# Error rate

**URL:** <https://www.ruby-forum.com/t/error-rate/232912>\
**Category:** GNU Radio\
**Created:** [November 4, 2014, 2:35pm UTC](https://www.ruby-forum.com/t/error-rate/232912 "2014-11-04T14:35:19Z")\
**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:** [November 4, 2014, 2:35pm UTC](https://www.ruby-forum.com/t/error-rate/232912/1 "2014-11-04T14:35:19Z")

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Hi, i would like get the error rate of my dbpsk system, the problem is  
that  
the inputs of the ERROR RATE block have to be syncronized because of the  
delay. how can i do that? some suggestions.  
regards  
Lucas

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**Author:** ![Lucas\_Lopez](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e36b37/32.png) [@Lucas\_Lopez](https://www.ruby-forum.com/u/Lucas_Lopez)\
**Post date:** [November 4, 2014, 3:33pm UTC](https://www.ruby-forum.com/t/error-rate/232912/2 "2014-11-04T15:33:13Z")

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That is a very very interesting question, and synchronization is usually  
one of the hardest parts of a communication system.  
GNU Radio does come with some packet encoders and decoders which will  
basically do what you want.

Also, all implementation imperfections aside, for psk systems you can  
derive the error rate from the SNR; for BPSK it’s rather simple,  
for Gaussian uncorrelated noise with a power of $N\_0$ it’s  
$\frac{1}{2} \operatorname{erfc}{\sqrt{\frac{E\_\textrm{bit}}{N\_0}}}$,  
with erfc being the complementary Gauss Error Function.  
The differentialness of DBPSK makes things a bit more complicated (I’m  
not even sure it’s derivable at all for all DPSKs), but for DBPSK it’s  
known.

So maybe this is a situation where estimating SNR is sufficient, and  
synchronization is not necessary at all?

Greetings,  
Marcus