diff --git a/piker/tsp/_anal.py b/piker/tsp/_anal.py
index 26c3740e..bcf20a26 100644
--- a/piker/tsp/_anal.py
+++ b/piker/tsp/_anal.py
@@ -275,6 +275,10 @@ def get_null_segs(
         # diff of abs index steps between each zeroed row
         absi_zdiff: np.ndarray = np.diff(absi_zeros)
 
+        if zero_t.size < 2:
+            breakpoint()
+            return None
+
         # scan for all frame-indices where the
         # zeroed-row-abs-index-step-diff is greater then the
         # expected increment of 1.
@@ -434,8 +438,8 @@ def get_null_segs(
 
 def iter_null_segs(
     timeframe: float,
-    frame: Frame | None = None,
-    null_segs: tuple | None = None,
+    frame: Frame|None = None,
+    null_segs: tuple|None = None,
 
 ) -> Generator[
     tuple[
@@ -487,7 +491,8 @@ def iter_null_segs(
         start_dt = None
         if (
             absi_start is not None
-            and start_t != 0
+            and
+            start_t != 0
         ):
             fi_start: int = absi_start - absi_first
             start_row: Seq = frame[fi_start]
@@ -501,8 +506,8 @@ def iter_null_segs(
         yield (
             absi_start, absi_end,  # abs indices
             fi_start, fi_end,  # relative "frame" indices
-            start_t, end_t,
-            start_dt, end_dt,
+            start_t, end_t,  # epoch times
+            start_dt, end_dt,  # dts
         )