GNU Radio 3.7.1-34 C++ API
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:
gr::sync_block gr::blocks::control_loop gr::block gr::basic_block gr::msg_accepter gr::messages::msg_accepter

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
void forecast (int noutput_items, gr_vector_int &ninput_items_required)
 Estimate input requirements given output request.
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
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.
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.
- 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
void advance_loop (float error)
 Advance the control loop based on the current gain settings and the inputted error signal.
void phase_wrap ()
 Keep the phase between -2pi and 2pi.
void frequency_limit ()
 Keep the frequency between d_min_freq and d_max_freq.
virtual void set_loop_bandwidth (float bw)
 Set the loop bandwidth.
void set_damping_factor (float df)
 Set the loop damping factor.
void set_alpha (float alpha)
 Set the loop gain alpha.
void set_beta (float beta)
 Set the loop gain beta.
void set_frequency (float freq)
 Set the control loop's frequency.
void set_phase (float phase)
 Set the control loop's phase.
void set_max_freq (float freq)
 Set the control loop's maximum frequency.
void set_min_freq (float freq)
 Set the control loop's minimum frequency.
float get_loop_bandwidth () const
 Returns the loop bandwidth.
float get_damping_factor () const
 Returns the loop damping factor.
float get_alpha () const
 Returns the loop gain alpha.
float get_beta () const
 Returns the loop gain beta.
float get_frequency () const
 Get the control loop's frequency estimate.
float get_phase () const
 Get the control loop's phase estimate.
float get_max_freq () const
 Get the control loop's maximum frequency.
float get_min_freq () const
 Get the control loop's minimum frequency.
- 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

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_bwinternal 2nd order loop bandwidth (~ 2pi/100)
orderthe loop order, either 2, 4, or 8

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