Measuring A Low-Level Signal - Keysight Technologies N9340B User Manual

Measuring a Low-Level Signal

This section provides information on measuring
low-level signals and distinguishing them from spectrum
noise. There are four main useful techniques as follows
to measure a low-level signal.
Reducing Input Attenuation
The ability to measure a low-level signal is limited by
internally generated noise in the spectrum analyzer.
The input attenuator affects the level of a signal passing
through the analyzer. If a signal is very close to the noise
floor, reducing input attenuation will bring the signal out
of the noise.
1 Preset the analyzer:
2 Input a signal (1 GHz, –80 dBm) to RF IN.
3 Set the CF, span and reference level:
•
•
•
4 Move the desired peak (in this example, 1 GHz) to the
center of the display:
•
•
Figure 4-5 A signal closer to the noise level (Atten: 10 dB)
Press [FREQ] > 1 > {GHz}
Press [SPAN] > 5 > {MHz}
Press [AMPTD] > –40 > {dBm}
Press [MARKER] > {Peak Search}
Press [MARKER] > {Marker To} > {To Center}
Making Measurements
Measuring a Low-Level Signal
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