diff --git a/where_fi/application.py b/where_fi/application.py
index b8156de..2144e3e 100644
--- a/where_fi/application.py
+++ b/where_fi/application.py
@@ -7,6 +7,7 @@ from typing import Any, Callable, NamedTuple
 import numpy.typing as npt
 
 from where_fi.collection import CSIMatrix, ingest
+from where_fi.collection.csi_frame import CSI
 from where_fi.collection.protocols import CSIProducer, MergedCSI
 from where_fi.config import config
 from where_fi.processing.preprocess import Preprocessor
@@ -125,12 +126,13 @@ class CSIApplication:
         return decorator
 
     def on_pre_merge(
-        self,
-    ) -> Callable[[Callable[[dict[ingest.Host, ingest.CSI]], None]], None]:
-        def decorator(func: Callable[[dict[ingest.Host, ingest.CSI]], None]) -> None:
-            self.pre_merge_callback = func
-
-        return decorator
+        self, func: Callable[[dict[ingest.Host, CSI]], None]
+    ) -> Callable[[dict[ingest.Host, CSI]], None]:
+        """
+        Decorator to register a callback for the samples before merging.
+        """
+        self.pre_merge_callback = func
+        return func
 
     def on_process(
         self, func: Callable[[CSIMatrix], None]
diff --git a/where_fi/utils/antenna_order.py b/where_fi/utils/antenna_order.py
index 254b88a..25a4c9b 100644
--- a/where_fi/utils/antenna_order.py
+++ b/where_fi/utils/antenna_order.py
@@ -2,6 +2,8 @@ import logging
 from collections import deque
 from typing import Any, Collection
 
+from where_fi.application import CSIApplication
+
 from ..collection import ingest
 from ..config import config
 
@@ -32,6 +34,10 @@ def average(data: Collection[Any]) -> float:
     return sum(data) / len(data)
 
 
+app = CSIApplication(ingest.RealtimeCSIProducer())
+
+
+@app.on_pre_merge
 def callback(antenna_data: dict[ingest.Host, ingest.CSI]) -> None:
     global prev_unplugged
     global antenna_average
@@ -73,4 +79,4 @@ def callback(antenna_data: dict[ingest.Host, ingest.CSI]) -> None:
 
 
 def main() -> None:
-    ingest.start_processing(pre_merge_callback=callback)
+    app.start()