k-Wave Toolbox


Compute the single sided amplitude and phase spectrums.


func_as = spect(func, Fs)
func_as = spect(func, Fs, ...)
[f, func_as] = spect(func, Fs)
[f, func_as] = spect(func, Fs, ...)
[f, func_as, func_ps] = spect(func, Fs)
[f, func_as, func_ps] = spect(func, Fs, ...)


spect computes the single-sided amplitude and phase spectrums of a 1, 2, or 3 dimensional input signal. If the optional input 'Dim' is not specified, the spectrum is computed along the first non-singleton dimension. For example, running the commands

% define signal
Fs = 10e6;              % [Hz]
dt = 1 / Fs;            % [s]
t = 0:dt:(1000 * dt);   % [s]
signal = 10 * sin(0.5e6 * 2 * pi * t) + 5 * sin(1e6 * 2 * pi * t) + 2 * sin(2.5e6 * 2 * pi * t);

% calculate spectrum
spect(signal, Fs, 'Plot', [true, false]);

will produce the following amplitude spectrum.


func signal to analyse
Fs sampling frequency [Hz]

Optional Inputs

Optional 'string', value pairs that may be used to modify the default computational settings.

Input Valid Settings Default Description
'Dim' (integer scalar) first non-singleton dimension Dimension over which the spectrum is computed.
'FFTLength' (integer scalar) signal length Length of the FFT. If the set length is larger than the signal length, the signal is zero padded. If the set length is smaller than the signal length, the default value is used instead.
'PowerTwo' (Boolean scalar) false Boolean controlling whether the FFT length is forced to be the next highest power of 2.
'Plot' (Boolean scalar or two element vector) false Boolean controlling whether the amplitude and phase spectrums are plotted. Can be given as a two element array to control the display of the amplitude and phase spectrums, respectively.
'Unwrap' (Boolean scalar) false Boolean controlling whether the phase spectrum is unwrapped.
'Window' (string) 'Rectangular' Parameter string controlling the window type used to filter the signal before the FFT is taken. Any valid input types for getWin may be used.


f frequency array
func_as single sided amplitude spectrum
func_ps single sided phase spectrum


See Also

smooth, filterTimeSeries