normal bursts detection now works, but the code is a little dirty

This commit is contained in:
piotr 2009-06-04 13:12:03 +02:00
parent 83ca8d75e2
commit 6497de667a
4 changed files with 171 additions and 26 deletions

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@ -3,7 +3,7 @@
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "burst_types.h"
#include <gsm_constants.h>
/*
* Synchronization channel.
@ -251,8 +251,8 @@ int decode_sch(const unsigned char *buf, int * t1_o, int * t2_o, int * t3_o, int
// extract encoded data from synchronization burst
/* buf, 39 bit */
/* buf + 39 + 64 = 103, 39 */
memcpy(data, buf, SB_EDATA_LEN_1);
memcpy(data + SB_EDATA_LEN_1, buf + SB_EDATA_LEN_1 + N_SYNC_BITS, SB_EDATA_LEN_2);
memcpy(data, buf, SCH_DATA_LEN);
memcpy(data + SCH_DATA_LEN, buf + SCH_DATA_LEN + N_SYNC_BITS, SCH_DATA_LEN);
// Viterbi decode
if (errors = conv_decode(data, decoded_data)) {

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@ -16,6 +16,7 @@
#define FCCH_BITS USEFUL_BITS
#define BURST_SIZE (USEFUL_BITS+2*TAIL_BITS)
#define SCH_DATA_LEN 39
#define TS_BITS (TAIL_BITS+USEFUL_BITS+TAIL_BITS+GUARD_BITS) //a full TS (156 bits)
#define TS_PER_FRAME 8
#define FRAME_BITS (TS_PER_FRAME * TS_BITS + 2) // 156.25 * 8
@ -30,7 +31,7 @@
#define CHAN_IMP_RESP_LENGTH 5
static const int SYNC_BITS[] = {
static const unsigned char SYNC_BITS[] = {
1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0,
0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1,
@ -39,7 +40,7 @@ static const int SYNC_BITS[] = {
const unsigned FCCH_FRAMES[] = {0,10,20,30,40};
const unsigned SCH_FRAMES[] = {1,11,21,31,41};
const unsigned BCCH_FRAMES[] = {2,3,4,5, 12}; //remove 12
// Sync : .+...++.+..+++.++++++.++++++....++.+..+.+.+++.+.+...+..++++..+..
// Diff Encoded Sync: .++..+.+++.+..++.....++.....+...+.+++.+++++..+++++..++.+...+.++.
@ -52,10 +53,11 @@ const unsigned SCH_FRAMES[] = {1,11,21,31,41};
#define TSC5 5
#define TSC6 6
#define TSC7 7
#define TS_FCCH 8
#define TS_DUMMY 9
#define TS_DUMMY 8
static const unsigned char train_seq[10][N_TRAIN_BITS] = {
#define TRAIN_SEQ_NUM 9
static const unsigned char train_seq[TRAIN_SEQ_NUM][N_TRAIN_BITS] = {
{0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1},
{0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1},
{0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0},
@ -64,10 +66,10 @@ static const unsigned char train_seq[10][N_TRAIN_BITS] = {
{0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0},
{1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1},
{1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0},
{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, //#9 FCCH ;-)
{0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 0, 1} // DUMMY
};
//Dummy burst 0xFB 76 0A 4E 09 10 1F 1C 5C 5C 57 4A 33 39 E9 F1 2F A8
static const unsigned char dummy_burst[] = {
1, 1, 1, 1, 1, 0, 1, 1, 0, 1,

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@ -37,6 +37,7 @@
#define FCCH_BUFFER_SIZE (FCCH_HITS_NEEDED)
#define SYNC_SEARCH_RANGE 30
#define TRAIN_SEARCH_RANGE 40
//TODO !! - move this methods to some else place
@ -76,7 +77,12 @@ gsm_receiver_cf::gsm_receiver_cf(gr_feval_dd *tuner, int osr)
// d_x_temp(0),//!!
// d_x2_temp(0)//!!
