EGAT TRACKING SYSTEM

https://stackoverflow.com/questions/11217674/how-to-calculate-distance-from-wifi-router-using-signal-strength/11249007

FSPL depends on two parameters: First is the frequency of radio signals；Second is the wireless transmission distance. The following formula can reflect the relationship between them.

FSPL (dB) = 20log10(d) + 20log10(f) + K

d = distance
f = frequency
K= constant that depends on the units used for d and f
If d is measured in kilometers, f in MHz, the formula is:

FSPL (dB) = 20log10(d)+ 20log10(f) + 32.44

From the Fade Margin equation, Free Space Path Loss can be computed with the following equation.

Free Space Path Loss=Tx Power-Tx Cable Loss+Tx Antenna Gain+Rx Antenna Gain - Rx Cable Loss - Rx Sensitivity - Fade Margin

With the above two Free Space Path Loss equations, we can find out the Distance in km.

Distance (km) = 10(Free Space Path Loss – 32.44 – 20log10(f))/20

The Fresnel Zone is the area around the visual line-of-sight that radio waves spread out into after they leave the antenna. You want a clear line of sight to maintain strength, especially for 2.4GHz wireless systems. This is because 2.4GHz waves are absorbed by water, like the water found in trees. The rule of thumb is that 60% of Fresnel Zone must be clear of obstacles. Typically, 20% Fresnel Zone blockage introduces little signal loss to the link. Beyond 40% blockage the signal loss will become significant.

FSPLr=17.32*√(d/4f)

d = distance [km]
f = frequency [GHz]
r = radius [m]

Source : http://www.tp-link.com/en/support/calculator/

http://appinventor.mit.edu/explore/ai2/firebase.html

<html>
<head>
  <meta charset=utf-8 />
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Email/Password Authentication Example</title>

  <!-- Material Design Theming -->
  <link rel="stylesheet" href="https://code.getmdl.io/1.1.3/material.orange-indigo.min.css">
  <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
  <script defer src="https://code.getmdl.io/1.1.3/material.min.js"></script>

  <!-- Firebase -->


<script src="https://www.gstatic.com/firebasejs/3.7.2/firebase.js"></script>
<script>
  // Initialize Firebase
  
  // Get the Firebase configuration from App Inventor via the WebViewer.WebViewString property
  var config = JSON.parse(window.AppInventor.getWebViewString());
  
  firebase.initializeApp(config);
</script>

  <script type="text/javascript">
    function tellAppInventor(message) {
        try {
            window.AppInventor.setWebViewString( message );
        } catch(e) {
            console.log("App Inventor Communication Error",e)
        }
    }
    
    /**
     * Handles the sign in button press.
     */
    function toggleSignIn() {
      if (firebase.auth().currentUser) {
        // [START signout]
        firebase.auth().signOut();
        // [END signout]
      } else {
        var email = document.getElementById('email').value;
        var password = document.getElementById('password').value;
        if (email.length < 4) {
          tellAppInventor('Please enter an email address.');
          return;
        }
        if (password.length < 4) {
          tellAppInventor('Please enter a password.');
          return;
        }
        // Sign in with email and pass.
        // [START authwithemail]
        firebase.auth().signInWithEmailAndPassword(email, password).catch(function(error) {
          // Handle Errors here.
          var errorCode = error.code;
          var errorMessage = error.message;
          // [START_EXCLUDE]
          if (errorCode === 'auth/wrong-password') {
            tellAppInventor('Wrong password.');
          } else {
            tellAppInventor(errorMessage);
          }
          console.log(error);
          document.getElementById('quickstart-sign-in').disabled = false;
          // [END_EXCLUDE]
        });
        // [END authwithemail]
      }
      document.getElementById('quickstart-sign-in').disabled = true;
    }
    /**
     * Handles the sign up button press.
     */
    function handleSignUp() {
      var email = document.getElementById('email').value;
      var password = document.getElementById('password').value;
      if (email.length < 4) {
        tellAppInventor('Please enter an email address.');
        return;
      }
      if (password.length < 4) {
        tellAppInventor('Please enter a password of 4 or more characters.');
        return;
      }
      // Sign in with email and pass.
      // [START createwithemail]
      firebase.auth().createUserWithEmailAndPassword(email, password).catch(function(error) {
        // Handle Errors here.
        var errorCode = error.code;
        var errorMessage = error.message;
        // [START_EXCLUDE]
        if (errorCode == 'auth/weak-password') {
          tellAppInventor('The password is too weak.');
        } else {
          tellAppInventor(errorMessage);
        }
        console.log(error);
        // [END_EXCLUDE]
      });
      // [END createwithemail]
    }
    /**
     * Sends an email verification to the user.
     */
    function sendEmailVerification() {
      // [START sendemailverification]
      firebase.auth().currentUser.sendEmailVerification().then(function() {
        // Email Verification sent!
        // [START_EXCLUDE]
        tellAppInventor('Email Verification Sent!');
        // [END_EXCLUDE]
      });
      // [END sendemailverification]
    }
    function sendPasswordReset() {
      var email = document.getElementById('email').value;
      // [START sendpasswordemail]
      firebase.auth().sendPasswordResetEmail(email).then(function() {
        // Password Reset Email Sent!
        // [START_EXCLUDE]
        tellAppInventor('Password Reset Email Sent!');
        // [END_EXCLUDE]
      }).catch(function(error) {
        // Handle Errors here.
        var errorCode = error.code;
        var errorMessage = error.message;
        // [START_EXCLUDE]
        if (errorCode == 'auth/invalid-email') {
          tellAppInventor(errorMessage);
        } else if (errorCode == 'auth/user-not-found') {
          tellAppInventor(errorMessage);
        }
        console.log(error);
        // [END_EXCLUDE]
      });
      // [END sendpasswordemail];
    }
    /**
     * initApp handles setting up UI event listeners and registering Firebase auth listeners:
     *  - firebase.auth().onAuthStateChanged: This listener is called when the user is signed in or
     *    out, and that is where we update the UI.
     */
    function initApp() {
      // Listening for auth state changes.
      // [START authstatelistener]
      firebase.auth().onAuthStateChanged(function(user) {
        // [START_EXCLUDE silent]
        document.getElementById('quickstart-verify-email').disabled = true;
        // [END_EXCLUDE]
        if (user) {
          // User is signed in.
          var displayName = user.displayName;
          var email = user.email;
          var emailVerified = user.emailVerified;
          var photoURL = user.photoURL;
          var isAnonymous = user.isAnonymous;
          var uid = user.uid;
          var providerData = user.providerData;

