diff --git a/dsp.c b/dsp.c
index 6e9f607..4b616dc 100644
--- a/dsp.c
+++ b/dsp.c
@@ -41,10 +41,10 @@ const int16_t sincos_tbl[48][2] = {
   {-24636, -21605 }, {-32698,  -2143 }, {-27246,  18205 }, {-10533,  31029 }
 };
 
-int32_t acc_samp_s;
-int32_t acc_samp_c;
-int32_t acc_ref_s;
-int32_t acc_ref_c;
+float acc_samp_s;
+float acc_samp_c;
+float acc_ref_s;
+float acc_ref_c;
 
 void
 dsp_process(int16_t *capture, size_t length)
@@ -79,10 +79,10 @@ dsp_process(int16_t *capture, size_t length)
     ref_c = __SMLATT(sr, sc, ref_c);
 #endif
   }
-  acc_samp_s = samp_s;
-  acc_samp_c = samp_c;
-  acc_ref_s = ref_s;
-  acc_ref_c = ref_c;
+  acc_samp_s += samp_s;
+  acc_samp_c += samp_c;
+  acc_ref_s += ref_s;
+  acc_ref_c += ref_c;
 }
 
 void
diff --git a/main.c b/main.c
index 3c480fc..a346aeb 100644
--- a/main.c
+++ b/main.c
@@ -418,7 +418,16 @@ int16_t dump_buffer[AUDIO_BUFFER_LEN];
 int16_t dump_selection = 0;
 #endif
 
-volatile int16_t wait_count = 0;
+volatile uint8_t wait_count = 0;
+volatile uint8_t accumerate_count = 0;
+
+const int8_t bandwidth_accumerate_count[] = {
+  1, // 1kHz
+  3, // 300Hz
+  10, // 100Hz
+  33, // 30Hz
+  100 // 10Hz
+};
 
 float measured[2][101][2];
 
@@ -426,8 +435,9 @@ static void
 wait_dsp(int count)
 {
   wait_count = count;
-  //reset_dsp_accumerator();
-  while (wait_count)
+  accumerate_count = bandwidth_accumerate_count[bandwidth];
+  reset_dsp_accumerator();
+  while (accumerate_count > 0)
     __WFI();
 }
 
@@ -453,13 +463,16 @@ void i2s_end_callback(I2SDriver *i2sp, size_t offset, size_t n)
   (void)i2sp;
   (void)n;
 
-  if (wait_count > 0) {
-    if (wait_count == 1) 
+  if (wait_count > 1) {
+    --wait_count;
+  } else if (wait_count > 0) {
+    if (accumerate_count > 0) {
       dsp_process(p, n);
+      accumerate_count--;
+    }
 #ifdef ENABLED_DUMP
-      duplicate_buffer_to_dump(p);
+    duplicate_buffer_to_dump(p);
 #endif
-    --wait_count;
   }
 
 #if PORT_SUPPORTS_RT
diff --git a/nanovna.h b/nanovna.h
index 876a6d3..341132b 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -312,7 +312,9 @@ typedef struct {
   int8_t _active_marker;
   uint8_t _domain_mode; /* 0bxxxxxffm : where ff: TD_FUNC m: DOMAIN_MODE */
   uint8_t _marker_smith_format;
+  uint8_t _bandwidth;
   uint8_t _reserved[50];
+
   int32_t checksum;
 } properties_t;
 
@@ -338,6 +340,7 @@ extern properties_t current_props;
 #define domain_mode current_props._domain_mode
 #define velocity_factor current_props._velocity_factor
 #define marker_smith_format current_props._marker_smith_format
+#define bandwidth current_props._bandwidth
 
 int caldata_save(int id);
 int caldata_recall(int id);
diff --git a/ui.c b/ui.c
index cfb4fee..ff792b0 100644
--- a/ui.c
+++ b/ui.c
@@ -728,6 +728,13 @@ menu_transform_cb(int item)
   }
 }
 
+static void
+menu_bandwidth_cb(int item)
+{
+  bandwidth = item;
+  draw_menu();
+}
+
 static void 
 choose_active_marker(void)
 {
@@ -1042,12 +1049,23 @@ const menuitem_t menu_transform[] = {
   { MT_NONE, NULL, NULL } // sentinel
 };
 
+const menuitem_t menu_bandwidth[] = {
+  { MT_CALLBACK, "1 kHz", menu_bandwidth_cb },
+  { MT_CALLBACK, "300 Hz", menu_bandwidth_cb },
+  { MT_CALLBACK, "100 Hz", menu_bandwidth_cb },
+  { MT_CALLBACK, "30 Hz", menu_bandwidth_cb },
+  { MT_CALLBACK, "10 Hz", menu_bandwidth_cb },
+  { MT_CANCEL, S_LARROW" BACK", NULL },
+  { MT_NONE, NULL, NULL } // sentinel
+};
+
 const menuitem_t menu_display[] = {
   { MT_SUBMENU, "TRACE", menu_trace },
   { MT_SUBMENU, "FORMAT", menu_format },
   { MT_SUBMENU, "SCALE", menu_scale },
   { MT_SUBMENU, "CHANNEL", menu_channel },
   { MT_SUBMENU, "TRANSFORM", menu_transform },
+  { MT_SUBMENU, "BANDWIDTH", menu_bandwidth },  
   { MT_CANCEL, S_LARROW" BACK", NULL },
   { MT_NONE, NULL, NULL } // sentinel
 };
@@ -1454,6 +1472,11 @@ menu_item_modify_attribute(const menuitem_t *menu, int item,
       *bg = 0x0000;
       *fg = 0xffff;
     }
+  } else if (menu == menu_bandwidth) {
+      if (item == bandwidth) {
+        *bg = 0x0000;
+        *fg = 0xffff;
+      }
   } else if (menu == menu_transform) {
       if ((item == 0 && (domain_mode & DOMAIN_MODE) == DOMAIN_TIME)
        || (item == 1 && (domain_mode & TD_FUNC) == TD_FUNC_LOWPASS_IMPULSE)