Conductance catheter system is used to estimate real-time ventricular volume by measuring the time-varying ventricular conductance/admittance. However, the system is generally calibrated only with known resistors, while neither the frequency response nor the bandwidth of the system is calibrated and measured. The main difficulty of measuring its bandwidth is that the sensed signal of the conductance catheter system, which can be viewed as the input of the system, is a modulated signal, rather than a typical sin wave. Therefore, its bandwidth cannot be measured by typical frequency response analyzers, since they are designed for pure sin-wave input. The waveform of the sensed signal is analyzed. Moreover, a waveform simulator designed to mimic the sensed signal is presented. It can be used to measure the bandwidth of conductance catheter system.