Re: [Discuss-gnuradio] Clock Recovery MM documentation

[Tom Rondeau]

On Thu, Jul 30, 2015 at 3:03 PM, Iluta V <address@hidden> wrote:

Hi, Tom,

Could you be more specific where exactly it is not "the right algorithm"? We'd appreciate that and would correct that in own work as well, if Security Research Assessment made a mistake here.

I will be looking forward to your response,

Iluta

Iluta,

I shouldn't be so hard on the M&M block. In most situations, it's tended to work fine, but it's suboptimal. It's based on hardware techniques of clock recovery that approximate a derivative. The PFB algorithm actually calculates the derivative to the numerical approximation required by setting the number of filterbank arms. So the results are much better. You also get to apply your own filter to this block so you don't have to apply a separate matched filter.

Also, and I can't find any papers on this, but fred harris tells me that the M&M algorithm behaves particularly poorly in fading environments.

Tom

 

On Thu, Jul 30, 2015 at 9:55 PM, Tom Rondeau <address@hidden> wrote:

On Thu, Jul 30, 2015 at 2:38 PM, Iluta V <address@hidden> wrote:

Research paper CONVERTING RADIO SIGNALS TO DATA PACKETS (Examination of Using GNU Radio Companion for Security Research and Assessment) deals with Clock Recovery MM, I attached the paper, have a look at:

6.Section 6.Counting the Bits
7.Analyzing Demodulated Data

Both deal with Clock Recovery MM usage and has flowgraphs.

Best regards,

Iluta

That's great, and I'm glad they got it to work for their application. Looks like they provide a good explanation of its use, too. Still, it's not the right algorithm.

 

Tom

 

On Thu, Jul 30, 2015 at 9:23 PM, Tom Rondeau <address@hidden> wrote:

Another point to keep in mind is that the M&M block isn't great in fading environments. It's really suboptimal in general. Look at the pfb_clock_recovery block, instead.

Tom

On Thu, Jul 30, 2015 at 2:18 PM, Daniel Camara <address@hidden> wrote:

Hi Klauss,

You could also take a look at https://www.tablix.org/~avian/blog/archives/2015/03/notes_on_m_m_clock_recovery/, it helped me quite a bit!

 Best regards...

   Daniel

On Thu, Jul 30, 2015 at 7:17 PM, Martin Braun <address@hidden> wrote:

Klaus,

the manual page for this block has a paper reference in it:
http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1clock__recovery__mm__ff.html#details

M

On 30.07.2015 10:16, Klauss Wolfeinstein wrote:
> Hello,
>
> I would like to find a proper documentation on MM algorithm block (paper
> for example). Any ideas ?
>
> Thank you.
>
> Regards.
>

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    Best regards...
           
                     Daniel

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