Agilent Technologies 8614 B Series, User Manual, Page: 81 / 272

3-7
Function Reference
Amplitude Setup
Auto Ranging
The Auto Range function allows the OSA to automatically change the gain of the transimpedance
amplifier during a sweep. This allows measurements to be made at the largest dynamic range
and at the fastest sweep speed.
Pressing the front-panel Preset key turns Auto Ranging
ON
.
N o t e It is recommended that Auto Ranging always be turned on.
Auto Zero
Turns Auto Zero
ON
and
OFF
. Auto Zero
ON
enables the internal amplifiers to be zeroed between
sweeps. Selecting
OFF
disables this feature. Pressing the front-panel Preset key resets this func-
tion to
ON
.
N o t e Turning Auto Zero off allows the instrument to sweep faster, but results in less accuracy on low
level signals. The optical spectrum analyzer performs a more complete zeroing when the
instrument is first turned on. You can run this more complete routine anytime by pressing the Zero
Now softkey.
Auto Chop Mode
(Not available on 86146B models)
Enables the optical spectrum analyzer chop mode. Chop mode increases dynamic range for long
sweep times by subtracting ambient light. Subtracting the ambient light can improve sensitivity
but slows down the sweep speed.
Pressing the front-panel Preset key turns this function
OFF
.
N o t e Sweep times of 50 msec × the # of trace points, or longer, use a special “chop” mode. Chop mode
increases dynamic range, stabilizes measurements against drift, and reduces effects of stray light.
This special chop mode is enabled by setting the Auto Chop mode to on.
Power Calibration
Power Calibration allows you to use amplitude correction factors either from the factory calibra-
tion or from the last successful user calibration. Pressing the front-panel Preset key resets this
function to User. If a user calibration has not been performed, the factory calibration data is used.
User Power Cal Date
The User Power Cal Date displays the date of the last successful user-performed amplitude cali-
bration.