Agilent Technologies N9340A manual Measuring a Low-Level Signal, Reducing Input Attenuation

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, –80 dBm) to the analyzer RF input connector.

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)

N9340A User’s Guide 31