No Harmonic Distortion - HP 8590 E-Series User Manual

6. Compare the response in trace A to the response in trace B. If the distortion product
decreases as the attenuation increases, distortion products are caused by the spectrum
analyzer input mixer.
Note
When the source signal amplitude is changed between trace A and trace B and
there is a resulting change in the distortion product, this is shown by a change
in the marker amplitude (marker-delta value). An example of the marker-delta
value produced by a change in the distortion product is shown in Figure 3-22.
A change in the distortion product is indicative of high-level input signals
causing circuit overload conditions and producing distortion. This distortion is a
function of the internal hardware of the analyzer. The input signals must be
attenuated to eliminate the interference caused by the internal distortion.
However, if is no change in the distortion product with an increase in
attenuation, the distortion is not caused internally but is a result of distortion
that is present on the input signal as supplied from the signal source. An
example of this is shown in Figure 3-23, where the source signal is not high
enough to cause internal distortion in the spectrum analyzer, therefore, any
distortion that is displayed is present on the input signal.
C E N T E R 400 0 MHZ C E N T E R 400 0 MHZ
RF Attenuation Attenuation of 10
Figure 3-22. RF Figure 3-22.
52: 39 APR 07. 1 9 4 3
PEAK
C E N T E R a00 0 MHZ
Figure 3-23. No Harmonic Distortion
of 10 dB
Making Basic Measurements 3-21