/* Copyright 2023 OneOfEleven
* https://github.com/DualTachyon
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// code to 'try' and reduce the AM demodulator saturation problem
//
// that is until someone works out how to properly configure the BK chip !
#include <string.h>
#include "am_fix.h"
#include "app/main.h"
#include "board.h"
#include "driver/bk4819.h"
//#include "external/printf/printf.h"
#include "frequencies.h"
#include "functions.h"
#include "misc.h"
#include "settings.h"
#ifdef ENABLE_AM_FIX
typedef struct
{
uint16_t reg_val;
int8_t gain_dB;
} __attribute__((packed)) t_gain_table;
// REG_10 AGC gain table
//
// <15:10> ???
//
// <9:8> = LNA Gain Short
// 3 = 0dB < original value
// 2 = -19dB // was -11
// 1 = -24dB // was -16
// 0 = -28dB // was -19
//
// <7:5> = LNA Gain
// 7 = 0dB
// 6 = -2dB
// 5 = -4dB < original value
// 4 = -6dB
// 3 = -9dB
// 2 = -14dB
// 1 = -19dB
// 0 = -24dB
//
// <4:3> = MIXER Gain
// 3 = 0dB < original value
// 2 = -3dB
// 1 = -6dB
// 0 = -8dB
//
// <2:0> = PGA Gain
// 7 = 0dB
// 6 = -3dB < original value
// 5 = -6dB
// 4 = -9dB
// 3 = -15dB
// 2 = -21dB
// 1 = -27dB
// 0 = -33dB
// front end register dB values
//
// these values need to be accurate for the code to properly/reliably switch
// between table entries when adjusting the front end registers.
//
// these 4 tables need a measuring/calibration update
//
//// static const int16_t lna_short_dB[] = { -19, -16, -11, 0}; // was (but wrong)
// static const int16_t lna_short_dB[] = { (-28), (-24), (-19), 0}; // corrected'ish
// static const int16_t lna_dB[] = { (-24), (-19), (-14), ( -9), (-6), (-4), (-2), 0};
// static const int16_t mixer_dB[] = { ( -8), ( -6), ( -3), 0};
// static const int16_t pga_dB[] = { (-33), (-27), (-21), (-15), (-9), (-6), (-3), 0};
// lookup table is hugely easier than writing code to do the same
//
#define LOOKUP_TABLE 1
#if LOOKUP_TABLE
static const t_gain_table gain_table[] =
{
{0x03BE, -7}, // 0 .. 3 5 3 6 .. 0dB -4dB 0dB -3dB .. -7dB original
{0x0000,-93}, // 1 .. 0 0 0 0 .. -28dB -24dB -8dB -33dB .. -93dB
{0x0008,-91}, // 2 .. 0 0 1 0 .. -28dB -24dB -6dB -33dB .. -91dB
{0x0100,-89}, // 3 .. 1 0 0 0 .. -24dB -24dB -8dB -33dB .. -89dB
{0x0020,-88}, // 4 .. 0 1 0 0 .. -28dB -19dB -8dB -33dB .. -88dB
{0x0108,-87}, // 5 .. 1 0 1 0 .. -24dB -24dB -6dB -33dB .. -87dB
{0x0028,-86}, // 6 .. 0 1 1 0 .. -28dB -19dB -6dB -33dB .. -86dB
{0x0018,-85}, // 7 .. 0 0 3 0 .. -28dB -24dB 0dB -33dB .. -85dB
{0x0200,-84}, // 8 .. 2 0 0 0 .. -19dB -24dB -8dB -33dB .. -84dB
{0x0101,-83}, // 9 .. 1 0 0 1 .. -24dB -24dB -8dB -27dB .. -83dB
{0x0208,-82}, // 10 .. 2 0 1 0 .. -19dB -24dB -6dB -33dB .. -82dB
{0x0118,-81}, // 11 .. 1 0 3 0 .. -24dB -24dB 0dB -33dB .. -81dB
{0x0038,-80}, // 12 .. 0 1 3 0 .. -28dB -19dB 0dB -33dB .. -80dB
