TUTORIAL plot_SK

This function plots ASK, FSK and PSK coded signals in the time domain or as a constellation diagram. If there is no further specification, the default properties of plot_SK are used.

% parameter:

type='ASK'; ('FSK,' 'PSK') % type of modulation

mode='time'; ('constellation') % time or constellation diagram

fs: % sampling frequency (take care of the Nyquist frequency)

f_c: % carrier frequency

BR: % default - symbolrate

eta: % default - modulation index for FSK

m: 0<=m<=1 % default modulation index for ASK

u_c: % default- carrier amplitude

If there are more bits representing a symbol, there are

different states. plot_SK identifies the number of bits per symbol within the input vector. Since adjacent Gray-coded symbols differ in only one bit, a misinterpreted symbol contains just a single faulty bit. This is the reason why the Graycode is used here.

example 1:

default-plot (ASK) of an input-sequence:

disp('example 1')

example 1

x=['1';'0';'1';'0';'0'];

plot_SK(x);

example 2:

a change of the diagram:

disp('example 2')

example 2

x=['1';'0';'1';'0';'0'];

plot_SK(x,'mode','constellation');

example 3:

a plot of an 8-ASK-signal:

disp('example 3')

example 3

x=['101';'100';'111';'010';'000'];

plot_SK(x,'type','ASK','u_T',7);

example 4:

a plot of an FSK-signal:

disp('example 4')

example 4

x=['1';'0';'1';'0';'0'];

plot_SK(x,'type','FSK');

example 5:

a PSK-signal (time and constellation):

disp('example 5')

example 5

x=['1';'0';'1';'0';'0'];

plot_SK(x,'type','PSK');

plot_SK(x,'type','PSK','mode','constellation');