diff --git a/View/mainwindow.py b/View/mainwindow.py
index 278191f..1c7d05f 100644
--- a/View/mainwindow.py
+++ b/View/mainwindow.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import os
 
 # Form implementation generated from reading ui file 'mainwindow.ui'
 #
@@ -19,7 +20,7 @@ import numpy as np
 import pandas as pd
 import sys
 from os import chdir
-from subprocess import check_call
+from subprocess import check_call, run
 
 import time
 # from View.acoustic_data_tab import AcousticDataTab
@@ -65,9 +66,9 @@ class Ui_MainWindow(object):
         self.tab6 = QtWidgets.QWidget()
         self.tab6.setObjectName("tab6")
         self.tabWidget.addTab(self.tab6, "")
-        self.tab7 = QtWidgets.QWidget()
-        self.tab7.setObjectName("tab7")
-        self.tabWidget.addTab(self.tab7, "")
+        # self.tab7 = QtWidgets.QWidget()
+        # self.tab7.setObjectName("tab7")
+        # self.tabWidget.addTab(self.tab7, "")
         self.verticalLayout.addWidget(self.tabWidget)
         MainWindow.setCentralWidget(self.centralwidget)
         self.menubar = QtWidgets.QMenuBar(MainWindow)
@@ -140,6 +141,8 @@ class Ui_MainWindow(object):
         self.actionSave_As.setObjectName("actionSave_As")
         self.actionAbout = QtWidgets.QAction(MainWindow)
         self.actionAbout.setObjectName("actionAbout")
+        self.actionUserManual = QtWidgets.QAction(MainWindow)
+        self.actionUserManual.setText("User Manual")
         self.actionDB_Browser_for_SQLite = QtWidgets.QAction(MainWindow)
         self.actionDB_Browser_for_SQLite.setObjectName("actionDB_Browser_for_SQLite")
         self.menuLanguage.addAction(self.actionEnglish)
@@ -155,6 +158,7 @@ class Ui_MainWindow(object):
         self.menuFile.addAction(self.menuExport.menuAction())
         self.menuTools.addAction(self.actionDB_Browser_for_SQLite)
         self.menuHelp.addAction(self.actionAbout)
+        self.menuHelp.addAction(self.actionUserManual)
         self.menubar.addAction(self.menuFile.menuAction())
         self.menubar.addAction(self.menuTools.menuAction())
         self.menubar.addAction(self.menuHelp.menuAction())
@@ -193,6 +197,9 @@ class Ui_MainWindow(object):
         # --- Connect Action About ---
         self.actionAbout.triggered.connect(self.about_window)
 
+        # --- Connect Action User Manual ---
+        self.actionUserManual.triggered.connect(self.user_manual)
+
         # --- Create Context Menu ---
         self.createContextMenu()
 
@@ -228,15 +235,12 @@ class Ui_MainWindow(object):
         print("about")
         aw = AboutWindow()
         aw.exec()
-        # w.show()
-        # self.main_window = QtWidgets.QMainWindow()
-        # self.window = AboutWindow(mainWindow=self.main_window)
-        # self.main_window.show()
-        # import sys
-        # new_app = QtWidgets.QApplication(sys.argv)
-        # w = AboutWindow()
-        # w.show()
-        # sys.exit(new_app.exec_())
+
+    def user_manual(self):
+        print(os.getcwd())
+        print(check_call("ls"))
+        open('User_manual_0.pdf')
+        run(["open", 'User_manual_0.pdf'])
 
     def export_table_of_acoustic_BS_values_to_excel_or_libreOfficeCalc_file(self):
 
@@ -307,7 +311,7 @@ class Ui_MainWindow(object):
         self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab4), _translate("MainWindow", "Sediment Calibration"))
         self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab5), _translate("MainWindow", "Acoustic inversion"))
         self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab6), _translate("MainWindow", "Note"))
-        self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab7), _translate("MainWindow", "User manual"))
+        # self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab7), _translate("MainWindow", "User manual"))
         self.menuFile.setTitle(_translate("MainWindow", "File"))
         self.menuSettings.setTitle(_translate("MainWindow", "Settings"))
         self.menuLanguage.setTitle(_translate("MainWindow", "Language"))
diff --git a/main.py b/main.py
index 969f408..e737626 100644
--- a/main.py
+++ b/main.py
@@ -5,7 +5,7 @@ from PyQt5.QtWidgets import QApplication, QMainWindow
 from PyQt5.QtCore import QCoreApplication
 
 from View.mainwindow import Ui_MainWindow
-from View.acoustic_data_tab import AcousticDataTab
+from View.acoustic_data_tab0 import AcousticDataTab
 from View.signal_processing_tab import SignalProcessingTab
 from View.sample_data_tab import SampleDataTab
 from View.sediment_calibration_tab import SedimentCalibrationTab
@@ -75,7 +75,7 @@ class MainApplication(QMainWindow):
             # **************************************************
             # ---------------- User Manual tab -----------------
 
-            self.user_manual_tab = UserManualTab(self.ui_mainwindow.tab7)
+            # self.user_manual_tab = UserManualTab(self.ui_mainwindow.tab7)
 
         # **************************************************
         # ---------------- Text File Error -----------------