Atec Agilent-8563E - Manual (Page 90)

ESG Family Signal Generators Performance Tests
21. Measuring Phase Noise and Residual FM (ESG-AP and ESG-DP Series Signal Generators)
Calibration Guide 4-41
Figure 4-37
Measuring Residual FM
Residual FM is closely related to phase noise. Good phase noise typically implies good
residual FM. Directly measuring residual FM at very low levels is difficult, but the
HP/Agilent E5500 system can integrate the phase noise results to determine an accurate
value. This is done under the E5500 software Trace Integration menu by selecting a data
type of
Snu(f) or Spectral density of frequency fluctuations .
In the ESG-P series, residual FM is defined only within a 300-3000 Hz bandwidth and
with a specified frequency response within this band. That frequency response is specified
by a CCITT filter characteristic. In the E5500 system, software revision 5.0 or higher, use
of this filter response can be achieved by simply checking the
CCITT weighting box under
the Trace Integration menu.
If you use the older HP/Agilent 3048 phase noise system, there is no direct way to measure
residual FM, but because residual FM and phase noise are so closely related and
interdependent, it is safe to assume that if the DUT’s phase noise meets specification,
looks typical (between 300 and 3000 Hz), and shows no unexpected large spikes in the
response, then it will most likely also meet the residual FM specification.