gr_costas_loop_cc.h File Reference

#include <gr_sync_block.h>
#include <stdexcept>
#include <fstream>

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Classes
class	gr_costas_loop_cc
	Carrier tracking PLL for QPSK input: complex; output: complex The Costas loop can have two output streams: stream 1 is the baseband I and Q; stream 2 is the normalized frequency of the loop. More...
Typedefs
typedef boost::shared_ptr < gr_costas_loop_cc >	gr_costas_loop_cc_sptr
Functions
gr_costas_loop_cc_sptr	gr_make_costas_loop_cc (float alpha, float beta, float max_freq, float min_freq, int order) throw (std::invalid_argument)
	A Costas loop carrier recovery module.

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Typedef Documentation

typedef boost::shared_ptr<gr_costas_loop_cc> gr_costas_loop_cc_sptr

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Function Documentation

gr_costas_loop_cc_sptr gr_make_costas_loop_cc	(	float	alpha,
		float	beta,
		float	max_freq,
		float	min_freq,
		int	order
	)			throw (std::invalid_argument)

A Costas loop carrier recovery module.

The Costas loop locks to the center frequency of a signal and downconverts it to baseband. The second (order=2) order loop is used for BPSK where the real part of the output signal is the baseband BPSK signal and the imaginary part is the error signal. When order=4, it can be used for quadrature modulations where both I and Q (real and imaginary) are outputted.

More details can be found online:

J. Feigin, "Practical Costas loop design: Designing a simple and inexpensive BPSK Costas loop carrier recovery circuit," RF signal processing, pp. 20-36, 2002.

http://rfdesign.com/images/archive/0102Feigin20.pdf

Parameters:

	alpha	the loop gain used for phase adjustment
	beta	the loop gain for frequency adjustments
	max_freq	the maximum frequency deviation (normalized frequency) the loop can handle
	min_freq	the minimum frequency deviation (normalized frequency) the loop can handle
	order	the loop order, either 2 or 4