PLL Carrier Tracking: Difference between revisions

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[[Category:Block Docs]]
[[Category:Block Docs]]
Implements a PLL which locks to the input frequency and outputs the input signal mixed with that carrier.
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
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 ==
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; Loop bandwidth (''R'')
; Loop bandwidth (''R'')
: The loop bandwidth determines the lock range and should be set around pi/200 2pi/100.
: 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
; Max freq
: Maximum frequency of the carrier in radians per sample
: Maximum frequency of the carrier in <i>radians per sample</i>. See Notes above.


; Min freq
; Min freq
: Minimum frequency of the carrier in radians per sample
: 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