diff --git a/src/preprocess.py b/src/preprocess.py
index 3965e92..0154f3f 100644
--- a/src/preprocess.py
+++ b/src/preprocess.py
@@ -15,6 +15,10 @@ class ApplicationNotFoundException (Exception):
     def __init__(self, deviceId):
         self.deviceId = deviceId
 
+class SensorTypeNotFoundException (Exception): 
+    def __init__(self, sensorType):
+        self.sensorType = sensorType
+
 class DbOp(object):
     def __init__(self, config):
         self.conn = None
@@ -91,23 +95,35 @@ def mqttOnMessageCallback(client, userdata, message):
         application = dbh.getApplication(device_id)
 
         frame = base64.b64decode(parse_payload['uplink_message']['frm_payload'])
+        measurement = {}
+        
+        match application['sensor_type']:
+            case 'LDDS75':
+                battery = struct.unpack('>H', frame[0:2])[0]
+                distance = struct.unpack('>H', frame[2:4])[0]
+                status = struct.unpack('?', frame[7:8])[0]
+                logger.debug(f"{frame=}, {battery=}, {distance=}, {status=}")
 
-        battery = struct.unpack('>H', frame[0:2])[0]
-        distance = struct.unpack('>H', frame[2:4])[0]
-        status = struct.unpack('?', frame[7:8])[0]
-        logger.debug(f"{frame=}, {battery=}, {distance=}, {status=}")
+                statusText = 'Ok'
+                if not status:
+                    statusText = 'No sensor'
+                elif distance == 20:
+                    statusText = 'Too close'
+
+                measurement = {
+                    'application_name': application['label'],
+                    'raw_level': distance,
+                    'level': application['ground_level'] - distance,
+                    'status': statusText,
+                    'battery': battery / 1000
+                }
+            case _:
+                raise SensorTypeNotFoundException(application['sensor_type'])
 
-        measurement = {
-            'application_name': application['label'],
-            'raw_level': distance,
-            'level': application['ground_level'] - distance,
-            'status': 'Ok' if status else 'No sensor',
-            'battery': battery / 100
-        }
         logger.debug(f"{measurement=}")
-
         dbh.storeMeasurement(measurement)
-
+    except SensorTypeNotFoundException as e:
+        logger.error(f"application has unknown sensor type {e.sensorType}")
     except ApplicationNotFoundException as e:
         logger.error(f"message from unknown device {e.deviceId}")
     except Exception as e: