/* 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 { #if 1 // bitfields take up less flash bytes uint8_t lna_short:2; // 0 ~ 3 uint8_t lna:3; // 0 ~ 7 uint8_t mixer:2; // 0 ~ 3 uint8_t pga:3; // 0 ~ 7 #else uint8_t lna_short; // 0 ~ 3 uint8_t lna; // 0 ~ 7 uint8_t mixer; // 0 ~ 3 uint8_t pga; // 0 ~ 7 #endif } t_gain_table; //} __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 // 4 = -6dB // 3 = -9dB // 2 = -14dB < original value // 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[] = { {.lna_short = 3, .lna = 2, .mixer = 3, .pga = 6}, // 0 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 {0, 2, 3, 6}, // 1 .. -33dB -14dB 0dB -3dB .. -50dB {1, 2, 3, 6}, // 2 .. -30dB -14dB 0dB -3dB .. -47dB {2, 2, 3, 6}, // 3 .. -24dB -14dB 0dB -3dB .. -41dB {3, 2, 3, 6} // 4 .. 0dB -14dB 0dB -3dB .. -17dB }; const unsigned int original_index = 1; #else {0, 0, 0, 0}, // 1 .. -33dB -24dB -8dB -33dB .. -98dB {0, 0, 1, 0}, // 2 .. -33dB -24dB -6dB -33dB .. -96dB {1, 0, 0, 0}, // 3 .. -30dB -24dB -8dB -33dB .. -95dB {0, 1, 0, 0}, // 4 .. -33dB -19dB -8dB -33dB .. -93dB {0, 0, 0, 1}, // 5 .. -33dB -24dB -8dB -27dB .. -92dB {0, 1, 1, 0}, // 6 .. -33dB -19dB -6dB -33dB .. -91dB {0, 0, 1, 1}, // 7 .. -33dB -24dB -6dB -27dB .. -90dB {1, 0, 0, 1}, // 8 .. -30dB -24dB -8dB -27dB .. -89dB {0, 1, 2, 0}, // 9 .. -33dB -19dB -3dB -33dB .. -88dB {1, 0, 3, 0}, // 10 .. -30dB -24dB 0dB -33dB .. -87dB {0, 0, 0, 2}, // 11 .. -33dB -24dB -8dB -21dB .. -86dB {1, 1, 2, 0}, // 12 .. -30dB -19dB -3dB -33dB .. -85dB {0, 0, 3, 1}, // 13 .. -33dB -24dB 0dB -27dB .. -84dB {0, 3, 0, 0}, // 14 .. -33dB -9dB -8dB -33dB .. -83dB {1, 1, 3, 0}, // 15 .. -30dB -19dB 0dB -33dB .. -82dB {1, 0, 3, 1}, // 16 .. -30dB -24dB 0dB -27dB .. -81dB {0, 2, 3, 0}, // 17 .. -33dB -14dB 0dB -33dB .. -80dB {1, 2, 0, 1}, // 18 .. -30dB -14dB -8dB -27dB .. -79dB {0, 3, 2, 0}, // 19 .. -33dB -9dB -3dB -33dB .. -78dB {1, 4, 0, 0}, // 20 .. -30dB -6dB -8dB -33dB .. -77dB {1, 1, 3, 1}, // 21 .. -30dB -19dB 0dB -27dB .. -76dB {0, 0, 2, 3}, // 22 .. -33dB -24dB -3dB -15dB .. -75dB {1, 3, 0, 1}, // 23 .. -30dB -9dB -8dB -27dB .. -74dB {1, 6, 0, 0}, // 24 .. -30dB -2dB -8dB -33dB .. -73dB {0, 7, 1, 0}, // 25 .. -33dB 0dB -6dB -33dB .. -72dB {0, 6, 2, 0}, // 26 .. -33dB -2dB -3dB -33dB .. -71dB {2, 1, 3, 1}, // 27 .. -24dB -19dB 0dB -27dB .. -70dB {0, 3, 1, 2}, // 28 .. -33dB -9dB -6dB -21dB .. -69dB {0, 0, 0, 6}, // 29 .. -33dB -24dB -8dB -3dB .. -68dB {0, 5, 2, 1}, // 30 .. -33dB -4dB -3dB -27dB .. -67dB {0, 0, 1, 6}, // 31 .. -33dB -24dB -6dB -3dB .. -66dB {1, 2, 3, 2}, // 32 .. -30dB -14dB 0dB -21dB .. -65dB {2, 1, 1, 3}, // 33 .. -24dB -19dB -6dB -15dB .. -64dB {1, 7, 3, 