Home Engineering



Principle of Derivative AlgorithmTo obtain se(t)se(t — s)* from the beat signal, a controllable delay line is usually involved in nonlinearity correction algorithms. The delay line technique provides a controllable time delay sref of the original signal without changing its amplitude. Therefore, the nonlinear error phase can be calculated from Eq. 5.3.8 as
Meta et al. [15] proposed an estimation algorithm which is genetic to all nonlinearity models. This algorithm regards the difference of e(t_{r}) in beat signal as the derivative of e(t_{r}) in the case that the time delay s_{re}f is far smaller than PRI. Therefore, the nonlinear phase error can be approximated as Thus, s(t_{r}) can be estimated as
The algorithm in [15], referred to as derivative algorithm, is an efficient method with simple processing steps. If s_{re}f is far smaller than PRI, it will give an accurate estimation of transmitted nonlinearity. However, it is inherently a biased algorithm since it is based on the derivative approximation, which makes it inapplicable in high resolution imaging. Moreover, estimation performance decreases sharply as time delay increases. 
<<  CONTENTS  >> 

Related topics 