Decimation Filter Specification Object

Started by October 18, 2010

Thanks for a helpful forum. I have two questions.

1. I am trying to implement a simple FIR filter. All I do is sum 100 samples of the input to get the output.

Y = X(100) + X(99)..........X(1).

I want to create a filter object for this filter. The question is - Do I use a FORM I, or a FORM II structure, i.e, do I use dfilt.df1, or dfilt.df2 function in matlab?

2. I cascade two such filters, and create a cascaded filter object. I use fvtool to plot the magnitude response of the cascaded filter.

I have to downsample the output of cascaded filter by 100. The question I have is how can I represent the downsampling function as a filter specification object, so that I can cascade it to the above filter, and plot the whole response?