Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 475)

<Appendix E Computation Scheme>
App.E-2
IM 11B08A01-01E
 Detector Signal Processing
Detector signal processing receives signals from each detector, eliminates noise from the
signals, and transmits the fi ltered signals to the following peak detection processing.
The fi gure below shows the fl ow of the processing.
Signal filtering
Data sampling
Signal evalution
Signals from each detector
Processed data
Standard deviation values
F0202.ai
(1) Signal Filtering
The fi ltering step eliminates high-frequency components from the signals transmitted from each
detector every 20 ms. The fi ltering formula is:
y
t
= f (x
t
– y
t-1
) + y
t-1
Where:
y
t
: filtered data
y
t-1
: previous data from 20 ms before
f : filtering coefficient (variable between 0.01 and 1.000)
x
t
: signal from a detector
(2) Data Sampling
At every time t smp , the data sampling step averages the signals acquired every 20 ms from
detectors. Note that t smp is a value calculated from multiplying 20 ms by 2
n
(n=0 or a variable
integer from 1 to 9; therefore, t smp is a variable between 20 ms and 10.24 s).
2nd Edition : May 11, 2012-00