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GARDNER works, but we need a better way to calculate the error

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ha7ilm 2017-03-05 19:56:15 +01:00
parent 306e4aeb91
commit dde8fa0d08
2 changed files with 35 additions and 22 deletions
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46
libcsdr.c
View file

@ -1644,7 +1644,7 @@ void pll_cc(pll_t* p, complexf* input, float* output_dphase, complexf* output_nc
} }
} }
void octave_plot_point_on_cplxsig(complexf* signal, int signal_size, float error, int index, int writefiles, int points_size, ...) void octave_plot_point_on_cplxsig(complexf* signal, int signal_size, float error, int index, int correction_offset, int writefiles, int points_size, ...)
{ {
static int figure_output_counter = 0; static int figure_output_counter = 0;
int* points_z = (int*)malloc(sizeof(int)*points_size); int* points_z = (int*)malloc(sizeof(int)*points_size);
@ -1668,7 +1668,7 @@ void octave_plot_point_on_cplxsig(complexf* signal, int signal_size, float error
(char)points_color[i]&0xff, (i<points_size-1)?',':' ' (char)points_color[i]&0xff, (i<points_size-1)?',':' '
); );
va_end(vl); va_end(vl);
fprintf(stderr, ");\ntitle(\"index = %d, error = %f\");\nsubplot(2,2,1);\nplot(zsig, isig,\"b-\",", index, error); fprintf(stderr, ");\ntitle(\"index = %d, error = %f, cxoffs = %d\");\nsubplot(2,2,1);\nplot(zsig, isig,\"b-\",", index, error, correction_offset);
for(int i=0;i<points_size;i++) for(int i=0;i<points_size;i++)
fprintf(stderr, "[%d],[%f],\"%c.\"%c", fprintf(stderr, "[%d],[%f],\"%c.\"%c",
points_z[i], iof(signal, points_z[i]), points_z[i], iof(signal, points_z[i]),
@ -1697,7 +1697,7 @@ timing_recovery_state_t timing_recovery_init(timing_recovery_algorithm_t algorit
to_return.debug_count = 3; to_return.debug_count = 3;
to_return.debug_force = 0; to_return.debug_force = 0;
to_return.debug_writefiles = 0; to_return.debug_writefiles = 0;
//to_return.last_phase_offset = 0; to_return.last_correction_offset = 0;
return to_return; return to_return;
} }
@ -1712,6 +1712,7 @@ void timing_recovery_cc(complexf* input, complexf* output, int input_size, timin
{ {
//We always assume that the input starts at center of the first symbol cross before the first symbol. //We always assume that the input starts at center of the first symbol cross before the first symbol.
//Last time we consumed that much from the input samples that it is there. //Last time we consumed that much from the input samples that it is there.
int correction_offset = state->last_correction_offset;
int current_bitstart_index = 0; int current_bitstart_index = 0;
int num_samples_bit = state->decimation_rate; int num_samples_bit = state->decimation_rate;
int num_samples_halfbit = state->decimation_rate / 2; int num_samples_halfbit = state->decimation_rate / 2;
@ -1744,6 +1745,7 @@ void timing_recovery_cc(complexf* input, complexf* output, int input_size, timin
octave_plot_point_on_cplxsig(input+current_bitstart_index, state->decimation_rate*2, octave_plot_point_on_cplxsig(input+current_bitstart_index, state->decimation_rate*2,
error, error,
current_bitstart_index, current_bitstart_index,
correction_offset,
state->debug_writefiles, state->debug_writefiles,
3, //number of points to draw below: 3, //number of points to draw below:
num_samples_halfbit * 1, 'r', num_samples_halfbit * 1, 'r',
@ -1756,30 +1758,37 @@ void timing_recovery_cc(complexf* input, complexf* output, int input_size, timin
if(MTIMINGR_HDEBUG) fprintf(stderr, "new current_bitstart_index = %d\n", current_bitstart_index); if(MTIMINGR_HDEBUG) fprintf(stderr, "new current_bitstart_index = %d\n", current_bitstart_index);
if(si>=input_size) { break; } if(si>=input_size) { break; }
} }
state->input_processed = current_bitstart_index;
state->output_size = si;
} }
else if(state->algorithm == TIMING_RECOVERY_ALGORITHM_EARLYLATE) else if(state->algorithm == TIMING_RECOVERY_ALGORITHM_EARLYLATE)
{ {
//bitstart index should be at symbol maximum effect point //bitstart index should be at symbol maximum effect point
for(si=0;;si++) for(si=0;;si++)
{ {
//the MathWorks style algorithm has correction_offset.
//correction_offset = 0;
if(current_bitstart_index + num_samples_halfbit * 3 >= input_size) break; if(current_bitstart_index + num_samples_halfbit * 3 >= input_size) break;
if(MTIMINGR_HDEBUG) fprintf(stderr, "current_bitstart_index = %d, input_size = %d\n", if(MTIMINGR_HDEBUG) fprintf(stderr, "current_bitstart_index = %d, input_size = %d, correction_offset(prev) = %d\n",
current_bitstart_index, input_size); current_bitstart_index, input_size, correction_offset);
if(correction_offset<=-num_samples_quarterbit*0.9 || correction_offset>=0.9*num_samples_quarterbit)
{
if(MTIMINGR_HDEBUG) fprintf(stderr, "correction_offset = %d, reset to 0!\n", correction_offset);
correction_offset = 0;
}
output[si++] = input[current_bitstart_index]; output[si++] = input[current_bitstart_index];
error = ( int el_point_left_index = current_bitstart_index + num_samples_quarterbit * 3;
iof(input, current_bitstart_index + num_samples_quarterbit * 3) - iof(input, current_bitstart_index + num_samples_quarterbit) int el_point_right_index = current_bitstart_index + num_samples_quarterbit * 1 - correction_offset;
) * iof(input, current_bitstart_index + num_samples_halfbit); int el_point_mid_index = current_bitstart_index + num_samples_halfbit;
error = ( iof(input, el_point_left_index) - iof(input, el_point_right_index)) * iof(input, el_point_mid_index);
if(state->use_q) if(state->use_q)
{ {
error += ( error += ( qof(input, el_point_left_index) - qof(input, el_point_right_index)) * qof(input, el_point_mid_index);
qof(input, current_bitstart_index + num_samples_quarterbit * 3) - qof(input, current_bitstart_index + num_samples_quarterbit)
) * qof(input, current_bitstart_index + num_samples_halfbit);
error /= 2; error /= 2;
} }
//Correction method #1: this version can only move a single sample in any direction //Correction method #1: this version can only move a single sample in any direction
//current_bitstart_index += num_samples_halfbit * 2 + (error)?((error<0)?1:-1):0; //current_bitstart_index += num_samples_halfbit * 2 + (error)?((error<0)?1:-1):0;
//Correction method #2: this can move in proportional to the error //Correction method #2: this can move in proportional to the error
if(error>2) error=2; if(error>2) error=2;
if(error<-2) error=-2; if(error<-2) error=-2;
@ -1790,24 +1799,27 @@ void timing_recovery_cc(complexf* input, complexf* output, int input_size, timin
octave_plot_point_on_cplxsig(input+current_bitstart_index, state->decimation_rate*2, octave_plot_point_on_cplxsig(input+current_bitstart_index, state->decimation_rate*2,
error, error,
current_bitstart_index, current_bitstart_index,
correction_offset,
state->debug_writefiles, state->debug_writefiles,
3, 4,
0 , 'b',
num_samples_quarterbit * 1, 'r', num_samples_quarterbit * 1, 'r',
num_samples_quarterbit * 2, 'r', num_samples_quarterbit * 2, 'r',
num_samples_quarterbit * 3, 'r', num_samples_quarterbit * 3, 'r',
0 , 'b',
0); 0);
} }
current_bitstart_index += num_samples_bit + num_samples_halfbit * (-error/2); correction_offset = num_samples_halfbit * (-error/2);
current_bitstart_index += num_samples_bit + correction_offset;
if(si>=input_size) if(si>=input_size)
{ {
if(MTIMINGR_HDEBUG) fprintf(stderr, "oops_out_of_si!\n"); if(MTIMINGR_HDEBUG) fprintf(stderr, "oops_out_of_si!\n");
break; break;
} }
} }
}
state->input_processed = current_bitstart_index; state->input_processed = current_bitstart_index;
state->output_size = si; state->output_size = si;
} state->last_correction_offset = correction_offset;
} }
#define MTIMINGR_GAS(NAME) \ #define MTIMINGR_GAS(NAME) \

