Merge pull request #471 from corrscope/fix-trigger-corr-kernel

Fix bug which would add correlation buffers to slope finder

CHANGELOG.md

@@ -1,5 +1,10 @@
 ## 0.9.1 (unreleased)
 
+### Major Changes
+
+- Fix bug which would add correlation buffers to slope finder (#471, found by Tachometer)
+    - NOTE: This affects triggering behavior compared to older program versions.
+
 ## 0.9.0
 
 ### Features

corrscope/triggers.py

@@ -438,7 +438,7 @@ class CorrelationTrigger(MainTrigger):
         slope_width: float = np.clip(cfg.slope_width * period, 1.0, self.A / 3)
 
         # This is a fudge factor. Adjust it until it feels right.
-        slope_strength = cfg.edge_strength * 5
+        slope_strength = cfg.edge_strength * 2
         # slope_width is 1.0 or greater, so this doesn't divide by 0.
 
         slope_finder = np.empty(kernel_size, dtype=f32)  # type: np.ndarray[f32]
@@ -548,11 +548,12 @@ class CorrelationTrigger(MainTrigger):
         else:
             corr_quality = np.zeros(corr_nsamp, f32)
 
-        # array[A+B] Amplitude
-        corr_kernel = slope_finder
-        del slope_finder
         if corr_enabled:
-            corr_kernel += self._corr_buffer * cfg.buffer_strength
+            # array[A+B] Amplitude
+            # Don't mutate (self._prev_slope_finder = slope_finder).
+            corr_kernel = slope_finder + self._corr_buffer * cfg.buffer_strength
+        else:
+            corr_kernel = slope_finder
 
         # `corr[x]` = correlation of kernel placed at position `x` in data.
         # `corr_kernel` is not allowed to move past the boundaries of `data`.