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A Appendix
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Measurement Modes
Offset Compensation:
The P
-
9710 not only measures and calculates the sum of the pulse signal, but
also electronic offset / ambient light or detector dark current are included in the
calculated sum. To minimize the error produced by these offset signals, the
measurement window should be set as short as possible (but long enough to
catch the whole pulse, practical value: pulse time + 2 seconds).
Any offset error produced can also be minimized by measuring the offset sig-
nal beforehand without the applied pulse signal. This offset is subtracted later
from the measurement result.
There are two methods to measure the offset signal:
If offset compensation “Setup / Pulse Offset” is set to “Static”, the offset
can be measured under menu “Offset”. With menu “Offset” the offset
value can be set to the actual CW value (no pulse signal has to be ap-
plied) or set to zero.
If offset compensation “Setup / Pulse Offset” is set to “Continuous” the
P
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9710 uses the last measured CW value before pulse measurement is
started as offset value. This mode has the advantage, that small chang-
es of the offset value are compensated more effectively. For continuous
offset compensation it is important, that the pulses are applied only
after the pulse measurement is started (not during the preceding CW /
offset measurement). This is the reason why for infinite pulse chains
“Setup / Pulse Offset” has to be set to “Static”.
Measurement Range:
The P
-
9710 measurement range has to be matched to that of the input signal.
This can be done manually be selecting a certain range (manual range selec-
tion) or by selecting the autorange function (menu “Range” set to “Auto”).
If the autorange function is set, the P
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9710 will display "OVL" (overload) or
"UDL" (underload) if the range of the last pulse measurement was not optimal
The offset must be measured without applied pulse signal!
The offset signal level can be determined by starting pulse measurement
without the presence of the pulses (
the measurement range has to be set to
fixed range
). The displayed measurement value represents the error contri-
bution produced by offset signal.