{
gmsk_mapper(SYNC_BITS, d_sch_training_seq, N_SYNC_BITS);
int i;
gmsk_mapper(SYNC_BITS, N_SYNC_BITS, d_sch_training_seq, gr_complex(0.0,-1.0));
for (i = 0; i < TRAIN_SEQ_NUM; i++) {
gmsk_mapper(train_seq[i], N_TRAIN_BITS, d_norm_training_seq[i], gr_complex(1.0,0.0));
}
}
/*
@ -142,10 +148,12 @@ gsm_receiver_cf::general_work(int noutput_items,
DCOUT("sch burst_start: " << burst_start);
d_burst_nr.set(t1, t2, t3, 0);
DCOUT("bcc: " << d_bcc << " ncc: " << d_ncc << " t1: " << t1 << " t2: " << t2 << " t3: " << t3);
d_channel_conf.set_multiframe_type(0, multiframe_51);
d_channel_conf.set_burst_types(0, FCCH_FRAMES, sizeof(FCCH_FRAMES) / sizeof(unsigned), fcch_burst);
d_channel_conf.set_burst_types(0, SCH_FRAMES, sizeof(SCH_FRAMES) / sizeof(unsigned), sch_burst);
d_channel_conf.set_multiframe_type(TSC0, multiframe_51);
d_channel_conf.set_burst_types(TSC0, FCCH_FRAMES, sizeof(FCCH_FRAMES) / sizeof(unsigned), fcch_burst);
d_channel_conf.set_burst_types(TSC0, SCH_FRAMES, sizeof(SCH_FRAMES) / sizeof(unsigned), sch_burst);
d_channel_conf.set_burst_types(TSC0, BCCH_FRAMES, sizeof(BCCH_FRAMES) / sizeof(unsigned), normal_burst);
d_burst_nr++;
consume_each(burst_start + BURST_SIZE * d_OSR);
d_state = synchronized;
} else {
@ -159,7 +167,7 @@ gsm_receiver_cf::general_work(int noutput_items,
//in this state receiver is synchronized and it processes bursts according to burst type for given burst number
case synchronized: {
gr_complex chan_imp_resp[100];//!!
gr_complex chan_imp_resp[d_chan_imp_length*d_OSR];
burst_type b_type = d_channel_conf.get_burst_type(d_burst_nr);
int burst_start;
int offset = 0;
@ -169,7 +177,7 @@ gsm_receiver_cf::general_work(int noutput_items,
switch (b_type) {
case fcch_burst: {
int ii;
int first_sample = ceil((GUARD_PERIOD + 2*TAIL_BITS) * d_OSR)+1;
int first_sample = ceil((GUARD_PERIOD + 2 * TAIL_BITS) * d_OSR) + 1;
int last_sample = first_sample + USEFUL_BITS * d_OSR;
double phase_sum = 0;
for (ii = first_sample; ii < last_sample; ii++) {
@ -177,18 +185,18 @@ gsm_receiver_cf::general_work(int noutput_items,
phase_sum += phase_diff;
}
double freq_offset = compute_freq_offset(phase_sum, last_sample - first_sample);
if(abs(freq_offset) > FCCH_MAX_FREQ_OFFSET){
if (abs(freq_offset) > FCCH_MAX_FREQ_OFFSET) {
d_freq_offset -= freq_offset;
set_frequency(d_freq_offset);
DCOUT("adjusting frequency, new frequency offset: " << d_freq_offset << "\n");
}
}
break;
case sch_burst: {
int t1, t2, t3, d_ncc, d_bcc;
burst_start = get_sch_chan_imp_resp(in, chan_imp_resp);
detect_burst(in, chan_imp_resp, burst_start, output_binary);
detect_burst(in, &d_channel_imp_resp[0], burst_start, output_binary);
if (decode_sch(&output_binary[3], &t1, &t2, &t3, &d_ncc, &d_bcc) == 0) {
// d_burst_nr.set(t1, t2, t3, 0);
DCOUT("bcc: " << d_bcc << " ncc: " << d_ncc << " t1: " << t1 << " t2: " << t2 << " t3: " << t3);
@ -198,8 +206,25 @@ gsm_receiver_cf::general_work(int noutput_items,
}
}
break;
case normal_burst:
// std::cout << "# name: norm_complex\n" ;
// std::cout << "# type: complex matrix\n" ;
// std::cout << "# rows: 1\n" ;
// std::cout << "# columns: " << floor(d_OSR*(TS_BITS+GUARD_PERIOD)) << "\n";
burst_start = get_norm_chan_imp_resp(in, chan_imp_resp, TRAIN_SEARCH_RANGE);
// std::cout << burst_start << "\n" ;
detect_burst(in, &d_channel_imp_resp[0], burst_start, output_binary);
// printf("burst = [ ");
//
