Meansquare (power) spectrum
Hmss = dspdata.msspectrum(Data)
Hmss = dspdata.msspectrum(Data,Frequencies)
Hmss = dspdata.msspectrum(...,'Fs',Fs)
Hmss = dspdata.msspectrum(...,'SpectrumType',SpectrumType)
Hmss = dspdata.msspectrum(...,'CenterDC',flag)
Note:
The use of 
The meansquared spectrum (MSS) is intended for discrete spectra. Unlike the power spectral density (PSD), the peaks in the MSS reflect the power in the signal at a given frequency. The MSS of a signal is the Fourier transform of that signal's autocorrelation.
Hmss = dspdata.msspectrum(Data)
uses the meansquare (power)
spectrum data contained in Data
, which can be
in the form of a vector or a matrix, where each column is a separate
set of data. Default values for other properties of the object are
as follows:
Property  Default Value  Description 

Name 
 Readonly string 

type  Vector of frequencies at which the spectrum is evaluated.
The range of this vector depends on the The length of the If you do not specify If 

 Sampling frequency, which is 

 Nyquist interval over which the spectral density is calculated.
Valid values are The interval for 

 Whether the frequency is normalized ( 
Hmss = dspdata.msspectrum(Data,Frequencies)
uses the mean–square
spectrum data contained in Data
and Frequencies
vectors.
Hmss = dspdata.msspectrum(...,'Fs',Fs)
uses the sampling frequency Fs
. Specifying Fs
uses a default set
of linear frequencies (in Hz
) based on Fs
and sets NormalizedFrequency
to false
.
Hmss = dspdata.msspectrum(...,'SpectrumType',SpectrumType)
uses
the SpectrumType
string to specify the interval
over which the mean–square spectrum was calculated. For data
that ranges from [0 pi) or [0 pi],
set the SpectrumType
to onesided
; for data that ranges from [0 2pi), set the the SpectrumType
to twosided
.
Hmss = dspdata.msspectrum(...,'CenterDC',flag)
uses the value
of flag
to indicate whether the zerofrequency
(DC) component is centered. If flag
is true
, it indicates that the DC component is in the center
of the twosided spectrum. Set the flag
to false
if the DC component is on the left edge of the spectrum.
Methods provide ways of performing functions directly on your dspdata
object without having to specify the parameters
again. You can apply a method directly on the variable you assigned
to your dspdata.msspectrum
object. You can use
the following methods with a dspdata.msspectrum
object.
centerdc
normalizefreq
onesided
plot
sfdr
twosided
For example, to normalize the frequency and set the NormalizedFrequency
parameter to true, use
Hmss = normalizefreq(Hs)
For detailed information on using the methods and plotting the
spectrum, see the dspdata
reference
page.
In this example, we construct a meansquare spectrum data object from the onesided PSD estimate of a signal. The signal consists of two sinusoids in additive noise.
Fs = 32e3; t = 0:1/Fs:1(1/Fs); x = cos(2*pi*t*1.24e3)+cos(2*pi*t*10e3)+randn(size(t)); X = fft(x); X = X(1:length(X)/2+1); % Onesided DFT P = (abs(X)/length(x)).^2; % Compute the meansquare power P(2:end1) = 2*P(2:end1); % Factor of two for onesided estimate % at all frequencies except zero and the Nyquist Hmss = dspdata.msspectrum(P,'Fs',Fs,'spectrumtype','onesided'); plot(Hmss) % Plot the meansquare spectrum.