into
the following stages:
1. Interrupt processing,
When
power
is turned
on,
the
micro-
processor
changes from
the data protect
mode to the execution mode.
It outputs the
data from the internal memory to the logic
circuit and waits for instructions to be input.
In this condition, recording is possible with
the bias and equalization that were
being
used before power was switched off.
If one
of the tape select buttons is pressed, the
data from the corresponding memory is out-
put to the logic circuit.
2. Testing
Fig. 2 is a flowchart of the testing process.
With the deck set to the recording mode, the
test start button is pressed and the deck
enters the test mode.
a) Adjusting to the optimum recording level.
The signal generator shown in the block
diagram outputs a1 kHz signal which is
recorded.
The recording level is adjusted
so
that
it does
not
exceed
the
level
specified by the microprocessor in subse-
quent adjustment of the bias and equali-
zation values.
b) Error check
When recording is not possible (when the
leader tape is used,
etc.), an error is
indicated.
c) Setting optimum bias current
The bias is varied from minimum to max-
imum while recording and playing back
the reference signal to obtain the bias
which gives the maximum
playback out-
put.
Next the bias is varied from max-
imum
to minimum
to obtain
the bias
which gives the maximum playback out-
put. The average of these two bias values
is adopted as the optimum bias.
By vary-
ing
the
bias
through
32
steps,
the
optimum bias can be detected with high
precision.
22
Recording level setting
Was recording
possible ?
Obtaining optimum bias
Compensating for tape sensitivity
Setting medium frequency equalization
Setting high frequency equalization
as testing
been performed
three times ?
Was
recording possible ?
Error indication
Fig. 2.
Flowchart
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