Number of antenna to perform MUSIC algorithm When the MUSIC algorithm is used for direction of arrival (DOA) estimation it can identify up M-1 signals, where M is the number of array elements. MUSIC can also be used for spectral frequency estimation. Does MUSIC require more than one receiver (or more than one receive antenna) for frequency estimation of a single signal?
In the field of array signal processing, the signal model is
$$
\mathbf{x}(n) = [x_0(n), x_1(n), \ldots, x_{M-1}(n)]^T
$$
where $M$ denotes the number of sensor and $n$ is the discrete time.
While in the field of spectral estimation, the signal model is
$$
\mathbf{x}(n) = [x(n), x(n-1), \ldots, x(n-M+1)]^T
$$
where $M$ is the number of samples of the observed signal, and $x(n-m)$ represents the previous signal before $m$ samples.
The autocorrelation matrix is
$$
\mathbf{R}_{xx} = E\{ \mathbf{x}(n) \mathbf{x}^H(n) \}
$$
and it is usually replaced by its estimation $\mathbf{\hat{R}}_{xx}$ in practice.