User`s guide
Table Of Contents
- Overview
- Getting Started
- System Setting
- Making Measurements
- Measuring Multiple Signals
- Measuring a Low-Level Signal
- Improving Frequency Resolution and Accuracy
- Making Distortion Measurements
- One-button Power Measurement
- Making a Stimulus Response Transmission Measurement
- Measuring Stop Band Attenuation of a Low-pass Filter
- Making a Reflection Calibration Measurement
- Measuring Return Loss Using the Reflection Calibration Routine
- Making an Average Power Measurement
- Key Reference
- SCPI Command Reference
- Error Messages
- Menu Map
Making Measurements 4
N9340A User’s Guide 47
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 to measure a low- level signal:
Reducing Input Attenuation
The ability to measure a low- level signal is limited
by the 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 6 A signal closer to the noise level (Atten:10 dB)