{0x0220,-79}, // 13 .. 2 1 0 0 .. -19dB -19dB -8dB -33dB .. -79dB
{0x0201,-78}, // 14 .. 2 0 0 1 .. -19dB -24dB -8dB -27dB .. -78dB
{0x0228,-77}, // 15 .. 2 1 1 0 .. -19dB -19dB -6dB -33dB .. -77dB
{0x0218,-76}, // 16 .. 2 0 3 0 .. -19dB -24dB 0dB -33dB .. -76dB
{0x0119,-75}, // 17 .. 1 0 3 1 .. -24dB -24dB 0dB -27dB .. -75dB
{0x0240,-74}, // 18 .. 2 2 0 0 .. -19dB -14dB -8dB -33dB .. -74dB
{0x0221,-73}, // 19 .. 2 1 0 1 .. -19dB -19dB -8dB -27dB .. -73dB
{0x0248,-72}, // 20 .. 2 2 1 0 .. -19dB -14dB -6dB -33dB .. -72dB
{0x0238,-71}, // 21 .. 2 1 3 0 .. -19dB -19dB 0dB -33dB .. -71dB
{0x0219,-70}, // 22 .. 2 0 3 1 .. -19dB -24dB 0dB -27dB .. -70dB
{0x0260,-69}, // 23 .. 2 3 0 0 .. -19dB -9dB -8dB -33dB .. -69dB
{0x0241,-68}, // 24 .. 2 2 0 1 .. -19dB -14dB -8dB -27dB .. -68dB
{0x0268,-67}, // 25 .. 2 3 1 0 .. -19dB -9dB -6dB -33dB .. -67dB
{0x0280,-66}, // 26 .. 2 4 0 0 .. -19dB -6dB -8dB -33dB .. -66dB
{0x0300,-65}, // 27 .. 3 0 0 0 .. 0dB -24dB -8dB -33dB .. -65dB
{0x02A0,-64}, // 28 .. 2 5 0 0 .. -19dB -4dB -8dB -33dB .. -64dB
{0x0308,-63}, // 29 .. 3 0 1 0 .. 0dB -24dB -6dB -33dB .. -63dB
{0x02C0,-62}, // 30 .. 2 6 0 0 .. -19dB -2dB -8dB -33dB .. -62dB
{0x0290,-61}, // 31 .. 2 4 2 0 .. -19dB -6dB -3dB -33dB .. -61dB
{0x0320,-60}, // 32 .. 3 1 0 0 .. 0dB -19dB -8dB -33dB .. -60dB
{0x0301,-59}, // 33 .. 3 0 0 1 .. 0dB -24dB -8dB -27dB .. -59dB
{0x0328,-58}, // 34 .. 3 1 1 0 .. 0dB -19dB -6dB -33dB .. -58dB
{0x0318,-57}, // 35 .. 3 0 3 0 .. 0dB -24dB 0dB -33dB .. -57dB
{0x02C1,-56}, // 36 .. 2 6 0 1 .. -19dB -2dB -8dB -27dB .. -56dB
{0x0340,-55}, // 37 .. 3 2 0 0 .. 0dB -14dB -8dB -33dB .. -55dB
{0x0321,-54}, // 38 .. 3 1 0 1 .. 0dB -19dB -8dB -27dB .. -54dB
{0x0348,-53}, // 39 .. 3 2 1 0 .. 0dB -14dB -6dB -33dB .. -53dB
{0x0338,-52}, // 40 .. 3 1 3 0 .. 0dB -19dB 0dB -33dB .. -52dB
{0x0319,-51}, // 41 .. 3 0 3 1 .. 0dB -24dB 0dB -27dB .. -51dB
{0x0360,-50}, // 42 .. 3 3 0 0 .. 0dB -9dB -8dB -33dB .. -50dB
{0x0341,-49}, // 43 .. 3 2 0 1 .. 0dB -14dB -8dB -27dB .. -49dB
{0x0368,-48}, // 44 .. 3 3 1 0 .. 0dB -9dB -6dB -33dB .. -48dB
{0x0380,-47}, // 45 .. 3 4 0 0 .. 0dB -6dB -8dB -33dB .. -47dB
{0x0339,-46}, // 46 .. 3 1 3 1 .. 0dB -19dB 0dB -27dB .. -46dB
{0x03A0,-45}, // 47 .. 3 5 0 0 .. 0dB -4dB -8dB -33dB .. -45dB
{0x0361,-44}, // 48 .. 3 3 0 1 .. 0dB -9dB -8dB -27dB .. -44dB
{0x03C0,-43}, // 49 .. 3 6 0 0 .. 0dB -2dB -8dB -33dB .. -43dB
{0x0390,-42}, // 50 .. 3 4 2 0 .. 0dB -6dB -3dB -33dB .. -42dB
{0x03E0,-41}, // 51 .. 3 7 0 0 .. 0dB 0dB -8dB -33dB .. -41dB
{0x03B0,-40}, // 52 .. 3 5 2 0 .. 0dB -4dB -3dB -33dB .. -40dB
{0x03E8,-39}, // 53 .. 3 7 1 0 .. 0dB 0dB -6dB -33dB .. -39dB
{0x03D0,-38}, // 54 .. 3 6 2 0 .. 0dB -2dB -3dB -33dB .. -38dB
{0x03C1,-37}, // 55 .. 3 6 0 1 .. 0dB -2dB -8dB -27dB .. -37dB
{0x03F0,-36}, // 56 .. 3 7 2 0 .. 0dB 0dB -3dB -33dB .. -36dB
