Agilent Technologies E7402A, E7405A, E7404A Making Noise Measurements, Noise Measurement Example

NOTE

Making Basic Measurements

Making Noise Measurements

Making Noise Measurements

There are a variety of ways to measure noise power. The first decision you must make is whether you want to measure noise power at a specific frequency or the total power over a specified frequency range, for example over a channel bandwidth.

Noise Measurement Example 1:

Using the marker function, Marker Noise, is a simple method to make a measurement at a single frequency. In this example, attention must be made to the potential errors due to discrete signal (spectral components). This measurement will be made near the 50 MHz amplitude reference signal to illustrate the use of Marker Noise.

1.Perform a factory preset by pressing Preset, Factory Preset (if present).

2.Turn on the internal 50 MHz amplitude reference signal of the analyzer as follows:

•For the E7401A, use the internal 50 MHz amplitude reference signal of the analyzer as the signal being measured. Press

Input/Output, Amptd Ref (On).

•For all other models connect a cable between the front-panel AMPTD REF OUT to the analyzer INPUT, then press

Input/Output, Amptd Ref Out (On).

3.Set the center frequency to 49.98 MHz by pressing FREQUENCY,

Center Freq, 49.98, MHz.

4.Set the span to 100 kHz by pressing SPAN, Span, 100, kHz.

5.Set the resolution bandwidth to 1 kHz by pressing BW/Avg,

Res BW (Man), 1, kHz.

6.Set the Y-Axis Units to dBm by pressing AMPLITUDE, More, Y-Axis Units, dBm.

7.Set the attenuation to 60 dB by pressing AMPLITUDE, Attenuation (Man), 60, dB. See Figure 1-42.

When making noise measurements and AMPLITUDE, Scale Type (Log) is selected (10 dB/division), position the trace between 3 and 6 graticule lines above the bottom by adjusting the reference level (AMPLITUDE, Ref Level). Measurement inaccuracies may occur if displayed trace is positioned outside this range.

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