          if (emailVerified && !isAnonymous) {
                tellAppInventor( uid + ',' + email + ',' + displayName + ',' + photoURL );
            } else if (!emailVerified) {
                tellAppInventor( 'Please click the Send Email Verification button to confirm your account.' );
            }
          
          // [START_EXCLUDE]
//          document.getElementById('quickstart-sign-in-status').textContent = 'Signed in';
//          document.getElementById('quickstart-sign-in').textContent = 'Sign out';
//          document.getElementById('quickstart-account-details').textContent = JSON.stringify(user, null, '  ');
          if (!emailVerified) {
            document.getElementById('quickstart-verify-email').disabled = false;
          }
          // [END_EXCLUDE]
        } else {
          // User is signed out.
          // [START_EXCLUDE]
//          document.getElementById('quickstart-sign-in-status').textContent = 'Signed out';
//          document.getElementById('quickstart-sign-in').textContent = 'Sign in';
//          document.getElementById('quickstart-account-details').textContent = 'null';
          // [END_EXCLUDE]
        }
        // [START_EXCLUDE silent]
        document.getElementById('quickstart-sign-in').disabled = false;
        // [END_EXCLUDE]
      });
      // [END authstatelistener]
      document.getElementById('quickstart-sign-in').addEventListener('click', toggleSignIn, false);
      document.getElementById('quickstart-sign-up').addEventListener('click', handleSignUp, false);
      document.getElementById('quickstart-verify-email').addEventListener('click', sendEmailVerification, false);
      document.getElementById('quickstart-password-reset').addEventListener('click', sendPasswordReset, false);
    }
    window.onload = function() {
      initApp();
    };
  </script>
</head>
<body>
<div class="demo-layout mdl-layout mdl-js-layout mdl-layout--fixed-header">

  <!-- Header section containing title 
  <header class="mdl-layout__header mdl-color-text--white mdl-color--light-blue-700">
    <div class="mdl-cell mdl-cell--12-col mdl-cell--12-col-tablet mdl-grid">
      <div class="mdl-layout__header-row mdl-cell mdl-cell--12-col mdl-cell--12-col-tablet mdl-cell--8-col-desktop">
        <a href="/"><h3>Firebase Authentication</h3></a>
      </div>
    </div>
  </header>
  -->

  <main class="mdl-layout__content mdl-color--grey-100">
    <div class="mdl-cell mdl-cell--12-col mdl-cell--12-col-tablet mdl-grid">

      <!-- Container for the demo -->
      <div class="mdl-card mdl-shadow--2dp mdl-cell mdl-cell--12-col mdl-cell--12-col-tablet mdl-cell--12-col-desktop">
        <div class="mdl-card__title mdl-color--light-blue-600 mdl-color-text--white">
          <h2 class="mdl-card__title-text">Sign In or Sign Up</h2>
        </div>
        <div class="mdl-card__supporting-text mdl-color-text--grey-600">
          <p>Enter an email and password below and either sign in to an existing account or sign up</p>

          <input class="mdl-textfield__input" style="display:inline;width:auto;" type="text" id="email" name="email" placeholder="Email"/>
          <p/><p/>
          <input class="mdl-textfield__input" style="display:inline;width:auto;" type="password" id="password" name="password" placeholder="Password"/>
          <p/>
          <button disabled class="mdl-button mdl-js-button mdl-button--raised" id="quickstart-sign-in" name="signin">Sign In</button>
             
          <button class="mdl-button mdl-js-button mdl-button--raised" id="quickstart-sign-up" name="signup">Sign Up</button>
          <p/>
          <button class="mdl-button mdl-js-button mdl-button--raised" disabled id="quickstart-verify-email" name="verify-email">Send Email Verification</button>
          <p/>
          <button class="mdl-button mdl-js-button mdl-button--raised" id="quickstart-password-reset" name="verify-email">Send Password Reset Email</button>
          <p/>

          <!-- Container where we'll display the user details -->
          <div class="quickstart-user-details-container" style="display:none">
            Sign-in status: <span id="quickstart-sign-in-status">Unknown</span>
            <div>Authorization <code>currentUser</code> object value:</div>
            <pre><code id="quickstart-account-details">null</code></pre>
          </div>
        </div>
      </div>

    </div>
  </main>
</div>
</body>
</html>

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FSPL depends on two parameters: First is the frequency of radio signals；Second is the wireless transmission distance

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