Sd
AFR AFR
n
iav
i
n
=
−
=
∑
()
2
1
g
using data from the entire recording. As with the Average Deviation of AFR (DEV), the
greater Sd gets, the "rougher" the recorded AFR is. Sd is different from the real-time
parameter DEV. DEV is calculated from a computationally simpler formula more suited for
real-time calculation and display.
The "hidden" sample at t=0 is used for the statistical calculations. The second display
containing the maximum, the minimum, and the times of the maximum and minimum is
accessed by pressing any key other than "SYS". Pressing any key (other than "SYS") once
more will return the AFRecorder to the statistics menu.
AVERAGE: 17.63
Sd: 0.012
SAMPLES: 1251
Figure 8a: Example of Statistical Results Screen 1
MAXIMUM: 18.78
@T= 2.40 SEC
MINIMUM: 16.62
@T= 5.20 SEC
Figure 8b: Example of Statistical Results Screen 2
Choosing "EXIT" from the statistics menu will return the AFRecorder to the results menu.
Results - Point
Selecting "POINT" from the results menu allows the examination of the AFRs at a given
time (point) in the recording. To examine the data, the keypad is used to enter the time
followed by the "ENT" (enter) key. Then, "+" and "-" can be used to step through the
recording. Pressing "ENT" again returns the AFRecorder to the results menu.
Setup Menu
"SETUP" is the third selection in the main menu and is used to configure the AFRecorder.
The setup menu is shown in Figure 9. During setup, the defaults or previous selections are
displayed for acceptance (using the "ENT" (enter) key) or for modification. Any improper or
out-of-range entries are rejected by the AFRecorder and the "-" key is used as a backspace to
erase an entry. The entry of any setup parameter must be completed by the pressing of the
"ENT" key. The "EXIT" option returns the AFRecorder to the main menu.
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