commit 4cbf8d72f8ebef2ebddf05614824f338c0a93f91
Author: Mika <kontakt@donau2space.de>
Date:   Sun Jan 11 04:11:40 2026 +0000

    Add data_logging/src/data_logging/core.py

diff --git a/data_logging/src/data_logging/core.py b/data_logging/src/data_logging/core.py
new file mode 100644
index 0000000..a085d94
--- /dev/null
+++ b/data_logging/src/data_logging/core.py
@@ -0,0 +1,41 @@
+import json
+import os
+from pathlib import Path
+from typing import Optional
+
+
+def log_data(timestamp: str, temperature: float, signal_noise_ratio: float) -> None:
+    """Schreibt einen Datenpunkt mit Zeitstempel, Temperatur und SNR in ein JSON-Logfile."""
+    # Validierung der Eingabewerte
+    if not isinstance(timestamp, str) or not timestamp:
+        raise ValueError("timestamp muss ein nicht-leerer String sein.")
+    if not isinstance(temperature, (int, float)):
+        raise ValueError("temperature muss numerisch sein.")
+    if not isinstance(signal_noise_ratio, (int, float)):
+        raise ValueError("signal_noise_ratio muss numerisch sein.")
+
+    datapoint = {
+        "timestamp": timestamp,
+        "temperature": float(temperature),
+        "signal_noise_ratio": float(signal_noise_ratio)
+    }
+
+    log_dir = Path("output")
+    log_dir.mkdir(parents=True, exist_ok=True)
+    log_file = log_dir / "log_data.json"
+
+    if log_file.exists():
+        try:
+            with log_file.open("r", encoding="utf-8") as f:
+                existing_data = json.load(f)
+            if not isinstance(existing_data, list):
+                existing_data = []
+        except (json.JSONDecodeError, OSError):
+            existing_data = []
+    else:
+        existing_data = []
+
+    existing_data.append(datapoint)
+
+    with log_file.open("w", encoding="utf-8") as f:
+        json.dump(existing_data, f, indent=2, ensure_ascii=False)