3
libcsdr.h
View file

@ -307,6 +307,7 @@ typedef struct timing_recovery_state_s
int debug_count; int debug_count;
int debug_force; int debug_force;
int debug_writefiles; int debug_writefiles;
int last_correction_offset;
} timing_recovery_state_t; } timing_recovery_state_t;
timing_recovery_state_t timing_recovery_init(timing_recovery_algorithm_t algorithm, int decimation_rate, int use_q); timing_recovery_state_t timing_recovery_init(timing_recovery_algorithm_t algorithm, int decimation_rate, int use_q);
@ -314,4 +315,4 @@ void timing_recovery_cc(complexf* input, complexf* output, int input_length, tim
timing_recovery_algorithm_t timing_recovery_get_algorithm_from_string(char* input); timing_recovery_algorithm_t timing_recovery_get_algorithm_from_string(char* input);
char* timing_recovery_get_string_from_algorithm(timing_recovery_algorithm_t algorithm); char* timing_recovery_get_string_from_algorithm(timing_recovery_algorithm_t algorithm);
void timing_recovery_trigger_debug(timing_recovery_state_t* state, int debug_phase); void timing_recovery_trigger_debug(timing_recovery_state_t* state, int debug_phase);
void octave_plot_point_on_cplxsig(complexf* signal, int signal_size, float error, int index, int writefiles, int points_size, ...); void octave_plot_point_on_cplxsig(complexf* signal, int signal_size, float error, int index, int correction_offset, int writefiles, int points_size, ...);