11位巴克码的LP滤波器及其在多普勒频移下的性能

 本文介绍使最大旁瓣值最小的11位巴克码滤波器（LP滤波器）的计算结果。并介绍多普勒频移对这种滤波器性能影响。LP滤波器长度为53时,旁瓣电平降到—39.5dB,比匹配滤波器改善18.7dB。对加权序列长度L为41、45、49和53的11位巴克码的LP滤波器计算结果表明,其性能受多普勒频移的影响表现为:它们的主瓣电平下降、主瓣展宽、最小旁瓣电平上升、旁瓣电平平方和上升和信噪比损失增大。在较小的多普勒频移（f_d）时,L大的LP滤波器其性能优于L小的LP滤波器,在多普勒频移交大时,这种优势逐渐消失,不同长度LP滤波器性能大体一致。

LP FILTER FOR 11-ELEMENT BARKER CODE AND IT'S PERFOR- MANCES ON THE DOPPLER SHIFT

Tnis paper introduces the results of computation of the filters （LP filters） for 11-element barker code, which reduce the level of maximal side-lobe level to minimum, and the filter performances affected by the dopp-ler shift. When the length of the LP filter is 53, the sidelobe level is reduced to -39.5 dB and it is 18.7 dB better than that by matched filter. The computations of the LP filters with weigthing sequence lengths （L） of 41, 45, 49 and 53 for the 11-element Barker code show that the effects of the doppler shift on the performances are presented, as the degradation and widening of the mainlobe level, the raise of the minimal side-lobe level, the raise of the sum of mean square of sidelobe levels and the increasing the loss of the signal to noise ratio. In smaller doppler shift （fd）, the performances of the LP filter with large L are better than one's with small L. But these superiorities diminish gradully and the performances of the filters with different lengths roughly are unanimous as the doppler shift increases.