CITYLIGHT FIBRE CHANNEL CARD
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Note the short haul optics are limited in distance by the spectral
width of the laser and not the power budget available on the link.
See Specifications Section for more details of drive distance.
2.3 External Attenuator
All high-power or long haul CityLIGHT cards have been designed for long
distance transmission and provide a minimum optical budget ranging between
20dB and 25dB. This provides transmission distances between 40km and
50km based on an average fiber attenuation of 0.5dB/km.
When these products are used for short distance applications, the received
power may exceed the saturation limit of the receiver and external attenuation
will be necessary to prevent optical overload and the inevitable data errors.
For these applications, an external 10dB attenuator is available to ensure that
the optical receive power falls within the operating limits of the receiver.
The fixed value 10dB attenuator, LCL505A, is of a doped-fiber design which
eliminates the troublesome reflections which an air-gap attenuator may
introduce. These reflections can upset the operation of lasers, particularly
those used in high data rate systems.
The 10dB attenuator may be deployed anywhere in the single-mode fiber link
but it is recommended that it be deployed at the receive end (rather than the
transmit end) of any particular point-to-point link.
The attenuator has a female connector at one end and a male connector at
the other end. The connector style should be specified at the time of ordering.
