Re: [Discuss-gnuradio] Gardner timing sync loop quetion

[Tom Rondeau]

On Tue, Jun 3, 2014 at 4:12 AM, Tiankun Hu <address@hidden> wrote:

Hi all,
I am designing a 2 order Gardner timing sync loop(with 1 order PI loop filter) for QAM64.
As Best's PLL book metioned, timing sync loop's parameter can be calculated by using PLL theory.
Now I need calculate the PI loop filter's factor K1(P gain) and K2(I gain). According PLL theory, we can get them from Wn(nature freq) Kd(phase detector gain) Ko(NCO gain).
I can get Kd from open loop simulate, and Ko equals to 1
Wn can get from BL(noise bandwidth).
My quetion is how to define BL, anyone can tell me how to calculate it from PPM(ADC's freq offset)?


Thanks
Tiankun

Take a look at this:

http://www.trondeau.com/blog/2011/8/13/control-loop-gain-values.html

I don't think it exactly answers your question, but might be helpful. Also, we have the gr::blocks::control_loop class that you can inherit from to make this easier for you to use. See the costas_loop_cc block for an example of how.

Tom