diff --git a/Makefile b/Makefile
index 39a09f3..ff212bb 100644
--- a/Makefile
+++ b/Makefile
@@ -120,7 +120,7 @@ CSRC = $(STARTUPSRC) \
        $(STREAMSSRC) \
        $(SHELLSRC) \
        usbcfg.c \
-       main.c si5351.c tlv320aic3204.c dsp.c plot.c ui.c ili9341.c numfont20x24.c Font5x7.c flash.c adc.c
+       main.c si5351.c tlv320aic3204.c dsp.c plot.c ui.c ili9341.c numfont20x24.c Font5x7.c flash.c adc.c FFT.c
 
 #       $(TESTSRC) \
 
diff --git a/main.c b/main.c
index 06ef386..724c1eb 100644
--- a/main.c
+++ b/main.c
@@ -59,12 +59,15 @@ int8_t stop_the_world = FALSE;
 
 BaseSequentialStream *saved_chp;
 
-static THD_WORKING_AREA(waThread1, 640);
+static THD_WORKING_AREA(waThread1, 640-64);
 static THD_FUNCTION(Thread1, arg)
 {
     (void)arg;
     chRegSetThreadName("sweep");
 
+//FFT(measured[0],measured[1],101,0);
+
+
     while (1) {
       if (stop_the_world) {
           __WFI();
@@ -293,7 +296,7 @@ int16_t dump_selection = 0;
 
 volatile int16_t wait_count = 0;
 
-float measured[2][101][2];
+float measured[2][MEASURED_LENGTH][2];
 
 static void
 wait_dsp(int count)
@@ -1470,6 +1473,16 @@ static void cmd_trace(BaseSequentialStream *chp, int argc, char *argv[])
     }
     return;
   } 
+#if 0
+  if (strcmp(argv[0], "tdr") == 0) {
+    set_trace_type(1, TRC_TDR);
+    trace[0].channel = 1; // Get data from S21 after doing the FFT
+    set_trace_type(1, TRC_OFF);
+    set_trace_type(2, TRC_OFF);
+    set_trace_type(3, TRC_OFF);
+    goto exit;
+  }
+#endif
 
   if (strcmp(argv[0], "all") == 0 &&
       argc > 1 && strcmp(argv[1], "off") == 0) {
@@ -1539,7 +1552,10 @@ static void cmd_trace(BaseSequentialStream *chp, int argc, char *argv[])
  usage:
   chprintf(chp, "trace {0|1|2|3|all} [logmag|phase|smith|linear|delay|swr|real|imag|r|x|off] [src]\r\n");
   chprintf(chp, "trace {0|1|2|3} {scale|refpos} {value}\r\n");
-}
+#if 0
+  chprintf(chp, "trace tdr\r\n");
+#endif
+  }
 
 
 void set_electrical_delay(float picoseconds)
@@ -1800,7 +1816,7 @@ static void cmd_version(BaseSequentialStream *chp, int argc, char *argv[])
   chprintf(chp, "%s\r\n", NANOVNA_VERSION);
 }
 
-static THD_WORKING_AREA(waThread2, /* cmd_* max stack size + alpha */410);
+static THD_WORKING_AREA(waThread2, /* cmd_* max stack size + alpha */410+64);
 
 static const ShellCommand commands[] =
 {
diff --git a/nanovna.h b/nanovna.h
index 4ddebe4..029c8b8 100644
--- a/nanovna.h
+++ b/nanovna.h
@@ -22,7 +22,8 @@
 /*
  * main.c
  */
-extern float measured[2][101][2];
+#define MEASURED_LENGTH 101
+extern float measured[2][MEASURED_LENGTH][2];
 
 #define CAL_LOAD 0
 #define CAL_OPEN 1
@@ -149,7 +150,7 @@ extern const uint32_t numfont20x24[][24];
 #define TRACES_MAX 4
 
 enum {
-  TRC_LOGMAG, TRC_PHASE, TRC_DELAY, TRC_SMITH, TRC_POLAR, TRC_LINEAR, TRC_SWR, TRC_REAL, TRC_IMAG, TRC_R, TRC_X, TRC_OFF
+  TRC_LOGMAG, TRC_PHASE, TRC_DELAY, TRC_SMITH, TRC_POLAR, TRC_LINEAR, TRC_SWR, TRC_REAL, TRC_IMAG, TRC_R, TRC_X, TRC_OFF, TRC_TDR
 };
 
 // LOGMAG: SCALE, REFPOS, REFVAL
@@ -218,7 +219,7 @@ void request_to_draw_cells_behind_menu(void);
 void request_to_draw_cells_behind_numeric_input(void);
 void redraw_marker(int marker, int update_info);
 void trace_get_info(int t, char *buf, int len);
-void plot_into_index(float measured[2][101][2]);
+void plot_into_index(float measured[2][MEASURED_LENGTH][2]);
 void force_set_markmap(void);
 void draw_all_cells(void);
 
diff --git a/plot.c b/plot.c
index 4055870..3ee640a 100644
--- a/plot.c
+++ b/plot.c
@@ -504,6 +504,7 @@ trace_into_index(int x, int t, int i, float coeff[2])
     v = refpos - phase(coeff) * scale;
     break;
   case TRC_LINEAR:
+  case TRC_TDR:
     v = refpos + linear(coeff) * scale;
     break;
   case TRC_SWR:
@@ -785,9 +786,21 @@ mark_cells_from_index(void)
   }
 }
 
-void plot_into_index(float measured[2][101][2])
+void plot_into_index(float measured[2][MEASURED_LENGTH][2])
 {
   int i, t;
+#if 0
+  if (trace[0].type == TRD_TDR && trace[0].enabled) {
+// Covert real part of S11 to complex FFT in S21
+   for (i = 0; i < sweep_points; i++) {
+      int x = i * (WIDTH-1) / (sweep_points-1);
+        trace_index[t][i] = trace_into_index(x, 0, i, measured[1][i]);
+      }
+    }
+
+
+  } else
+  #endif
   for (i = 0; i < sweep_points; i++) {
     int x = i * (WIDTH-1) / (sweep_points-1);
     for (t = 0; t < TRACES_MAX; t++) {