A measurement device and method for testing a device under test (DUT). The device includes an input terminal for receiving a RF signal from the DUT; at least one analog-to-digital (A/D) converter configured to generate a digital data including a plurality of sampled signals from the received RF signal; at least one filter configured to filter the digital data generated by the at least one A/D converter based on an intermediate-frequency bandwidth (IFBW) set in the at least one filter; a detector configured to analyse the filtered digital data based on a pre-set number of samples from the filtered digital data; and a controller configured to calculate a signal-to-noise ratio (SNR) value of the analysed filtered digital data, and to adjust at least one of the IFBW of the at least one filter and the number of samples of the detector based on the calculated SNR value.