Abstract: In order to track Doppler signal effectively, a linear discrete-time tracking-differentiator is designed. For the integral-bounded input signal on an arbitrarily finite field, the progressive stabilization and the rapidity of this kind of tracking-differentiator are proved from mathematical analysis and the result of simulation. The obvious error occurred in difference method can be basically removed by using this kind of linear discrete-time tracking-differentiator and the design process is simple.