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Altera_Forum
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15 years ago

Round or truncate? 截取和舍入对滤波器输出精度影响？

turncat and rounding on the accuracy of the filter output? designing filter with Fpga, there are two output modes, turncut and rounding. What effect on accuracy on Both methods have? Is t...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

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In my project, the case is that I use the FIR compilier v9.0 to build a filter ，whic output width is 30 bits, but only 10 bits to need。So I choose the “round” output mode, and what different between this mode and the example of convergence you have given?

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Re-read the discussion I had with Kaz. If the FIR compiler 'round' option uses the same method as the MATLAB round() function, and you then process the FIR filter output to measure the magnitude or power, then you will get a slight error in your estimate.

However, Altera may just generically refer to the operation as 'rounding', but actually implement convergent rounding, or round-to-even. You will need to read the FIR compiler guide to see what it implements.

Cheers,

Dave