DFS-V数字地震仪去假频滤波器的前两级双T网络中,由于C_4电容的存在,使得对称双T网络的传递特性发生了重大变化。其特性曲线是非对称的,因此,它成为一个低通滤波器,完全不同于一般对称双T带阻滤波器。采用这种双T网络做成的陷波电路,可使通带外的频带衰减陡度增大,而通带内的有效信号损失减小。 In the first two stages of double T network of DFS-V digital seismograph to anti-aliasing filter, the transfer characteristic of symmetric double T network has undergone significant changes due to the existence of C_4 capacitor. Its characteristic curve is asymmetric, so it becomes a low-pass filter, completely different from the general symmetrical double T-band rejection filter. The use of such a dual-T network made of the trap circuit, the passband can be made outside the band attenuation steepness increases, while the passband effective signal loss decreases.