{0x03E1,-35}, // 57 .. 3 7 0 1 .. 0dB 0dB -8dB -27dB .. -35dB
{0x03B1,-34}, // 58 .. 3 5 2 1 .. 0dB -4dB -3dB -27dB .. -34dB
{0x03F8,-33}, // 59 .. 3 7 3 0 .. 0dB 0dB 0dB -33dB .. -33dB
{0x03D1,-32}, // 60 .. 3 6 2 1 .. 0dB -2dB -3dB -27dB .. -32dB
{0x03C2,-31}, // 61 .. 3 6 0 2 .. 0dB -2dB -8dB -21dB .. -31dB
{0x03F1,-30}, // 62 .. 3 7 2 1 .. 0dB 0dB -3dB -27dB .. -30dB
{0x03E2,-29}, // 63 .. 3 7 0 2 .. 0dB 0dB -8dB -21dB .. -29dB
{0x03B2,-28}, // 64 .. 3 5 2 2 .. 0dB -4dB -3dB -21dB .. -28dB
{0x03F9,-27}, // 65 .. 3 7 3 1 .. 0dB 0dB 0dB -27dB .. -27dB
{0x03D2,-26}, // 66 .. 3 6 2 2 .. 0dB -2dB -3dB -21dB .. -26dB
{0x03C3,-25}, // 67 .. 3 6 0 3 .. 0dB -2dB -8dB -15dB .. -25dB
{0x03F2,-24}, // 68 .. 3 7 2 2 .. 0dB 0dB -3dB -21dB .. -24dB
{0x03E3,-23}, // 69 .. 3 7 0 3 .. 0dB 0dB -8dB -15dB .. -23dB
{0x03B3,-22}, // 70 .. 3 5 2 3 .. 0dB -4dB -3dB -15dB .. -22dB
{0x03FA,-21}, // 71 .. 3 7 3 2 .. 0dB 0dB 0dB -21dB .. -21dB
{0x03D3,-20}, // 72 .. 3 6 2 3 .. 0dB -2dB -3dB -15dB .. -20dB
{0x03C4,-19}, // 73 .. 3 6 0 4 .. 0dB -2dB -8dB -9dB .. -19dB
{0x03F3,-18}, // 74 .. 3 7 2 3 .. 0dB 0dB -3dB -15dB .. -18dB
{0x03E4,-17}, // 75 .. 3 7 0 4 .. 0dB 0dB -8dB -9dB .. -17dB
{0x03C5,-16}, // 76 .. 3 6 0 5 .. 0dB -2dB -8dB -6dB .. -16dB
{0x03FB,-15}, // 77 .. 3 7 3 3 .. 0dB 0dB 0dB -15dB .. -15dB
{0x03E5,-14}, // 78 .. 3 7 0 5 .. 0dB 0dB -8dB -6dB .. -14dB
{0x03C6,-13}, // 79 .. 3 6 0 6 .. 0dB -2dB -8dB -3dB .. -13dB
{0x03F4,-12}, // 80 .. 3 7 2 4 .. 0dB 0dB -3dB -9dB .. -12dB
{0x03E6,-11}, // 81 .. 3 7 0 6 .. 0dB 0dB -8dB -3dB .. -11dB
{0x03C7,-10}, // 82 .. 3 6 0 7 .. 0dB -2dB -8dB 0dB .. -10dB
{0x03FC, -9}, // 83 .. 3 7 3 4 .. 0dB 0dB 0dB -9dB .. -9dB
{0x03E7, -8}, // 84 .. 3 7 0 7 .. 0dB 0dB -8dB 0dB .. -8dB
{0x03BE, -7}, // 85 .. 3 5 3 6 .. 0dB -4dB 0dB -3dB .. -7dB original
{0x03FD, -6}, // 86 .. 3 7 3 5 .. 0dB 0dB 0dB -6dB .. -6dB
{0x03DE, -5}, // 87 .. 3 6 3 6 .. 0dB -2dB 0dB -3dB .. -5dB
{0x03BF, -4}, // 88 .. 3 5 3 7 .. 0dB -4dB 0dB 0dB .. -4dB
{0x03FE, -3}, // 89 .. 3 7 3 6 .. 0dB 0dB 0dB -3dB .. -3dB
{0x03DF, -2}, // 90 .. 3 6 3 7 .. 0dB -2dB 0dB 0dB .. -2dB
{0x03FF, 0}, // 91 .. 3 7 3 7 .. 0dB 0dB 0dB 0dB .. 0dB
};
const uint8_t gain_table_size = ARRAY_SIZE(gain_table);
#else
t_gain_table gain_table[100] = {{0x03BE, -7}}; //original
uint8_t gain_table_size = 0;
void CreateTable()
{
typedef union {
struct {
uint8_t pgaIdx:3;
uint8_t mixerIdx:2;
uint8_t lnaIdx:3;
uint8_t lnaSIdx:2;
};
uint16_t __raw;
} GainData;
static const int8_t lna_short_dB[] = {-28, -24, -19, 0}; // corrected'ish
static const int8_t lna_dB[] = {-24, -19, -14, -9, -6, -4, -2, 0};
static const int8_t mixer_dB[] = { -8, -6, -3, 0};
static const int8_t pga_dB[] = {-33, -27, -21, -15, -9, -6, -3, 0};
unsigned i;
for (uint8_t lnaSIdx = 0; lnaSIdx < ARRAY_SIZE(lna_short_dB); lnaSIdx++) {
