Tektronix OM4006D, User Manual

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Taking measurements
Setting up your measurement
Since the OM4000 is a recon fi gurable (complex, dual-polarized) reference
receiver, it requires a modulated signal on the input fi ber. Depending on
the options con fi gured in the receiver, this modulation can be single- or
dual-polarized, with several formats available, including OOK (on-off keying),
BPSK (binary phase-shift keying), and QPSK (quadrature phase-shift keying),
and either coherent or differential QAM and other formats are also available.
The OM4000 includes two network-tunable sources (C- or L-band); you can
use these or your own lasers for signal and reference inputs. Furthermore, each
polarization can be independently driven by a distinct source, though all sources
must be tuned to the same ITLA channel, or at least to the same wavelength.
While no phase locking of the sources is necessary, the beatnote between
any signal laser and the reference should be at a low enough frequency that
the bandwidth of the real-time oscilloscope can accommodate the modulation
bandwidth plus the beatnote frequency.
Before testing a modulated source, ensure that there is no modulation of the
lasers (i.e. that your data source [pattern generator] is not enabled). With both
lasers emitting and tuned to the same channel, use the
fi ne-tune feature of
the Laser/Receiver Control Panel to obtain a 100-500 MHz beat note on the
oscilloscope. Then enable modulation, e.g. by activating your data source or
pattern generator.
OM4000D Series Coherent Lightwave Signal Analyzer 63