MEASUREMENT SYSTEM FOR CHARACTERIZING A DEVICE UNDER TEST

The present invention relates to a method for determining at least one characteristic of a device under test (DUT) as a function of time across a frequency range of a periodic modulated signal. The method comprises :- generating a first periodic modulated signal across the frequency range and a second periodic modulated signal with a frequency offset from the frequency range;- performing a measurement at one or more ports of a plurality of ports of the DUT while the first periodic modulated signal is applied to a first port and the second periodic modulated signal to a second port, wherein performing the measurement comprises:- obtaining probed signals,- receiving two probed signals, wherein in each of a plurality of receivers a corresponding one of the two probed signals is phase coherently digitized with a respective digitizer having its own sample clock, wherein the respective sample clocks are synchronized in a synchronization block comprising a reference clock derived from a master clock, and- processing the phase coherently digitized probed signals to obtain one or more of the measured voltages and currents, or the incident and reflected waves; and- determining said at least one characteristic, using one or more of the measured voltages and currents, or incident and reflected waves.