Particle Counting 6-5
Autoranging
Three running-average buffers and one live-time buffer are used to
average particle counts. The buffers are updated every second,
discarding the oldest 1-second value.
There is one buffer for each of four averages: 1, 2, 20, and 200
seconds. The photometric mode is used for displays with exponents
of e4, e5, and e6. The 1-second live-time counter is used with
exponent display, e3; the 2-second buffer with exponent display,
e2; the 20-second buffer with exponent display, e1, and no
exponent; and the 200-second buffer is used when the display
shows three digits after the decimal.
The autoranging algorithm chooses among these buffers or selects
the photometric calibration. A downward hysteresis of 10 percent is
used when going from one exponent range to another in order to
avoid rapid and unreadable display changes. If the display is on a
fixed exponent range, then the correct buffer or photometric
calibration is used for the concentration magnitude, but the display
has a fixed exponent range.
All buffers are cleared when you press the Clear button.
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