/* 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 #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