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Using the Optical Spectrum Analyzer
The Bandwidth/Sweep Menus
Using the Bandwidth/Sweep functions
To change the resolution bandwidth
The ability to display two closely spaced signals as two distinct responses is
determined by resolution bandwidth.
1
Press the front-panel
Bandwidth/Sweep
key.
2
Press the
Res BW
softkey.
3
Toggle between selecting the resolution bandwidth automatically or manually.
4
Use the knob, step keys or numeric entry pad to enter the desired value.
The resolution bandwidth can be set to one of the following values:
0.07 (0.06 for the HP 86142A and 86145A), 0.1, 0.2, 0.5, 1, 2, 5, or 10 nm.
Resolution bandwidth filtering occurs before detection of the light.
In Auto mode, the resolution bandwidth is coupled to the span in a preset
0.01:1 ratio. This means that the optical spectrum analyzer attempts to set a
bandwidth value that is 1% of the span setting. You can alter this behavior by
manually setting the resolution bandwidth.
To change the video bandwidth
1
Press the front-panel
Bandwidth/Sweep
key.
2
Press the
Video BW
softkey.
3
Toggle between selecting the video bandwidth automatically or manually.
4
Use the knob, step keys or numeric entry pad to enter the desired value.
Video bandwidth filtering occurs after detection of the light. In the autocou-
pled mode, the video bandwidth has an extremely wide range. This allows the
optical spectrum analyzer to avoid unnecessary filtering that would reduce the
sweep speed more than required.
Normally, the video bandwidth is coupled to the requested sensitivity. Manu-
ally entering a video bandwidth breaks this coupling. The video bandwidth can
be manually set from 100 mHz to 3 kHz, or the bandwidth of the currently
selected transimpedance amplifier, whichever is less.
book.book Page 15 Monday, January 31, 2000 10:34 AM