Phase noise is present in all electronic signals. Phase noise is caused by the unintentional phase modulation of an RF waveform, no RF signals are perfect. The phase noise component will then reduce the fidelity of an RF signal which can have significant effects, causing higher symbol errors in communications systems or masking returns in radar systems. To describe phase noise another way, the same phenomena in the time domain is called jitter. Like phase noise, it will affect the signal’s overall fidelity. One of the main ways to optimize system performance is by reducing phase noise as much as possible. Due to phase noise’s potential significant negative impacts, it is essential to be able to optimally measure phase noise throughout the testing process.