The PDM-QPSK test network consists of seven channels on a 50 GHz grid, a recirculating loop and a coherent receiver with custom demodulation, Fig. 1. Even and odd channels are modulated separately using independent commercial I/Q modulators (Oclaro) at either 28 or 32 Gb/s. After modulation all seven channels are interleaved with a commercial wavelengthselective switch (WSS) (Nistica). The channels are then polarization multiplexed to form either 112 or 128 Gb/s data signals. The inset in Fig. 1 depicts the measured spectral content of the seven PDM-QPSK channels just before transmission.