diff --git a/rfg_adc_plotter/gui/pyqtgraph_backend.py b/rfg_adc_plotter/gui/pyqtgraph_backend.py
index 40cb62b..a2495c1 100644
--- a/rfg_adc_plotter/gui/pyqtgraph_backend.py
+++ b/rfg_adc_plotter/gui/pyqtgraph_backend.py
@@ -465,6 +465,23 @@ def resolve_visible_aux_curves(aux_curves: SweepAuxCurves, enabled: bool) -> Swe
     return aux_1_arr, aux_2_arr
 
 
+def compute_aux_phase_curve(aux_curves: SweepAuxCurves) -> Optional[np.ndarray]:
+    """Compute phase-like curve atan2(aux_2, aux_1) for raw CH2/CH1 display."""
+    if aux_curves is None:
+        return None
+    try:
+        aux_1, aux_2 = aux_curves
+    except Exception:
+        return None
+    aux_1_arr = np.asarray(aux_1, dtype=np.float32).reshape(-1)
+    aux_2_arr = np.asarray(aux_2, dtype=np.float32).reshape(-1)
+    width = min(aux_1_arr.size, aux_2_arr.size)
+    if width <= 0:
+        return None
+    phase = np.arctan2(aux_2_arr[:width], aux_1_arr[:width]).astype(np.float32, copy=False)
+    return phase
+
+
 def decimate_curve_for_display(
     xs: Optional[np.ndarray],
     ys: Optional[np.ndarray],
@@ -717,6 +734,21 @@ def run_pyqtgraph(args) -> None:
         except Exception:
             pass
 
+    p_line_phase = win.addPlot(row=2, col=0, title="Raw phase: atan(CH2/CH1)")
+    p_line_phase.showGrid(x=True, y=True, alpha=0.3)
+    curve_phase = p_line_phase.plot(pen=pg.mkPen((230, 180, 40), width=1))
+    p_line_phase.setLabel("bottom", "ГГц")
+    p_line_phase.setLabel("left", "рад")
+    try:
+        p_line_phase.setXLink(p_line)
+    except Exception:
+        pass
+    if not complex_sweep_mode:
+        try:
+            p_line_phase.hide()
+        except Exception:
+            pass
+
     p_img = win.addPlot(row=0, col=1, title="Сырые данные водопад")
     p_img.invertY(False)
     p_img.showGrid(x=False, y=False)
@@ -1820,6 +1852,7 @@ def run_pyqtgraph(args) -> None:
             )
             displayed_calib = None
             displayed_aux = resolve_visible_aux_curves(runtime.current_aux_curves, parsed_data_enabled)
+            displayed_phase = compute_aux_phase_curve(displayed_aux)
 
             if runtime.current_sweep_raw is not None:
                 raw_x, raw_y = decimate_curve_for_display(xs, runtime.current_sweep_raw)
@@ -1841,6 +1874,14 @@ def run_pyqtgraph(args) -> None:
                 curve_aux_1.setData([], [])
                 curve_aux_2.setData([], [])
 
+            if displayed_phase is not None:
+                phase_width = min(xs.size, displayed_phase.size)
+                phase_x, phase_y = decimate_curve_for_display(xs[:phase_width], displayed_phase[:phase_width])
+                phase_x, phase_y = sanitize_curve_data_for_display(phase_x, phase_y)
+                curve_phase.setData(phase_x, phase_y, autoDownsample=False)
+            else:
+                curve_phase.setData([], [])
+
             if runtime.calib_envelope is not None:
                 if runtime.current_sweep_raw is not None:
                     displayed_calib = resample_envelope(runtime.calib_envelope, runtime.current_sweep_raw.size)
@@ -1887,10 +1928,14 @@ def run_pyqtgraph(args) -> None:
                     )
                     if aux_limits is not None:
                         p_line_aux_vb.setYRange(aux_limits[0], aux_limits[1], padding=0)
+                phase_limits = compute_auto_ylim(displayed_phase)
+                if phase_limits is not None:
+                    p_line_phase.setYRange(phase_limits[0], phase_limits[1], padding=0)
 
             line_x_bounds = resolve_axis_bounds(xs)
             if line_x_bounds is not None:
                 p_line.setXRange(line_x_bounds[0], line_x_bounds[1], padding=0)
+                p_line_phase.setXRange(line_x_bounds[0], line_x_bounds[1], padding=0)
 
             sweep_for_fft = runtime.current_fft_input
             if sweep_for_fft is None:
diff --git a/tests/test_processing.py b/tests/test_processing.py
index 88ee0d7..9a87aae 100644
--- a/tests/test_processing.py
+++ b/tests/test_processing.py
@@ -13,6 +13,7 @@ from rfg_adc_plotter.gui.pyqtgraph_backend import (
     build_main_window_layout,
     coalesce_packets_for_ui,
     compute_background_subtracted_bscan_levels,
+    compute_aux_phase_curve,
     decimate_curve_for_display,
     resolve_axis_bounds,
     resolve_heavy_refresh_stride,
@@ -217,6 +218,19 @@ class ProcessingTests(unittest.TestCase):
         self.assertTrue(np.allclose(visible[0], aux[0]))
         self.assertTrue(np.allclose(visible[1], aux[1]))
 
+    def test_compute_aux_phase_curve_returns_atan2_of_aux_channels(self):
+        aux = (
+            np.asarray([1.0, 1.0, -1.0, 0.0], dtype=np.float32),
+            np.asarray([0.0, 1.0, 1.0, 1.0], dtype=np.float32),
+        )
+
+        phase = compute_aux_phase_curve(aux)
+
+        self.assertIsNotNone(phase)
+        expected = np.asarray([0.0, np.pi / 4.0, 3.0 * np.pi / 4.0, np.pi / 2.0], dtype=np.float32)
+        self.assertEqual(phase.shape, expected.shape)
+        self.assertTrue(np.allclose(phase, expected, atol=1e-6))
+
     def test_decimate_curve_for_display_preserves_small_series(self):
         xs = np.linspace(3.3, 14.3, 64, dtype=np.float64)
         ys = np.linspace(-1.0, 1.0, 64, dtype=np.float32)