diff --git a/rfg_vna_viewer.py b/rfg_vna_viewer.py
index f0c1a3c..d6bf931 100644
--- a/rfg_vna_viewer.py
+++ b/rfg_vna_viewer.py
@@ -30,6 +30,7 @@ READ_CHUNK = 65536
 MARKER_MAIN = 0x000A
 MARKER_REF = 0x00A8
 MAX_SWEEP_POINTS = 4096  # safety limit — force finalize if dict grows past this
+MIN_SWEEP_POINTS = 400   # discard fragments shorter than this
 
 DATA_PATH = "/tmp/ttyADC_data"
 
@@ -74,7 +75,6 @@ class SweepAccumulator:
         self._buf = bytearray()
         self._main = {}  # step → (ch1_i16, ch2_i16)
         self._ref = {}
-        self._last_main_step = -1
 
     def feed(self, data):
         """Feed raw bytes. Return list of completed sweep dicts."""
@@ -98,14 +98,7 @@ class SweepAccumulator:
 
             # Main channel data point
             if w0 == MARKER_MAIN and w1 != 0xFFFF:
-                step = w1
-                # Detect sweep wrap (step regression) without start marker
-                if self._last_main_step >= 0 and step < self._last_main_step - 10:
-                    sw = self._finalize()
-                    if sw is not None:
-                        sweeps.append(sw)
-                self._main[step] = (_i16(w2), _i16(w3))
-                self._last_main_step = step
+                self._main[w1] = (_i16(w2), _i16(w3))
                 # Safety: force finalize if accumulator grew too large
                 if len(self._main) >= MAX_SWEEP_POINTS:
                     sw = self._finalize()