# Trying to decode 2-gfsk from TI CC1125 **URL:** \ **Category:** GNU Radio\ **Created:** [January 23, 2016, 5:03pm UTC](https://www.ruby-forum.com/t/trying-to-decode-2-gfsk-from-ti-cc1125/243901 "2016-01-23T17:03:26Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [January 23, 2016, 5:03pm UTC](https://www.ruby-forum.com/t/trying-to-decode-2-gfsk-from-ti-cc1125/243901/1 "2016-01-23T17:03:26Z")
Hi, I’m trying to decode data transmitted by TI cc1125 [http://www.ti.com/lit/ug/swru295e/swru295e.pdf](http://www.ti.com/lit/ug/swru295e/swru295e.pdf) radiochip and received with hackrf. The transmission is using 2-gfsk modulation and the transmissions are encoded with TI:s own packet format. The symbol rate is 9600 ksps. The preamble is 6 bytes of 0xAA. My current pipeline in GNURadio is: file source → throttle → low pass filter → simple squelch → quadrature demod → clock recovery MM → binary slicer → Correlate Access Code Tag → Tag Debug. The problem is that the “Correlate Access Code - Tag” can’t find the preambles. If I use Scope Sink after the Quadrature Demod I can clearly see the preamble pattern from the sink. For testing purposes I changed the the deviation of the transmission to its maximum value (300kHz), but that didn’t help either. The sample data is recorded with that deviation and the flow graph uses that sample data. Is there something obviously wrong or incorrect in my graph? I also don’t really understand the effect of the parameters in Clock Recovery MM. I have tried to use the low pass filter and squelch to remove the noise from the signal. This is my first time trying to do something with GNURadio and radios in general so still trying to wrap my head around all the new stuff. Any suggestions or ideas what I should try next? -Juho