diff --git a/main.c b/main.c
index 86e3055..4925363 100644
--- a/main.c
+++ b/main.c
@@ -56,6 +56,7 @@ int8_t sweep_once = FALSE;
 int8_t cal_auto_interpolate = TRUE;
 uint16_t redraw_request = 0; // contains REDRAW_XXX flags
 int16_t vbat = 0;
+uint8_t avg = 1;
 
 
 static THD_WORKING_AREA(waThread1, 640);
@@ -657,24 +658,53 @@ ensure_edit_config(void)
 // main loop for measurement
 bool sweep(bool break_on_operation)
 {
-  int i;
+  int i, j;
+  float tmp[2];
 
   for (i = 0; i < sweep_points; i++) {
     int delay = set_frequency(frequencies[i]);
     tlv320aic3204_select_in3(); // CH0:REFLECT
-    wait_dsp(delay);
+    wait_dsp(delay-1);
 
     // blink LED while scanning
     palClearPad(GPIOC, GPIOC_LED);
 
     /* calculate reflection coeficient */
-    (*sample_func)(measured[0][i]);
+    if (avg > 1) {
+        measured[0][i][0] = 0.0;
+        measured[0][i][1] = 0.0;
+        for (j = 0; j < avg; j++) {
+            wait_dsp(1);
+            (*sample_func)(tmp);
+            measured[0][i][0] += tmp[0];
+            measured[0][i][1] += tmp[1];
+        }
+        measured[0][i][0] /= avg;
+        measured[0][i][1] /= avg;
+    } else {
+        wait_dsp(1);
+        (*sample_func)(measured[0][i]);
+    }
 
     tlv320aic3204_select_in1(); // CH1:TRANSMISSION
-    wait_dsp(delay + DELAY_CHANNEL_CHANGE);
+    wait_dsp(delay + DELAY_CHANNEL_CHANGE - 1);
 
     /* calculate transmission coeficient */
-    (*sample_func)(measured[1][i]);
+    if (avg > 1) {
+        measured[1][i][0] = 0.0;
+        measured[1][i][1] = 0.0;
+        for (j = 0; j < avg; j++) {
+            wait_dsp(1);
+            (*sample_func)(tmp);
+            measured[1][i][0] += tmp[0];
+            measured[1][i][1] += tmp[1];
+        }
+        measured[1][i][0] /= avg;
+        measured[1][i][1] /= avg;
+    } else {
+        wait_dsp(1);
+        (*sample_func)(measured[1][i]);
+    }
 
     // blink LED while scanning
     palSetPad(GPIOC, GPIOC_LED);
diff --git a/nanovna.h b/nanovna.h
index 7f35500..ca9f4e8 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -258,6 +258,7 @@ extern uint16_t redraw_request;
 #define REDRAW_MARKER     (1<<3)
 
 extern int16_t vbat;
+extern uint8_t avg;
 
 /*
  * ili9341.c
diff --git a/ui.c b/ui.c
index 5b79af0..da95ae7 100644
--- a/ui.c
+++ b/ui.c
@@ -68,7 +68,7 @@ enum {
 };
 
 enum {
-  KM_START, KM_STOP, KM_CENTER, KM_SPAN, KM_CW, KM_SCALE, KM_REFPOS, KM_EDELAY, KM_VELOCITY_FACTOR, KM_SCALEDELAY
+  KM_START, KM_STOP, KM_CENTER, KM_SPAN, KM_CW, KM_SCALE, KM_REFPOS, KM_EDELAY, KM_VELOCITY_FACTOR, KM_SCALEDELAY, KM_AVG
 };
 
 uint8_t ui_mode = UI_NORMAL;
@@ -726,6 +726,22 @@ menu_transform_cb(int item)
   }
 }
 
+static void
+menu_avg_cb(void)
+{
+    int status;
+
+    status = btn_wait_release();
+    if (status & EVT_BUTTON_DOWN_LONG) {
+      ui_mode_numeric(KM_AVG);
+      ui_process_numeric();
+    } else {
+      ui_mode_keypad(KM_AVG);
+      ui_process_keypad();
+    }
+    ui_mode_normal();
+}
+
 static void 
 choose_active_marker(void)
 {
@@ -986,6 +1002,7 @@ const menuitem_t menu_display[] = {
   { MT_SUBMENU, "SCALE", menu_scale },
   { MT_SUBMENU, "CHANNEL", menu_channel },
   { MT_SUBMENU, "TRANSFORM", menu_transform },
+  { MT_CALLBACK, "AVG", menu_avg_cb },
   { MT_CANCEL, S_LARROW" BACK", NULL },
   { MT_NONE, NULL, NULL } // sentinel
 };
@@ -1227,11 +1244,12 @@ const keypads_t * const keypads_mode_tbl[] = {
   keypads_scale, // refpos
   keypads_time, // electrical delay
   keypads_scale, // velocity factor
-  keypads_time // scale of delay
+  keypads_time, // scale of delay
+  keypads_scale // avg
 };
 
 const char * const keypad_mode_label[] = {
-  "START", "STOP", "CENTER", "SPAN", "CW FREQ", "SCALE", "REFPOS", "EDELAY", "VELOCITY%", "DELAY"
+  "START", "STOP", "CENTER", "SPAN", "CW FREQ", "SCALE", "REFPOS", "EDELAY", "VELOCITY%", "DELAY", "AVG"
 };
 
 void
@@ -1494,6 +1512,9 @@ fetch_numeric_target(void)
   case KM_SCALEDELAY:
     uistat.value = get_trace_scale(uistat.current_trace) * 1e12;
     break;
+  case KM_AVG:
+    uistat.value = avg;
+    break;
   }
   
   {
@@ -1723,6 +1744,8 @@ keypad_click(int key)
     case KM_SCALEDELAY:
       set_trace_scale(uistat.current_trace, value * 1e-12); // pico second
       break;
+    case KM_AVG:
+      avg = value;
     }
 
     return KP_DONE;