How to pass fixed-point conversion for some specific block?

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Jury 2012-12-11

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https://ww2.mathworks.cn/matlabcentral/answers/56339-how-to-pass-fixed-point-conversion-for-some-specific-block

Hi!

I have a Simulink model with standart block Abs and cos (trigonometric function). I'm trying to convert my scheme to fixed-point. I got the following error with Abs and cos block:

--> Input port and output port of 'rx12/Subsystem128/Abs ' must be of type 'single' or 'double' when complex --> An error occurred while propagating numeric type complex from 'rx12/Subsystem128/IFFT13 ', output port 1.

IFFT13 block is connected directly to Abs without type conversion. When I insert conversion to double before Abs, Fixed-Point Advisor doens't return error, but notes that I should convert one float-point data type to fixed-point.

The same situation I have with cos block, connected to the output of Delay block.

How I can do it?

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Kaustubha Govind 2012-12-26

You should probably chase the signal up to its original source and make sure that it produces a fixed-point type?

Walter Roberson 2012-12-26

Is the message not effectively saying that you cannot use Abs on a complex fixed-point signal? If so it might be necessary to put in the blocks needed to calculate abs, breaking up the parts, squaring, etc.,

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Answer 1

Jury 2013-1-1

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https://ww2.mathworks.cn/matlabcentral/answers/56339-how-to-pass-fixed-point-conversion-for-some-specific-block#answer_69877

I've replaced these block with block from IQMath library, which are supporting fixed-point. I got next problem - there isn't HDL realisation these new blocks.