for (uint8_t lnaIdx = 0; lnaIdx < ARRAY_SIZE(lna_dB); lnaIdx++) {
for (uint8_t mixerIdx = 0; mixerIdx < ARRAY_SIZE(mixer_dB); mixerIdx++) {
for (uint8_t pgaIdx = 0; pgaIdx < ARRAY_SIZE(pga_dB); pgaIdx++) {
int16_t db = lna_short_dB[lnaSIdx] + lna_dB[lnaIdx] + mixer_dB[mixerIdx] + pga_dB[pgaIdx];
GainData gainData = {{
pgaIdx,
mixerIdx,
lnaIdx,
lnaSIdx,
}};
for (i = 1; i < ARRAY_SIZE(gain_table); i++) {
t_gain_table * gain = &gain_table[i];
if (db == gain->gain_dB)
break;
if (db > gain->gain_dB)
continue;
if (db < gain->gain_dB) {
if(gain->gain_dB)
memmove(gain + 1, gain, 100 - i);
gain->gain_dB = db;
gain->reg_val = gainData.__raw;
break;
}
gain->gain_dB = db;
gain->reg_val = gainData.__raw;
break;
}
}
}
}
}
gain_table_size = i+1;
}
#endif
#ifdef ENABLE_AM_FIX_SHOW_DATA
// display update rate
static const unsigned int display_update_rate = 250 / 10; // max 250ms display update rate
unsigned int counter = 0;
#endif
unsigned int gain_table_index[2] = {0, 0};
// used simply to detect a changed gain setting
unsigned int gain_table_index_prev[2] = {0, 0};
// holds the previous RSSI level .. we do an average of old + new RSSI reading
int16_t prev_rssi[2] = {0, 0};
// to help reduce gain hunting, peak hold count down tick
unsigned int hold_counter[2] = {0, 0};
// -89dBm, any higher and the AM demodulator starts to saturate/clip/distort
const int16_t desired_rssi = (-89 + 160) * 2;
int8_t currentGainDiff;
bool enabled = true;
void AM_fix_init(void)
{ // called at boot-up
for (int i = 0; i < 2; i++) {
gain_table_index[i] = 0; // re-start with original QS setting
}
#if !LOOKUP_TABLE
CreateTable();
#endif
}
void AM_fix_reset(const unsigned vfo)
{ // reset the AM fixer upper
if (vfo > 1)
return;
#ifdef ENABLE_AM_FIX_SHOW_DATA
counter = 0;
#endif
prev_rssi[vfo] = 0;
hold_counter[vfo] = 0;
gain_table_index_prev[vfo] = 0;
}
// adjust the RX gain to try and prevent the AM demodulator from
// saturating/overloading/clipping (distorted AM audio)
//
// we're actually doing the BK4819's job for it here, but as the chip
// won't/don't do it for itself, we're left to bodging it ourself by
// playing with the RF front end gain setting
//
void AM_fix_10ms(const unsigned vfo)
{
if(!gSetting_AM_fix || !enabled || vfo > 1 )
return;
switch (gCurrentFunction)
{
case FUNCTION_TRANSMIT:
case FUNCTION_BAND_SCOPE:
case FUNCTION_POWER_SAVE:
#ifdef ENABLE_AM_FIX_SHOW_DATA
counter = display_update_rate; // queue up a display update as soon as we switch to RX mode
#endif
return;
// only adjust stuff if we're in one of these modes、
case FUNCTION_FOREGROUND:
case FUNCTION_RECEIVE:
case FUNCTION_MONITOR:
case FUNCTION_INCOMING:
break;
}
#ifdef ENABLE_AM_FIX_SHOW_DATA
if (counter > 0) {
if (++counter >= display_update_rate) { // trigger a display update
counter = 0;
gUpdateDisplay = true;
}
}
#endif
