cellular-infrastructure
/
osmocom-analog
9
1
Fork 2
Code Issues 10 Pull Requests 2 Projects Releases Wiki Activity

Compandor: Remove unused option for unaffected level

pull/1/head
Andreas Eversberg 2018-10-14 13:07:25 +02:00
parent 56d8df5351
commit e9a7f610ee
7 changed files with 14 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
src/amps/dsp.c
View File

@ -99,7 +99,6 @@
#define PI M_PI
#define COMPANDOR_0DB 1.0 /* A level of 0dBm (1.0) shall be unaccected */
#define AMPS_MAX_DEVIATION 8000.0
#define AMPS_MAX_MODULATION 10000.0
#define AMPS_DBM0_DEVIATION 2900.0 /* deviation of dBm0 at 1 kHz */
@ -195,7 +194,7 @@ int dsp_init_sender(amps_t *amps, int tolerant)
int half;
/* attack (3ms) and recovery time (13.5ms) according to amps specs */
init_compandor(&amps->cstate, 8000, 3.0, 13.5, COMPANDOR_0DB);
init_compandor(&amps->cstate, 8000, 3.0, 13.5);
PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Init DSP for transceiver.\n");

3
src/cnetz/dsp.c
View File

@ -43,7 +43,6 @@
#define MAX_DEVIATION 4000.0
#define MAX_MODULATION 3000.0
#define DBM0_DEVIATION 4000.0 /* deviation of dBm0 at 1 kHz */
#define COMPANDOR_0DB 1.0 /* A level of 0dBm (1.0) shall be unaccected */
#define FSK_DEVIATION (2500.0 / DBM0_DEVIATION) /* no emphasis */
#define MAX_DISPLAY 1.4 /* something above dBm0, no emphasis */
#define BITRATE 5280.0 /* bits per second */
@ -151,7 +150,7 @@ int dsp_init_sender(cnetz_t *cnetz, int measure_speed, double clock_speed[2], en
/* init compandor, according to C-Netz specs, attack and recovery time
* shall not exceed according to ITU G.162 */
init_compandor(&cnetz->cstate, 8000, 5.0, 22.5, COMPANDOR_0DB);
init_compandor(&cnetz->cstate, 8000, 5.0, 22.5);
/* use this filter to compensate level changes between two subsequent audio chunks */
RC = 1.0 / (CUT_OFF_OFFSET * 2.0 *3.14);

26
src/libcompandor/compandor.c
View File

@ -32,7 +32,7 @@
#define EXPAND_ATTACK_FACTOR 1.145 /* about 0.57 after 6 dB step up */
#define EXPAND_RECOVERY_FACTOR 0.753 /* about 1.51 after 6 dB step down */
/* Minimum level value to keep state */
/* Minimum level value to keep state (-60 dB) */
#define ENVELOPE_MIN 0.001
/* Maximum level, to prevent sqrt_tab to overflow */
@ -46,7 +46,7 @@ static double sqrt_tab[10000];
* Hopefully this is correct
*
*/
void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms, double unaffected_level)
void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms)
{
int i;
@ -60,8 +60,6 @@ void init_compandor(compandor_t *state, double samplerate, double attack_ms, dou
state->c.step_down = pow(COMPRESS_RECOVERY_FACTOR, 1000.0 / recovery_ms / samplerate);
state->e.step_up = pow(EXPAND_ATTACK_FACTOR, 1000.0 / attack_ms / samplerate);
state->e.step_down = pow(EXPAND_RECOVERY_FACTOR, 1000.0 / recovery_ms / samplerate);
state->c.unaffected = unaffected_level;
state->e.unaffected = unaffected_level;
// FIXME: make global, not at instance
for (i = 0; i < 10000; i++)
@ -70,19 +68,17 @@ void init_compandor(compandor_t *state, double samplerate, double attack_ms, dou
void compress_audio(compandor_t *state, sample_t *samples, int num)
{
double value, peak, envelope, step_up, step_down, unaffected;
double value, peak, envelope, step_up, step_down;
int i;
step_up = state->c.step_up;
step_down = state->c.step_down;
peak = state->c.peak;
envelope = state->c.envelope;
unaffected = state->c.unaffected;
// printf("envelope=%.4f\n", envelope);
for (i = 0; i < num; i++) {
/* normalize sample value to unaffected level */
value = *samples / unaffected;
value = *samples;
/* 'peak' is the level that raises directly with the signal
* level, but falls with specified recovery rate. */
@ -101,11 +97,9 @@ void compress_audio(compandor_t *state, sample_t *samples, int num)
if (envelope > ENVELOPE_MAX)
envelope = ENVELOPE_MAX;
value = value / sqrt_tab[(int)(envelope / 0.001)];
*samples++ = value / sqrt_tab[(int)(envelope / 0.001)];
//if (i > 47000.0 && i < 48144)
//printf("time=%.4f envelope=%.4fdb, value=%.4f\n", (double)i/48000.0, 20*log10(envelope), value);
*samples++ = value * unaffected;
}
//exit(0);
@ -115,18 +109,16 @@ void compress_audio(compandor_t *state, sample_t *samples, int num)
void expand_audio(compandor_t *state, sample_t *samples, int num)
{
double value, peak, envelope, step_up, step_down, unaffected;
double value, peak, envelope, step_up, step_down;
int i;
step_up = state->e.step_up;
step_down = state->e.step_down;
peak = state->e.peak;
envelope = state->e.envelope;
unaffected = state->e.unaffected;
for (i = 0; i < num; i++) {
/* normalize sample value to 0 DB level */
value = *samples / unaffected;
value = *samples;
/* for comments: see compress_audio() */
if (fabs(value) > peak)
@ -140,9 +132,7 @@ void expand_audio(compandor_t *state, sample_t *samples, int num)
if (envelope < ENVELOPE_MIN)
envelope = ENVELOPE_MIN;
value = value * envelope;
*samples++ = value * unaffected;
*samples++ = value * envelope;
}
state->e.envelope = envelope;

