Sensor Circuits - The Electronic Nose Artificial Olfaction Technology - page 194

Fig. 7.22 Schematic of process in data analysis techniques

The selection of signal preprocessing is important and also it has a significant
impact on the performance of subsequent module in the pattern analysis system.
Although signal preprocessing is somewhat dependent on the underlying sensor
technology, the most commonly used three general stages can be identified:
baseline manipulation, compression, and normalization.

Table 7.2 Signal
processingalgorithm [ 2 ]

Signal processing algorithms Formula

X ij ¼ X ij X 0 b ; ij Difference signal

X ij ¼ X 0 a ; ij . X 0 b ; ij

Relative signal

¼ P j ¼ 1 X ij . N

Averaging

ij

X

X ij ¼ ð X 0 a ; ij X 0 b ; ij Þ . X 0 b ; ij

Fractional difference

Linearization

X ij ¼ log X 0 max
ij

X 0 min
ij

q

X 0 max

ij X 0 min

X ij ¼

ij

k ij ¼ X ij . X 0 a ; ij X b ; ij

Normalization

;

k ij ¼ X ij . P i ¼ 1 X ij

Autoscaling

ij

X ij X

k ij ¼

r i