Covering frequency range up to 50 GHz, R&S FSWP phase noise tester can measure spectral purity of such signal sources as generators, synthesizers, and VCOs. Phase noise of local oscillator, coupled with cross-correlation, facilitates signal source measurement. In addition to being able to measure phase noise of pulsed sources as well as residual phase noise under pulsed conditions, unit can also be upgraded to signal and spectrum analyzer.