Vertical position control of shaped plasma is essential for all elongated tokamaks to achieve safe and stable plasma discharge. In EAST, the in-vessel coil (IC) is employed for fast control of plasma vertical motion which power supply capabilities limits the controllability of vertical instability. Besides, adequate signal-to-noise ratio of vertical position measurement can also realize an improvement in vertical control. In EAST, plasma vertical position Z(p) is produced nearly by all integrated magnetics, fast Z error signal is obtained by filtering from Z(p). Then this fast Z error and its derivative term (dz/dt) are controlled by IC with a separate PD controller. However, it has a low signal-to-noise ratio which limits the gains that can be used successfully in the PD control loops. To provide less noisy dz/dt signal, the successful use of multiple up/down loop voltage pairs instead of derivative of z derived from magnetic probe signals will be discussed. Experiment show that even a single pair of loop voltage signal has better signal-to-noise ratio than differentiation of Z(p). In addition, flux loop pickup signals from the IC current are also measured with series of positive and negative IC current pulses.