User manual

Audio Generator
4-10
AM700 Audio Measurement Set User Manual
User-specified multitone files can be created and used to set the frequency,
amplitude, and phase of the individual tones used to make up the multitone signal.
These files must be created externally using an editor that generates ASCII files in
DOS format. When constructing a multitone signal there are some rules to make
sure the multitone signal will be properly detected by the AM700. Those rules
follow the multitone file description.
NOTE. The amplitude level is for individual tones that make up the multitone signal.
The generator amplitude setting is 0.707 x peak voltage, which is RMS voltage for
sine waves only. The level of transmitted multitones depends on the crest factor of
the signal. That varies each time the multitone signal is sent by the generator
(unless in file mode with absolute phases provided).
In both file mode and list mode the amplitude parameter for an individual tone is
used only to control the relative amplitude of that tone with respect to the other
tones.
Summary: The only way you can determine the received level of each tone is to work
backwards from the peak level of the complex waveform, with knowledge of the crest
factor.
Creating a User Multitone File. Here is an example AM700 multitone file indicating
frequency in Hertz, amplitude in dBV, and phase in degrees:
am700 multitone 1.0 10
1000.0 0 12.0
2000.0 0 45.0
This example makes two tones:
1000 Hz at 0 dBV with a phase of 12 degrees, and 2000 Hz at 0 dBV with a
phase of 45 degrees.