Patent ID: 7519338

Claim:
A measurement apparatus for measuring peak pulses of a radio frequency input signal (RF input ) comprising: mixing means for mixing the radio frequency input signal (RF input ) with a local oscillator signal (LO) in order to convert the radio frequency input signal (RF input ) directly to zero centre frequency thereby suppressing frequency components in a range (B, C) close to zero frequency; and control means for controlling the frequency (f LO ) of the local oscillator signal (LO) in a manner that a first measurement is performed in a first frequency range (E) and that at least a second measurement is performed in a second frequency range (F) shifted with respect to the first frequency range (E); wherein the measurement apparatus further comprises a low-pass filter downstream of the mixing means; wherein a cut-off frequency of the low-pass filter is 3 to 10 times the highest frequency suppressed by the mixing means; and wherein the highest frequency suppressed by the mixing means is about ¼ the cut-off frequency of the low-pass filter.