Display eye diagram of time-domain signal
Comm Sinks
The Eye Diagram block displays multiple traces of a modulated signal to produce an eye diagram. You can use the block to reveal the modulation characteristics of the signal, such as the effects of pulse shaping or channel distortions.
The Eye Diagram block has one input port. This block accepts a column vector or scalar input signal. The block accepts a signal with the following data types: double, single, base integer, and fixed point. All data types are cast as double before the block displays results.
To modify the eye diagram display, select View > Configuration Properties or click the Configuration Properties button (). Then select the Main, 2D color
histogram, Axes, or Export tabs
and modify the settings.
Display mode of the eye diagram, specified as Line plot
or
2D color histogram
. Selecting 2D color
histogram
makes the histogram tab available. This parameter is
tunable.
Select this check box to enable eye measurements of the input signal.
Select this radio button to display the jitter histogram. This parameter is available
when Display mode is 2D color histogram
and Enable measurements is selected. This can also be accessed by
using the histogram button drop down on the toolbar.
Select this radio button to display the noise histogram. This parameter is available
when Display mode is 2D color histogram
and Enable measurements is selected. This can also be accessed by
using the histogram button drop down on the toolbar.
Select this check box to display the horizontal bathtub curve. This parameter is available when Enable measurements is selected. This can also be accessed by using the bathtub curve button on the toolbar.
Select this check box to display the vertical bathtub curve. This parameter is available when Enable measurements is selected. This can also be accessed by using the bathtub curve button on the toolbar.
Select either Real only
or Real and
imaginary
to display one or both eye diagrams. To make eye
measurements, this parameter must be Real only
. This
parameter is tunable.
Select this check box to fade the points in the display as the interval of time after
they are first plotted increases. The default value is false
. This
parameter is available only when the Display mode is
Line plot
. This property is tunable.
Number of samples per symbol. Use with Symbols per trace to determine the number of samples per trace. This parameter is tunable.
Sample offset, specified as a nonnegative integer smaller than the product of Samples per symbol and Symbols per trace. The offset provides the number of samples to omit before plotting the first point. This parameter is tunable.
Number of symbols plotted per trace, specified as a positive integer. This parameter is tunable.
Number of traces plotted. This parameter is available only when the Display
mode is Line plot
. This parameter is
tunable.
Label that appears above the eye diagram plot. By default, the plot has no title. This parameter is tunable.
Toggle this check box to turn the grid on and off. This parameter is tunable.
Minimum value of the y-axis. This parameter is tunable.
Maximum value of the y-axis. This parameter is tunable.
Text that the scope displays along the real axis. This parameter is tunable.
Text that the scope displays along the imaginary axis. This parameter is tunable.
The 2D histogram tab is available when you click the histogram button or when the
display mode is set to 2D color histogram
.
Oversampling method, specified as None
,
Input interpolation
, or Histogram
interpolation
. This parameter is tunable.
To plot eye diagrams as quickly as possible, set the Oversampling
method to None
. The drawback to not
oversampling is that the plots look pixelated when the number of samples per
trace is small. To create smoother, less-pixelated plots using a small number of
samples per trace, set the Oversampling method to
Input interpolation
or Histogram
interpolation
. Input interpolation
is the faster of the two interpolation methods and produces good results when
the signal-to-noise ratio (SNR) is high. With a lower SNR, this oversampling
method is not recommended because it introduces a bias to the centers of the
histogram ranges. Histogram interpolation
is not as
fast as the other techniques, but it provides good results even when the SNR is
low.
Color scale of the histogram plot, specified as either
Linear
or Logarithmic
.
Set Color scale to Logarithmic
if certain areas of the eye diagram include a disproportionate number of points.
This parameter is tunable.
The toolbar contains a histogram reset button , which resets the internal histogram buffers and clears the
display. This button is not available when the display mode is set to
Line plot
.
Select this check box export the eye diagram measurements to the MATLAB® workspace. This parameter is tunable.
Specify the name of the variable to which the eye diagram measurements are
saved. The default is EyeData
. This parameter is tunable. The
data is saved as a structure having these fields:
MeasurementSettings
Measurements
JitterHistogram
NoiseHistogram
HorizontalBathtub
VerticalBathtub
BlockName
In the Style dialog box, you can customize the style of the active display. You can change the color of the figure containing the displays, the background and foreground colors of display axes, and properties of lines in a display. To open this dialog box, select View > Style.
Specify the background color of the scope figure. By default, the figure color is black.
Specify the fill and line colors for the axes.
Specify the line style, line width, and line color for the displayed signal.
Specify data point markers for the selected signal. This parameter is similar to
the Marker
property for MATLAB
Handle
Graphics® plot objects.
Specifier | Marker Type |
---|---|
none | No marker (default) |
![]() | Circle |
![]() | Square |
![]() | Cross |
![]() | Point |
![]() | Plus sign |
![]() | Asterisk |
![]() | Diamond |
![]() | Downward-pointing triangle |
![]() | Upward-pointing triangle |
![]() | Left-pointing triangle |
![]() | Right-pointing triangle |
![]() | Five-pointed star (pentagram) |
![]() | Six-pointed star (hexagram) |
Specify the colormap of the histogram plots as one of these schemes:
Parula
, Jet
, HSV
,
Hot
, Cool
, Spring
,
Summer
, Autumn
, Winter
,
Gray
, Bone
, Copper
,
Pink
, Lines
, or Custom
.
This parameter is active when the Eye Diagram is in
Histogram
mode. The default is
Hot
. If you select Custom
, a dialog box pops
up from which you can enter code to specify your own colormap.