Tektronix WFM 601A User Manual

WFM 601A, WFM 601E & WFM 601M User Manual

This section provides detailed information on the waveform monitor functions.
The topics are organized alphabetically. Most topics are named after the front
panel labels and button names.

The Audio display allows you to measure stereo audio phase errors of 20 kHz
analog stereo audio signals. Connect the audio signals to the Remote Connector
described in Appendix B on page B–2.

Correct phasing between two audio channels is quickly verified by the degree of
separation in the pattern shown on the display. Amplitudes are verified by the
direction of the pattern’s axis.

Audio amplitude and phase is monitored using a calibrated X/Y Lissajous
display. Using this display you can verify that the program audio will be properly
reproduced on both monaural and stereo receivers.

Any oscilloscope, including a vectorscope, that has identical X and Y amplifiers
can make accurate stereo audio phase measurements. When identical signals of
equal amplitude are input, the display pattern produced will be a Lissajous
pattern. The opening of the Lissajous pattern is relative to the phase error
between the signals. The remainder of this section discusses some of the
Lissajous patterns generated by the waveform monitor.

Figure 3–1 depicts an input audio signal from one channel. The figure on the left
depicts input from the X channel only, which produces a line pattern along the X
axis of an XY plot. Similarly, a line pattern along the Y axis of an XY plot
indicates an input audio signal from the Y channel only, as shown in the figure
on the right.