add motion detector example

This demonstrates a simple example of how to use the framework

examples/motion_detector.py

@@ -0,0 +1,64 @@
+"""Motion Detection example
+This example shows how to use the CSI framework to connect to a FeitCSI host and
+detect changes in the environment
+"""
+
+import logging
+from queue import Queue
+
+import numpy as np
+import numpy.typing as npt
+
+from where_fi.application import CSIApplication
+from where_fi.collection.ingest import RealtimeCSIProducer
+
+# Connect to a FeitCSI host
+producer = RealtimeCSIProducer()
+app = CSIApplication(producer)
+
+# Store historical CSI data to compare with the current data
+# This allows us to detect sudden changes in the environment,
+# most likely to be cause by motion
+
+# This is stored individually for each receiving antenna, for each subcarrier
+historical: dict[tuple[int, int], Queue[np.complex64]] = {}
+
+MAGN_THRESHOLD = 20
+PHASE_THRESHOLD = 0.5
+
+
+@app.on_process
+def _(antenna_data: npt.NDArray[np.complex64]) -> None:
+    for antenna in range(antenna_data.shape[1]):
+        for subcarrier in range(antenna_data.shape[0]):
+            # Get the current subcarrier data
+            current = antenna_data[subcarrier, antenna, 0]
+
+            # Get the historical data for this antenna and subcarrier
+            if (antenna, subcarrier) not in historical:
+                historical[(antenna, subcarrier)] = Queue(maxsize=100)
+            historical_data = historical[(antenna, subcarrier)]
+
+            # Calculate the average of the historical data
+            mean: np.complex64 = np.mean(historical_data.queue)
+
+            # If we have enough historical data, compare it with the current data
+            if historical_data.full():
+                historical_data.get()
+
+            # Add the current data to the historical data
+            historical_data.put(current)
+
+            # Compare the current data with the historical data
+            if (
+                np.abs(mean - current) > MAGN_THRESHOLD
+                or np.abs(np.angle(mean) - np.angle(current)) > PHASE_THRESHOLD
+            ):
+                logging.info(
+                    f"Change detected on antenna {antenna}, subcarrier {subcarrier} "
+                    f"|{np.abs(mean - current)}| <{np.angle(mean) - np.angle(current)}>"
+                )
+
+
+# Start the application
+app.start()