Communications Toolbox

eyediagram

Generate an eye diagram

Syntax

• eyediagram(x,n);
  eyediagram(x,n,period);
  eyediagram(x,n,period,offset);
  eyediagram(x,n,period,offset,plotstring);
  eyediagram(x,n,period,offset,plotstring,h);
  h = eyediagram(...);
  

Description

eyediagram(x,n) creates an eye diagram for the signal x, plotting n samples in each trace. n must be an integer greater than 1. The labels on the horizontal axis of the diagram range between -1/2 and 1/2. The function assumes that the first value of the signal, and every nth value thereafter, occur at integer times. The interpretation of x and the number of plots depend on the shape and complexity of x:

• If x is a real two-column matrix, then eyediagram interprets the first column as in-phase components and the second column as quadrature components. The two components appear in different subplots of a single figure window.
• If x is a complex vector, then eyediagram interprets the real part as in-phase components and the imaginary part as quadrature components. The two components appear in different subplots of a single figure window.
• If x is a real vector, then eyediagram interprets it as a real signal. The figure window contains a single plot.

eyediagram(x,n,period) is the same as the syntax above, except that the labels on the horizontal axis range between -period/2 and period/2.

eyediagram(x,n,period,offset) is the same as the syntax above, except that the function assumes that the (offset+1)st value of the signal, and every nth value thereafter, occur at times that are integer multiples of period. The variable offset must be a nonnegative integer between 0 and n-1.

eyediagram(x,n,period,offset,plotstring) is the same as the syntax above, except that plotstring determines the plotting symbol, line type, and color for the plot. plotstring is a string whose format and meaning are the same as in the plot function. The default string is 'b-', which produces a blue solid line.

eyediagram(x,n,period,offset,plotstring,h) is the same as the syntax above, except that the eye diagram is in the figure whose handle is h, rather than a new figure. h must be a handle to a figure that eyediagram previously generated.

Note    You cannot use hold on to plot multiple signals in the same figure.

h = eyediagram(...) is the same as the earlier syntaxes, except that h is the handle to the figure that contains the eye diagram.

Examples

See Example: Eye Diagrams for an example. For an online demonstration, type playshow scattereyedemo.

See Also
scatterplot, plot, scattereyedemo

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