AM Noise Measurement for 1GHz signal

Measurement Setup

1. Press Meas/View > AM Noise to select the AM noise measurement window. Press Window Max to maximize the window.  

2. Press Trigger > Trigger to AM Noise > Continuous to start measurements.
   
   Press Trigger > Source > Internal.

3. Press Setup > Auto Setting.  

4. Press Start/Center (Stop/Span), set Start > 1Hz and Stop > 40MHz.

5. Press Avg/BW > Avg factor 5 > Averaging > ON to reduce fluctuation, then press Averaging Restart.

6. Press Scale > Auto Scale.

7. Press Marker > Marker1 > 1 > M/u to check phase noise at 1MHz offset.
   
   The marker value is displayed in the upper part of the trace screen.
   
   

Analysis

Correlation

If the 1GHz signal is a clean signal, the correlation function can be used for noise floor reduction.

1. Press Avg/BW > Correlation > 1, then set Avg factor > 5 and turn Averaging > ON, then press Averaging Restart.

2. In the bottom right part of screen, Averaging Status n/m is displayed. When the average status becomes “5/5”, press Trigger > Hold.

3. Press Setup > Auto Setting.

4. Press Trace/View > Data -> Mem, then press Display Trace > Data & Mem

5. Press Avg/BW > Correlation > 10, then Averaging Restart.
   
   The measurement result (Data trace) is improved about 5dB.
   
   

• Generally, the measurement for the AM noise of a VCO requires considerable time because the AM noise level of a VCO is small as compared with its phase noise level.

Spurious

1. Press Trace/View > Spurious > Power (dBc). Then set Spur Sensibility > 1 and Minimum Spur Level > -115 dBc.

2. Press Scale > Auto Scale.

3. Spurious are displayed by high light. Then press Spurious List, you can view response values for the spurious in a text file.

More Information

For more information about AM Noise Measurement, see AM Noise Measurement.