Clock Recovery MM: Difference between revisions

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(Created page with "Category:Block Docs Category:Stub Docs This is the template for the "Page-per-block Docs". This first section should describe what the block...")
 
(Note symbol_sync instead, since Deprecated in 3.9)
 
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[[Category:Block Docs]]
[[Category:Block Docs]]
[[Category:Stub Docs]]
This block is meant to act as a clock recovery, to synchronize to a signal's frequency and phase, so that symbols can be extracted.
This is the template for the [[:Category:Block_Docs|"Page-per-block Docs"]].  This first section should describe what the block does and how to use it, using however many paragraphs necessary.  Note that the title of the wiki page should match the block's name in GRC, i.e. the one defined in the block's .grc file. Look at the [[FFT]] Block for a good example.
<br><code>Deprecated in 3.9</code> (Favor [[Symbol_Sync]] instead.)


As this is a basic template, it's also in the [[:Category:Stub_Docs|"Stub Docs category"]]. Please improve it.
Specifically, this implements the Mueller and Mueller (M&M) discrete-time error-tracking synchronizer.  The peak to peak input signal amplitude must be symmetrical about zero, as the M&M timing error detector (TED) is a decision directed TED, and this block uses a symbol decision slicer referenced at zero.  The input signal peak amplitude should be controlled to a consistent level (e.g. +/- 1.0) before this block to achieve consistent results for given gain settings; as the TED's output error signal is directly affected by the input amplitude.  The input signal must have peaks in order for the TED to output a correct error signal. If the input signal pulses do not have peaks (e.g. rectangular pulses) the input signal should be conditioned with a matched pulse filter or other appropriate filter to peak the input pulses. For a rectangular base pulse that is N samples wide, the matched filter taps would be [1.0/float(N)]*N, or in other words a moving average over N samples. This block will output samples at a rate of one sample per recovered symbol, and is thus not outputting at a constant rate.  Output symbols are not a subset of input, but may be interpolated. 
 
The complex version here is based on: Modified Mueller and Muller clock recovery circuit: G. R. Danesfahani, T.G. Jeans, "Optimisation of modified Mueller  and Muller algorithm," Electronics Letters, Vol. 31, no. 13, 22 June 1995, pp. 1032 - 1033.
 
For more info see [https://www.tablix.org/~avian/blog/archives/2015/03/notes_on_m_m_clock_recovery/]


== Parameters ==
== Parameters ==
(''R''): <span class="plainlinks">[https://wiki.gnuradio.org/index.php/GNURadioCompanion#Variable_Controls ''Run-time adjustable'']</span>
(''R''): <span class="plainlinks">[https://wiki.gnuradio.org/index.php/GNURadioCompanion#Variable_Controls ''Run-time adjustable'']</span>


; Param 1 (''R'')
; Omega (''R'')
: Description of parameter, provide any tips or recommended values.  Note that the name of the parameter above should match the param's label that shows up in grc (e.g. Sample Rate).
: Initial estimate of samples per symbol
 
; Param 2
: blah blah blah
 
== Example Flowgraph ==


Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI.  Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately.  The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.
; Gain Omega (''R'')
: Gain setting for omega update loop


== Source Files ==
; Mu (''R'')
: Initial estimate of phase of sample


; C++ files
; Gain Mu (''R'')
: [https://github.com/gnuradio/gnuradio TODO]
: Gain setting for mu update loop


; Header files
; Omega Relative Limit
: [https://github.com/gnuradio/gnuradio TODO]
: Limit on omega


; Public header files
== Example Flowgraph ==
: [https://github.com/gnuradio/gnuradio TODO]


; Block definition
== Source Files ==
: [https://github.com/gnuradio/gnuradio TODO]

Latest revision as of 20:31, 24 March 2021

This block is meant to act as a clock recovery, to synchronize to a signal's frequency and phase, so that symbols can be extracted.
Deprecated in 3.9 (Favor Symbol_Sync instead.)

Specifically, this implements the Mueller and Mueller (M&M) discrete-time error-tracking synchronizer. The peak to peak input signal amplitude must be symmetrical about zero, as the M&M timing error detector (TED) is a decision directed TED, and this block uses a symbol decision slicer referenced at zero. The input signal peak amplitude should be controlled to a consistent level (e.g. +/- 1.0) before this block to achieve consistent results for given gain settings; as the TED's output error signal is directly affected by the input amplitude. The input signal must have peaks in order for the TED to output a correct error signal. If the input signal pulses do not have peaks (e.g. rectangular pulses) the input signal should be conditioned with a matched pulse filter or other appropriate filter to peak the input pulses. For a rectangular base pulse that is N samples wide, the matched filter taps would be [1.0/float(N)]*N, or in other words a moving average over N samples. This block will output samples at a rate of one sample per recovered symbol, and is thus not outputting at a constant rate. Output symbols are not a subset of input, but may be interpolated.

The complex version here is based on: Modified Mueller and Muller clock recovery circuit: G. R. Danesfahani, T.G. Jeans, "Optimisation of modified Mueller and Muller algorithm," Electronics Letters, Vol. 31, no. 13, 22 June 1995, pp. 1032 - 1033.

For more info see [1]

Parameters

(R): Run-time adjustable

Omega (R)
Initial estimate of samples per symbol
Gain Omega (R)
Gain setting for omega update loop
Mu (R)
Initial estimate of phase of sample
Gain Mu (R)
Gain setting for mu update loop
Omega Relative Limit
Limit on omega

Example Flowgraph

Source Files