PLL Carrier Tracking: Difference between revisions

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Implements a Phase Locked Loop (PLL) which locks to the carrier of the input frequency and outputs the input signal mixed with that carrier.
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.


As this is a basic template, it's also in the [[:Category:Stub_Docs|"Stub Docs category"]]. Please improve it.
This PLL locks onto a [possibly noisy] reference carrier on the input and outputs that signal, downconverted to DC.
 
=== Notes ===
 
* <b>Important:</b> The frequency parameters below are in <i>radians per sample</i> rather than Hz.<br>
<pre>radians per sample = 2 * pi * centerfreq / sample rate</pre>
* Example:
** input signal, centered at 0Hz, centerfreq = 0 Hz.
** Sample rate = 48kHz.
** frequency variations to track +- 500Hz.
** Max Phase/sample = 2*pi*(0+500)/48,000 = 0.0654
** Min Phase/sample = 2*pi*(0-500)/48,000 = -0.0654
* If the input signal were centered at 10kHz,
** Then:
** The Max Phase/sample = 2*pi*(10,000+500)/48,000 = 1.374
** The Min Phase/sample = 2*pi*(10,000-500)/48,000 = 1.246
 
* This block seems to require an input signal of at least -30db in order to lock to the carrier.


== 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'')
; Loop bandwidth (''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).
: The loop bandwidth determines the lock range and should be set in the range of pi/200 to 2pi/100 (0.0157 to 0.0628).


; Param 2
; Max freq
: blah blah blah
: Maximum frequency of the carrier in <i>radians per sample</i>. See Notes above.
 
; Min freq
: Minimum frequency of the carrier in <i>radians per sample</i>. See Notes above.


== Example Flowgraph ==
== 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.
This flowgraph shows the use of a PLL Carrier Tracking block in an AM receiver.
 
[[File:Complex_to_Mag.png|800px]]


== Source Files ==
== Source Files ==

Latest revision as of 11:17, 1 June 2023

Implements a Phase Locked Loop (PLL) which locks to the carrier of the input frequency and outputs the input signal mixed with that carrier.

This PLL locks onto a [possibly noisy] reference carrier on the input and outputs that signal, downconverted to DC.

Notes

  • Important: The frequency parameters below are in radians per sample rather than Hz.
radians per sample = 2 * pi * centerfreq / sample rate
  • Example:
    • input signal, centered at 0Hz, centerfreq = 0 Hz.
    • Sample rate = 48kHz.
    • frequency variations to track +- 500Hz.
    • Max Phase/sample = 2*pi*(0+500)/48,000 = 0.0654
    • Min Phase/sample = 2*pi*(0-500)/48,000 = -0.0654
  • If the input signal were centered at 10kHz,
    • Then:
    • The Max Phase/sample = 2*pi*(10,000+500)/48,000 = 1.374
    • The Min Phase/sample = 2*pi*(10,000-500)/48,000 = 1.246
  • This block seems to require an input signal of at least -30db in order to lock to the carrier.

Parameters

(R): Run-time adjustable

Loop bandwidth (R)
The loop bandwidth determines the lock range and should be set in the range of pi/200 to 2pi/100 (0.0157 to 0.0628).
Max freq
Maximum frequency of the carrier in radians per sample. See Notes above.
Min freq
Minimum frequency of the carrier in radians per sample. See Notes above.

Example Flowgraph

This flowgraph shows the use of a PLL Carrier Tracking block in an AM receiver.

Complex to Mag.png

Source Files

C++ files
TODO
Header files
TODO
Public header files
TODO
Block definition
TODO
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