Short-Time Fourier Transform and Decision Tree-Based Pattern Recognition for Gas Identification Using Temperature Modulated Microhotplate Gas Sensors

Figure 6

The feature vectors for three analytes (150 ppm carbon monoxide, 3000 ppm methane, and 50 ppm ethanol) with sawtooth modulated operating temperature ( s) at the first 11 frequencies: (a)  mHz; (b)  mHz; (c)  mHz; (d)  mHz; (e)  mHz; (f)  mHz; (g)  mHz; (h)  mHz; (i)  mHz; (j)  mHz; (k)  mHz.

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