Agilent Technologies E7401A, E7402A, E7403A, E7404A, E7405A Making Noise Measurements

Chapter 1 51

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 50MHz

amplitude reference signal to illustrate the use of MarkerNoise.

1. Perform a factory preset by pressing Preset, FactoryPrese t (if

present).

2. Turn on the internal 50 MHz amplitude reference signal of t h e

analyzer as follows:

•For the E7401A, use the internal 50MHz 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 49.98MHz by pressing FREQUENCY,

Center Freq, 49.98, MHz.

4. Set the span to 100kHz 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-AxisUnits, dBm.

7. Set the attenuation to 60dB by pressing AMPLITUDE, Attenuation

(Man), 60, dB. See Figure1-42.

NOTE 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.

Contents

Main Signal Analysis Measurement Guide Agilent Technologies EMC Series Analyzers Notice Safety Information Warrant y LIMITATION OF WARRANTY EXCLUSIVE REMEDIES Where to Find the Latest Informa tion Page Contents Page What is in This Chapter Test Equ ipm ent Comparing Signals Signal Comparison Example 1: Page Signal Comparison Example 2: Page Resolving Signals of Equal Amplitude Resolving Signals Example: Page Page Resolving Small Signals Hidden by Large Signals Resolving Signals Example: Page Page Making Better Frequency Measurements Better Frequency Measurement Example: Page Decreasing the Frequency Span Around the Signal Decreasing the Frequency Span Example: Page Page Tracking Drifting Signals Tracking Signal Drift Example 1: Page Page Tracking Signal Drift Example 2: Page Page Page Measuring Low Level Signals Measuring Low Level Signals Example 1: Page Measuring Low Level Signals Example 2: Measuring Low Level Signals Example 3: Page Measuring Low Level Signals Example 4: Page Page Identifying Distortion Products Distortion from the Analyzer Identifying Analyzer Generated Distortion Example: Page Page Third-Order Intermodulation Distortion Identifying TOI Distortion Example: Page Page Page Measuring Signal-to-Noise Signal-to-Noise Measurement Example: S/N 70 dB/Hz10 30 kHz()log+ 25.23 dB30 kHz()== Making Noise Measurements Noise Measurement Example 1: Page Page Page Page Noise Measurement Example 2: Noise Measurement Example 3: Page Page Demodulating AM Signals (Using the Analyzer As a Fixed Tuned Receiver) Demodulating an AM Signal Example 1: Page Page Page Page Page Demodulating FM Signals Demodulating a FM Signal Example: Page Page Page Page Whats in This Chapter Required Test Equipment Making Stimulus Response Measu rements What Are Stimulus Response Measurements? Using An Analyzer With A Tracking Generator Stepping Through a Transmission Measurement Page Page Page Page Tracking Generator Unleveled Condition Measuring Device Bandwidth Page Page Measuring Stop Band Attenuation Using Log Sweep Page Page Page Page Making a Reflection Calibration Measurement Example: Reflection Calibration Measuring the Return Loss Chapter 2 87 VSWR 110 Making Complex Measurements Making a Reflection Calibration Measurement -----------------------= Table 2-1 Power to VSWR Conversion + 110 Demodulating and Listening to an AM Signal Demodulating and Listening to an AM Signal Example 1: Demodulating and Listening to an AM Signal Example 2: