# Fwd: Proposal for GSoC on gr-gsm **URL:** \ **Category:** GNU Radio\ **Created:** [March 11, 2014, 11:16am UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709 "2014-03-11T11:16:44Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [March 11, 2014, 11:16am UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/1 "2014-03-11T11:16:44Z")
---------- Forwarded message ---------- From: zhenhua han [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Date: 2014-03-11 16:00 GMT+08:00 Subject: Re: [Discuss-gnuradio] Proposal for GSoC on gr-gsm To: Bogdan D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Thank you, Bogdan. Your work is a great help in developing the channel hopping part. As there are only 14 weeks in GSoC, the schedule is a little tight. However, I will continue working on this project after GSoC (if I am selected). And Channel hopping will be the first task after I finish all the tasks planned in GSoC. Best wishes, Zhenhua 2014-03-11 15:34 GMT+08:00 Bogdan D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): Hi Zhenhua, ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 11, 2014, 1:32pm UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/2 "2014-03-11T13:32:07Z")
On 03/11/2014 11:14 AM, zhenhua han wrote: > As there are only 14 weeks in GSoC, the schedule is a little tight. > However, I will continue working on this project after GSoC (if I am > selected). And Channel hopping will be the first task after I finish all > the tasks planned in GSoC. You should definitely check out the PFB channelization, though. For multi-ARFCN applications, this will always be a requirement. M ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 11, 2014, 2:42pm UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/3 "2014-03-11T14:42:16Z")
I totally agree with Martin regarding PFB channelizer. The PFB for gsm will be also a good challenge for gnuradio in general as obtaining only a moderate number of channels(say 50) takes a lot of processing power and achieving realtime processing is not possible currently. Split per thereads and VOLK should be taken in consideration. Bogdan On Tuesday, March 11, 2014 2:30 PM, Martin B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: On 03/11/2014 11:14 AM, zhenhua han wrote: > As there are only 14 weeks in GSoC, > the schedule is a little tight. > However, I will continue working on this project after GSoC (if I am > selected). And Channel hopping will be the first task after I finish all > the tasks planned in GSoC. You should definitely check out the PFB channelization, though. For multi-ARFCN applications, this will always be a requirement. M ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 13, 2014, 4:26am UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/4 "2014-03-13T04:26:32Z")
Hi, I have implemented the algorithm in the paper for test and uploaded my code to github. > **[GitHub - hzhua/gr-fchdetection: Detecting FCCH of GSM with GNU Radio](https://github.com/hzhua/gr-fchdetection)** > > Detecting FCCH of GSM with GNU Radio. Contribute to hzhua/gr-fchdetection development by creating an account on GitHub. The result given by the algorithm seems great. Here is a figure generated by my program which is the ratio of average error power to input power. It is very low at frequency burst and high at other bursts. [image: ǶͼƬ 1] I have also added this part in my proposal. Best, Zhenhua 2014-03-11 21:41 GMT+08:00 Bogdan D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 13, 2014, 2:13pm UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/5 "2014-03-13T14:13:42Z")
The figure in the previous mail is incorrect. It is too weird that the ratio is so low and with narrow transition. And the sample count is not match the FB. After some debugs, I found the reason. I got the sample data with GNU Radio companion. When I execute the flow graph, it starts to write data into the file before my RTL-SDR started. So there are lots of invalid samples at the start. I have fixed this bug. Here is a correct (maybe 🙂 ) figure. The sample rate is 1.25M sps. The FCCH burst lasts about 700 samples which equals 0.56 ms. The duration of a standard FB is 0.57 ms. It seems correct. I have updated this part in my proposal. Sorry for my mistakes.[image: ǶͼƬ 1] Best, Zhenhua 2014-03-13 11:27 GMT+08:00 zhenhua han [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 16, 2014, 8:28am UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/6 "2014-03-16T08:28:39Z")
Hi, My proposal has been updated on github. The proposal has been changed a lot according to the comments on Melange. 1.The flow graph has been changed. A new architecture is designed. 2.A state machine is added which explains more details on GSM decoder. 3.The deliverable list has been changed. 4.The schedule has been changed according to the new architecture. Looking forward to further advises 🙂 Best wishes, Zhenhua 2014-03-13 21:12 GMT+08:00 zhenhua han [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 13, 2014, 4:28am UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/7 "2014-03-13T04:28:59Z")
Oh, I forgot to say. The data is sampled by a RTL-SDR. Zhenhua 2014-03-13 11:25 GMT+08:00 zhenhua han [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): ---
**Author:** ![zhenhua\_han](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/d2c977/32.png) [@zhenhua\_han](https://www.ruby-forum.com/u/zhenhua_han)\ **Post date:** [March 21, 2014, 4:18pm UTC](https://www.ruby-forum.com/t/fwd-proposal-for-gsoc-on-gr-gsm/239709/8 "2014-03-21T16:18:08Z")
Great thanks to all of you here and in melange! The content below is updated according to the advises above: 1.More details in time synchronization and burst extraction; 2.More details in using streamed tag to get more stable frequency resetting; 3.More details in frequency correlation; 4.A state machine is added; 5.The structure of flow graph is changed; 6.New deliverable list and schedule; 7.More references. 8.Deleted the words of promising some tasks after GSoC. 2014-03-16 15:27 GMT+08:00 zhenhua han [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):