/* 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"
#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 = -24dB // was -11
// 1 = -30dB // was -16
// 0 = -33dB // 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
//
//
// QUESTION: why do I have to surround the negative numbers in brackets ???
// if I don't add the brackets, reading the table returns unexpected/different values !!!
//
//
//// static const int16_t lna_short_dB[] = { -19, -16, -11, 0}; // was (but wrong)
// static const int16_t lna_short_dB[] = { (-33), (-30), (-24), 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
//
static const t_gain_table gain_table[] =
{
{0x035E, -17}, // 0 .. 3 2 3 6 .. 0dB -14dB 0dB -3dB .. -17dB original
#ifdef ENABLE_AM_FIX_TEST1
// test table that lets me manually set the lna-short register
// to measure it's actual dB change using an RF signal generator
{0x005E, -50}, // 1 .. 0 2 3 6 .. -33dB -14dB 0dB -3dB .. -50dB
{0x015E, -47}, // 2 .. 1 2 3 6 .. -30dB -14dB 0dB -3dB .. -47dB
{0x025E, -41}, // 3 .. 2 2 3 6 .. -24dB -14dB 0dB -3dB .. -41dB
{0x035E, -17} // 4 .. 3 2 3 6 .. 0dB -14dB 0dB -3dB .. -17dB original
};
static const unsigned int original_index = 1;
#else
{0x0000, -98}, // 1 .. 0 0 0 0 .. -33dB -24dB -8dB -33dB .. -98dB
{0x0008, -96}, // 2 .. 0 0 1 0 .. -33dB -24dB -6dB -33dB .. -96dB
{0x0100, -95}, // 3 .. 1 0 0 0 .. -30dB -24dB -8dB -33dB .. -95dB
{0x0020, -93}, // 4 .. 0 1 0 0 .. -33dB -19dB -8dB -33dB .. -93dB
{0x0001, -92}, // 5 .. 0 0 0 1 .. -33dB -24dB -8dB -27dB .. -92dB
{0x0028, -91}, // 6 .. 0 1 1 0 .. -33dB -19dB -6dB -33dB .. -91dB
{0x0009, -90}, // 7 .. 0 0 1 1 .. -33dB -24dB -6dB -27dB .. -90dB
{0x0101, -89}, // 8 .. 1 0 0 1 .. -30dB -24dB -8dB -27dB .. -89dB
{0x0030, -88}, // 9 .. 0 1 2 0 .. -33dB -19dB -3dB -33dB .. -88dB
{0x0118, -87}, // 10 .. 1 0 3 0 .. -30dB -24dB 0dB -33dB .. -87dB
{0x0002, -86}, // 11 .. 0 0 0 2 .. -33dB -24dB -8dB -21dB .. -86dB
{0x0130, -85}, // 12 .. 1 1 2 0 .. -30dB -19dB -3dB -33dB .. -85dB
{0x0019, -84}, // 13 .. 0 0 3 1 .. -33dB -24dB 0dB -27dB .. -84dB
{0x0060, -83}, // 14 .. 0 3 0 0 .. -33dB -9dB -8dB -33dB .. -83dB
{0x0138, -82}, // 15 .. 1 1 3 0 .. -30dB -19dB 0dB -33dB .. -82dB
{0x0119, -81}, // 16 .. 1 0 3 1 .. -30dB -24dB 0dB -27dB .. -81dB
{0x0058, -80}, // 17 .. 0 2 3 0 .. -33dB -14dB 0dB -33dB .. -80dB
{0x0141, -79}, // 18 .. 1 2 0 1 .. -30dB -14dB -8dB -27dB .. -79dB
{0x0070, -78}, // 19 .. 0 3 2 0 .. -33dB -9dB -3dB -33dB .. -78dB
{0x0180, -77}, // 20 .. 1 4 0 0 .. -30dB -6dB -8dB -33dB .. -77dB
{0x0139, -76}, // 21 .. 1 1 3 1 .. -30dB -19dB 0dB -27dB .. -76dB
{0x0013, -75}, // 22 .. 0 0 2 3 .. -33dB -24dB -3dB -15dB .. -75dB
{0x0161, -74}, // 23 .. 1 3 0 1 .. -30dB -9dB -8dB -27dB .. -74dB
{0x01C0, -73}, // 24 .. 1 6 0 0 .. -30dB -2dB -8dB -33dB .. -73dB
{0x00E8, -72}, // 25 .. 0 7 1 0 .. -33dB 0dB -6dB -33dB .. -72dB
{0x00D0, -71}, // 26 .. 0 6 2 0 .. -33dB -2dB -3dB -33dB .. -71dB
