Making Measurements 3
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.
1Preset the analyzer:
2Input a signal (1 GHz,
3Set the center frequency, span and reference level:
•Press [FREQ] > {Center Freq} > 1 > {GHz}
•Press [SPAN] > 5 > {MHz}
•Press [AMPTD] > {Ref Level} > –40 > {dBm}
4Move the desired peak (in this example, 1 GHz) to the center of the display:
•Press [MARKER] > {Peak Search}
•Press [MARKER] > {Marker To} > {To Center}
Figure 6 A signal closer to the noise level (Atten:10 dB)
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