Specifications

50 Chapter 7
Measuring Noise
Measuring Noise Using the Noise Marker
Measuring Noise
Measuring Noise Using the Noise Marker
This procedure uses the marker function, Marker Noise, to measure
noise in a 1 Hz bandwidth. In this example the noise marker
measurement is made near the 50 MHz reference signal to illustrate
the use of
Marker Noise.
Step 1.
Enable the internal 50 MHz reference signal of the analyzer:
(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 INPUT:
Press
Input/Output, Amptd Ref Out (On).
Step 2. Preset the analyzer and modify the analyzer settings:
Press
Preset, Factory Preset (if present).
Press
FREQUENCY Channel, Center Freq, 49.98, MHz.
Press
SPAN X Scale, Span, 100, kHz.
Press
AMPLITUDE Y Scale, Ref Level, −10, dBm.
Press
AMPLITUDE Y Scale, Attenuation, 40, dB.
Step 3. Activate the noise marker:
(ESA) Press
Marker, More, Function, Marker Noise.
(PSA) Press
Marker Fctn, Marker Noise.
Note that display detection automatically changes to “Avg”; average
detection calculates the noise marker from an average value of the
displayed noise. Notice that the noise marker floats between the
maximum and the minimum displayed noise points. The marker
readout is in dBm (1 Hz) or dBm per unit bandwidth.
For noise power in a different bandwidth, add . For example,
for noise power in a 1 kHz bandwidth, dBm (1 kHz), add or
30 dB to the noise marker value.
NOTE ESA average detection is available for firmware revisions A.08.00 and
later. Earlier firmware revisions earlier use sample detection for
marker noise calculations.
Step 4. Reduce the variations of the sweep-to-sweep marker value by
increasing the sweep time:
Press
Sweep, Sweep Time, 3, s.
10 log× BW()
10 log 1000()×