From aca8f2dbccd3f21399962fa02fcc3e3b7ce93db5 Mon Sep 17 00:00:00 2001
From: erikkaashoek <erik@kaashoek.com>
Date: Wed, 7 Oct 2020 13:20:56 +0200
Subject: [PATCH] THD measurement added

---
 nanovna.h |  5 +++--
 plot.c    | 28 ++++++++++++++++++++++++++++
 ui_sa.c   |  5 ++++-
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/nanovna.h b/nanovna.h
index f320635..1bea3ad 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -39,7 +39,7 @@
 //#define __ULTRA__             // Add harmonics mode on low input.
 //#define __ULTRA_SA__            // Adds ADF4351 control for extra high 1st IF stage
 #define __SPUR__                // Does spur reduction by shifting IF
-#define __USE_SERIAL_CONSOLE__  // Enable serial I/O connection (need enable HAL_USE_SERIAL as TRUE in halconf.h)
+//#define __USE_SERIAL_CONSOLE__  // Enable serial I/O connection (need enable HAL_USE_SERIAL as TRUE in halconf.h)
 /*
  * main.c
  */
@@ -235,6 +235,7 @@ extern int32_t frequencyExtra;
 void set_10mhz(uint32_t);
 void set_modulation(int);
 void set_modulation_frequency(int);
+int search_maximum(int m, int center, int span);
 //extern int setting.modulation;
 void set_measurement(int);
 // extern int settingSpeed;
@@ -998,7 +999,7 @@ uint32_t calc_min_sweep_time_us(void);
 pureRSSI_t perform(bool b, int i, uint32_t f, int e);
 
 enum {
-  M_OFF, M_IMD, M_OIP3, M_PHASE_NOISE, M_STOP_BAND, M_PASS_BAND, M_LINEARITY, M_AM, M_FM
+  M_OFF, M_IMD, M_OIP3, M_PHASE_NOISE, M_STOP_BAND, M_PASS_BAND, M_LINEARITY, M_AM, M_FM, M_THD
 };
 
 enum {
diff --git a/plot.c b/plot.c
index 0538340..507b8de 100644
--- a/plot.c
+++ b/plot.c
@@ -2081,7 +2081,35 @@ static void cell_draw_marker_info(int x0, int y0)
       active++;
     }
   }
+  if (setting.measurement == M_THD && active >= 1)
+    active = 2;
   for (int i = 0; i < MARKER_COUNT; i++) {
+    if (i >= 2 && setting.measurement == M_THD) {
+      if (i == 2) {
+        int old_unit = setting.unit;
+        setting.unit = U_WATT;
+        float p = value((actual_t[markers[0].index]));
+        int j = 2;
+        uint32_t f = markers[0].frequency;
+        float h = 0.0;
+        while (f * j < frequencies[sweep_points-1]) {
+          if (search_maximum(1, f*j, 4*j) )             // use marker 1 for searching harmonics
+            h += value((actual_t[markers[1].index]));
+          j++;
+        }
+        float thd = 100.0 * sqrt(h/p);
+        setting.unit = old_unit;
+
+        plot_printf(buf, sizeof buf, "THD: %4.1f%%", thd);
+        j = 1;
+        int xpos = 1 + (j%2)*(WIDTH/2) + CELLOFFSETX - x0;
+        int ypos = 1 + (j/2)*(16) - y0;
+        cell_drawstring_7x13(buf, xpos, ypos);
+//        cell_drawstring(buf, xpos, ypos);
+        break;
+      }
+      break;
+    } else
     if (i >= 2 && setting.measurement == M_OIP3 && markers[2].enabled && markers[3].enabled) {
       float il = value((actual_t[markers[2].index]));
       float ir = value((actual_t[markers[3].index]));
diff --git a/ui_sa.c b/ui_sa.c
index 2f4ebc8..0808735 100644
--- a/ui_sa.c
+++ b/ui_sa.c
@@ -851,7 +851,6 @@ static UI_FUNCTION_ADV_CALLBACK(menu_measure_acb)
       break;
     case M_LINEARITY:
       set_measurement(M_LINEARITY);
-      ui_mode_normal();
       break;
     case M_AM:                                     // OIP3
       reset_settings(setting.mode);
@@ -882,6 +881,9 @@ static UI_FUNCTION_ADV_CALLBACK(menu_measure_acb)
       set_sweep_frequency(ST_SPAN, uistat.value*30);
       set_measurement(M_FM);
       break;
+    case M_THD:
+      set_measurement(M_THD);
+      break;
   }
 #endif
 //  selection = -1;
@@ -1682,6 +1684,7 @@ static const menuitem_t menu_measure2[] = {
 //  { MT_ADV_CALLBACK | MT_LOW,   M_LINEARITY,  "LINEAR",         menu_measure_acb},
   { MT_ADV_CALLBACK,            M_AM,           "AM",           menu_measure_acb},
   { MT_ADV_CALLBACK,            M_FM,           "FM",           menu_measure_acb},
+  { MT_ADV_CALLBACK,            M_THD,          "THD",           menu_measure_acb},
   { MT_CANCEL, 0,               S_LARROW" BACK", NULL },
   { MT_NONE,   0, NULL, NULL } // sentinel
 };