Language Reference

VB

Description The VB command sets the post-detection, video-bandwidth ￿lter. The video-bandwidth and sensitivity settings are coupled to yield the maximum

amplitude response. Specifying a bandwidth with VB, or executing VB MAN breaks the coupling. To reestablish coupling, execute VB AUTO .

There are two types of detectors used in conjunction with post-detection processing. The optical spectrum analyzer ￿rmware automatically determines which detection mode to enable. The following information explains the uses of the di￿erent detector modes.

￿Sample detection is used when digital ￿ltering is enabled, and the analyzer is in gated sweep and pulsed current modes of operation. When the sample detector is active, an S appears on the display beside the video bandwidth information.

￿Peak detection is enabled at all other times. (The S is not displayed.)

There are two modes of operation for video bandwidth. They are automatic and manual mode. The conditions of these modes is listed below:

￿In automatic, video-bandwidth mode, the optical spectrum analyzer

￿rmware determines whether to use digital ￿ltering and determines the appropriate bandwidth for the current measurement conditions.

The video bandwidth information displayed is the overall post-detection bandwidth, and it may represent the bandwidth of the transimpedance ampli￿er hardware in cases where digital ￿ltering is disabled.

￿In manual, video-bandwidth mode, digital ￿ltering is enabled, unless gated sweeps and pulsed current modes are selected. The ￿ltering is ￿xed at the bandwidth entered by the operator.

The minimum bandwidth available is 0.1 Hz. The maximum bandwidth available is the lesser of 3 kHz and the bandwidth of the currently selected transimpedance ampli￿er.

Query Response

See Also RB, SP, ST, SENS

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