Specifications

5.4 Optical power on /off
The transmitter can be configured as a back-up transmitter with optical output power
off. This allows to turn on the transmitter within less than 10 seconds in situations
where a fast switching to a redundant transmitter is requested.
The optical power on/off switching can be performed via the buttons on the front panel
or via the Ethernet interface.
5.5 SBS suppression setting (ES10-XLa only)
The ES10 enables to change the SBS suppression of the transmitter.
SBS (Stimulated Brillouin Scattering) is a well known problem in long distance, high
power transmission. For extremely coherent optical light, SBS occurs already at optical
powers of around +6 dBm (4 mW) in standard single mode fibers. With electronic
measures the coherency of the light can be degraded which increases the SBS threshold,
that means that optical power which leads to strongly perturbing SBS effects, which
destroy the CNR and CSO performance especially in the lower transmission frequency
band.
If the SBS threshold is increased, another problem SPM (self phase modulation) comes
up, which degrades the CSO performance in the higher frequency band. SPM depends
on the total dispersion which is present in the transmission system.
SBS and SPM are both nonlinear effects in optical fibers and depend on
• the launched optical power
• the fiber properties (especially fiber loss and mode field diameter)
• the link properties (number of splices and total splice loss)
Both effects are worse with
• higher optical power
• lower mode field fiber diameter
• higher quality, lower loss fiber
• fewer, lower loss splices
Bktel tests the SBS and SPM performance of the ES10 with a standard IEC rec. G652 fiber
and worst case conditions: link containing no splices and providing a fiber loss of only
0.19 dB/km.
For this test arrangement the SBS suppression is specified keeping in mind the SPM
problems.
SBS suppressions between 13 and 16.5 dBm are recommended for fiber links with
lengths of 65 km or more.
It is recommended to use the high SBS threshold settings (> 16.5 dBm) for distances
below 65 km, and the lower SBS thresholds for longer distances.
The SBS threshold can be selected in 0.5 dB steps between 13.0 and 19.0 dBm in order to
optimize the SBS performance for the individual application and link characteristics.
5.6 LED Display
The ES10 has a LED display (3 LED’s for MODUL, INPUT and OUTPUT) and a LCD in
combination with 6 menue buttons on the front panel for read and set parameters:
For normal operation all LED’s should light green. In case of warnings and alarms the
responsible LED’s turn into yellow or red and the LCD shows furter explanations.
Modul status
Normal operation: MODUL LED green
Non urgent alarms: MODUL LED yellow
• fan 1 or fan 2 failure
• Power supply 1 or power supply 2 failure
• Laser cooler current >90 %. In this case the temperature of the transmitter is too
high. Improve thermal heat flow in order to decrease the operating
temperature.
• Laser bias current >130%. The laser has degraded.
Funea Broadband Services bv product information page 24 of 31
version: 11-02