Eye Diagram

Display eye diagram of time-domain signal

Since R2023b

• 

Libraries:
Communications Toolbox / Comm Sinks
Communications Toolbox HDL Support / Comm Sinks
Mixed-Signal Blockset / Utilities
SerDes Toolbox / Utilities

Description

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 SCOPE and click the Settings button () in CONFIGURATION.

Examples

View Eye Diagram

Display the eye diagram of a filtered QPSK signal using the Eye Diagram block.

Open the model EyeDiagramofQPSKSignal. Run the model and observe the eye diagram displayed.

Ports

Input

In — Input signal

scalar | column vector

Input signal, specified as a scalar or column vector.

Data Types: double

Parameters

Display and Traces

Samples per symbol — Samples per symbol

8 (default) | positive integer

Number of samples per symbol, specified as a positive integer. Use with Symbols per trace to determine the number of samples per trace.

Tunable: Yes

Sample offset — Sample offset

0 (default) | nonnegative integer

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.

Tunable: Yes

Symbols per trace — Symbols per trace

2 (default) | positive integer

Number of symbols plotted per trace, specified as a positive integer.

Tunable: Yes

Traces to display — Number of traces to display

40 (default) | positive integer

Number of traces plotted, specified as a positive integer.

Tunable: Yes

Dependencies

Color fading — Color fading

off (default) | on

Select this check box to fade the points in the display as the interval of time after they are first plotted increases.

Plot Imaginary Axes — Plot imaginary axes

on (default) | off

Select this check box to display the imaginary plot of the eye diagram.

Axes and Labels

Real axes label — Real axis label

Real Amplitude (default)

Text that the scope displays along the real axis.

Tunable: Yes

Title — Title label

None (default)

Label that appears above the eye diagram plot.

Tunable: Yes

Imaginary axes label — Imaginary axis label

Imaginary Amplitude (default)

Text that the scope displays along the imaginary axis.

Tunable: Yes

Y-limits — Lower and upper limit values

[-1.1,1 1] (default) | scalar

Lower and upper limit values of the y-axis.

Tunable: Yes

Show grid — Show grid on plot

on (default) | off

Select this radio button to show the grid on the scope window.

COLOR AND STYLING

Use this tab to 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.

Preserve colors for copy to clipboard — Preserve colors for copy to clipboard

off (default) | on

Select this radio button to preserve the colors when copying to a clipboard.

Background — Background colors

black (default)

Specify the background color for the plot..

Axes — Axes colors

black (default)

Specify the fill and line colors for the axes.

Labels — Label colors

grey (default)

Specify the color of the labels on the axes.

Style — Line style

continuous (default)

Specify the line style for the displayed signal.

Width — Thickness for line plots

1.5 (default)

Specify the line thickness for the lines on displayed signal.

Marker — Data point marker

None (default) | ...

Data point marker for the selected signal, specified as one of the choices in this table data point markers. 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)

Color — Color for lines

yellow (default)

Specify the color for the lines on displayed signal.

Block Characteristics

Data Types	Boolean | double | enumerated | fixed point | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

More About

Using Eye Diagram in Conditionally Executed Subsystems

When an Eye Diagram block is placed in a conditionally executed subsystem, for example in a triggered or enabled subsystem:

• Input size must be an integer multiple of SamplesPerSymbol * SymbolsPerTrace

• Sample offset must be zero

• The rightmost part of the display is intentionally omitted. This figure compares typical eye diagram display when placed in a normal system versus one placed in a conditionally executed subsystem.

  Eye Diagram Plot in Normal System	Eye Diagram Plot in Conditionally Executed Subsystem
  In a regular Eye Diagram,​ the rightmost part is a line between the last sample of a trace and the first sample of the next trace.	In conditionally executed subsystems,​ these traces may be non-contiguous,​ thus this rightmost segment could corrupt the display and is omitted.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

This block is excluded from the generated code when code generation is performed on a system containing this block.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

This block can be used for simulation visibility in subsystems that generate HDL code, but is not included in the hardware implementation.

Version History

Introduced in R2023b