\begin{table}%t3
\caption{\label{tab3}Definition of the signals used in the BL/PC variability test.}
\small%\centerline
{
\begin{tabular}{ll}
\hline\hline
Type & Time dependence \\
\hline
AM &  $A(t) = A\sin~(\Omega t + \Phi)$; 
\hfill $\omega(t)$, $\varphi(t)=$~const. \\
PM &  $\varphi(t) = A_{\varphi}\sin~(\Omega t + \Psi)$; 
\hfill $\omega(t)$, $A(t)=$~const.\\
FM &  $\omega(t)  = \omega_0+A_{\omega}\sin~(\Omega t + \Gamma)$; 
\hfill $A(t)$, $\varphi(t)=$~const.\\
PC         &  $\omega(t)  = \omega_0/(1+\beta t/P_0)$; 
\hfill $A(t)$, $\varphi(t)=$~const.\\
\hline
\end{tabular}}
\smallskip
 {Note:} signal form: $x(t)=(1+A(t))\sin~(\omega(t)t+\varphi(t))$; 
$\omega_0=2\pi/P_0$; $P_0=0.377$; $\Omega=2\pi/P_{\rm BL}$; 
$P_{\rm BL} =$~BL period; 
AM = amplitude modulation; 
PM = phase modulation;
FM = frequency modulation;
PC = secular frequency change; 
and $\Phi$, $\Psi$, and $\Gamma$ are arbitrary constant phases.
\end{table}