SM-SX100 (serv.man2) - Sharp Audio Service Manual (repair manual). Page 13

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ANALOG  0v-

1 BIT 
SIGNAL

"0" Area

"1" Area

Integrator output : Lateral bar of thick line (-): 1

                         Lateral bar of doubled line (=): 0

Analog signal 
waveform

The operation of the 

 modulation is explained using Fig. 13-1. Here, the analog signal component from the input section

is expressed with the black-filled vector, and the binary value negatively fed back is expressed with the white-blank vector.
In this block, the following operation is applied.

1

 If the output of the integrator is "positive", subtraction of "positive unit vector" is applied to the input side.

(In the figure, the downward white-blank vector is added.)

2

 If the output of the integrator is "native", subtraction of "negative unit vector" is applied to the input side.

(In the figure, the upward white-blank vector is added.)

If the output of the integrator increases or the amplitude of the input signal increases, the figure shows that the negative
feedback is applied to suppress the increase.
In the other words, the continuous "positive" output of the integrator means that the amplitude of the input signal is large,
and the frequency of "1" coding increases.
On the contrary, the continuous "negative" output of the integrator means that the amplitude of the input signal is small,
and the frequency of "0" coding increases.
Thus, "binary codes corresponding to the amplitude" can be gained through the operation of the 

 modulation.

Slant view of analog signal

Front view of analog signal

1 Bit Signal

1 Bit Signal