plot a inear sweep & stepped sweep

CHIRP Swept-frequency cosine generator. Y = CHIRP(T) generates samples of a swept-frequency signal at the time instances defined in array T. By default, the instantaneous frequency at time 0 is 0, and the instantaneous frequency one second later is 100 Hz. Y = CHIRP(T,F0,T1,F1) generates samples of a linear swept-frequency signal at the time instances defined in array T. The instantaneous frequency at time 0 is F0 Hz. The instantaneous frequency F1 is achieved at time T1. Y = CHIRP(T,F0,T1,F1,method) specifies alternate sweep methods. Available methods are 'linear', 'quadratic', and 'logarithmic'; the default is 'linear'. For a logarithmic-sweep, F0 must be greater than or equal to 1e-6 Hz, which is also the default value. Y = CHIRP(T,F0,T1,F1,method,PHI) specifies an initial phase PHI in degrees. By default, PHI = 0. Y = CHIRP(T,FO,T1,F1,'quadratic',PHI,'concave') generates samples of a quadratic swept-frequency chirp signal whose spectrogram is a parabola with its concavity in the positive frequency axis. Y = CHIRP(T,FO,T1,F1,'quadratic',PHI,'convex') generates samples of a quadratic swept-frequency signal whose spectrogram is a parabola with its convexity in the positive frequency axis. Y = CHIRP(...,sigtype) specifies sigtype as 'real' or 'complex'; the default is 'real'. When sigtype is set to 'real', CHIRP generates real chirp signals. When set to 'complex', CHIRP generates complex chirp signals. EXAMPLE 1: Compute the spectrogram of a linear chirp. t = 0:0.001:2; % 2 s at 1 kHz sample rate y = chirp(t,0,1,150); % Start at DC, cross 150 Hz at % t = 1 s spectrogram(y,256,250,256,1E3); % Display the spectrogram EXAMPLE 2: Compute the spectrogram of a quadratic chirp. t = -2:0.001:2; % +/-2 s at 1 kHz sample rate y = chirp(t,100,1,200,'q'); % Start at 100 Hz, cross 200 Hz at % t = 1 s spectrogram(y,128,120,128,1E3); % Display the spectrogram EXAMPLE 3: Compute the spectrogram of a convex quadratic chirp t = 0:0.001:1; % 1 s at 1 kHz sample rate fo = 25; % Start at 25 Hz, f1 = 100; % go up to 100 Hz y = chirp(t,fo,1,f1,'q',[],'convex'); spectrogram(y,256,200,256,1000); % Display the spectrogram. EXAMPLE 4: Compute the spectrogram of a concave quadratic chirp t = 0:0.001:1; % 1 s at 1 kHz sample rate fo = 100; % Start at 100 Hz, f1 = 25; % go down to 25 Hz y = chirp(t,fo,1,f1,'q',[],'concave'); spectrogram(y,256,200,256,1000); % Display the spectrogram. EXAMPLE 5: Compute the spectrogram of a logarithmic chirp t = 0:0.001:10; % 10 s at 1 kHz sample rate fo = 10; % Start at 10 Hz, f1 = 400; % go up to 400 Hz y = chirp(t,fo,10,f1,'logarithmic'); spectrogram(y,256,200,256,1000); % Display the spectrogram EXAMPLE 6: Compute a complex-valued linear chirp t = 0:0.001:2; % 2 s at 1 kHz sample rate fo = -50; % Start at -50 Hz, t1 = 1; f1 = 200; % cross 200 Hz at t = 1 s y = chirp(t,fo,t1,f1,'complex'); spectrogram(y,256,200,256,1000,'centered'); % Display the spectrogram See also GAUSPULS, SAWTOOTH, SINC, SQUARE. Documentation for chirp doc chirp