Endace DAG 4.2S, Руководство пользователя

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EDM01-02: DAG 4.2S Card User Guide
©2005 7 Version 7: May 2006
Chapter 3: Setting Optical Power
Introduction
The optical power range depends on the particular device fitted on the
DAG 4.2S card.
The DAG 4.2S card is shipped fitted with HFCT 5402D 1300nm single-
mode short range optics module by default.
Optical power
measure
Optical power is measured in dBm – decibels relative to 1 mW where 10
dB is equivalent to a factor of 10 in power.
The numbers are all negative, showing powers below 1 mW. The most
sensitive devices can work down to about –30 dBm, or 1 uW.
Configuration The following table describes the DAG 4.2S card optics power module
part, single-mode fibre [SMF], and configuration.
Part No. Fibre Data Rate Max Pwr
[dBm]
Min Pwr
[dBm]
Nominal pwr
[dBm]
HFCT 5402D SMF 2488 -3 -18.5 -14
MMF: Multi-Mode Fibre SMF: Single-Mode Fibre
In this chapter This chapter covers the following sections of information.
DAG 4.2S Card Optical Power Input
Splitter Losses
3.1 DAG 4.2S Card Optical Power Input
Description The optical power input to the DAG 4.2S card must be within a receiver’s
dynamic range.
When optical power is slightly out of range an increased bit error rate is
experienced. If power is well out of range the system cannot lock onto the
SONET frames. In extreme cases of being out range excess power will
damage a receiver.
When power is above the upper limit the optical receiver saturates and
fails to function. When power is below the lower limit the bit error rate
increases until the device is unable to obtain lock and fails.
Input power When the DAG card is set up, measure the optical power at the receiver
and ensure that it is within the specified power range. The recommended
power is -14 dBm.
Input power is adjusted by:
Changing splitter ratio if power is too high or too low, or
Inserting an optical attenuator if power is too high.