0}, // 34 .. -30dB 0dB 0dB -33dB .. -63dB {1, 3, 0, 3}, // 35 .. -30dB -9dB -8dB -15dB .. -62dB {0, 1, 2, 5}, // 36 .. -33dB -19dB -3dB -6dB .. -61dB {2, 0, 2, 4}, // 37 .. -24dB -24dB -3dB -9dB .. -60dB {1, 6, 3, 1}, // 38 .. -30dB -2dB 0dB -27dB .. -59dB {1, 2, 0, 5}, // 39 .. -30dB -14dB -8dB -6dB .. -58dB {2, 5, 0, 2}, // 40 .. -24dB -4dB -8dB -21dB .. -57dB {2, 6, 2, 1}, // 41 .. -24dB -2dB -3dB -27dB .. -56dB {0, 5, 2, 3}, // 42 .. -33dB -4dB -3dB -15dB .. -55dB {2, 0, 2, 6}, // 43 .. -24dB -24dB -3dB -3dB .. -54dB {0, 3, 0, 6}, // 44 .. -33dB -9dB -8dB -3dB .. -53dB {0, 6, 0, 4}, // 45 .. -33dB -2dB -8dB -9dB .. -52dB {0, 3, 1, 6}, // 46 .. -33dB -9dB -6dB -3dB .. -51dB {1, 2, 3, 5}, // 47 .. -30dB -14dB 0dB -6dB .. -50dB {0, 5, 1, 5}, // 48 .. -33dB -4dB -6dB -6dB .. -49dB {0, 3, 3, 5}, // 49 .. -33dB -9dB 0dB -6dB .. -48dB {0, 6, 2, 4}, // 50 .. -33dB -2dB -3dB -9dB .. -47dB {1, 5, 2, 4}, // 51 .. -30dB -4dB -3dB -9dB .. -46dB {3, 0, 1, 3}, // 52 .. 0dB -24dB -6dB -15dB .. -45dB {0, 6, 1, 6}, // 53 .. -33dB -2dB -6dB -3dB .. -44dB {1, 5, 2, 5}, // 54 .. -30dB -4dB -3dB -6dB .. -43dB {0, 4, 2, 7}, // 55 .. -33dB -6dB -3dB 0dB .. -42dB {2, 2, 2, 7}, // 56 .. -24dB -14dB -3dB 0dB .. -41dB {2, 5, 2, 4}, // 57 .. -24dB -4dB -3dB -9dB .. -40dB {2, 3, 3, 5}, // 58 .. -24dB -9dB 0dB -6dB .. -39dB {1, 6, 3, 5}, // 59 .. -30dB -2dB 0dB -6dB .. -38dB {2, 5, 1, 6}, // 60 .. -24dB -4dB -6dB -3dB .. -37dB {3, 3, 3, 1}, // 61 .. 0dB -9dB 0dB -27dB .. -36dB {3, 2, 3, 2}, // 62 .. 0dB -14dB 0dB -21dB .. -35dB {2, 5, 2, 6}, // 63 .. -24dB -4dB -3dB -3dB .. -34dB {3, 0, 1, 6}, // 64 .. 0dB -24dB -6dB -3dB .. -33dB {3, 0, 0, 7}, // 65 .. 0dB -24dB -8dB 0dB .. -32dB {2, 5, 3, 6}, // 66 .. -24dB -4dB 0dB -3dB .. -31dB {3, 3, 3, 2}, // 67 .. 0dB -9dB 0dB -21dB .. -30dB {2, 6, 3, 6}, // 68 .. -24dB -2dB 0dB -3dB .. -29dB {3, 2, 0, 5}, // 69 .. 0dB -14dB -8dB -6dB .. -28dB {3, 5, 0, 3}, // 70 .. 0dB -4dB -8dB -15dB .. -27dB {3, 3, 0, 4}, // 71 .. 0dB -9dB -8dB -9dB .. -26dB {3, 1, 1, 7}, // 72 .. 0dB -19dB -6dB 0dB .. -25dB {3, 4, 2, 3}, // 73 .. 0dB -6dB -3dB -15dB .. -24dB {3, 4, 0, 4}, // 74 .. 0dB -6dB -8dB -9dB .. -23dB {3, 2, 0, 7}, // 75 .. 0dB -14dB -8dB 0dB .. -22dB {3, 7, 1, 3}, // 76 .. 0dB 0dB -6dB -15dB .. -21dB {3, 6, 2, 3}, // 77 .. 0dB -2dB -3dB -15dB .. -20dB {3, 5, 3, 3}, // 78 .. 0dB -4dB 0dB -15dB .. -19dB {3, 3, 3, 4}, // 79 .. 0dB -9dB 0dB -9dB .. -18dB {3, 2, 3, 6}, // 80 .. 0dB -14dB 0dB -3dB .. -17dB original {3, 6, 0, 5}, // 81 .. 0dB -2dB -8dB -6dB .. -16dB {3, 7, 1, 4}, // 82 .. 0dB 0dB -6dB -9dB .. -15dB {3, 2, 3, 7}, // 83 .. 0dB -14dB 0dB 0dB .. -14dB {3, 6, 0, 6}, // 84 .. 0dB -2dB -8dB -3dB .. -13dB {3, 3, 2, 7}, // 85 .. 