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rootmusic

Ffrequency and power content using root MUSIC algorithm

Syntax

Description

[w,pow] = rootmusic(x,p) estimates the frequency content in the time samples of a signal x, and returns w, a vector of frequencies in rad/sample, and the corresponding signal power in the vector pow in dB per rad/sample. The input signal x is specified either as:

The second input argument, p is the number of complex sinusoids in x. You can specify p as either:

The extra threshold parameter in the second entry in p provides you more flexibility and control in assigning the noise and signal subspaces.

The length of the vector w is the computed dimension of the signal subspace. For real-valued input data x, the length of the corresponding power vector pow is given by

For complex-valued input data x, pow and w have the same length.

[f,pow] = rootmusic(...,fs) returns the vector of frequencies f calculated in Hz. You supply the sampling frequency fs in Hz. If you specify fs with the empty vector [], the sampling frequency defaults to 1 Hz. [w,pow] = rootmusic(...,'corr') forces the input argument x to be interpreted as a correlation matrix rather than a matrix of signal data. For this syntax, you must supply a square matrix for x, and all of its eigenvalues must be nonnegative.

Examples

Find the frequency content in a signal composed of three complex exponentials in noise. Use the modified covariance method to estimate the correlation matrix used by the MUSIC algorithm:

Algorithm

The MUSIC algorithm used by rootmusic is the same as that used by pmusic. The algorithm performs eigenspace analysis of the signal's correlation matrix in order to estimate the signal's frequency content.

The difference between pmusic and rootmusic is:

rootmusic is most useful for frequency estimation of signals made up of a sum of sinusoids embedded in additive white Gaussian noise.

Diagnostics

If the input signal, x is real and an odd number of sinusoids, p is specified, this error message is displayed

See Also

corrmtx, peig, pmusic, powerest method of spectrum, rooteig, spectrum.music


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