A measurement and control system for use in performing a medical procedure, employing an energy source, the measurement and control system comprising: a measurement system configured to sample an output signal generated by the energy source, the sampled output signal having a magnitude and phase; a control system operatively connected to the measurement system and including: a calibration unit configured to receive and store loss information for the transmission line, the calibration unit further configured to generate a calibration signal having a magnitude and phase that are representative of the sampled output signal of the measurement system and of the loss information for the transmission line; and a control unit configured to receive the calibration signal and to adjust the energy source in response to a value of the calibration signal. characterised in that: the measurement system includes a directional coupler; the directional coupler is configured to sample the output signal generated by the energy source; the measurement system is configured to measure sampled forward and reflected voltages (51, 52) obtained by the directional coupler and generated by the energy source and is configured to obtain or calculate, from the measured forward and reflected voltages, power, magnitude and phase of the output signal; the control unit is further configured to receive forward, reflected and load power portions of the sampled output signal. a measurement system configured to sample an output signal generated by the energy source, the sampled output signal having a magnitude and phase; a control system operatively connected to the measurement system and including: a calibration unit configured to receive and store loss information for the transmission line, the calibration unit further configured to generate a calibration signal having a magnitude and phase that are representative of the sampled output signal of the measurement system and of the loss information for the transmission line; and a control unit configured to receive the calibration signal and to adjust the energy source in response to a value of the calibration signal. characterised in that: the measurement system includes a directional coupler; the directional coupler is configured to sample the output signal generated by the energy source; the measurement system is configured to measure sampled forward and reflected voltages (51, 52) obtained by the directional coupler and generated by the energy source and is configured to obtain or calculate, from the measured forward and reflected voltages, power, magnitude and phase of the output signal; the control unit is further configured to receive forward, reflected and load power portions of the sampled output signal. a calibration unit configured to receive and store loss information for the transmission line, the calibration unit further configured to generate a calibration signal having a magnitude and phase that are representative of the sampled output signal of the measurement system and of the loss information for the transmission line; and a control unit configured to receive the calibration signal and to adjust the energy source in response to a value of the calibration signal. the measurement system includes a directional coupler; the directional coupler is configured to sample the output signal generated by the energy source; the measurement system is configured to measure sampled forward and reflected voltages (51, 52) obtained by the directional coupler and generated by the energy source and is configured to obtain or calculate, from the measured forward and reflected voltages, power, magnitude and phase of the output signal; the control unit is further configured to receive forward, reflected and load power portions of the sampled output signal.