PLL Carrier Tracking

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


  • Important: The frequency parameters below are in radians per sample rather than Hz.
    • for example:
      • input centered at 0 Hz.
      • Sample rate = 48kHz.
      • frequency variations to track +- 500Hz.
      • Max freq = 0.0654
      • Min freq = -0.0654
  • This block requires an input signal of at least -30db in order to lock to the carrier.


(R): Run-time adjustable

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

Example Flowgraph

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

FunCube AM.png

Source Files

C++ files
Header files
Public header files
Block definition