How do I measure power spectral density (PSD) on my spectrum analyzer or vector signal analyzer?
PSD is typically measured in units of Vrms2 /Hz or Vrms/rt Hz , where “rt Hz” means “square root Hertz”. Alternatively, PSD can be expressed in units of dBm/Hz. On a spectrum analyzer such as the PSA, ESA, 856XE/EC or 859XE, power spectral density can be measured with the noise marker. On a vector signal analyzer such as the 89600S or 89400, there is a PSD Measurement Data type. The easiest way to make the measurement on a spectrum analyzer in units of Vrms/rt Hz is to: Select amplitude units of Volts in the AMPLITUDE menu (AMPLITUDE [hardkey] > More > Y Axis Units > Volts). Turn on the noise marker in the Marker or Marker Function menu (on the ESA, for example, the sequence is Marker [hardkey] > More > Function > Marker Noise). Place the marker on the desired data point and observe the marker readout. Let’s say that the noise marker readout is 16 uV(Hz) or 16 uV/Hz. The “(Hz)” indicates that the result is normalized to a 1Hz noise bandwidth (RBW), but the correct unit denominator shou
