:PNOise Subsystem

The Phase Noise analysis feature measures phase noise in a clock source. It can use the two-channel cross-correlation technique that lowers the oscilloscope's phase noise measurement floor by splitting the clock source signal into two oscilloscope input channels.

As the oscilloscope runs, continuing to make acquisitions, a specified number of cross-correlations are performed to reduce noise. After the specified number of cross-correlations are performed, measurement results are averaged to smooth the roughness of the phase noise plot.

Phase noise measurement results are presented in a log frequency plot where the amplitude units are dBc/Hz (decibels relative to the carrier power normalized to a 1 Hz bandwidth). The X-axis is the single-sideband (SSB) frequency offset from the nominal signal or "carrier" frequency.