From 3478d908196469ee34461365e2f5c107651e8dae Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Thu, 4 Jan 2024 18:21:35 +0100
Subject: [PATCH] [SX126x] Improved image calibration

---
 src/modules/SX126x/SX1262.cpp | 21 ++-------------------
 src/modules/SX126x/SX1268.cpp | 15 ++-------------
 src/modules/SX126x/SX126x.h   | 14 +-------------
 3 files changed, 5 insertions(+), 45 deletions(-)

diff --git a/src/modules/SX126x/SX1262.cpp b/src/modules/SX126x/SX1262.cpp
index d24e0f43..b6f68cb4 100644
--- a/src/modules/SX126x/SX1262.cpp
+++ b/src/modules/SX126x/SX1262.cpp
@@ -54,26 +54,9 @@ int16_t SX1262::setFrequency(float freq) {
 int16_t SX1262::setFrequency(float freq, bool calibrate) {
   RADIOLIB_CHECK_RANGE(freq, 150.0, 960.0, RADIOLIB_ERR_INVALID_FREQUENCY);
 
-  // calibrate image
+  // calibrate image rejection - assume band to be the selected frequency +- 4 MHz
   if(calibrate) {
-    uint8_t data[2];
-    if(freq > 900.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_902_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_902_MHZ_2;
-    } else if(freq > 850.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_863_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_863_MHZ_2;
-    } else if(freq > 770.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_779_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_779_MHZ_2;
-    } else if(freq > 460.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_470_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_470_MHZ_2;
-    } else {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_430_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_430_MHZ_2;
-    }
-    int16_t state = SX126x::calibrateImage(data);
+    int16_t state = SX126x::calibrateImage(freq - 4, freq + 4);
     RADIOLIB_ASSERT(state);
   }
 
diff --git a/src/modules/SX126x/SX1268.cpp b/src/modules/SX126x/SX1268.cpp
index 596ce7e4..8aad25b7 100644
--- a/src/modules/SX126x/SX1268.cpp
+++ b/src/modules/SX126x/SX1268.cpp
@@ -55,20 +55,9 @@ int16_t SX1268::setFrequency(float freq) {
 int16_t SX1268::setFrequency(float freq, bool calibrate) {
   RADIOLIB_CHECK_RANGE(freq, 410.0, 810.0, RADIOLIB_ERR_INVALID_FREQUENCY);
 
-  // calibrate image
+  // calibrate image rejection - assume band to be the selected frequency +- 4 MHz
   if(calibrate) {
-    uint8_t data[2];
-    if(freq > 770.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_779_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_779_MHZ_2;
-    } else if(freq > 460.0) {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_470_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_470_MHZ_2;
-    } else {
-      data[0] = RADIOLIB_SX126X_CAL_IMG_430_MHZ_1;
-      data[1] = RADIOLIB_SX126X_CAL_IMG_430_MHZ_2;
-    }
-    int16_t state = SX126x::calibrateImage(data);
+    int16_t state = SX126x::calibrateImage(freq - 4, freq + 4);
     RADIOLIB_ASSERT(state);
   }
 
diff --git a/src/modules/SX126x/SX126x.h b/src/modules/SX126x/SX126x.h
index 5e8c03b6..2fb3fdb4 100644
--- a/src/modules/SX126x/SX126x.h
+++ b/src/modules/SX126x/SX126x.h
@@ -188,18 +188,6 @@
 #define RADIOLIB_SX126X_CALIBRATE_RC64K_ON                      0b00000001  //  0     0                               enabled
 #define RADIOLIB_SX126X_CALIBRATE_ALL                           0b01111111  //  6     0   calibrate all blocks
 
-//RADIOLIB_SX126X_CMD_CALIBRATE_IMAGE
-#define RADIOLIB_SX126X_CAL_IMG_430_MHZ_1                       0x6B
-#define RADIOLIB_SX126X_CAL_IMG_430_MHZ_2                       0x6F
-#define RADIOLIB_SX126X_CAL_IMG_470_MHZ_1                       0x75
-#define RADIOLIB_SX126X_CAL_IMG_470_MHZ_2                       0x81
-#define RADIOLIB_SX126X_CAL_IMG_779_MHZ_1                       0xC1
-#define RADIOLIB_SX126X_CAL_IMG_779_MHZ_2                       0xC5
-#define RADIOLIB_SX126X_CAL_IMG_863_MHZ_1                       0xD7
-#define RADIOLIB_SX126X_CAL_IMG_863_MHZ_2                       0xDB
-#define RADIOLIB_SX126X_CAL_IMG_902_MHZ_1                       0xE1
-#define RADIOLIB_SX126X_CAL_IMG_902_MHZ_2                       0xE9
-
 //RADIOLIB_SX126X_CMD_SET_PA_CONFIG
 #define RADIOLIB_SX126X_PA_CONFIG_HP_MAX                        0x07
 #define RADIOLIB_SX126X_PA_CONFIG_PA_LUT                        0x01
@@ -1119,7 +1107,7 @@ class SX126x: public PhysicalLayer {
     int16_t setDioIrqParams(uint16_t irqMask, uint16_t dio1Mask, uint16_t dio2Mask = RADIOLIB_SX126X_IRQ_NONE, uint16_t dio3Mask = RADIOLIB_SX126X_IRQ_NONE);
     virtual int16_t clearIrqStatus(uint16_t clearIrqParams = RADIOLIB_SX126X_IRQ_ALL);
     int16_t setRfFrequency(uint32_t frf);
-    int16_t calibrateImage(uint8_t* data);
+    int16_t calibrateImage(float freqMin, float freqMax);
     uint8_t getPacketType();
     int16_t setTxParams(uint8_t power, uint8_t rampTime = RADIOLIB_SX126X_PA_RAMP_200U);
     int16_t setModulationParams(uint8_t sf, uint8_t bw, uint8_t cr, uint8_t ldro);