ABSTRACT: Today’s communication systems (e.g., 5G and Wi-Fi) utilize high order modulation to achieve fast data rates. However, symbol errors can slow the data flow. When symbol errors exist, one potential source is poor phase noise of system local oscillators (LOs). To troubleshoot, engineers can utilize low phase noise synthesizers as an LO substitute or measure the LO’s phase noise. This demonstration highlights the capabilities of the Holzworth HSY9000A series of multi-channel RF synthesizers with the ULN ultralow phase noise option and the Holzworth HA7062D series of real-time phase noise analyzers used in conjunction with a Holzworth HA7063A 50 GHz downconverter.