206 Keysight InfiniiVision HD3-Series Oscilloscopes User's Guide
14 Measurements
Adjacent Channel Power Ratio (ACPR)
Adjacent Channel Power Ratio or just Adjacent Power Ratio (or channel leakage
ratio) measures the ratio of the power contained in one or more sidebands to the
power in the main frequency range.
The main range is specified by a channel width and a center frequency. The
Channel Width is one of the measurement's parameters. The center frequency
used in the measurement is the one defined for the FFT function.
Sidebands (with the same width as the main range) exist above and below the
main range separated by the channel spacing width. The Channel Spacing width
is another measurement parameter.
The sideband used for the measurement is selected with the Channel Select
parameter. You can select the first through fifth sidebands above or below the
main range (1H through 5H above and 1L through 5L below). The full sideband
must be in the graticule to be measured. Otherwise, the measurement results will
be "Incomplete".
When this measurement is tracked with markers, the markers show the sideband
being measured.
Total Harmonic Distortion (THD)
Total Harmonic Distortion (THD) is the ratio of power in the fundamental frequency to
the power contained in the rest of the harmonics and noise. THD is a measure of
signal purity.
Main 1H
2H
3H
4H
5H
5L
4L
3L
2L
1L
Width
Spacing
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