DD IEC PAS 61280-2-10:2003 pdf download Fibre optic communication subsystem test procedures — Part 2-10: Digital systems — Time-resolved chirp and alpha-factor measurement of laser transmitters
7,1.1Pattern generator
The pattern generator supplies the PRBS modulation signal to the DUT and the trigger to theoptical oscilloscope. The modulation rate and format are those required by the DUT. ThePRBS pattern length should be 2°-1 or longer. Shorter pattern lengths may be used but maynot fully explore pattern-dependent chirp effects. Longer patterns may be used but wilincrease the measurement time. The trigger signal must be synchronous with the PRBSpattern – not the clock.
7.1.2EDFA
the erbium-doped fibre amplifier is optiona. it is required only if the optical power from theDUT is too low to provide sufficient signal level to the optical oscilloscope. For opticalfrequencies other than the C or the L-bands, alternative amplifier technologies must be used.
7.1.3Monochromator
The monochromator has a bandwidth adjustable between 100 pm and 500 pm. lt is a doublepass monochromator arranged so that chromatic dispersion is nomally zero at band centren practice, a chromatic dispersion of less than Polarization dependence is less than 0.5 dBand insertion loss is less than 10 dB.
7.1.4Optical oscilloscope
The optical oscilloscope consists of a DC-coupled broadband optical-to-electrical converterand a sampling oscilloscope. The combined frequency response of the optical-to-electricaconverter and oscilloscope must be at least twice the bit rate and the impulse responseshould have no ringing, overshoot, or undershoot. lt must accept a trigger input and have ameans to means to set the trigger and observable time range. The bandwidth shall be greaterthan twice the bit rate.
7.2Procedure
1)Connect the equipment as shown in Figure 8. The EDFA is required only if the powerfrom the DUT is insufficient to provide a sufficiently high signal level to the opticaoscilloscope.
2Adjust the time range on the optical oscilloscope to display the desired number of bits.
DD IEC PAS 61280-2-10:2003 pdf download
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