diff --git a/rfg_vna_viewer.py b/rfg_vna_viewer.py
index 36049c0..f0c1a3c 100644
--- a/rfg_vna_viewer.py
+++ b/rfg_vna_viewer.py
@@ -29,6 +29,7 @@ READ_CHUNK = 65536
 
 MARKER_MAIN = 0x000A
 MARKER_REF = 0x00A8
+MAX_SWEEP_POINTS = 4096  # safety limit — force finalize if dict grows past this
 
 DATA_PATH = "/tmp/ttyADC_data"
 
@@ -105,6 +106,11 @@ class SweepAccumulator:
                         sweeps.append(sw)
                 self._main[step] = (_i16(w2), _i16(w3))
                 self._last_main_step = step
+                # Safety: force finalize if accumulator grew too large
+                if len(self._main) >= MAX_SWEEP_POINTS:
+                    sw = self._finalize()
+                    if sw is not None:
+                        sweeps.append(sw)
                 del buf[:8]
                 continue
 
@@ -204,8 +210,8 @@ def process_main(main_ch1, main_ch2, ref_amplitude, ref_phase_aligned):
 
     # Normalize ch1/ch2 individually by ref amplitude
     ref_amp_safe = np.where(ref_amplitude > 1e-12, ref_amplitude, 1e-12)
-    norm_ch1 = ch1_v#ref_amp_safe
-    norm_ch2 = ch2_v#/ ref_amp_safe
+    norm_ch1 = ch1_v / ref_amp_safe
+    norm_ch2 = ch2_v / ref_amp_safe
 
     # Build normalized complex signal and subtract ref phase
     z_norm = (norm_ch1 + 1j * norm_ch2) * np.exp(-1j * ref_phase_aligned)
@@ -298,6 +304,9 @@ def make_update(reader, accumulator, curves):
 
         sweep = sweeps[-1]  # latest complete sweep
         n = sweep["num_points"]
+        print(f"[VNA] sweeps_in_batch={len(sweeps)}  points={n}  "
+              f"main_ch1_range=[{sweep['main_ch1'].min():.0f}..{sweep['main_ch1'].max():.0f}]  "
+              f"ref_ch1_range=[{sweep['ref_ch1'].min():.0f}..{sweep['ref_ch1'].max():.0f}]")
         if n < 2:
             return