{0x0239, -70}, // 27 .. 2 1 3 1 .. -24dB -19dB 0dB -27dB .. -70dB
{0x006A, -69}, // 28 .. 0 3 1 2 .. -33dB -9dB -6dB -21dB .. -69dB
{0x0006, -68}, // 29 .. 0 0 0 6 .. -33dB -24dB -8dB -3dB .. -68dB
{0x00B1, -67}, // 30 .. 0 5 2 1 .. -33dB -4dB -3dB -27dB .. -67dB
{0x000E, -66}, // 31 .. 0 0 1 6 .. -33dB -24dB -6dB -3dB .. -66dB
{0x015A, -65}, // 32 .. 1 2 3 2 .. -30dB -14dB 0dB -21dB .. -65dB
{0x022B, -64}, // 33 .. 2 1 1 3 .. -24dB -19dB -6dB -15dB .. -64dB
{0x01F8, -63}, // 34 .. 1 7 3 0 .. -30dB 0dB 0dB -33dB .. -63dB
{0x0163, -62}, // 35 .. 1 3 0 3 .. -30dB -9dB -8dB -15dB .. -62dB
{0x0035, -61}, // 36 .. 0 1 2 5 .. -33dB -19dB -3dB -6dB .. -61dB
{0x0214, -60}, // 37 .. 2 0 2 4 .. -24dB -24dB -3dB -9dB .. -60dB
{0x01D9, -59}, // 38 .. 1 6 3 1 .. -30dB -2dB 0dB -27dB .. -59dB
{0x0145, -58}, // 39 .. 1 2 0 5 .. -30dB -14dB -8dB -6dB .. -58dB
{0x02A2, -57}, // 40 .. 2 5 0 2 .. -24dB -4dB -8dB -21dB .. -57dB
{0x02D1, -56}, // 41 .. 2 6 2 1 .. -24dB -2dB -3dB -27dB .. -56dB
{0x00B3, -55}, // 42 .. 0 5 2 3 .. -33dB -4dB -3dB -15dB .. -55dB
{0x0216, -54}, // 43 .. 2 0 2 6 .. -24dB -24dB -3dB -3dB .. -54dB
{0x0066, -53}, // 44 .. 0 3 0 6 .. -33dB -9dB -8dB -3dB .. -53dB
{0x00C4, -52}, // 45 .. 0 6 0 4 .. -33dB -2dB -8dB -9dB .. -52dB
{0x006E, -51}, // 46 .. 0 3 1 6 .. -33dB -9dB -6dB -3dB .. -51dB
{0x015D, -50}, // 47 .. 1 2 3 5 .. -30dB -14dB 0dB -6dB .. -50dB
{0x00AD, -49}, // 48 .. 0 5 1 5 .. -33dB -4dB -6dB -6dB .. -49dB
{0x007D, -48}, // 49 .. 0 3 3 5 .. -33dB -9dB 0dB -6dB .. -48dB
{0x00D4, -47}, // 50 .. 0 6 2 4 .. -33dB -2dB -3dB -9dB .. -47dB
{0x01B4, -46}, // 51 .. 1 5 2 4 .. -30dB -4dB -3dB -9dB .. -46dB
{0x030B, -45}, // 52 .. 3 0 1 3 .. 0dB -24dB -6dB -15dB .. -45dB
{0x00CE, -44}, // 53 .. 0 6 1 6 .. -33dB -2dB -6dB -3dB .. -44dB
{0x01B5, -43}, // 54 .. 1 5 2 5 .. -30dB -4dB -3dB -6dB .. -43dB
{0x0097, -42}, // 55 .. 0 4 2 7 .. -33dB -6dB -3dB 0dB .. -42dB
{0x0257, -41}, // 56 .. 2 2 2 7 .. -24dB -14dB -3dB 0dB .. -41dB
{0x02B4, -40}, // 57 .. 2 5 2 4 .. -24dB -4dB -3dB -9dB .. -40dB
{0x027D, -39}, // 58 .. 2 3 3 5 .. -24dB -9dB 0dB -6dB .. -39dB
{0x01DD, -38}, // 59 .. 1 6 3 5 .. -30dB -2dB 0dB -6dB .. -38dB
{0x02AE, -37}, // 60 .. 2 5 1 6 .. -24dB -4dB -6dB -3dB .. -37dB
{0x0379, -36}, // 61 .. 3 3 3 1 .. 0dB -9dB 0dB -27dB .. -36dB
{0x035A, -35}, // 62 .. 3 2 3 2 .. 0dB -14dB 0dB -21dB .. -35dB
{0x02B6, -34}, // 63 .. 2 5 2 6 .. -24dB -4dB -3dB -3dB .. -34dB
{0x030E, -33}, // 64 .. 3 0 1 6 .. 0dB -24dB -6dB -3dB .. -33dB
{0x0307, -32}, // 65 .. 3 0 0 7 .. 0dB -24dB -8dB 0dB .. -32dB
{0x02BE, -31}, // 66 .. 2 5 3 6 .. -24dB -4dB 0dB -3dB .. -31dB
{0x037A, -30}, // 67 .. 3 3 3 2 .. 0dB -9dB 0dB -21dB .. -30dB
{0x02DE, -29}, // 68 .. 2 6 3 6 .. -24dB -2dB 0dB -3dB .. -29dB
{0x0345, -28}, // 69 .. 3 2 0 5 .. 0dB -14dB -8dB -6dB .. -28dB
{0x03A3, -27}, // 70 .. 3 5 0 3 .. 0dB -4dB -8dB -15dB .. -27dB
{0x0364, -26}, // 71 .. 3 3 0 4 .. 0dB -9dB -8dB -9dB .. -26dB
