# CMA Equalizer

**URL:** <https://www.ruby-forum.com/t/cma-equalizer/234696>\
**Category:** GNU Radio\
**Created:** [March 23, 2015, 11:53am UTC](https://www.ruby-forum.com/t/cma-equalizer/234696 "2015-03-23T11:53:43Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [March 23, 2015, 11:53am UTC](https://www.ruby-forum.com/t/cma-equalizer/234696/1 "2015-03-23T11:53:43Z")

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Sir,

What do the number of taps in the CMA equalizer block represent, I hope  
it  
is the channel size. Should it be the number of tap coefficients given  
for  
the variable ‘taps’ in the channel model block. If I give ‘taps’ in the  
channel model block (I am considering the basic awgn channel model  
block)  
as taps =[a1+jb1,a2+jb2,a3+jb3,a4+jb4], what should be the Num. Taps in  
the  
CMA equalizer block.I am using the polyphase clock synchronizer between  
the  
channel model block and the equalizer.

Please help.Looking forward for your reply.

Thanks  
Merry

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**Author:** ![mjm\_11](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ba8739/32.png) [@mjm\_11](https://www.ruby-forum.com/u/mjm_11)\
**Post date:** [March 23, 2015, 3:26pm UTC](https://www.ruby-forum.com/t/cma-equalizer/234696/2 "2015-03-23T15:26:53Z")

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On Mon, Mar 23, 2015 at 3:51 AM, Merry D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Please help.Looking forward for your reply.
> 
> Thanks  
> Merry

Yes and no. The number of taps is to shape the equalizer’s response  
appropriately for the channel. Generally, we don’t know anymore more  
than  
some statistics about the channel and so we try to select the number of  
taps in the filter according to that. It won’t be perfect since channels  
are always changing, so we try and balance the complexity of the  
algorithm  
with the response to the channel. The more taps, the more accurate you  
get,  
but at greater computational cost.

So no one can really answer this question for you.

Tom