User manual

Audio Generator
AM700 Audio Measurement Set User Manual
4-9
Jittered Sine (digital generator in AES mode only). This selection adds a sine wave on
the audio and jitters (phase modulates) the digital interface. The frequency
(modulating) signal and jitter amplitude can be set in the Waveform Control screen.
Measurement units for jitter amplitude are in unit intervals peak-to-peak.
One common use for a jittered sine wave is in testing D-to-A converters. This is
done by sending a jittered sine wave to a D-to-A converter and observing the
resulting audio sine wave for sidebands with an FFT analyzer. The purpose of this
test is to see how much of the jitter on the interface finds its way into the audio. If
the D-to-A converter derives its clock from the interface, jitter on the interface can
enter the D-to-A clock and phase-modulate the A-to-D converter clock, creating
unwanted sidebands.
Follow. Follow A selections are available in the Waveform pop-up menus of the
Channel B and SF1 generators. Follow Analog is an available choice in the SF1
digital generator. These waveform selections cause the following generators to send
the same signal on both channels in phase, effectively producing a monaural output.
In Follow mode, any change made to the output configuration of one generator
channel is reflected on the following generator. Using the Follow selections, it is
possible to configure analog generator Channel A and slave the remaining
generators to produce the same output signal and amplitude. When generators are
following, they also follow the same list for sweep and multitone signal generation.
NOTE. This is not the same as explicitly selecting the same output for each generator
channel. When you select the same output explicitly, the signals may not be in
phase.
Additional waveform parameters can be specified by selecting the Waveform
Control soft key.
There are four multitone files included in the AM700 firmware. These are files that
generate multitones corresponding to the four signals generated by the Tektronix
ASG 100 Audio Signal Generator. They are located in the file system in the
dos:/mtone directory and are named asgmton1.ton, asgmton2.ton, asgmton3.ton, and
asgmton4.ton.
Multitone
Files