Analysis of M-QAM Data Communication System Using 3D Eye Diagram

When designing digital systems and incorporating a high-speed digital device with the need of quick transfer of large data amounts between chips and peripherals, jitter will be a key parameter to measure. In this paper, we are able to determine the initial phase of a carrier sine wave by performing carrier recovery loop in Digital communication systems of M-ary quadrature amplitude modulation (M-QAM) schemes. It is important for the M-ary QAM carrier recovery circuits to have low phase jitter as well as only four stable phase points as we see below. We examined the effect of channel noise on carrier recovery. More specifically, we examined what behaviour can occur when channel noise is significant enough to prevent carrier locking. We saw the symbols on the 3D Eye Diagram and constellation plot begin to jitter at first, and then settle closer to the ideal symbol locations after a short period of time.