Audio Analyzer Measurement Functions 5Keysight U8903A User’s Guide 121The SINAD measurement is shown as follows.Figure 5-9 SINAD measurementSNR and Noise LevelSignal-to-noise ratio (SNR) is defined as the ratio of the signal amplitude to noiseamplitude. Both the signal and noise amplitude must be measured at the same orequivalent points in a system, and within the same system bandwidth.The U8903A implementation of the SNR measurement is a closed loopconfiguration in which both the generator and the analyzer are used in the testsetup. Channel 1 of the generator will be used for measurement on the analyzerchannel 1.The SNR for an audio system such as an amplifier at a specified input or outputlevel is the ratio between the output signal power and noise level. An SNR value isfurther defined by the measurement bandwidth specification. The measurementbandwidth is up to 20 kHz, with or without weighting filters. Refer to Chapter 3,“Input Settings” on page 76 for the information on selecting the input settings.