for (int i = 0; i < BURST_SIZE ; i++) {
printf(" %d", output_binary[i]);
}
printf("];\n");
//
// for(int i=0; i<floor(d_OSR*(TS_BITS+GUARD_PERIOD)); i++){
// std::cout << in[i] << "\n";
// }
break;
case rach_burst:
@ -517,14 +542,14 @@ void gsm_receiver_cf::detect_burst(const gr_complex * in, gr_complex * chan_imp_
}
//TODO consider placing this funtion in a separate class for signal processing
void gsm_receiver_cf::gmsk_mapper(const int * input, gr_complex * output, int ninput)
void gsm_receiver_cf::gmsk_mapper(const unsigned char * input, int ninput, gr_complex * gmsk_output, gr_complex start_point)
{
gr_complex j = gr_complex(0.0, 1.0);
int current_symbol;
int encoded_symbol;
int previous_symbol = 2 * input[0] - 1;
output[0] = gr_complex(1.0, 0.0);
gmsk_output[0] = start_point;
for (int i = 1; i < ninput; i++) {
//change bits representation to NRZ
@ -532,7 +557,7 @@ void gsm_receiver_cf::gmsk_mapper(const int * input, gr_complex * output, int ni
//differentially encode
encoded_symbol = current_symbol * previous_symbol;
//and do gmsk mapping
output[i] = j * gr_complex(encoded_symbol, 0.0) * output[i-1];
gmsk_output[i] = j * gr_complex(encoded_symbol, 0.0) * gmsk_output[i-1];
previous_symbol = current_symbol;
}
}
@ -583,6 +608,121 @@ inline void gsm_receiver_cf::mafi(const gr_complex * input, int input_length, gr
{
int ii = 0, n, a;
for (n = 0; n < input_length; n++) {
a = n * d_OSR;
output[n] = 0;
ii = 0;
while (ii < filter_length) {
if ((a + ii) >= input_length*d_OSR)
break;
output[n] += input[a+ii] * filter[ii];
ii++;
}
}
}
int gsm_receiver_cf::get_norm_chan_imp_resp(const gr_complex *in, gr_complex * chan_imp_resp, unsigned search_range)
{
vector_complex correlation_buffer;
vector_float power_buffer;
vector_float window_energy_buffer;
int strongest_window_nr;
int burst_start = 0;
int chan_imp_resp_center;
float max_correlation = 0;
float energy = 0;
int search_start_pos = floor((TRAIN_POS + GUARD_PERIOD) * d_OSR);
int search_stop_pos = search_start_pos + search_range * d_OSR;
// std::cout << "# name: correlation\n" ;
// std::cout << "# type: complex matrix\n" ;
// std::cout << "# rows: 1\n" ;
// std::cout << "# columns: " << (search_stop_pos - search_start_pos) << "\n";
for (int ii = search_start_pos; ii < search_stop_pos; ii++) {
// for (int ii = SYNC_POS * d_OSR; ii < (SYNC_POS + SYNC_SEARCH_RANGE) *d_OSR; ii++) {
// for (int ii = 1; ii < (150) *d_OSR; ii++) {
gr_complex correlation = correlate_sequence(&d_norm_training_seq[d_bcc][5], &in[ii], N_TRAIN_BITS - 10);
// std::cout << correlation << "\n" ;
correlation_buffer.push_back(correlation);
power_buffer.push_back(pow(abs(correlation), 2));
}
//compute window energies
vector_float::iterator iter = power_buffer.begin();
bool loop_end = false;
while (iter != power_buffer.end()) {
vector_float::iterator iter_ii = iter;
energy = 0;
for (int ii = 0; ii < (d_chan_imp_length)*d_OSR; ii++, iter_ii++) {
if (iter_ii == power_buffer.end()) {
loop_end = true;
break;
}
energy += (*iter_ii);
}
if (loop_end) {
break;
}
iter++;
// std::cout << energy << "\n";
window_energy_buffer.push_back(energy);
}
strongest_window_nr = max_element(window_energy_buffer.begin(), window_energy_buffer.end()) - window_energy_buffer.begin();
d_channel_imp_resp.clear();
strongest_window_nr = 36;
max_correlation = 0;
for (int ii = 0; ii < (d_chan_imp_length)*d_OSR; ii++) {
