PLL Carrier Tracking
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.
radians per sample = 2 * pi * centerfreq / sample rate
- 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,
- 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.
- 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.
This flowgraph shows the use of a PLL Carrier Tracking block in an AM receiver.
- C++ files
- Header files
- Public header files
- Block definition