Specifications

52 Chapter 7
Measuring Noise
Measuring Noise-Like Signals Using Marker Pairs
Measuring Noise
Measuring Noise-Like Signals Using Marker
Pairs
Marker pairs let you measure power over a frequency span. The
markers allow you to easily and conveniently select any arbitrary
portion of the displayed signal. However, while the analyzer, when
autocoupled, makes sure the analysis is power-responding (rms
voltage-responding), you must set all of the other parameters.
Step 1. Preset the analyzer:
Press
Preset, Factory Preset (if present).
Step 2. Set the center frequency, span, reference level and attenuation:
Press
FREQUENCY Channel, Center Freq, 50, MHz.
Press
SPAN X Scale, Span, 100, kHz.
Press
AMPLITUDE Y Scale, Ref Level, −20, dBm.
Press
AMPLITUDE Y Scale, Attenuation, 40, dB.
Step 3. Turn on the marker span pair to setup the band power measurement in
step 5:
Press
Marker, Span Pair, Span Pair (Span), 40, kHz.
Step 4. Set the resolution and video bandwidths:
Press
BW/Avg, Res BW, 1, kHz.
Press
BW/Avg, Video BW, 10, kHz.
Common practice is to set the resolution bandwidth from 1% to 3% of
the measurement (marker) span, 40 kHz in this example. For ESA, the
video bandwidth should be at least ten times wider than the resolution
bandwidth.
Step 5. Measure the total noise power between the markers:
(ESA)
Marker, More, Function, Band Power.
(PSA)
Marker Fctn, Band/Intvl.
Step 6. Add a discrete tone to see the effects on the reading. Enable the internal
50 MHz amplitude reference signal of the analyzer as follows:
(PSA)
Press
Input/Output, Input Port, Amptd Ref.
(ESA E4401B and E4411B)
Press
Input/Output, Amptd Ref (On).
(ESA E4402B, E4403B, E4404B, E4405B, E4407B and E4408B)
Connect a cable from the front panel AMPTD REF OUT to the analyzer
RF input:
Press
Input/Output, Amptd Ref Out (On).