Fixed-point FIR eyediagram problem

Sep 19, 2006 2 Replies
Y

Hi,



I am designing a fixed-point FIR using Xilinx block set.But it seems that only the upper half of the output eyediagram ramains while the lower half has been truncated.In the design, I just use random integer Generator, then going through a Gateway In block, then upsampling block, then fixed-point FIR filer,Gateway Out block, AWGN block, Gateway In block, fixed-point FIR filter, downsampling, Gateway Out block and output display. Could anyone give me some suggestions about this eyediagram problem?



Thanks a lot!


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T

Is this in Matlab? Check the blockset for how it treats negative numbers -- it may be displaying exactly the correct behavior.

Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ "Applied Control Theory for Embedded Systems" came out in April. See details at http://www.wescottdesign.com/actfes/actfes.html
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Y

Thanks, Tim.

Yes, I do it in MatLab. I have designed a floating-point FIR and the eyediagram is good. Should I add some blocks which function as channel encoding/decoding or something else to my fixed-point FIR design? I am not sure about that.

YFLuo

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