{0x032F, -25}, // 72 .. 3 1 1 7 .. 0dB -19dB -6dB 0dB .. -25dB
{0x0393, -24}, // 73 .. 3 4 2 3 .. 0dB -6dB -3dB -15dB .. -24dB
{0x0384, -23}, // 74 .. 3 4 0 4 .. 0dB -6dB -8dB -9dB .. -23dB
{0x0347, -22}, // 75 .. 3 2 0 7 .. 0dB -14dB -8dB 0dB .. -22dB
{0x03EB, -21}, // 76 .. 3 7 1 3 .. 0dB 0dB -6dB -15dB .. -21dB
{0x03D3, -20}, // 77 .. 3 6 2 3 .. 0dB -2dB -3dB -15dB .. -20dB
{0x03BB, -19}, // 78 .. 3 5 3 3 .. 0dB -4dB 0dB -15dB .. -19dB
{0x037C, -18}, // 79 .. 3 3 3 4 .. 0dB -9dB 0dB -9dB .. -18dB
{0x03CC, -17}, // 80 .. 3 6 1 4 .. 0dB -2dB -6dB -9dB .. -17dB
{0x03C5, -16}, // 81 .. 3 6 0 5 .. 0dB -2dB -8dB -6dB .. -16dB
{0x03EC, -15}, // 82 .. 3 7 1 4 .. 0dB 0dB -6dB -9dB .. -15dB
{0x035F, -14}, // 83 .. 3 2 3 7 .. 0dB -14dB 0dB 0dB .. -14dB
{0x03BC, -13}, // 84 .. 3 5 3 4 .. 0dB -4dB 0dB -9dB .. -13dB
{0x038F, -12}, // 85 .. 3 4 1 7 .. 0dB -6dB -6dB 0dB .. -12dB
{0x03E6, -11}, // 86 .. 3 7 0 6 .. 0dB 0dB -8dB -3dB .. -11dB
{0x03AF, -10}, // 87 .. 3 5 1 7 .. 0dB -4dB -6dB 0dB .. -10dB
{0x03F5, -9 }, // 88 .. 3 7 2 5 .. 0dB 0dB -3dB -6dB .. -9dB
{0x03D6, -8 }, // 89 .. 3 6 2 6 .. 0dB -2dB -3dB -3dB .. -8dB
{0x03BE, -7 }, // 90 .. 3 5 3 6 .. 0dB -4dB 0dB -3dB .. -7dB original
{0x03F6, -6 }, // 91 .. 3 7 2 6 .. 0dB 0dB -3dB -3dB .. -6dB
{0x03DE, -5 }, // 92 .. 3 6 3 6 .. 0dB -2dB 0dB -3dB .. -5dB
{0x03BF, -4 }, // 93 .. 3 5 3 7 .. 0dB -4dB 0dB 0dB .. -4dB
{0x03F7, -3 }, // 94 .. 3 7 2 7 .. 0dB 0dB -3dB 0dB .. -3dB
{0x03DF, -2 }, // 95 .. 3 6 3 7 .. 0dB -2dB 0dB 0dB .. -2dB
{0x03FF, 0 }, // 96 .. 3 7 3 7 .. 0dB 0dB 0dB 0dB .. 0dB
};
static const unsigned int original_index = 90;
#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
#ifdef ENABLE_AM_FIX_TEST1
// user manually sets the table index .. used to calibrate the desired dB gain table
unsigned int gain_table_index[2] = {1 + gSetting_AM_fix_test1, 1 + gSetting_AM_fix_test1};
#else
unsigned int gain_table_index[2] = {original_index, original_index};
#endif
// 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};
// used to correct the RSSI readings after our RF gain adjustments
int16_t rssi_gain_diff[2] = {0, 0};
// used to limit the max RF gain
unsigned int max_index = ARRAY_SIZE(gain_table) - 1;
#ifndef ENABLE_AM_FIX_TEST1
// -89dBm, any higher and the AM demodulator starts to saturate/clip/distort
const int16_t desired_rssi = (-89 + 160) * 2;
#endif
void AM_fix_init(void)
{ // called at boot-up
unsigned int i;
for (i = 0; i < 2; i++)
{
#ifdef ENABLE_AM_FIX_TEST1
gain_table_index[i] = 1 + gSetting_AM_fix_test1;
#else
gain_table_index[i] = original_index; // re-start with original QS setting
#endif
}
#if 0
{ // set a maximum gain to use
// const int16_t max_gain_dB = gain_dB[original_index];
const int16_t max_gain_dB = -10;
max_index = ARRAY_SIZE(gain_table);
while (--max_index > 1)
// if (gain_dB[max_index] <= max_gain_dB)
if (gain_table[max_index].gain_dB <= max_gain_dB)
break;
}
#else
// use the full range of available gains
