Fluke OF-500 OptiFiber, Техническое справочное руководство

Страница: 123 / 282

Using the OTDR
Using Manual OTDR Mode
3
3-49
Table 3-5. Manual OTDR Settings (cont.)
Setting Description and Selection Guidelines
PULSE WIDTH
The pulse width determines the deadzones of the trace and affects dynamic range.
Narrower pulses let you see more detail in and around reflective events and help you see events that
are close together (hidden events). However, narrower pulses limit the OTDR’s range and produce
traces with more background noise between events. With narrower pulses, you may not be able to
distinguish small loss events from the noise on the trace. The narrowest pulses are not suitable for
measuring loss, since linearity is not guaranteed (except on OFTM-57xx modules). The backscatter level
may be so low that it does not appear on the trace.
Wider pulses raise the backscatter level, which provides a better signal-to-noise ratio around non-
reflective events. This helps you see smaller loss events and measure their loss more accurately, but
increases the deadzones of reflective events.
Auto
: The tester selects the narrowest pulse that still reveals loss events.
-continued-