Anritsu MS9740B - Page 93

3.1 Calibrating Before Measurement
3-3
3
Measurement
Table 3.1-1 Calibration Functions (Cont’d)
No Calibration Items Where: Button Description

Sets auto offset
calibration for
temperature
change On/Off
3.1.2
Auto Cal
On/Off
At On, the internal temperature change is
monitored every 10 minutes and the offset is
auto-calibrated when temperature changes
significantly.
At Off, the above-described offset calibration is
not performed. (Default: Off)

Sets auto offset
calibration for
VBW change
On/Off
3.1.2
Auto Offset
On/Off
At On, when the Single or Repeat button is
pressed immediately after VBW is changed,
sweeping starts after offset calibration.
(Default: On)
At Off, the above-described offset calibration is
not performed.

Zero Calibration
3.1.2
Zero Cal
When Off is set at step

, offset calibration is
executed by pressing the Zero Cal button.
Offset calibration is a function for calibrating the offset level for each
VBW of the equipment. When the offset level changes, sometimes the
measurement results in the level direction are affected. Usually, offset
level changes with temperature. To obtain the highest-accuracy
measurement results, we recommend performing offset calibration (

)
once every 2 to 3 hours.
However, offset calibration requires a fixed time period of several seconds
(7 seconds). Refer to the following cases and perform setting and
calibration according to your usage conditions.
Table 3.1-2 Usage Status and Optimum Calibration
Case Calibration Condition Calibration Items
Case 1
Allow the equipment to warm-up for at least 2 hours after
power-on.
Calibrate whenever the equipment is transported or moved
between different locations.
Calibrate whenever the ambient temperature or air pressure
changes significantly.
Execute

.
Case 2
When measuring wavelength
Set Align with cal to On
and execute

.
Case 3
When measuring continuous spectrum, such as optical amplifier
ASE level and laser diodes
Execute

and

.
Case 4
When wanting to increase measurement throughput
(Shortening the offset calibration time when using applications
that switch VBW frequently can increase the measurement
system throughput.)
Set

and

to Off.
Moreover, execute

when the ambient
temperature changes.
Case 5
When performing measurements requiring a long time, such as
setting VBW (e.g. measuring DUT optical level and OSNR drift)
Set

to On.
Case 6
When performing long-term measurements while switching
multiple VBW settings
Set

and

to On.