max_index = ARRAY_SIZE(gain_table) - 1;
#endif
}
void AM_fix_reset(const int vfo)
{ // reset the AM fixer upper
#ifdef ENABLE_AM_FIX_SHOW_DATA
counter = 0;
#endif
prev_rssi[vfo] = 0;
hold_counter[vfo] = 0;
rssi_gain_diff[vfo] = 0;
#ifdef ENABLE_AM_FIX_TEST1
// gain_table_index[vfo] = 1 + gSetting_AM_fix_test1;
#else
// gain_table_index[vfo] = original_index; // re-start with original QS setting
#endif
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 int vfo)
{
int16_t diff_dB;
int16_t rssi;
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
{ // 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;
}
// save the corrected RSSI level
#ifdef ENABLE_AM_FIX_SHOW_DATA
{
const int16_t new_rssi = rssi - rssi_gain_diff[vfo];
if (gCurrentRSSI[vfo] != new_rssi)
{
gCurrentRSSI[vfo] = new_rssi;
if (counter == 0)
{ // trigger a display update
counter = 1;
gUpdateDisplay = true;
}
}
}
#else
gCurrentRSSI[vfo] = rssi - rssi_gain_diff[vfo];
#endif
#ifdef ENABLE_AM_FIX_TEST1
// user is manually adjusting a gain register - don't do anything automatically
{
int i = 1 + (int)gSetting_AM_fix_test1;
i = (i < 1) ? 1 : (i > ((int)ARRAY_SIZE(gain_table) - 1) ? ARRAY_SIZE(gain_table) - 1 : i;
if (gain_table_index[vfo] == i)
return; // no change
gain_table_index[vfo] = i;
}
#else
// 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
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;
//index = (gain_table_index[vfo] + index) / 2; // easy does it
}
else
{ // incrementally reduce the gain .. taking it slow improves noise/spike immunity
// if (index >= (1 + 3) && diff_dB >= 3)
// index -= 3; // faster gain reduction
// else
if (index > 1)
index--; // slow step-by-step gain reduction
}
index = (index < 1) ? 1 : (index > max_index) ? max_index : 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] = (index <= max_index) ? index : max_index; // limit the gain index
}
#if 0
if (gain_table_index[vfo] == gain_table_index_prev[vfo])
return; // no gain change - this is to reduce writing to the BK chip on ever call
#endif
#endif
{ // 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;
BK4819_WriteRegister(BK4819_REG_13, gain_table[index].reg_val);
// offset the RSSI reading to the rest of the firmware to cancel out the gain adjustments we make
// RF gain difference from original QS setting
rssi_gain_diff[vfo] = ((int16_t)gain_table[index].gain_dB - gain_table[original_index].gain_dB) * 2;
}
// save the corrected RSSI level
gCurrentRSSI[vfo] = rssi - rssi_gain_diff[vfo];
#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 int vfo, char *s)
{
if (s != NULL && vfo >= 0 && vfo < (int)ARRAY_SIZE(gain_table_index))
{
const unsigned int index = gain_table_index[vfo];
// sprintf(s, "%2u.%u %4ddB %3u", index, ARRAY_SIZE(gain_table) - 1, gain_table[index].gain_dB, prev_rssi[vfo]);
sprintf(s, "%2u %4ddB %3u", index, gain_table[index].gain_dB, prev_rssi[vfo]);
counter = 0;
}
}
#endif
#endif