Phasor monitoring of DxPSK signals using software-based synchronization technique

H. G. Choi, Y. Takushima, Y. C. Chung
2010 Optics Express  
We develop a novel phasor monitor to obtain the constellation diagram from asynchronously sampled data measured by using the delaydetection technique. This phasor monitor consists of three parts; a phaseadjustment-free delay-interferometer, an optical front-end made of three photodetectors, and analog-to-digital (A/D) convertors, and a digital signal processor. We operate the A/D convertor at the sampling rate much slower than the symbol rate and acquire the data asynchronously. However,
more » ... the use of such a slow and asynchronous sampling rate, we obtain the clear eye and constellation diagrams by utilizing the software-based synchronization technique based on a novel phased-reference detection algorithm. Thus, the proposed phasor monitor can be implemented without using high-speed A/D convertors and buffer memories, which have been the major obstacles for the cost-effective realization of the phasor monitor. For a demonstration, we realize the proposed phasor monitor by using an A/D converter operating at 9.77 MS/s and used it for the constellation monitoring and bit-error-rate (BER) estimation of 10.7-Gsymbol/s differential quadrature phase-shift keying (DQPSK) and differential 8-ary phase-shift keying (D8PSK) signals.
doi:10.1364/oe.18.021511 pmid:20941048 fatcat:nw5pierl4bdu7lm2ntjpp2eucy