Agilent Creating Custom Multitone with Keysight U8903A Audio Analyzer - Application Note 5991-2396EN c201407 free download

File name Creating Custom Multitone with Keysight U8903A Audio Analyzer - Application Note 5991-2396EN c201407

Keysight Technologies Creating Custom Multitone with Keysight U8903A Audio Analyzer Application Note Introduction A multitone waveform is an audio signal comprised of multiple tones. Figure 1 shows an example of a multitone signal consisting of 20 tones from 1 kHz to 20 kHz. Multitone wave- forms are widely used in modern audio measurements to test consumer and professional audio devices, broadcast devices, and internet audio. A multitone is an ideal test signal for an open-loop audio test where the analyzer does not need to coordinate with the genera- tor. This feature allows an audio signal to be tested over a long distance, such as audio via internet, or a playback device such as a mobile phone. Figure 1. An example of a multitone signal consisting of 20 tones Standard multitone signals have evenly-spaced tones with equal amplitudes as shown in Figure 1. However standard multitone signal do not represent real-world test conditions, making it necessary to create custom multitones. For example, when testing a filter, additional tones can provide detailed characterization of specific frequency ranges, such as the rising and falling edges of the filter curve. When testing a pre-amplifier, it may be desirable to lower individual tone amplitudes to avoid overloading the device under test (DUT). In other cases, it may be necessary to create custom multitones defined by industry standards such as Dolby or DTS. Creating a custom multitone waveform with the Keysight Technologies, Inc. audio analyzer is quick and convenient. This application note shows the Keysight U8903A audio analyzer can be used to create a standard multitone and then used to modify the parameters of the standard multitone to create a custom multitone waveform. Throughout the example, bold text is used to indicate keys on the instrument. Text in [ ] refers to softkeys presented on the instrument's screen. Process Overview There are four basic steps to creating custom multitone signals: 1. Create a standard (equally-spaced) multitone waveform. 2. Modify the frequency, amplitude, and phase values. 3. Verify the custom multitone waveform. 4. Save and recall the multitone waveform as an arbitrary file. To illustrate this process, the following sections demonstrate how to create a custom, six-