  A new algorithm for estimating the time-varying frequency of a noiseless
sinusoidal signal is considered. It is assumed that the amplitude and frequency
of the sinusoidal signal are unknown functions of time, but are solutions of
linear stationary differential equations with known parameters. The problem is
solved using gradient tuning algorithms based on a linear regression equation
obtained by parameterizing the original nonlinear sinusoidal signal. The
example presented in the article and the results of computer modeling
illustrate the efficiency of the proposed algorithm, as well as explain the
procedure for its synthesis.
