gr::digital::costas_loop_cc Class Reference

A Costas loop carrier recovery module. More...

#include <costas_loop_cc.h>

Inheritance diagram for gr::digital::costas_loop_cc:

Public Types
typedef boost::shared_ptr < costas_loop_cc >	sptr

Static Public Member Functions
static sptr	make (float loop_bw, int order)

Additional Inherited Members
Public Member Functions inherited from gr::sync_block
virtual int	work (int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)=0
	just like gr::block::general_work, only this arranges to call consume_each for you More...
void	forecast (int noutput_items, gr_vector_int &ninput_items_required)
	Estimate input requirements given output request. More...
int	general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
	compute output items from input items More...
int	fixed_rate_ninput_to_noutput (int ninput)
	Given ninput samples, return number of output samples that will be produced. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this. More...
int	fixed_rate_noutput_to_ninput (int noutput)
	Given noutput samples, return number of input samples required to produce noutput. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this. More...
Public Member Functions inherited from gr::blocks::control_loop
	control_loop (void)
	control_loop (float loop_bw, float max_freq, float min_freq)
virtual	~control_loop ()
void	update_gains ()
	update the system gains from the loop bandwidth and damping factor More...
void	advance_loop (float error)
	Advance the control loop based on the current gain settings and the inputted error signal. More...
void	phase_wrap ()
	Keep the phase between -2pi and 2pi. More...
void	frequency_limit ()
	Keep the frequency between d_min_freq and d_max_freq. More...
virtual void	set_loop_bandwidth (float bw)
	Set the loop bandwidth. More...
void	set_damping_factor (float df)
	Set the loop damping factor. More...
void	set_alpha (float alpha)
	Set the loop gain alpha. More...
void	set_beta (float beta)
	Set the loop gain beta. More...
void	set_frequency (float freq)
	Set the control loop's frequency. More...
void	set_phase (float phase)
	Set the control loop's phase. More...
void	set_max_freq (float freq)
	Set the control loop's maximum frequency. More...
void	set_min_freq (float freq)
	Set the control loop's minimum frequency. More...
float	get_loop_bandwidth () const
	Returns the loop bandwidth. More...
float	get_damping_factor () const
	Returns the loop damping factor. More...
float	get_alpha () const
	Returns the loop gain alpha. More...
float	get_beta () const
	Returns the loop gain beta. More...
float	get_frequency () const
	Get the control loop's frequency estimate. More...
float	get_phase () const
	Get the control loop's phase estimate. More...
float	get_max_freq () const
	Get the control loop's maximum frequency. More...
float	get_min_freq () const
	Get the control loop's minimum frequency. More...
Protected Types inherited from gr::basic_block
enum	vcolor { WHITE, GREY, BLACK }
Protected Member Functions inherited from gr::sync_block
	sync_block (void)
	sync_block (const std::string &name, gr::io_signature::sptr input_signature, gr::io_signature::sptr output_signature)
Protected Attributes inherited from gr::block
std::vector< long >	d_max_output_buffer
std::vector< long >	d_min_output_buffer
gr::thread::mutex	d_setlock
gr::logger_ptr	d_logger
gr::logger_ptr	d_debug_logger
Protected Attributes inherited from gr::blocks::control_loop
float	d_phase
float	d_freq
float	d_max_freq
float	d_min_freq
float	d_damping
float	d_loop_bw
float	d_alpha
float	d_beta

Detailed Description

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

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

Member Typedef Documentation

typedef boost::shared_ptr<costas_loop_cc> gr::digital::costas_loop_cc::sptr

Member Function Documentation

static sptr gr::digital::costas_loop_cc::make ( float  loop_bw, int  order  )

static

Make a Costas loop carrier recovery block.

Parameters

loop_bw	internal 2nd order loop bandwidth (~ 2pi/100)
order	the loop order, either 2, 4, or 8

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The documentation for this class was generated from the following file:

• costas_loop_cc.h