Tektronix RFA300A, Руководство пользователя

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Reference
3- 8
RFA300A Measurement Set 8VSB
Amplitude and Phase Errors
This section provides a brief overview of the Amplitude and Phase Errors
measurement window. For more in-depth information, refer to the online help.
This measurement measures amplitude and phase errors, which are nonlinear
distortions. A signal’s phase can shift with amplitude. Transmitters, particularly
high power ones, can exhibit amplitude errors in the form of clipping or
compression when close to full power. These errors decrease a transmitter’s
Signal-to-Noise ratio, thereby reducing the coverage area.
The measurement set performs the measurement by calculating ideal signal
magnitude and phase from the received I/Q signal and comparing it with the
actual signal.
The Amplitude and Phase Errors measurement window is shown in Figure 3--8.
The measurement window contains the following areas:
H
A listing of measurement results.
H
A mask test pass or fail indicator for each measurement.
H
Cursor direction controls.
H
A listing of each cursor’s position and the difference between the two.
H
Graphics showing signal amplitude error versus ideal signal amplitude
measured in dB versus constellation units (refer to the
Glossary
) and signal
phase errors versus ideal signal amplitude measured in degrees versus
constellation units. The selected masks are overlaid on the graphics, if
enabled from the setup (refer to
Amplitude and Phase Errors Setup next).