# ERRO RATE problem

**URL:** <https://www.ruby-forum.com/t/erro-rate-problem/234843>\
**Category:** GNU Radio\
**Created:** [October 31, 2014, 8:55pm UTC](https://www.ruby-forum.com/t/erro-rate-problem/234843 "2014-10-31T20:55:41Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**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:** [October 31, 2014, 8:55pm UTC](https://www.ruby-forum.com/t/erro-rate-problem/234843/1 "2014-10-31T20:55:41Z")

</div>

i was working in BPSK mod/demod and i’d like to see the BER performance.  
i  
used the BER ERROR RATE block, connecting in the input 1: random source  
and  
imput 2: output of the decodec. The problem is that the error always is  
0.5  
and the source noise (connected in the mod,) doesn’t affect it.

---

<div class="post-metadata">

**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:** [October 31, 2014, 10:00pm UTC](https://www.ruby-forum.com/t/erro-rate-problem/234843/2 "2014-10-31T22:00:06Z")

</div>

The BER error rate block does not realign data from its inputs.  
Experiment  
with different delays between the reference tream and the demod stream  
to  
account for FIR filters, clock recovery process, etc. Note, due to the  
nature of symbol recovery, the delay may not be the same every time.

Also, watch out for phase ambiguity in the BPSK demod.

-John