Appendix
$$ {\hat{\mathbf{B}}}_{k} \equiv \left[ {B_{k} \left( {p_{0,k} ,q_{0,k} } \right), \ldots ,B_{k} \left( {p_{0,k} ,q_{0,k} + N - 1} \right), \ldots ,B_{k} \left( {p_{0,k} + N - 1,q_{0,k} } \right), \ldots ,B_{k} \left( {p_{0,k} + N - 1,q_{0,k} + N - 1} \right)} \right]^{\text{T}} $$
(4)
$$ {\hat{\mathbf{B}}}_{k + 1} \equiv \left[ {B_{k + 1} \left( {0,0} \right), \ldots ,B_{k + 1} \left( {0,N - 1} \right), \ldots ,B_{k + 1} \left( {N - 1,0} \right), \ldots ,B_{k + 1} \left( {N - 1,N - 1} \right)} \right]^{\text{T}} $$
(5)
$$ {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) \equiv \left[ {\cos \left( {0\omega_{1} + 0\omega_{2} } \right), \ldots ,\cos \left( {0\omega_{1} + \left( {N - 1} \right)\omega_{2} } \right), \ldots ,\cos \left( {\left( {N - 1} \right)\omega_{1} + 0\omega_{2} } \right), \ldots ,\cos \left( {\left( {N - 1} \right)\omega_{1} + \left( {N - 1} \right)\omega_{2} } \right)} \right]^{\text{T}} $$
(6)
$$ {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) \equiv \left[ {\sin \left( {0\omega_{1} + 0\omega_{2} } \right), \ldots ,\sin \left( {0\omega_{1} + \left( {N - 1} \right)\omega_{2} } \right), \ldots ,\sin \left( {\left( {N - 1} \right)\omega_{1} + 0\omega_{2} } \right), \ldots ,\sin \left( {\left( {N - 1} \right)\omega_{1} + \left( {N - 1} \right)\omega_{2} } \right)} \right]^{\text{T}} $$
(7)
$$ \begin{aligned} - \frac{\text{d}}{{{\text{d}}\omega_{1} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) & = - \frac{\text{d}}{{{\text{d}}\omega_{1} }}\tan^{ - 1} \frac{{{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)}}{{{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)}} \\ & = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\frac{\text{d}}{{{\text{d}}\omega_{1} }}\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ - \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\frac{\text{d}}{{{\text{d}}\omega_{1} }}\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} \\ \end{aligned} $$
(9)
$$ {\tilde{\mathbf{B}}}_{k} \equiv \left[ {0B_{k} \left( {p_{0,k} ,q_{0,k} } \right), \ldots ,0B_{k} \left( {p_{0,k} ,q_{0,k} + N - 1} \right), \ldots ,\left( {N - 1} \right)B_{k} \left( {p_{0,k} + N - 1,q_{0,k} } \right), \ldots ,\left( {N - 1} \right)B_{k} \left( {p_{0,k} + N - 1,q_{0,k} + N - 1} \right)} \right]^{\text{T}} $$
(10)
$$ {\tilde{\mathbf{B}}}_{k + 1} \equiv \left[ {0B_{k + 1} \left( {0,0} \right), \ldots ,0B_{k + 1} \left( {0,N - 1} \right), \ldots ,\left( {N - 1} \right)B_{k + 1} \left( {N - 1,0} \right), \ldots ,\left( {N - 1} \right)B_{k + 1} \left( {N - 1,N - 1} \right)} \right]^{\text{T}} $$
(11)
$$ \begin{aligned} & - \frac{\text{d}}{{{\text{d}}\omega_{1} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) \\ & \quad = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \left( \begin{aligned} - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\tilde{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\tilde{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\tilde{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\tilde{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right) \hfill \\ - \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \left( \begin{aligned} - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\tilde{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\tilde{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\tilde{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\tilde{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{T} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{T} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} \\ \end{aligned} $$
(12)
$$ - \frac{\text{d}}{{{\text{d}}\omega_{1} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\left( {{\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{\dddot B}}_{k} - {\mathbf{\ddot{B}}}_{k} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{\dddot B}}_{k} - {\mathbf{\ddot{B}}}_{k} } \right){\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\dot{\mathbf{B}}}_{k} - {\dot{\mathbf{B}}}_{k}^{\text{T}} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right){\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{\ddot{B}}}_{k} - {\mathbf{\ddot{B}}}_{k}^{\text{T}} + {\mathbf{\dddot B}}_{k}^{\text{T}} - {\mathbf{\dddot B}}_{k} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\dot{\mathbf{B}}}_{k} - {\dot{\mathbf{B}}}_{k}^{\text{T}} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} $$
