MATLAB SIGNAL PROCESSING TOOLBOX 6 Manual do Utilizador descarregar pdf (Página 17)

Common Aperiodic Waveforms

2-9

Common Aperiodic Waveforms

The toolbox also provides functions for generating several widely used aperiodic

waveforms:

• gauspuls generates a Gaussian-modulated sinusoidal pulse with a specified time,

center frequency, and fractional bandwidth. Optional parameters return in-phase and

quadrature pulses, the RF signal envelope, and the cutoff time for the trailing pulse

envelope.

• chirp generates a linear, log, or quadratic swept-frequency cosine signal. An optional

parameter specifies alternative sweep methods. An optional parameter, phi, allows

initial phase to be specified in degrees.

To compute 2 seconds of a linear chirp signal with a sample rate of 1 kHz that starts at

DC and crosses 150 Hz at 1 second, use:

t = 0:1/1000:2;

y = chirp(t,0,1,150);

To plot the spectrogram, use:

spectrogram(y,256,250,256,1000,'yaxis')

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 59 60

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MATLAB SIGNAL PROCESSING TOOLBOX 6 Manual do Utilizador Página 17