Rohde & Schwarz SMB100A - Wideband Noise

Test Procedures R&S SMB
1407.0806.82 1.16 E-5
Wideband Noise
Test assembly Connect spectrum analyzer to RF socket of the DUT.
Test method The carrier power is measured first. Then the center frequency of the
analyzer is increased by 10 MHz and the noise power in a small
bandwidth is measured. The difference of the carrier power and the
n
oise power in 1 Hz bandwidth, which is calculated from the
measurement, is defined as wideband noise. Because wideband
noise degrades with lower electronic levels in front of the output step
attenuator the output level of the generator has to be set to the lowest
level before switching the step attenuator.
Measurement  Settings on DUT:
- frequency: test frequency
- Level: 0 dBm
- determine Att-fixed range upper Level P
u
pper
:
-  RF  Level Att fixed range  upper
- set level to P
upper
+ 0.1 dB
 Settings on analyzer:
- center: test frequency
- reference level P
upper
+ 1 dB
- Attenuator D
min
= P
upper
- P
1dBM
+ 5dB  round to next larger
available Attenuation of the analyzer (P
1
dBM
= analyzer P1dB level
at test frequency)
- span 110 kHz
- Detector RMS
- Sweep Time Manual 1s
- switch on channel power measurement with 100 kHz bandwidth
 Determine the channel power with the center frequency of the
analyzer set to the test frequency and note it down as P
ref
.
 Increase the analyzer center frequency by 9.9 MHz.
 Inhibit the switching of the attenuator with AMPT RF ATTEN
MANUAL without entering a value so that the input mixer is not
overdriven.
 Lower the reference level of the analyzer by 20 dB, read the new
channel power P
noise
.
 Minimize the output level on the DUT by means of RF OFF, read
the channel power P
res
.