Technical data

Chapter 5 91
Spectrum Analyzer
Measuring a Low−Level Signal
Spectrum Analyzer
Decreasing the Resolution Bandwidth
Resolution bandwidth settings affect the level of internal noise without
affecting the level of continuous wave (CW) signals. Decreasing the
RBW by a decade reduces the noise floor by 10 dB.
Step 1. Connect the RF Output of the signal generator to the analyzer RF Input
as shown in Figure 5-7.
Figure 5-16 Setup for Obtaining One Signal
Step 2. Set the frequency of the signal source to 295 MHz. Set the source
amplitude to −80 dBm. Connect the source RF OUTPUT to the analyzer
RF INPUT.
Step 3. Select the spectrum analyzer mode:
Press
Mode, Spectrum Analyzer.
Step 4. Preset the analyzer:
Press
Mode Preset.
Step 5. Set the center frequency, span and reference level:
Press
FREQ Channel, Center Frequency, 295, MHz.
Press
SPAN X Scale, Span, 1, MHz.
Press
AMPTD Y Scale, Ref Level, 40, −dBm.
Step 6. Decrease the resolution bandwidth:
Press
BW, Res BW, ↓.
The low-level signal appears more clearly because the noise level is
reduced (see Figure 5-17).