(13)
$$ \begin{aligned} - \frac{\text{d}}{{{\text{d}}\omega_{2} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) & = - \frac{\text{d}}{{{\text{d}}\omega_{2} }}\tan^{ - 1} \frac{{{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)}}{{{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)}} \\ & \quad = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\frac{\text{d}}{{{\text{d}}\omega_{2} }}\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ - \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\frac{\text{d}}{{{\text{d}}\omega_{2} }}\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{{^{\text{T}} }} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{{^{\text{T}} }} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} \\ \end{aligned} $$
(14)
$$ {\bar{\mathbf{B}}}_{k} \equiv \left[ {0B_{k} \left( {p_{0,k} ,q_{0,k} } \right), \ldots ,\left( {N - 1} \right)B_{k} \left( {p_{0,k} ,q_{0,k} + N - 1} \right), \ldots ,0B_{k} \left( {p_{0,k} + N - 1,q_{0,k} } \right), \ldots ,\left( {N - 1} \right)B_{k} \left( {p_{0,k} + N - 1,q_{0,k} + N - 1} \right)} \right]^{\text{T}} $$
(15)
$$ {\bar{\mathbf{B}}}_{k + 1} \equiv \left[ {0B_{k + 1} \left( {0,0} \right), \ldots ,\left( {N - 1} \right)B_{k + 1} \left( {0,N - 1} \right), \ldots ,0B_{k + 1} \left( {N - 1,0} \right), \ldots ,\left( {N - 1} \right)B_{k + 1} \left( {N - 1,N - 1} \right)} \right]^{\text{T}} $$
(16)
$$ \begin{aligned} & - \frac{\text{d}}{{{\text{d}}\omega_{2} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) \\ & \quad = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \left( \begin{aligned} - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\bar{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\bar{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\bar{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\bar{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right) \hfill \\ - \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{T} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ \left( \begin{aligned} - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\bar{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\bar{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\bar{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\bar{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) - {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{\text{T}} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{T} \left( {\omega_{1} ,\omega_{2} } \right){\hat{\mathbf{B}}}_{k + 1} {\hat{\mathbf{B}}}_{k}^{T} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} \\ \end{aligned} $$
(17)
$$ - \frac{\text{d}}{{{\text{d}}\omega_{2} }}\angle H_{k} \left( {\omega_{1} ,\omega_{2} } \right) = - \frac{{\left( \begin{aligned} \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)\left( {{\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{B}}_{k}^{{{\prime \prime \prime }}} - {\mathbf{B}}_{k}^{{\prime \prime }} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{B}}_{k}^{{{\prime \prime \prime }}} - {\mathbf{B}}_{k}^{{\prime \prime }} } \right){\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right)} \right) \hfill \\ - {\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\dot{\mathbf{B}}}_{k} - {\dot{\mathbf{B}}}_{k}^{\text{T}} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right){\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\mathbf{B}}_{k}^{{\prime \prime }} - {\mathbf{B}}_{k}^{{{\prime \prime {\rm T}}}} + {\mathbf{B}}_{k}^{{{\prime \prime \prime {\rm T}}}} - {\mathbf{B}}_{k}^{{{\prime \prime \prime }}} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right) \hfill \\ \end{aligned} \right)}}{{\left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right)\left( {{\dot{\mathbf{B}}}_{k} - {\dot{\mathbf{B}}}_{k}^{\text{T}} } \right){\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} + \left( {{\mathbf{c}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{c}}\left( {\omega_{1} ,\omega_{2} } \right) + {\mathbf{s}}^{\text{T}} \left( {\omega_{1} ,\omega_{2} } \right){\dot{\mathbf{B}}}_{k} {\mathbf{s}}\left( {\omega_{1} ,\omega_{2} } \right)} \right)^{2} }} $$
(18)