diff --git a/src/nqrduck_measurement/controller.py b/src/nqrduck_measurement/controller.py
index 3b90034..0798a69 100644
--- a/src/nqrduck_measurement/controller.py
+++ b/src/nqrduck_measurement/controller.py
@@ -6,8 +6,8 @@ from nqrduck_spectrometer.measurement import Measurement
 
 logger = logging.getLogger(__name__)
 
-class MeasurementController(ModuleController):
 
+class MeasurementController(ModuleController):
     set_frequency_failure = pyqtSignal()
     set_averages_failure = pyqtSignal()
 
@@ -15,7 +15,14 @@ class MeasurementController(ModuleController):
         super().__init__(module)
 
     @pyqtSlot(str)
-    def set_frequency(self, value):
+    def set_frequency(self, value: str) -> None:
+        """Set frequency in MHz.
+
+        Args:
+            value (str): Frequency in MHz.
+
+        Raises:
+            ValueError: If value cannot be converted to float."""
         try:
             logger.debug("Setting frequency to: %s MHz" % value)
             self.module.nqrduck_signal.emit("set_frequency", float(value) * 1e6)
@@ -23,12 +30,18 @@ class MeasurementController(ModuleController):
             self.set_averages_failure.emit()
 
     @pyqtSlot(str)
-    def set_averages(self, value):
+    def set_averages(self, value: str) -> None:
+        """Set number of averages.
+
+        Args:
+            value (str): Number of averages.
+        """
         logger.debug("Setting averages to: " + value)
         self.module.nqrduck_signal.emit("set_averages", value)
-    
+
     @pyqtSlot()
-    def change_view_mode(self):
+    def change_view_mode(self) -> None:
+        """Change view mode between time and frequency domain."""
         logger.debug("Changing view mode.")
         if self.module.model.view_mode == self.module.model.FFT_VIEW:
             self.module.model.view_mode = self.module.model.TIME_VIEW
@@ -37,29 +50,53 @@ class MeasurementController(ModuleController):
 
         logger.debug("View mode changed to: " + self.module.model.view_mode)
 
-    def start_measurement(self):
+    def start_measurement(self) -> None:
+        """Emmit the start measurement signal."""
         logger.debug("Start measurement clicked")
         self.module.view.measurement_dialog.show()
-        self.module.nqrduck_signal.emit("start_measurement", None)  
+        self.module.nqrduck_signal.emit("start_measurement", None)
 
-    def process_signals(self, key: str, value: Measurement):
-        logger.debug("Measurement Dialog is visible: " + str(self.module.view.measurement_dialog.isVisible()))
+    def process_signals(self, key: str, value: object):
+        """Process incoming signal from the nqrduck module.
+        
+        Arguments:
+            key (str) -- The key of the signal.
+            value (object) -- The value of the signal.
+        """
+        logger.debug(
+            "Measurement Dialog is visible: "
+            + str(self.module.view.measurement_dialog.isVisible())
+        )
 
-        if key == "measurement_data" and self.module.view.measurement_dialog.isVisible():
+        if (
+            key == "measurement_data"
+            and self.module.view.measurement_dialog.isVisible()
+        ):
             logger.debug("Received single measurement.")
             self.module.model.displayed_measurement = value
             self.module.model.add_measurement(value)
             self.module.view.measurement_dialog.hide()
 
-        elif key == "measurement_error" and self.module.view.measurement_dialog.isVisible():
+        elif (
+            key == "measurement_error"
+            and self.module.view.measurement_dialog.isVisible()
+        ):
             logger.debug("Received measurement error.")
             self.module.view.measurement_dialog.hide()
-            self.module.nqrduck_signal.emit("notification", ["Error", "Error during measurement."])
+            self.module.nqrduck_signal.emit(
+                "notification", ["Error", "Error during measurement."]
+            )
 
-        elif key == "failure_set_frequency" and self.module.view._ui_form.frequencyEdit.text() == value:
+        elif (
+            key == "failure_set_frequency"
+            and self.module.view._ui_form.frequencyEdit.text() == value
+        ):
             logger.debug("Received set frequency failure.")
             self.set_frequency_failure.emit()
 
-        elif key == "failure_set_averages" and self.module.view._ui_form.averagesEdit.text() == value:
+        elif (
+            key == "failure_set_averages"
+            and self.module.view._ui_form.averagesEdit.text() == value
+        ):
             logger.debug("Received set averages failure.")
             self.set_averages_failure.emit()