User`s guide

Identifying Distortion Products Using the RF Attenuator and
Traces
Distortion from the Analyzer
High-level input signals may cause spectrum analyzer distortion products that could mask the
real distortion measured on the input signal. Using trace B and the RF attenuator, you can
determine which signals, if any, are internally generated distortion products.
Example: Using a signal from a signal generator, determine whether the harmonic distortion
products are generated by the spectrum analyzer.
1. Connect a signal generator to the spectrum analyzer INPUT 500. Set the signal generator
frequency to 200 MHz and the amplitude to 0 dBm.
Set the center frequency of the spectrum analyzer to 400 MHz and the span to 500 MHz:
press (-1, 400 m, (SPAN) 500 m. The signal shown in Figure 3-21 produces
harmonic distortion products in the spectrum analyzer input mixer.
PEAK
LOG
10
dE/
WA SE
SC F(
CDRR
c
L
CENTER 400 0 MHZ
5PAll 500 m
MHZ
RE: SW 3 MHz
YBW 1 MHZ
SWP 20
msec
Figure 3-2
1.
Harmonic Distortion
2. Change the span to 200 MHz: press (SPAN), 200 INIHz).
3. Change the attenuation to 0 dB: press [AMPLITUDE], ATTEN AUTO MAN , 0 IdBm_l.
4. To determine whether the harmonic distortion products are generated by the spectrum
analyzer, first save the screen data in trace B.
Press (ml, TRACE A B C (until trace B is underlined), then CLEAR WRITE B . Allow the
trace to update (two sweeps) and press VIEW B , [PEAK SEARCH), MARKER A . The spectrum
analyzer display shows the stored data in trace B and the measured data in trace A.
5. Next, increase the RF attenuation by 10 dB: press C-1, ATTEN AUTO MAN , and the
step-up key (m) once. See Figure 3-22.
3-20 Making Basic Measurements