4
src/libcompandor/compandor.h
View File

@ -1,14 +1,12 @@
typedef struct compandor {
struct {
double unaffected;
double step_up;
double step_down;
double peak;
double envelope;
} c;
struct {
double unaffected;
double step_up;
double step_down;
double peak;
@ -16,7 +14,7 @@ typedef struct compandor {
} e;
} compandor_t;
void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms, double unaffected_level);
void init_compandor(compandor_t *state, double samplerate, double attack_ms, double recovery_ms);
void compress_audio(compandor_t *state, sample_t *samples, int num);
void expand_audio(compandor_t *state, sample_t *samples, int num);

3
src/nmt/dsp.c
View File

@ -55,7 +55,6 @@
#define MAX_DEVIATION 4700.0
#define MAX_MODULATION 4055.0
#define DBM0_DEVIATION 3000.0 /* deviation of dBm0 at 1 kHz */
#define COMPANDOR_0DB 1.0 /* A level of 0dBm (1.0) shall be unaccected */
#define TX_PEAK_FSK (4200.0 / 1800.0 * 1000.0 / DBM0_DEVIATION)
#define TX_PEAK_SUPER (300.0 / 4015.0 * 1000.0 / DBM0_DEVIATION)
#define BIT_RATE 1200.0
@ -110,7 +109,7 @@ int dsp_init_sender(nmt_t *nmt, double deviation_factor)
int i;
/* attack (3ms) and recovery time (13.5ms) according to NMT specs */
init_compandor(&nmt->cstate, 8000, 3.0, 13.5, COMPANDOR_0DB);
init_compandor(&nmt->cstate, 8000, 3.0, 13.5);
PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Init DSP for Transceiver.\n");

3
src/r2000/dsp.c
View File

@ -48,7 +48,6 @@
#define MAX_DEVIATION 2500.0
#define MAX_MODULATION 2550.0
#define DBM0_DEVIATION 1500.0 /* deviation of dBm0 at 1 kHz */
#define COMPANDOR_0DB 1.0 /* A level of 0dBm (1.0) shall be unaccected */
#define TX_PEAK_FSK (1425.0 / 1500.0 * 1000.0 / DBM0_DEVIATION) /* with emphasis */
#define TX_PEAK_SUPER (300.0 / DBM0_DEVIATION) /* no emphasis */
#define FSK_BIT_RATE 1200.0
@ -76,7 +75,7 @@ static void super_receive_bit(void *inst, int bit, double quality, double level)
int dsp_init_sender(r2000_t *r2000)
{
/* attack (3ms) and recovery time (13.5ms) according to NMT specs */
init_compandor(&r2000->cstate, 8000, 3.0, 13.5, COMPANDOR_0DB);
init_compandor(&r2000->cstate, 8000, 3.0, 13.5);
PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Init DSP for Transceiver.\n");

2
src/test/test_compandor.c
View File

@ -72,7 +72,7 @@ int main(void)
sample_t samples[SAMPLERATE * 2];
int f;
init_compandor(&cstate, SAMPLERATE, ATTACK_MS, RECOVERY_MS, 1.0);
init_compandor(&cstate, SAMPLERATE, ATTACK_MS, RECOVERY_MS);
for (f = 0; f < 3; f++) {
/* -16 and -4 dB */