gr_complex correlation = correlation_buffer[strongest_window_nr + ii];
if (abs(correlation) > max_correlation) {
chan_imp_resp_center = ii;
max_correlation = abs(correlation);
}
d_channel_imp_resp.push_back(correlation);
chan_imp_resp[ii] = correlation;
}
std::cout << "center: " << strongest_window_nr + chan_imp_resp_center << " stronegest window nr: " << strongest_window_nr << "\n";
burst_start = search_start_pos + strongest_window_nr + chan_imp_resp_center - 66 * d_OSR - 2 * d_OSR + 2;
return burst_start;
}
void gsm_receiver_cf::detect_norm_burst(const gr_complex * in, gr_complex * chan_imp_resp, int burst_start, unsigned char * output_binary)
{
float output[BURST_SIZE];
gr_complex rhh_temp[CHAN_IMP_RESP_LENGTH*d_OSR];
gr_complex rhh[CHAN_IMP_RESP_LENGTH];
gr_complex filtered_burst[BURST_SIZE];
int start_state = 3;
unsigned int stop_states[2] = {4, 12};
autocorrelation(chan_imp_resp, rhh_temp, d_chan_imp_length*d_OSR);
for (int ii = 0; ii < (d_chan_imp_length); ii++) {
rhh[ii] = conj(rhh_temp[ii*d_OSR]);
}
mafi_norm(&in[burst_start], BURST_SIZE, chan_imp_resp, d_chan_imp_length*d_OSR, filtered_burst);
viterbi_detector(filtered_burst, BURST_SIZE, rhh, start_state, stop_states, 2, output);
for (int i = 0; i < BURST_SIZE ; i++) {
output_binary[i] = (output[i] > 0);
}
}
inline void gsm_receiver_cf::mafi_norm(const gr_complex * input, int input_length, gr_complex * filter, int filter_length, gr_complex * output)
{
int ii = 0, n, a;
for (n = 0; n < input_length; n++) {
a = n * d_OSR;
output[n] = 0;
@ -594,6 +734,5 @@ inline void gsm_receiver_cf::mafi(const gr_complex * input, int input_length, gr
output[n] += input[a+ii] * filter[ii]; //!!conj
ii++;
}
output[n] = output[n] * gr_complex(0, -1); //!!this shouldn't be here
}
}

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@ -247,7 +247,8 @@ class gsm_receiver_cf : public gr_block
const int d_chan_imp_length;
gr_complex d_sch_training_seq[N_SYNC_BITS]; //encoded training sequence of a SCH burst
gr_complex d_norm_training_seq[TRAIN_SEQ_NUM][N_TRAIN_BITS];
gr_feval_dd *d_tuner;
unsigned d_counter;
@ -284,11 +285,14 @@ class gsm_receiver_cf : public gr_block
bool find_sch_burst(const gr_complex *in, const int nitems , float *out);
int get_sch_chan_imp_resp(const gr_complex *in, gr_complex * chan_imp_resp);
void detect_burst(const gr_complex * in, gr_complex * chan_imp_resp, int burst_start, unsigned char * output_binary);
void gmsk_mapper(const int * input, gr_complex * gmsk_output, int ninput);
void gmsk_mapper(const unsigned char * input, int ninput, gr_complex * gmsk_output, gr_complex start_point);
gr_complex correlate_sequence(const gr_complex * sequence, const gr_complex * input_signal, int ninput);
inline void autocorrelation(const gr_complex * input, gr_complex * out, int length);
inline void mafi(const gr_complex * input, int input_length, gr_complex * filter, int filter_length, gr_complex * output);
int get_norm_chan_imp_resp(const gr_complex *in, gr_complex * chan_imp_resp, unsigned search_range);
void detect_norm_burst(const gr_complex * in, gr_complex * chan_imp_resp, int burst_start, unsigned char * output_binary);
inline void mafi_norm(const gr_complex * input, int input_length, gr_complex * filter, int filter_length, gr_complex * output);
public:
~gsm_receiver_cf();
void forecast(int noutput_items, gr_vector_int &ninput_items_required);