0dB -9dB -3dB 0dB .. -12dB {3, 7, 0, 6}, // 86 .. 0dB 0dB -8dB -3dB .. -11dB {3, 5, 3, 5}, // 87 .. 0dB -4dB 0dB -6dB .. -10dB {3, 7, 2, 5}, // 88 .. 0dB 0dB -3dB -6dB .. -9dB {3, 6, 3, 5}, // 89 .. 0dB -2dB 0dB -6dB .. -8dB {3, 5, 2, 7}, // 90 .. 0dB -4dB -3dB 0dB .. -7dB {3, 7, 2, 6}, // 91 .. 0dB 0dB -3dB -3dB .. -6dB {3, 6, 2, 7}, // 92 .. 0dB -2dB -3dB 0dB .. -5dB {3, 5, 3, 7}, // 93 .. 0dB -4dB 0dB 0dB .. -4dB {3, 7, 2, 7}, // 94 .. 0dB 0dB -3dB 0dB .. -3dB {3, 6, 3, 7}, // 95 .. 0dB -2dB 0dB 0dB .. -2dB {3, 7, 3, 7} // 96 .. 0dB 0dB 0dB 0dB .. 0dB }; const unsigned int original_index = 80; #endif // total RF gain for each table index int8_t gain_dB[ARRAY_SIZE(gain_table)] = {0}; // display update rate const unsigned int display_update_rate = 250 / 10; // max 250ms display update rate unsigned int counter = 0; #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 } // pre-compute the total gain for each table index .. saves doing it in real time for (i = 0; i < ARRAY_SIZE(gain_table); i++) { const t_gain_table gains = gain_table[i]; gain_dB[i] = lna_short_dB[gains.lna_short] + lna_dB[gains.lna] + mixer_dB[gains.mixer] + pga_dB[gains.pga]; } #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) 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 counter = 0; 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: counter = display_update_rate; // queue up a display update as soon as we switch to RX mode 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; } if (counter > 0) { if (++counter >= display_update_rate) { // trigger a display update counter = 0; gUpdateDisplay = true; } } { // 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 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; } } } #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_dB[index] - 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_dB[--index] <= 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; const t_gain_table gains = gain_table[index]; BK4819_WriteRegister(BK4819_REG_13, ((uint16_t)gains.lna_short << 8) | ((uint16_t)gains.lna << 5) | ((uint16_t)gains.mixer << 3) | ((uint16_t)gains.pga << 0)); // 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_dB[index] - gain_dB[original_index]) * 2; } // save the corrected RSSI level gCurrentRSSI[vfo] = rssi - rssi_gain_diff[vfo]; if (counter == 0) { counter = 1; gUpdateDisplay = true; } } #ifdef ENABLE_AM_FIX_SHOW_DATA void AM_fix_print_data(const int vfo, char *s) { if (s != NULL) { const unsigned int index = gain_table_index[vfo]; sprintf(s, "%2u.%u %4ddB %3u", index, ARRAY_SIZE(gain_table) - 1, gain_dB[index], prev_rssi[vfo]); counter = 0; } } #endif #endif