# GMSK\_DEMOD question, please help me :)

**URL:** <https://www.ruby-forum.com/t/gmsk-demod-question-please-help-me/230578>\
**Category:** GNU Radio\
**Created:** [June 24, 2014, 11:11pm UTC](https://www.ruby-forum.com/t/gmsk-demod-question-please-help-me/230578 "2014-06-24T23:11:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\
**Post date:** [June 24, 2014, 11:11pm UTC](https://www.ruby-forum.com/t/gmsk-demod-question-please-help-me/230578/1 "2014-06-24T23:11:57Z")

</div>

Hello everyone,  
I am an intern this summer doing signal demodulation and decoding.  
I am using GNU Radio software to demodulate the 9600 bps 12.5KHz wide  
GMSK  
modulated signal.

Here is my process:  
I get the data from the antenna, sampled it at 2.048MHz,  
Go through a low pass filter and decimate the sample rate to 76.8KHz.  
Then go through GMSK demodulator with 8 samples per symbol. (I think  
this maybe the problem…) In this way,the output baud rate is 76.8k/8  
= 9.6k

I could not get any repeated signal from this demodulation process. I  
wonder if you could point out what I did wrong?  
Thanks so much for your time!!!  
Really appreciated!

Cindy