E8267D ARB重建滤波器的顺序是什么？

我的小组正在使用带有选项2的E8267D，用于我们项目的各种应用。
一种应用是产生特殊类型的带限噪声，这阻止我们使用内置噪声应用。
为此，我们一直在matlab中生成噪声文件并将其下载到ARB。
为了改变带宽，我们只是改变了采样率。
这显然利用了ARB的内部重建滤波器，因为对于采样率的两个变化的每个因子，噪声带宽改变了两倍。
这对于对称的噪声频谱非常有用。
但是，现在，我需要生成一个更加随意的噪声频谱，中间有间隙。
由于我需要噪声的裙边是相同的，我想知道重建滤波器的一些细节，假设我是正确的，重建滤波器负责ARB产生的噪声的裙边。
谁能告诉我重建滤波器的FIR滤波器顺序？
系数怎么样？



     以下为原文

  My group is using an E8267D with Option 2 for various applications on our project.  One application was to generate bandlimited noise of a special type that prevents us from using the built-in noise application.  To do this, we have been generating the noise file in Matlab and downloading it to the ARB.  To change the bandwidth, we simply changed the sample rate.  This apparently takes advantage of the ARB's internal reconstruction filter, since the noise bandwidth changes by a factor of two for each factor of two change in sample rate.  This served us well for a symmetrical noise spectrum.  However, now, I need to generate a more arbitrary noise spectrum with gaps in the middle.  Since I need the skirts of the noise to be the same, I would like to know some details of the reconstruction filter, assuming I was correct that the reconstruction filter was responsible for the skirts of the noise generated by the ARB.  

Could anyone tell me the FIR filter order for the reconstruction filter?  How about the coefficients?