User manual

FFT Analyzer
4-90
AM700 Audio Measurement Set User Manual
Figure 4-41: Zoomed FFT display showing maximum expansion of the trace
Multitone Measurement Mode
Most audio tests consist of measuring a sine-wave audio tone, then stepping the
frequency and repeating the test. The process continues until measured level versus
frequency graphs can be assembled and displayed. Each audio test typically takes
several seconds.
The technique is accurate, and when time is not an issue, is the best way to perform
an audio test. But when only a few seconds are available to perform a complete
measurement, or for adjusting a processing device or nulling distortion, near
real-time updates of measurement data are necessary.
The AM700 Multitone measurement addresses this problem. Instead of measuring a
single-frequency sine wave, the measurement uses a test signal consisting of sine