f = plt.figure()
freq, t, Sxx = spectrogram(x, fs=1, nfft=256, window=('tukey', 0.25), detrend='constant',
                           nperseg=60, noverlap=30, scaling='density')
plt.pcolormesh(t, freq, Sxx)
plt.xlabel('Time [s]')
plt.ylabel('Frequency [Hz]')
plt.colorbar().set_label('PSD [V^2/Hz]')
plt.show()