Agilent Technologies N9340A - Manual (Page 51)

Making Measurements 4
N9340A User’s Guide 49
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 the analyzer
RF input connector.
3 Set the center frequency, span and reference level:
•
Press
[FREQ] > {Center Freq} > 1 > {GHz}
•
Press
[SPAN] > 5 > {MHz}
•
Press
[AMPTD] > {Ref Level} > 40 > {–dBm}
4 Move 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 4 A signal closer to the noise level (Atten:10 dB)