如何用matlab产生连续的线性调频信号串

楼主要学会用MATLAB的help命令啊：
help modulate
MODULATE Signal modulation for communications simulations.
Y = MODULATE(X,Fc,Fs,METHOD,OPT) modulates the message signal X with a
carrier frequency Fc and sampling frequency Fs,using the modulation
scheme in METHOD.OPT is an extra sometimes optional parameter whose
purpose depends on the modulation scheme you choose.
Fs must satisfy Fs > 2*Fc + BW,where BW is the bandwidth of the
modulated signal.
METHOD MODULATION SCHEME
'am',Amplitude modulation,double side-band,suppressed carrier
'amdsb-sc' OPT not used.
'amdsb-tc' Amplitude modulation,double side-band,transmitted carrier
OPT is a scalar which is subtracted from X prior to
multiplication by the carrier cosine.It defaults to
min(min(X)) so the offset message signal is positive and
has a minimum value of zero.
'amssb' Amplitude modulation,single side-band
OPT not used.
'fm' Frequency modulation
OPT is a scalar which specifies the constant of frequency
modulation kf.kf = (Fc/Fs)*2*pi/max(max(abs(X))) by
default for a maximum frequency excursion of Fc Hertz.
'pm' Phase modulation
OPT is a scalar which specifies the constant of phase
modulation kp.kp = pi/max(max(abs(x))) by default for a
maximum phase excursion of +/-pi radians.
'pwm' Pulse width modulation
If you let OPT = 'centered',the pulses are centered on the
carrier period rather than being "left justified".
'ppm' Pulse position modulation
OPT is a scalar between 0 and 1 which specifies the pulse
width in fractions of the carrier period.It defaults to .1.
'qam' Quadrature amplitude modulation
OPT is a matrix the same size as X which is modulated in
quadrature with X.
If X is a matrix,its columns are modulated.
[Y,T] = MODULATE(...) returns a time vector the same length as Y.