How to find phase and frequency spectrum of signal?

I have a signal:

t = -2:0.01:2;
x = zeros(size(t));
x(t >= -2 & t < -1) = -1;
x(t >= 0 & t <= 2) = -1;

how I can find frequency and phase spectrum of this signal? I need to plot all of it.

[Paul]

What is the value of x(t) for abs(t) > 2?

Answer 1

[Star Strider]

A one-sided fft —

t = -2:0.01:2;
x = zeros(size(t));
x(t >= -2 & t < -1) = -1;
x(t >= 0 & t <= 2) = -1;

figure
plot(t, x)
grid
xlabel('t')
ylabel('x')
title('Time Domain Plot of ‘x(t)’')
axis('padded')

Fs = 1/mean(diff(t));
Fn = Fs/2;
L = numel(t);
NFFT = 2^nextpow2(L);
FTx = fft(x(:).*hann(L), NFFT)/L;
Fv = linspace(0, 1, NFFT/2+1)*Fn;
Iv = 1:numel(Fv);

figure
tiledlayout(2,1)
nexttile
plot(Fv, abs(FTx(Iv))*2)
grid
ylabel('Magnitude (absolute)')
nexttile
plot(Fv, unwrap(angle(FTx(Iv))))
grid
xlabel('Frequency (cycles/(time unit))')
ylabel('Phase (rad)')
sgtitle('One-Sided Fourier Transform of ‘x(t)’')

Make appropriate changes to get the result you want.

.

[Paul]

Doesn't some adjustment need to be made to the phase to account for the fact that the signal "starts" in negative time, but fft assumes the the first point in the input corresponds to t = 0?