This paper presents the simulation performance of the all-digital symbol timing recovery using the Gardner Timing Error Detector over π/4-DQPSK modulation. The open loop statistics, the S-curve and the normalized timing error variance, were investigated to show the stable tracking performance of the system. The symbol timing recovery has a second order loop transfer function, which was able to track down phase, and frequency offsets. Modulation was observed to have a performance of 2 dB lower from the theoretical BER curve.