diff --git a/common/utils/T/tracer/gui.c b/common/utils/T/tracer/gui.c
new file mode 100644
index 0000000000000000000000000000000000000000..2963e4c34875c9c7c0823d4d037109067df74ce0
--- /dev/null
+++ b/common/utils/T/tracer/gui.c
@@ -0,0 +1,101 @@
+#include "defs.h"
+#include "gui/gui.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <string.h>
+#include <math.h>
+
+static struct {
+  gui *g;
+  widget *input_signal;      /* CC_id 0 antenna 0 */
+  volatile int input_signal_length;  /* unit: byte */
+  void *input_signal_iq;
+  pthread_mutex_t input_signal_lock;
+} eNB_data;
+
+static void *gui_thread(void *g)
+{
+  gui_loop(g);
+  exit(0);
+}
+
+static void *input_signal_plotter(void *_)
+{
+  short *iqbuf;
+  float *x;
+  float *y;
+  int i;
+  int length = eNB_data.input_signal_length / 4;
+
+  x = calloc(1, sizeof(float) * eNB_data.input_signal_length / 4);
+  y = calloc(1, sizeof(float) * eNB_data.input_signal_length / 4);
+  if (x == NULL || y == NULL) abort();
+
+  while (1) {
+    usleep(100 * 1000);
+
+    if (pthread_mutex_lock(&eNB_data.input_signal_lock)) abort();
+
+    if (length * 4 != eNB_data.input_signal_length) {
+      free(x);
+      free(y);
+      x = calloc(1, sizeof(float) * eNB_data.input_signal_length / 4);
+      y = calloc(1, sizeof(float) * eNB_data.input_signal_length / 4);
+      if (x == NULL || y == NULL) abort();
+      length = eNB_data.input_signal_length / 4;
+    }
+
+    iqbuf = eNB_data.input_signal_iq;
+
+    for (i = 0; i < length; i++) {
+      x[i] = i;
+      y[i] = 10*log10(1.0+(float)(iqbuf[2*i]*iqbuf[2*i]+
+                                  iqbuf[2*i+1]*iqbuf[2*i+1]));
+    }
+
+    xy_plot_set_points(eNB_data.g, eNB_data.input_signal,
+        length, x, y);
+
+    if (pthread_mutex_unlock(&eNB_data.input_signal_lock)) abort();
+  }
+}
+
+void t_gui_start(void)
+{
+  gui *g = gui_init();
+
+  widget *win = new_toplevel_window(g, 550, 140, "input signal");
+  widget *plot = new_xy_plot(g, 512, 100, "eNB 0 input signal", 20);
+  widget_add_child(g, win, plot, -1);
+  xy_plot_set_range(g, plot, 0, 76800, 30, 70);
+
+  eNB_data.input_signal = plot;
+  eNB_data.input_signal_length = 76800 * 4;
+  eNB_data.input_signal_iq = calloc(1, 76800 * 4);
+  if (eNB_data.input_signal_iq == NULL) abort();
+  pthread_mutex_init(&eNB_data.input_signal_lock, NULL);
+
+  eNB_data.g = g;
+
+  new_thread(gui_thread, g);
+  new_thread(input_signal_plotter, NULL);
+}
+
+void t_gui_set_input_signal(int eNB, int frame, int subframe, int antenna,
+    int size, void *buf)
+{
+  if (pthread_mutex_lock(&eNB_data.input_signal_lock)) abort();
+
+  if (eNB_data.input_signal_length != size * 10) {
+    free(eNB_data.input_signal_iq);
+    eNB_data.input_signal_length = size * 10;
+    eNB_data.input_signal_iq = calloc(1, eNB_data.input_signal_length);
+    if (eNB_data.input_signal_iq == NULL) abort();
+  }
+
+  memcpy((char *)eNB_data.input_signal_iq + subframe * size, buf, size);
+
+  if (pthread_mutex_unlock(&eNB_data.input_signal_lock)) abort();
+}