Clock Recovery MM: Difference between revisions
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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 | <br><code>Deprecated in 3.9</code> (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 [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> | ||
; | ; 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 == | |||
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