A signal analysis method is described. The signal analysis method comprises the following steps. An output signal is received from a device under test. A sampling point density is received and/or the sampling point density is determined based on the output signal. A response function of the device under test is determined based on the output signal and based on the sampling point density. The sampling point density represents a number of sampling points per frequency interval for determining the response function. The response function characterizes at least one property of the device under test as a function of frequency. Moreover a measurement system for determining a response function of a device under test is described.