Specifications

and/or >130% of the initial laserdiode drive current a B-grade alarm which indicates a
warning is generated. At 100% cooler drive current the laserdiode drive current is
switched off to protect the laserdiode against irregular temperature conditions and an
A-grade alarm indicating a severe malfunction is generated. Both types of alarms are
causing the corresponding LED on the front plate of the optical transmitter to emit. In
case of a B-grade alarm the yellow LED is lighting since the unit is still working properly,
however close to its limits. In case of an A-grade alarm the red LED is emitting. The
messages to the network management system are of course more detailed. They include
the actual values of the currents and temperature as well as alarm flags.
To suppress the Stimulated Brillouin Scattering (SBS) the optical signal is broadened.
Two technologies are used:
• Broadening the optical spectrum by modulating the laserdiode with a microwave
signal
• Broadening the optical spectrum by driving a optical phase modulator with a
microwave signal
These circuits are mandatory to avoid stimulated brillouin scattering (SBS) in optical
fibers and allow to operate with optical amplifiers feeding at least +13 dBm of optical
power into standard single mode fibers (ref. to chapter 3.1). All microwave signals can
be adjusted in amplitude via the push-buttons on the front panel to optimise the SBS
and SPM (self phase modulation) performance for the XL-version of the transmitter
(ICS1 or higher).
The coupling of light from the laserdiode to the modulator is performed using a
polarisation maintaining optical fiber. The optical modulator provides two optical
outputs. The signal of one of these outputs is tapped and led to an InGaAs photodiode.
The electrical signal of this photodiode is evaluated for two reasons:
1) To supervise a proper working of the CW laserdiode. In case of optical output power
drop of 2 dB of nominal power an B-grade alarm (=warning alarm) is generated, in case
of optical output power 0 dBm an A-grade alarm (=urgent alarm) is generated.
2) A detector circuit measures CSO and CTB distortions to optimise the bias point of the
electrooptical modulator. For a proper operation of the detection circuit at least two TV
carriers with a frequency spacing of 24 MHz have to be present. Using this standard
software setting of the detection scheme all known European and Chinese frequency
plans are supported: CENELEC frequency plan, all regular 8 MHz spacing frequency
plans as well as the German 7/8 MHz frequency plan. Additionally it is possible to
change the standard software setting to work with regular 6 MHz frequency plans
(NTSC) or pure 7 MHz frequency plans via push-buttons on the front panel or via the
NMS interface.
The ES10XLa is equipped with 3 data interfaces at the rear side:
• RS232 for a local set-up of the NMS Interface,
• RS485 for polling other BKtel equipment like EDFAs or optical switches and
translating this information to the Ethernet interface,
• Ethernet 10/100 MBps supporting SNMP and Webbrowser protocols for
interfacing to a EMS or NMS
The ES10XL is equipped with a RS485 interface for interfacing to a EMS or NMS.
Plug in power supply/fan modules for different input voltages are available for 100 ...
240 VAC, 36 ... 60 VDC and 24 VDC. Each module can be simply removed during
operation without disturbing the operation of the transmitter by removing 2 screws.
Funea Broadband Services bv product information page 9 of 31
version: 11-02