Rohde & Schwarz SMU200A - Page 57

R&S SMU200A Test Procedures
1007.9845.82 1.31
E-12
AM Distortion
Test assembly
See section "
Standard Test Assembly for Analog Modulations",
page 1.3.
Measurement
 Settings on DUT
:
RF
On
Level P
min
Amplitude Modulation menu:
LF Gen Frequency 1 kHz
Source Internal
AM depth 30%.
 Vary the carrier frequency from RF
min
to RF
max
. Recommended test
f
requencies: as with RF frequency response (see above)
 Repeat the measurement with PEP = P
max
and AM 80%.
Test Method Spectrum
Measurement
 Measure the power of the two sidebands
modfRF
P

,
modfRF
P
+
and
the harmonics
mod* fnRF
P

,
mod* fnRF
P
+
with the spectrum analyzer.
Calculate the distorti
on:


=
+
=
+
+
+
=
4
1
mod*mod*
4
2
mod*mod*
n
fnRFfnRF
n
fnRFfnRF
PP
PP
Distortion
Test Method Demodulation
Measurement
 Set up Analyzer as described under Amplitude Modulati
on
U
ncertainties
 Read THD from the display. To convert to percent calcul
ate
D
istortion = 100 * 10
THDdB / 20
.