static uint32_t lastFreq[2];
if(gEeprom.VfoInfo[vfo].pRX->Frequency != lastFreq[vfo]) {
lastFreq[vfo] = gEeprom.VfoInfo[vfo].pRX->Frequency;
AM_fix_reset(vfo);
}
int16_t rssi;
{ // sample the current RSSI level
// average it with the previous rssi (a bit of noise/spike immunity)
const int16_t new_rssi = BK4819_GetRSSI();
rssi = (prev_rssi[vfo] > 0) ? (prev_rssi[vfo] + new_rssi) / 2 : new_rssi;
prev_rssi[vfo] = new_rssi;
}
#ifdef ENABLE_AM_FIX_SHOW_DATA
{
static int16_t lastRssi;
if (lastRssi != rssi) { // rssi changed
lastRssi = rssi;
if (counter == 0) {
counter = 1;
gUpdateDisplay = true; // trigger a display update
}
}
}
#endif
// automatically adjust the RF RX gain
// update the gain hold counter
if (hold_counter[vfo] > 0)
hold_counter[vfo]--;
// dB difference between actual and desired RSSI level
int16_t diff_dB = (rssi - desired_rssi) / 2;
if (diff_dB > 0) { // decrease gain
unsigned int index = gain_table_index[vfo]; // current position we're at
if (diff_dB >= 10) { // jump immediately to a new gain setting
// this greatly speeds up initial gain reduction (but reduces noise/spike immunity)
const int16_t desired_gain_dB = (int16_t)gain_table[index].gain_dB - diff_dB + 8; // get no closer than 8dB (bit of noise/spike immunity)
// scan the table to see what index to jump straight too
while (index > 1)
if (gain_table[--index].gain_dB <= desired_gain_dB)
break;
}
else
{ // incrementally reduce the gain .. taking it slow improves noise/spike immunity
if (index > 1)
index--; // slow step-by-step gain reduction
}
index = MAX(1u, index);
if (gain_table_index[vfo] != index)
{
gain_table_index[vfo] = index;
hold_counter[vfo] = 30; // 300ms hold
}
}
if (diff_dB >= -6) // 6dB hysterisis (help reduce gain hunting)
hold_counter[vfo] = 30; // 300ms hold
if (hold_counter[vfo] == 0)
{ // hold has been released, we're free to increase gain
const unsigned int index = gain_table_index[vfo] + 1; // move up to next gain index
gain_table_index[vfo] = MIN(index, gain_table_size - 1u);
}
{ // apply the new settings to the front end registers
const unsigned int index = gain_table_index[vfo];
// remember the new table index
gain_table_index_prev[vfo] = index;
currentGainDiff = gain_table[0].gain_dB - gain_table[index].gain_dB;
BK4819_WriteRegister(BK4819_REG_13, gain_table[index].reg_val);
}
#ifdef ENABLE_AM_FIX_SHOW_DATA
if (counter == 0) {
counter = 1;
gUpdateDisplay = true;
}
#endif
}
#ifdef ENABLE_AM_FIX_SHOW_DATA
void AM_fix_print_data(const unsigned vfo, char *s) {
if (s != NULL && vfo < ARRAY_SIZE(gain_table_index)) {
const unsigned int index = gain_table_index[vfo];
sprintf(s, "%2u %4ddB %3u", index, gain_table[index].gain_dB, prev_rssi[vfo]);
counter = 0;
}
}
#endif
int8_t AM_fix_get_gain_diff()
{
return currentGainDiff;
}
void AM_fix_enable(bool on)
{
enabled = on;
}
#endif